06 Ninja 250 - So many problems/won't start again

[jk3099]

TLDR: no idea where to go now. Bike won't idle without stalling out; carbs. already cleaned by Ducatiman, petcock replaced, oil changed (but might have flooded already). Where do I go from here?

Hi all,

Apologies in advance for the lengthy post; I'm just having lots of issues with my '06 Ninja 250. Last May, I bought this bike that wasn't running, thinking it wasn't in horrible condition; unfortunately, I think I was wrong. Every time I fix something, another issue seems like it arises, and I'm really not sure where to go since I think I broke my bike again (we'll get to that part).

Here's a timeline of what happened since then...
1. Cleaned carbs; tried it out, nothing
2. Changed spark plugs, coolant, and battery; bike ran
3. Occasionally, I noticed the bike would have issues stopping, idling, then its rpms would slowly creep down further and further until it died. After 1 week, the bike died completely in the middle of riding it.
4. Due to school and the winter, the bike sat for a few months. In the meantime, I sent the carbs to Ducatiman to clean them. I got them back and was ready to reinstall them come springtime (so I was pretty confident the carbs haven't been an issue). However...
5. I noticed a ton of rust in the gas tank. I thought this explained why my bike died after a week of riding. I thoroughly cleaned the tank with vinegar (letting it sit for 2 weeks and confirmed that a ton of gunk came out and that the tanks were now clean). I reinstalled the tank, the newly cleaned carbs, replaced the petcock's filters (which were torn), and installed 2 in-line fuel filters. It ran! However...
6. The petcock appeared to be a bit leaky. I wanted to test it out still, so I made sure the screws were tight and watched to see if it dripped. It still was dripping very, very slowly, but not enough to worry about at the moment. After taking the bike out on a test run, I had the same issues with idling. To be more descriptive, I set the idle at around 1500 to start off. The bike was fine with this for a few minutes, but after warming up, it dropped down to around 1000 or so. From there, it would start sputtering, and I would watch as the rpms crept lower and lower. If I turned the choke on or engaged the throttle, the rpms would spike up again, and it would go back to 1500 for a few seconds, but then slowly go back down. If I got moving, it really wasn't a problem, but whenever I stopped and was idling, the bike wanted to die. I tried upping the idle rpm value, but it wouldn't respond immediately. Only after turning the idle knob for a while did it suddenly spike up to 6000, which caused me to immediately lower it back to 1500 again, leading to the same issues. I also tried holding the idle rpms at values between 1500-2000, but no luck. The issues sounded nearly identical to the ones described in this thread: https://www.ninjette.org/forums/showthread.php?t=78505
7. Seeing as though the solution in that thread was the petcock and mine was leaking, repairing the petcock made sense and probably was the issue. At this point, I also noticed that the oil was incredibly dark/black, and it was way above the upper line. So, I decided I'd do a petcock repair and oil change concurrently.
8. Today, I did both repairs. Both went relatively well, though I did notice that the bolts from the oil change were definitely overtightened (to the point where the crash washer on the drain bolt was completely deformed/dented; an impact drill was probably used, that's how bad the washer looked). The threads still seemed like they were intact, so I just tightened them appropriately (14.5 ft/lbs) and refilled the oil. I checked the oil level on the center stand, off the center stand while upright, and after a few minutes of idling, and filled it so that it was underneath the top oil line. Jumped on the bike, and it seemed like it was having even more issues this time in neutral/idle, where it would try to stick to 1000 and then slowly die. I got it running by turning the choke on to start it up and opening the throttle. I was able to ride around a bit, but the exact same issue with the idle occurred when stopped (but not when moving). Knowing that it might be sitting for a while before I could get around to working on it (like a week to get parts), I decided to top off the tank.
9. Went to the gas station and noticed it died as I was pulling in. I filled my tank up, but afterward, the bike wouldn't start at all. I tried with the choke fully on, trying to throttle while starting it up, and twisting the idle knob; nothing at all. Eventually, the bike didn't even sound like it was turning over and was just making clicking noises. Out of curiosity, I checked my oil levels, and they were completely overfilled. I knew my bike wasn't going to start again, so I walked it home.

This leads to a bunch of questions... Did I flood my engine/carbs when I tried opening the throttle while starting the bike up? How did gas already get into the oil? People on the other thread suggested a valve adjustment, but I've been wanting to hold off on that because of how complex it seems, and I thought my petcock was the issue. If that's the next step, though, I guess I'm doing a valve adjustment. Additionally, I was thinking of taking the carbs off and seeing what happened there. Do I also need to change the oil again and look at my sparkplugs? Where else could the oil/gas have gotten? Where do you all think I should go? Again, sorry for the lengthy post, and thanks for anyone who's willing to listen/help.

[Triple Jim]

The combination of dying at idle and increased oil level makes me think that one or both float needles are sticking open, letting fuel get into the oil.

When it's trying to stall at idle, is there black smoke from the exhaust pipes? You may have to shine a flashlight though the exhaust gasses to tell, depending on ambient lighting.

[ducatiman]

agreed a carb revisit is called for, as well as a petcock redo/revue

AND a revue of tank to assure no more junk in there

AND get your valve adjustment DONE

total mileage on bike? Mileage when last valve service completed?

When did i do your carbs?

Examine your battery....charge at very least, replace if need be.

PM a'comin.

[jk3099]

Thanks for your replies, @Triple Jim and @ducatiman! I appreciate y'all's help

I didn't notice black smoke from the exhaust pipe, but I also wasn't observing it too close, and it was at night when it last fired up. I did smell a little bit of burning and thought I saw some smoking at first, so it's very possible.

In taking a look at the carbs, externally, they didn't look horrible. I trust Ducatiman's work, so my guess is there's probably something going on outside of the carbs (especially since this happened before and occurred immediately as I fired the bike up). We're working together to double-check the petcock and the carbs.

I looked at the tank, and it looked good. I have a clear fuel line and removed some gas from the tank, and there is minimal rust; there might be some flash rust, but I only saw one or two specks.

Seems like a valve adjustment is the next step. The bike's at 10,118 miles. I doubt it's had a valve adjustment seeing how the previous owners maintained it (ex: the tires are 10 years old, which is what I have to change once I get it running).

Will do on checking the battery.

Thoughts on checking the airbox? Could a dirty filter be causing this issue?

[jk3099]

Thanks for all y'all's help! I greatly appreciate it

I didn't notice any black smoke, but that's very possible since I was testing it at night and wasn't looking out for it. I did smell and thought I saw a little smoke for a second, though.

I'm pretty sure the carbs are good! @ducatiman's work was fantastic; the immediacy and reoccurrence of the issue make me think that it wasn't the carbs (maybe a setting issue?) or the gas tank (I double-checked that, too, and it looked good; maybe one or two specks of flash rust that were caught in the in-line filters) and is probably something else wrong with the bike. The petcock is very likely.

Will do on examining the battery! I'll charge it before I try starting it up again.

I'm probably going to have to do a valve adjustment. The bike's at about 10,100 miles. Considering how the last owners maintained the bike (the tires are 10 years old, which I'll have to change once I get it running), I highly doubt it's been done.

Could the air filter be an issue? That's the only thing I can think of to check other than the valves.

[Triple Jim]

For gasoline to get into the engine oil, the petcock has be be leaking, and the float valves also have to be leaking. Either one working correctly will stop fuel flow.

[jk3099]

That makes sense. When I go to change my oil again, do I also need to replace the oil filter? Sorry, very new to this.

[Triple Jim]

If the engine was started with fuel in the oil, then yes, since the filter got that mix in it.

[jk3099]

Sounds good. Thanks!

[jk3099]

TLDR: (I think) I adjusted the valves, changed the sparkplugs, did an oil change, had @ducatiman check my valve and petcock (both were fine), reattached the carbs, and charged the battery, but here's the current issue: https://youtube.com/shorts/DQqvvaXhESw
Where do I go from here?

Hi all,

I finally got around to working on my bike again, and sadly, it's still having issues. Here's what I did to try to fix it between my last post and then:

1. The carbs and petcock were checked by @ducatiman. Other than an o-ring and a screw that I overtightened, both seemed like they were working perfectly. His work is exceptional, so the carbs have been something I've assumed hasn't been an issue.
2. Did a valve adjustment. Initially, I tried using the TDC method suggested by ninja250wiki, and all 4 valves appeared to be within the correct clearances using that. I then tried using the other method where you find T1 and T2 on the timing cuff to make a "Y", and this made it seem like Intake Valve #1 was too loose. I tightened this valve but left the rest unchanged.
3. Changed the spark plugs.
4. Changed the oil. Last post, I noted that it seemed like gas mixed the oil. However, I think the last time I changed my oil, I just added too much (I looked at my bottle from the last time and saw that way too much had been used, and I didn't note a smell of gasoline in the oil). Regardless, I still changed the oil and the filter to the proper amount this time (I double-checked the amount later, and it looked good).
5. Reattached the carbs and really spent a lot of time tightening the boots onto the carbs. I was worried that I didn't do a great job of putting the carbs onto the boots the last time, so I tightened the boots as much as I possibly could and tried to ensure that there were no leaks possible.
6. Fully charged the battery overnight (note: it was completely empty, so this may have explained why it didn't start up last time).

After all this, I tried firing it up. Sadly, this time it seemed worse. It would only run (if you can even call that) with the choke fully on and after twisting the throttle adjustment knob to the proper amount. It's easier to just show a video of what kept happening: https://youtube.com/shorts/DQqvvaXhESw

So, a couple of questions...
1. Is that a knocking sound? If so, I must've screwed my valve adjustment up on intake #1.
2. Where do I go from here?

Thanks, y'all. Really hoping to get to the root of this soon.

[DannoXYZ]

Measure your petcock's actual flow-rate.

1. disconnect petcock from carb-inlet and aim into measuring cup.

2. crank engine for 10-sec.

How much petrol did you collect?

[ducatiman]

turn the idle screw inwards to achieve a reasonable idle speed, according to your video, its set way too low

all vac hoses accounted for, installed correctly?

[jk3099]

Thanks! I'll do both tests tomorrow. Regarding the idle screw, I kept spinning it clockwise, but it didn't seem like it was helping. It seemed like after a certain point of just spinning it, too, it wouldn't even start up. The video was from finding a "sweet spot" by spinning it a bunch. Should I keep going clockwise?

For the vac hoses, there's one attached to the black nozzle between the left and right carb and the other hose going from the carb to the fuel tank. Anything I'm missing?

[ducatiman]

Question....."Anything I'm missing?"

Prior to any carb "starting phase" vac hose attachment must come FIRST, after assuring ALL hoses are present/accounted for....and tight, no possibility of leaking.

2 between the carbs (1 large, 1 small) run to the decel valve....present?
from LH and RH carb vac "stubs", LH to the petcock vac, RH to decel valve

Center, between carbs is a BREATHER/VENT...DO NOT PLUG OR CAP..... MUST remain free to breathe.

Answer.....you tell me.

[InvisiBill]

Originally Posted by jk3099

Regarding the idle screw, I kept spinning it clockwise, but it didn't seem like it was helping. It seemed like after a certain point of just spinning it, too, it wouldn't even start up. The video was from finding a "sweet spot" by spinning it a bunch. Should I keep going clockwise?

The idle adjuster is simply a screw with a knob on it. Turning it just adjusts how far it sticks out and holds the throttle open. It's exactly the same as turning the grip a little to open the throttle a bit.



Since yours is acting funny, I wonder if some part of it is broken. My Vulcan's managed to break while reinstalling the carbs (bolted together in an X shape, mounted in between the V cylinders, so a bit of a pain to deal with). It might be broken in the flex part, so the knob isn't securely affixed to the screw. It's also possible that it's stripped where the screw threads into the bracket - rather than screwing in or out smoothly, it might just be spinning in place or intermittently catching/slipping.

[DannoXYZ]

Originally Posted by jk3099

Thanks! I'll do both tests tomorrow. Regarding the idle screw, I kept spinning it clockwise, but it didn't seem like it was helping. It seemed like after a certain point of just spinning it, too, it wouldn't even start up. The video was from finding a "sweet spot" by spinning it a bunch. Should I keep going clockwise?

For the vac hoses, there's one attached to the black nozzle between the left and right carb and the other hose going from the carb to the fuel tank. Anything I'm missing?

Look at throttle-plate as you turn idle-adjuster screw to see how it operates. As InvisiBill mentioned, it's same as turning throttle-grip.

There's approximately 231.78 hoses to connect on carbs. Make sure each and every single one of them is plugged in correctly or bike will never start. Use diagram ducatiman provided. If you don't have CA model, ignore the "CA emissions fitting", it won't be there. The most important hose, even more important than fuel-hose between tank and carbs, is "vacuum hose to petcock". Do you have that plugged in properly to vacuum-port on petcock? If not, you might as well leave gas tank off bike because that is what turns ON fuel-flow.

[jk3099]

Thanks for everyone's help! Some interesting results from looking at the bike today...

1. The gas test suggested by @DannoXYZ was very interesting. I pulled the hose between the petcock and gas tank and tried collecting it into an empty container for 10 seconds; no gas/one drop came out. I thought it might be the fuel filters, so I took them all off and then tried again. Same result.
2. I spun the idle screw all the way inward and looked at the carb to ensure that it was actually moving. I watched the spring compress all the way, so the screw is working. The bike still had issues starting.
3. I checked the hoses (without taking the tank off, so I wasn't able to see the two closest to the airbox, but I know they're there). The fuel inlet and vacuum hoses were correctly attached to the petcock,and it looked like the coasting enricher vacuum hose was also correctly attached to both sides of the carb. The breather/vent between the carbs has a hose on it that isn't attached to anything and dangles underneath the seat.
4. I tried starting the bike up without the inline filters (there are two) but still had the same result.
5. Checked the carb boots; they looked airtight, at least from the sides.

Assuming that #1 means there's an issue with a vacuum, where should I go from here? Thanks again for everyone's help; really appreciate it

Here are some pictures of my carbs from the sides. Note: there is an excessive amount of tubing because of the two inline fuel filters. It was the shortest I could get without it kinking.

Description of photos:
8691: hose and inline fuel filters from petcock to carb
8692: finger pointed at the vacuum hose (in black) connected to the carb in the background
8695: picture from the right side of the bike of the coasting enriched vacuum hose connected (foreground) and the vacuum hose to petcock (background)
8697: right side of the carb, meant to show the boots to the airbox
8698: black hose is the overflow tube from the fuel tank, clear tube is from the breather from the middle of the carb

[jk3099]

Thanks for everyone's help! Some interesting results from looking at the bike yesterday...

1. The gas test suggested by @DannoXYZ was very interesting. I pulled the hose between the petcock and gas tank and tried collecting it into an empty container for 10 seconds; no gas/one drop came out. I thought it might be the fuel filters, so I took them all off and then tried again. Same result.
2. I spun the idle screw all the way inward and looked at the carb to ensure that it was actually moving. I watched the spring compress all the way, so the screw is working. The bike still had issues starting.
3. I checked the hoses (without taking the tank off, so I wasn't able to see the two closest to the airbox, but I know they're there). The fuel inlet and vacuum hoses were correctly attached to the petcock, and it looked like the coasting enricher vacuum hose was also correctly attached to both sides of the carb. The breather/vent between the carbs has a hose on it that isn't attached to anything and dangles underneath the seat.
4. I tried starting the bike up without the inline filters (there are two) but still had the same result.
5. Checked the carb boots; they looked airtight, at least from the sides.

Assuming that #1 means there's an issue with a vacuum, where should I go from here? Thanks again for everyone's help; really appreciate it

Here are some pictures of my carbs from the sides. Note: there is an excessive amount of tubing because of the two inline fuel filters. It was the shortest I could get without it kinking.

Description of photos:
8691: hose and inline fuel filters from petcock to carb
https://photos.app.goo.gl/J4VB2GLqyLTsSiqT7

8692: finger pointed at the vacuum hose (in black) connected to the carb in the background
https://photos.app.goo.gl/eKbKJRvxQBRJsCC69

8695: picture from the right side of the bike of the coasting enriched vacuum hose connected (foreground) and the vacuum hose to petcock (background)
https://photos.app.goo.gl/5uhDgEPLaShM1PHUA

8697: right side of the carb, meant to show the boots to the airbox
https://photos.app.goo.gl/5XhLadfE94beqo8t5

8698: black hose is the overflow tube from the fuel tank, clear tube is from the breather from the middle of the carb
https://photos.app.goo.gl/XzfLpn8emNCdyf6Z6

[DannoXYZ]

If petcock doesn't flow petrol, it can be one of 2 causes:

1. insufficient vacuum from carb, or...

2. petcock diaphragm is ripped and not opening fuel-flow even with sufficient vacuum

Determine which one it is by manually applying vacuum to petcock. For different model but same idea (ours still requires vacuum to flow in RES position).

[Triple Jim]

Right, and if you don't have a vacuum pump like that, your mouth can easily make enough vacuum to open it if it's working right. Just be aware that if the diaphragm is ripped, gasoline could get into the tube, so using a clear tube is a good idea.

[jk3099]

Thanks for everyone's help! Some interesting results from looking at the bike today...

1. The gas test suggested by @DannoXYZ was very interesting. I pulled the hose between the petcock and gas tank and tried collecting it into an empty container for 10 seconds; no gas/one drop came out. I thought it might be the fuel filters, so I took them all off and then tried again. Same result.
2. I spun the idle screw all the way inward and looked at the carb to ensure that it was actually moving. I watched the spring compress all the way, so the screw is working. The bike still had issues starting.
3. I checked the hoses (without taking the tank off, so I wasn't able to see the two closest to the airbox, but I know they're there). The fuel inlet and vacuum hoses were correctly attached to the petcock,and it looked like the coasting enricher vacuum hose was also correctly attached to both sides of the carb. The breather/vent between the carbs has a hose on it that isn't attached to anything and dangles underneath the seat.
4. I tried starting the bike up without the inline filters (there are two) but still had the same result.
5. Checked the carb boots; they looked airtight, at least from the sides.

Assuming that #1 means there's an issue with a vacuum, where should I go from here? Thanks again for everyone's help; really appreciate it

*Note: reposted since it seems like my reply got deleted somehow*

[Triple Jim]

Originally Posted by jk3099

1. The gas test suggested by @DannoXYZ was very interesting. I pulled the hose between the petcock and gas tank and tried collecting it into an empty container for 10 seconds; no gas/one drop came out. I thought it might be the fuel filters, so I took them all off and then tried again. Same result.

There should be no hose from the petcock to the gas tank. There is a hose from the petcock to the vacuum port of the carbs, and there is the fuel output hose from the petcock to the carbs. The petcock gets fuel from the large threaded fitting that mounts it to the tank.

[jk3099]

Originally Posted by Triple Jim

There should be no hose from the petcock to the gas tank. There is a hose from the petcock to the vacuum port of the carbs, and there is the fuel output hose from the petcock to the carbs. The petcock gets fuel from the large threaded fitting that mounts it to the tank.

Sorry, completely botched that wording; meant to say I pulled the hose from the petcock to the carb that delivers fuel. I triple checked before I posted, but this somehow got past me :P

[DannoXYZ]

Before doing additional petcock test, verify fuel hose isn't clogged. I think it was '95+ bikes that started using this internal filtre. Make sure it's not wadded up inside hose from being installed backwards. Even if OK, remove it



Also no need for 2 filters. First one would capture everything, so 2nd one is useless. Except it blocks flow. Make sure ONE filter is inline without drooping hose. Should be straight run from petcock without having petrol try to flow uphill.



With hose confirmed clear, now do your petcock testing

A

[jk3099]

Great advice; I'm using a new, clear fuel line, so there isn't the internal filter in there (though I do remember seeing a super old one in the last line I used). I'll make sure the 2nd inline filter gets removed, too.

I did the vacuum test by pulling the vacuum hose from the carb and confirmed that fuel flowed through the line from the tank, so it's not the petcock. @ducatiman confirmed this earlier in his tests on the petcock. This means it has to be insufficient vacuum from the carbs, right?

[DannoXYZ]

Originally Posted by jk3099

I did the vacuum test by [b]pulling the vacuum hose from the carb[b] and confirmed that fuel flowed through the line from the tank, so it's not the petcock. @ducatiman confirmed this earlier in his tests on the petcock. This means it has to be insufficient vacuum from the carbs, right?

I'm not understanding. So you disconnected petcock's vacuum hose from carbs? Then what did you do with it? What did you do to get fuel to flow from tank, through petcock and out fuel hose?

[jk3099]

Originally Posted by DannoXYZ

I'm not understanding. So you disconnected petcock's vacuum hose from carbs? Then what did you do with it? What did you do to get fuel to flow from tank, through petcock and out fuel hose?

Sorry, didn’t clarify enough. I used the vacuum hose that’s connected between the carbs and the petcock by disconnecting it from the carbs and leaving it attached to the petcock. I then disconnected the fuel hose that connects the petcock to the carbs from the carbs so it was hanging from the petcock. I then switched the petcock to reserve, put the fuel hose into a gas tank, then starting sucking on the vacuum line. At this point, both tubes were disconnected from the carbs and only attached to the petcock. By sucking on the vacuum line, fuel flowed easily out of the fuel hose into the gas tank (I watched it through the clear tubing). It didn’t take much to get the fuel to flow. I reattached the tubes to the correct places on the carbs and tried cranking the bike while watching for fuel flow. No fuel flowed.

Assumption: because fuel flowed by manually applying the vacuum to the petcock, it doesn’t seem like the petcock is the issue. Does this seem correct?

@ducatiman tested both the petcock and the carbs again and found both functional. Assuming that neither the carbs nor the petcock is the issue with causing fuel to flow, what might be causing the vacuum to not be applied? The carb boots? The air box? Somewhere else? I can double check all the hoses being reattached correctly on the carbs; that’s always a possibility.

Note: the boots attached to the air box and carbs have been “stuck”/left in place the last few times I’ve taken off/put on my carbs. Should I take these off and inspect them?

[jk3099]

I also tested it with the fuel hose connected between the carbs and petcock. I disconnected the vacuum hose from the carbs and sucked on the vacuum hose still connected to the petcock (set in reserve), and watched as fuel flowed from the petcock to the carbs.

[DannoXYZ]

Originally Posted by jk3099

Sorry, didn’t clarify enough. I used the vacuum hose that’s connected between the carbs and the petcock by disconnecting it from the carbs and leaving it attached to the petcock. I then disconnected the fuel hose that connects the petcock to the carbs from the carbs so it was hanging from the petcock. I then switched the petcock to reserve, put the fuel hose into a gas tank, then starting sucking on the vacuum line. At this point, both tubes were disconnected from the carbs and only attached to the petcock. By sucking on the vacuum line, fuel flowed easily out of the fuel hose into the gas tank (I watched it through the clear tubing). It didn’t take much to get the fuel to flow. I reattached the tubes to the correct places on the carbs and tried cranking the bike while watching for fuel flow. No fuel flowed.

Assumption: because fuel flowed by manually applying the vacuum to the petcock, it doesn’t seem like the petcock is the issue. Does this seem correct?

@ducatiman tested both the petcock and the carbs again and found both functional. Assuming that neither the carbs nor the petcock is the issue with causing fuel to flow, what might be causing the vacuum to not be applied? The carb boots? The air box? Somewhere else? I can double check all the hoses being reattached correctly on the carbs; that’s always a possibility.

Note: the boots attached to the air box and carbs have been “stuck”/left in place the last few times I’ve taken off/put on my carbs. Should I take these off and inspect them?

This is good! So you've confirmed petcock is functional and not issue in fuel-flow.

Are you sure, 100% positively that petcock has single dedicated vacuum-hose going to left carb as shown in diagram above? No splits/Ts anywhere that may be leaking?

Another test you can do is swap vacuum-ports and use right carb's vacuum port to connect to petcock. Does that provide sufficient vacuum to open petcock?

Definitive answer is to connect actual vacuum-gauge and measure actual vacuum amount generated when cranking engine. That one number will give us clue as to what problem may be and where to look next.

[jk3099]

Originally Posted by DannoXYZ

This is good! So you've confirmed petcock is functional and not issue in fuel-flow.

Are you sure, 100% positively that petcock has single dedicated vacuum-hose going to left carb as shown in diagram above? No splits/Ts anywhere that may be leaking?

Another test you can do is swap vacuum-ports and use right carb's vacuum port to connect to petcock. Does that provide sufficient vacuum to open petcock?

Definitive answer is to connect actual vacuum-gauge and measure actual vacuum amount generated when cranking engine. That one number will give us clue as to what problem may be and where to look next.

Alright, so I double checked my carbs, and I'm 99% sure that all of the hoses have been properly connected with the vacuum hose connecting the petcock with the left side of the carb. I'm 100% sure that the vacuum hose connecting the petcock and left carb is correct, as it is a single hose without any splits or potential areas where this might be leaking, and I've triple-checked that it's correctly plugged into both ends. The only area I haven't been able to fully see are the ones connected between the middle of the carb with the coasting enricher since I've been leaving the gas tank on.

I went out and bought a vacuum gauge to get that number; thanks for the advice! I took the hose connected to the gauge and plugged it into the left side of the carb where the vacuum hose (connecting the petcock and the carbs) is normally connected. I put the tank into reserve (don't really think this mattered, but just in case), then cranked the engine. Here is a video of my results (ps: ignore the extra tubing and inline fuel filters, I haven't had the chance to cut it down, but I know it's ridiculous at the moment): https://youtu.be/XPxPhL6qn_k

Seeing as though I'm basically getting no vacuum, that would explain why no fuel is flowing at all (though I'm not sure how I got it to work a month ago or even just idle even though it died earlier this week; it might've provided a minimal amount of vacuum earlier on).

I also was curious to see if the results would be different on the right side of the carbs, so I plugged the vacuum gauge's hose into the vacuum port on the right side of the carb that is connected to the coaching enricher and repeated the test. I think my battery was starting to die here, but here is what happened when I cranked the engine for a few seconds: https://youtu.be/VUZX93R2O6Y

Thoughts? Seeing no vacuum isn't too promising...

PS I'm going out of town for 1.5 weeks, so I won't be able to touch it or repeat any tests until then. I'm hoping I can order parts in the meantime and get ready for any maintenance I might have to do as soon as I get back. Really looking forward to getting back to working on this though :P

[jk3099]

Originally Posted by DannoXYZ

This is good! So you've confirmed petcock is functional and not issue in fuel-flow.

Are you sure, 100% positively that petcock has single dedicated vacuum-hose going to left carb as shown in diagram above? No splits/Ts anywhere that may be leaking?

Another test you can do is swap vacuum-ports and use right carb's vacuum port to connect to petcock. Does that provide sufficient vacuum to open petcock?

Definitive answer is to connect actual vacuum-gauge and measure actual vacuum amount generated when cranking engine. That one number will give us clue as to what problem may be and where to look next.

TLDR: vacuum on the carbs is effectively 0.
Video of a vacuum gauge on the left carb: https://youtu.be/XPxPhL6qn_k
Video of a vacuum gauge on the right carb: https://youtu.be/VUZX93R2O6Y


Alright, so I double checked my carbs, and I'm 99% sure that all of the hoses have been properly connected with the vacuum hose connecting the petcock with the left side of the carb. I'm 100% sure that the vacuum hose connecting the petcock and left carb is correct, as it is a single hose without any splits or potential areas where this might be leaking, and I've triple-checked that it's correctly plugged into both ends. The only area I haven't been able to fully see are the ones connected between the middle of the carb with the coasting enricher since I've been leaving the gas tank on.

I went out and bought a vacuum gauge to get that number; thanks for the advice! I took the hose connected to the gauge and plugged it into the left side of the carb where the vacuum hose (connecting the petcock and the carbs) is normally connected. I put the tank into reserve (don't really think this mattered, but just in case), then cranked the engine. Here is a video of my results (ps: ignore the extra tubing and inline fuel filters, I haven't had the chance to cut it down, but I know it's ridiculous at the moment): https://youtu.be/XPxPhL6qn_k

Seeing as though I'm basically getting no vacuum, that would explain why no fuel is flowing at all (though I'm not sure how I got it to work a month ago or even just idle even though it died earlier this week; it might've provided a minimal amount of vacuum earlier on).

I also was curious to see if the results would be different on the right side of the carbs, so I plugged the vacuum gauge's hose into the vacuum port on the right side of the carb that is connected to the coaching enricher and repeated the test. I think my battery was starting to die here, but here is what happened when I cranked the engine for a few seconds: https://youtu.be/VUZX93R2O6Y

Thoughts? Seeing no vacuum isn't too promising...

PS I'm going out of town for 1.5 weeks, so I won't be able to touch it or repeat any tests until then. I'm hoping I can order parts in the meantime and get ready for any maintenance I might have to do as soon as I get back. Really looking forward to getting back to working on this though :P

[ducatiman]

call me inquisitive.....when were valve clearances last checked on this 250?

Mileage at prior valve check? Mileage since?

[jk3099]

Originally Posted by ducatiman

call me inquisitive.....when were valve clearances last checked on this 250?

Mileage at prior valve check? Mileage since?

Valves last checked last weekend and mileage was at 10121. No change in mileage since. Bought used and I’m not sure it’s ever had a prior valve check. Only adjusted Intake 1.

[ducatiman]

Originally Posted by jk3099

Valves last checked last weekend and mileage was at 10121. No change in mileage since. Bought used and I’m not sure it’s ever had a prior valve check. Only adjusted Intake 1.

that makes no sense....exhaust valves are known to tighten (even at mileages between called for clearance checks)

[Triple Jim]

I don't remember... have you done a compression test recently? Valves not closing fully will make very low compression readings.

[DannoXYZ]

Originally Posted by jk3099

PS I'm going out of town for 1.5 weeks, so I won't be able to touch it or repeat any tests until then. I'm hoping I can order parts in the meantime and get ready for any maintenance I might have to do as soon as I get back. Really looking forward to getting back to working on this though :P

Sometimes, walking away and coming back with fresh eyes can help spot something that wasn't obvious before. Complete lack of vacuum is perplexing... Should at least show something.

1. inspect rubber manifolds. Make sure orientation with words "head" and "carb" printed on them facing proper direction. Both ends should be fully seated flush to flat surfaces on head and carbs.



2. do compression test. Remove both plugs and hold throttle WOT when cranking. Squirt 1cc oil into spark-plug hole. Repeat compression test. What did you measure?

[racered]

I watched the video's, I read the thread, here are my notes,
(I think) The petcock is "off" in the video's, not reserve or on. ( OK for the vacuum test but not for a fuel flow test).
I did not hear any "compression events" while you were cranking the engine,are the spark plugs installed in the video's?
When you adjusted the intake valve,did you have the cam out to change a shim? or is there an adjuster? Cam timing may not be accurate if you had to remove the cam, resulting in no compression, no vacuum.
For the vacuum test during cranking, the throttle plates need to be "closed" as in "idle" not held open by the adjuster screwed in a bunch. Spark plugs installed, and a charged battery that will spin the motor.
For a "compression" test you hold the throttle open.
No need to crank more than three seconds for vacuum test result.
On the oil overfill, how much are you pouring in?
I remember my 250 was just a little more than one quart.
How much oil is draining out when you think it is overfull, two quarts?
Nuance matters.
HTH
Paul

[jk3099]

Originally Posted by ducatiman

that makes no sense....exhaust valves are known to tighten (even at mileages between called for clearance checks)

Agreed - I was skeptical of it, too, so I ended up checking a few times and kept getting the same thing. I'm going to assume that I had messed up somewhere in the measuring process and am planning on rechecking.

For references, I used a combination of the Ninja250Wiki and the two linked articles on its page. I also used some random YouTube videos. Got any suggestions for additional references?

[jk3099]

Originally Posted by Triple Jim

I don't remember... have you done a compression test recently? Valves not closing fully will make very low compression readings.

No compression test lately! I'll add it to the list of things to do while doing the valve check. Thanks for the suggestion!

[jk3099]

Originally Posted by DannoXYZ

Sometimes, walking away and coming back with fresh eyes can help spot something that wasn't obvious before. Complete lack of vacuum is perplexing... Should at least show something.

1. inspect rubber manifolds. Make sure orientation with words "head" and "carb" printed on them facing proper direction. Both ends should be fully seated flush to flat surfaces on head and carbs.



2. do compression test. Remove both plugs and hold throttle WOT when cranking. Squirt 1cc oil into spark-plug hole. Repeat compression test. What did you measure?

For sure; the last few days have been good not having to think about this.

I'm definitely planning on taking the carb boots off. The boots between the carbs and the airbox have been stuck to the airbox for the last few carb changes, so I'm going to try to take those off. They seem like a reasonable culprit for these consistent issues. I'll check the directions of the other boots while I'm at it, too.

For the compression test, should I buy a compression tester, or is there a manual test I can perform? A YouTuber named Fortnine mentioned a test where he put his thumb over where the sparkplugs are and then cranked the engine to see if the compression was ~100 psi. Would this work instead? Just seeing if I could save some money