pre-gen runs rough under load

[n4mwd]

previous owners can be mean that way. I suggest you get your son or somebody else that's familiar with how the insides are supposed to look to give you a hand. another member here spent several months trying to clean a carburetor where the previous owner had monkeyed it up. It turned out that the previous owner had left out some vital components. he didn't know they were missing because he hadn't seen the insides of a ninja carburetor before.
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[emoyer]

QUESTION: if the only thing messed up on a jet is the sides of the screwdriver slot, but the orifices, threads, etc look ok, is that a problem? does the slot affect fuel flow?

i wanted to post some pics but i dont have a way to put them on the web. my phone does not do closeups well anyway.

also in one of the big passages into the engine there are some pretty noticeable scratches, i assume someone was careless with a screwdriver when getting the boot off -- do you think this is a problem?

the float bowl gaskets were dry & hard so i know i need new ones of those. i also think the gaskets were leaking (crud between gaskets & carb body, staining on outside of bowls, & i used to often smell gas when i got on the bike.) my son was wondering if air could have been pulled in there when the engine was running, further leaning things out.

the gaskets are $8.61 at my online parts place, or i could get a kit from murphs for $35 which also includes the float needles. my float needles look ok but the floats seemed to flop differently even tho the tabs looked the same, so i dunno. maybe theres some dirt in the passage.

so anyway, i have things pretty much apart & am assessing my options but havent done much actual cleaning yet. i will start on that next.

in the meantime i am interested in advice from you all about what parts should maybe be replaced.

thanks for putting up with my going on and on about all this. it is turning into more of a job than i thought. i am scheduled to take the BRC2 on 18 aug, & am hoping i have it together in time to get some riding in before that.

[emoyer]

Originally Posted by n4mwd

previous owners can be mean that way. I suggest you get your son or somebody else that's familiar with how the insides are supposed to look to give you a hand. another member here spent several months trying to clean a carburetor where the previous owner had monkeyed it up. It turned out that the previous owner had left out some vital components. he didn't know they were missing because he hadn't seen the insides of a ninja carburetor before.
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yeah thanks. he is kind of involved & i am also following pretty closely a couple articles from ninja250.org (they may be schmucks but i have gotten a ton of helpful info off their site) that have photos. i am starting to feel like this is an uphill battle. its enough of a challenge for me to maintain a bike in proper condition, without having stuff screwed up for me beforehand. but it is good what i am learning.

[choneofakind]

If only the screw driver alot is buggered up, I would still replace it, just because it won't be a problem in the future then.

www.jetsrus.com has jets for relatively cheep. Stock mains are 105, stock pilots are 38 (I think that's the stock pilot size) the keihin equivalent jets work perfectly fine and cost half of what the keihin jets cost.
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[emoyer]

Originally Posted by choneofakind

If only the screw driver alot is buggered up, I would still replace it, just because it won't be a problem in the future then.

www.jetsrus.com has jets for relatively cheep. Stock mains are 105, stock pilots are 38 (I think that's the stock pilot size) the keihin equivalent jets work perfectly fine and cost half of what the keihin jets cost.
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cool thanks, i will check them out. by the way i was able to put the pics in an album "carb project" in my profile area. they are not great but....

[n4mwd]

Originally Posted by emoyer

QUESTION: if the only thing messed up on a jet is the sides of the screwdriver slot, but the orifices, threads, etc look ok, is that a problem? does the slot affect fuel flow?

also in one of the big passages into the engine there are some pretty noticeable scratches, i assume someone was careless with a screwdriver when getting the boot off -- do you think this is a problem?

the float bowl gaskets were dry & hard so i know i need new ones of those.
...
my float needles look ok but the floats seemed to flop differently even tho the tabs looked the same, so i dunno. maybe theres some dirt in the passage.

Jet slots: I would replace them, however the buggered slots wont affect the operation of the carb, but it will make it a lot harder to get them out the next time you rebuild. I forget whether you said you did that or the previous guy, but use a flat head screwdriver that fits the slot with no slop. I know some people have used larger screwdrivers for the pilot jet and ground the sides off so it would fit in the hole. Remember, always use the right tool for the job.

Scratched passages: Makes you wonder what the previous guy was thinking, but they don't look serious. If it bothers you, use some fine grit sandpaper to smooth them off a little. Make sure you use compressed air or a computer duster to get the grit out or it could damage the engine.

Bowl gaskets: They should be OK as long as they aren't broken. The bowls are vented to the outside air anyway so it doesn't have to be a perfect seal. If the floats and needle valves are right, the gas doesn't get up that high I don't think. It certainly wont hurt to use new gaskets.

Floats: They should flop evenly and be set to the proper level. Attached is a photo of how to measure them.

The hard part is getting it off the bike. Once you have experience rebuilding it, it should take you no more than an hour to rebuild one.

Originally Posted by choneofakind

www.jetsrus.com has jets for relatively cheep. Stock mains are 105, stock pilots are 38 (I think that's the stock pilot size) the keihin equivalent jets work perfectly fine and cost half of what the keihin jets cost.

I went to that web site and the main jet section pictures look like its just the top part that screws into the jet. Do they sell you both or just the top part?

[choneofakind]

The top part IS the jet. They're tiny. There's no need to remove/replace the sleeve as well

[n4mwd]

Originally Posted by choneofakind

The top part IS the jet. They're tiny. There's no need to remove/replace the sleeve as well

I think you mean that they don't make different sizes for the sleeve part of the main jet. Mine were plugged up so I wouldn't agree that they don't need to be removed during cleaning.



Note the little holes in the side.

[choneofakind]

Well to answer your question, no I don't think jetsrus sells the sleeves, but you'd have to check more closely.

But the sleeve is the sleeve. The jet is the jet. Different parts. The jet, no matter what size you choose for your intake/exhaust needs, screws into the sleeve. The sleeve isn't part of the jet, but this is really just semantics i guess
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[emoyer]

so tues nite my son helped me with the cleaning, and we decided to skip shimming the needles for now. got the carbs mostly back together but realized that on one of the float needles the little inner plunger was stuck. so i ordered a rebuild kit from murphs, which includes 2 gaskets, 2 keihin float needles, & 2 sets of washers & o-rings for the idle screws.

i decided to re-use the existing jets since you guys said the damaged screw slots should not hurt anything.

i hope the parts will come today or tomorrow. i have a little time off on friday so i hope i can get the bike all back together and be riding sometime this weekend.

thank you all again for the help.

[choneofakind]

Well, its not fixed yet I'm waiting to hear you say it's up and running like normal
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[emoyer]

bike is all back together but wont start. just cranks & cranks with nary a pop. i tried long enough to get gas thru the carbs. smelled gas out the pipes.

actually this is the same thing it did the last time i tried to ride it, when i knew i needed to clean the carbs but was reluctant to start the job. thats why i finally said screw it & took it apart.

did it one time before too but finally did start.

anyway, i know i need to get to the plug wires & see if i have spark, but in the meantime is there any classic problems with the pre-gens that cause this?

thanks.

[Motofool]

Verify that the floats and valves are closing properly, so the level inside the bowls is correct.

Try with full open throttle while cranking (get ready to quickly close it as soon as it fires up).

Don't kill the starter and the battery in the process.

[n4mwd]

Sometimes they get finicky after being worked on like that. Spark is a good thing to check, but before that, try starting with choke OFF and throttle wide open.

[emoyer]

tried cranking with no choke but full throttle, no difference.

there is spark on both cylinders.

to verify float valve operation i have to take carbs off again right?

i put new float needles in when i had the carbs apart & i checked the float heights (with carb held sideways, etc) and both floats were at 17mm which i understand to be correct.

however, after i checked the spark, since i had tank off, i drained both bowls to make sure there was fuel in there & i think too much came out. i dont have much experience with this but one time i drained them right after a ride to check for water & there was maybe 1/4 inch in the bottom of a soda can from each bowl, but this time it was more like 1/2 inch.

thought maybe petcock was bad. put tank back on and started cranking right after opening petcock but still not even one pop.

i did clean & oil the air filter last nite, but i dont think i could have screwed that up bad enough that NO air would get thru.

i will keep working on it (after the battery tops up again) but id be grateful for any ideas. it is a new battery that measured 12.7V after the last go-round.

thanks.

[n4mwd]

You should test the compression and check the plugs. Compression should be mostly equal.

But before that, you can have a look at your petcock. To test it is simple. Turn it to ON and then remove both of the hoses. There might be an initial drop of gas that was in the line, but after that, there should be nothing. Switch to reserve and there should still be no gas coming out. Then get a rubber tube and put it on the smaller port and suck on it with your mouth while holding a cup under the big port. The gas should free flow. And then shut off completely when you stop sucking. Should work the same for both reserve and ON. Should not come out for OFF.

[emoyer]

the plugs were new 700 miles ago when we did the valves. should i still check them?

i would have to get a compression gauge but maybe i can do that.

thanks for the info about testing the petcock. i was wondering about that. i tried testing it by opening one of the bowl drains, waiting until the flow stopped, and then cranking the bike a little more, and more fuel did drain out. do you think that was a good enough test?

thanks.

[emoyer]

UPDATE: just went out again after letting it sit awhile, turned on the petcock & cranked it for maybe 15 seconds, then pulled a plug. it was dry, didnt even smell like gas.

what could i have screwed up in the carbs that there is fuel in the bowls but not getting to the cylinders?

[Motofool]

Originally Posted by emoyer

.....to verify float valve operation i have to take carbs off again right?

No need to disassemble them.

If the level is per spec and there is a strong vacuum at the throttles (with no vacuum leaks from the boots or hoses), proper mix should be flowing into the cylinders.

I would spray some WD-40 or carb cleaner into the air box while cranking with full open throttle, just to verify that proper mix is not being produced by the carbs.

[n4mwd]

I don't think WD-40 is a good choice, but you can get starting fluid at the parts store or hardware store. Nevertheless, I have never had any luck getting it to start with that on a Ninja. Not sure why. I did have a little luck with a propane torch, cracked open, unlit, shoved into one of the breather holes.

Gas has to be slightly higher up in the bowl to reach the pilot jet tube than the main jet. So do the test that Motofool described above. The pilot jet is what you need to start and idle the engine. However, I find it very unusual that you would have both carbs failing. Even if one was totally choked off, you should get some kind of fire from the other side.

The compression test is a standard test. Its next to impossible to find a gauge that will read correctly on a Ninja, so if you test it, you are looking for two readings that are close to the same. Officially, its supposed to be around 175 psi or something, but because of the small displacement and small head space, the tube that runs to the gauge creates an error. Don't be alarmed if it shows around 100 psi. If they are both the same, its probably gauge error.

But if they are different. Drop a teaspoon of motor oil in the lower pressure cylinder and retest. If the pressure is significantly higher, your rings are shot. If its about the same, its your valves - either not seating properly or maladjusted.

[emoyer]

thanks for all the info. just one more report before i quit for today: i tried spraying some starting ether into the airbox while cranking and with the throttle open and it made no difference. however, one of my friends here says that spraying it into the airbox doesnt work, that you have to spray it directly into the carbs.

if i have to take it apart again i might go further and take off the rear wheel so i can get the airbox out and cut off the battery box. OR... what do you guys think of pod filters??

thanks again.

[n4mwd]

Originally Posted by emoyer

thanks for all the info. just one more report before i quit for today: i tried spraying some starting ether into the airbox while cranking and with the throttle open and it made no difference. however, one of my friends here says that spraying it into the airbox doesnt work, that you have to spray it directly into the carbs.

if i have to take it apart again i might go further and take off the rear wheel so i can get the airbox out and cut off the battery box. OR... what do you guys think of pod filters??

thanks again.

I don't think pod filters give adequate protection in the rain, but they do let more air in so if you use them, you have to rejet for sure.

You don't have to remove the wheel to get the airbox out. It splits in two down the middle. You just need to remove the bolt that holds the fender to the bike that is located in front of the rear wheel. You can get a small 1/4" socket wrench in there no problem.

There is a very short list of design flaws on this bike, but having the battery box permanently molded to the airbox was one of them. Separating them is a pretty simple mod that doesn't really hurt anything.

As far as cutting the battery box off, there was a trick a guy showed me with cotton string to cut plastic. Loop the string under the box and up through the top making sure there are no wires or other stuff touching the string. Then rapidly pull the string back and forth - up and down - and it will cut through the plastic. It has to be cotton or else it wont work.

I never had any luck with ether either. Spraying directly into the carbs is a good idea. But also you can spray directly into the engine if you have the carbs off.

[Motofool]

Originally Posted by emoyer

thanks for all the info........, one of my friends here says that spraying it into the airbox doesnt work, that you have to spray it directly into the carbs.

You are very welcome.

I would say that if direct mix feeding failed, your problem may be lack of spark under pressure and/or any of the mechanical problems listed by D above.

Those problems may be present, but they were no so big just because the engine was working pretty well before, except for the middle range.

Since then, the only modification has been the disassembling, cleaning and re-assembling of the carbs; hence, your current problem should be mix related.

Proper mix can be affected by either airflow or fuel-flow (vacuum leaks, air restriction, fuel feed, carbs' passages, bowls' level, bad gasoline or malfunctioning diaphragm-needle).

[choneofakind]

Don't change to pod filters until you're sure you have the bike running. You'll just add jetting into the mix of variables.

That said, if you can stand the intake roar (no joke, my intake is louder than my muzzy), pods are awesome. They're perfectly fine in rain unless you're going swimming with your ninjette. I've ridden in the rain without any white smoke from the exhaust at all. You can also get a dry bag thing from k&n to keep water out of your intake if it makes you feel better. Pod filters free up a ton of space under the tank and make the throttle a little more responsive.
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[emoyer]

tonite if i have time i will try to cut off the battery box in place. it will make everything else easier.

also this morning i tested the petcock by sucking on a hose attached to the vacuum connection -- the flow started right up when i started sucking but did not stop quickly -- it tapered off slowly over 5 or 6 seconds, as if the spring was weak or the mechanism gummed up. it did this for both main & reserve, as one would expect.

[n4mwd]

I don't think the petcock is your primary problem, but when you get a chance, you can strengthen the little tiny spring by stretching it out a bit. I think its made of brass. You can buy new ones from Ron Ayers, but everyone I have talked to said that unless its broken or corroded, stretching is usually good enough.

****** EDIT ********

I forgot to mention that if you disassemble the petcock you need to be especially careful when handling the membrane. Its like wet toilet paper almost and tears really easy. The replacement is $20.

[alex.s]

unless the float valve in your carbs isnt working, the extra flow should not be an issue

[emoyer]

did battery box mod to get room to work (just cut it in place with hacksaw, worked fine.)

tried spraying ether into carbs but engine did not fire while cranking. removed carbs & boots and sprayed directly into intake ports, but still nothing.

i checked again that i have spark and i do.

i am asking around for a compression gage. its the only other thing i can think of. unless the valves are not moving but it kind of sounds like they are.

if the cam chain broke would i hear some kind of clatter, or would it just lay in the bottom of the engine?

and then sometimes i fear i must be doing something really stupid.

thoughts? thanks.

[n4mwd]

Exactly how were you checking for spark? Something isn't right there. Are your plugs gaped properly and snug. Coil wires (both low and high voltage) look good? Pushed all the way down?

In case I didn't mention this before, make sure you aren't using champion spark plugs.

Honestly, I have never had any luck with starting fluid on the Ninja. Not sure why. I did have some luck with propane once, but too much will stop the engine. Maybe try a very small amount of starting fluid in each intake as too much may be flooding it.

If the cam chain was broken, the engine would seize. Its not that. You should be able to hear the air running into the cylinders if the valves are working.

[emoyer]

plugs are NGKs that were new 700 miles ago, and i gapped them to spec.

im checking spark by pulling plug, putting the wire on it, holding side of plug against engine block, and cranking engine. i dont know how big the spark should look but from ive seen in the past when working on generators & such it looks healthy to me.

im not sure what wires you mean. and when you say pushed all the way down do you mean the plug wires?

i believe you when you say youve had no luck with starting fluid on a ninja, but its an aerosol thats crazy flammable, i dont understand why i shouldnt get at least some kind of a pop. not sure how to do it with propane.

thanks.

[alex.s]

is spark timing correct? check your pickup coil and timing wheel and make sure they are you know still attached and all

[Motofool]

Originally Posted by emoyer

.......
i am asking around for a compression gage. its the only other thing i can think of. unless the valves are not moving but it kind of sounds like they are.

"If you don't have a compression gauge handy, all is not lost. A down and dirty way to do it is to simply press your thumb over the spark plug hole and hold it there tight. Now have someone kick the engine over. No matter how hard you push your thumb, the compression pressure should blow it off the hole smartly. If it won't, you don't have enough compression to start the engine."

http://www.dansmc.com/compression_test.htm

http://www.dansmc.com/leakdown.htm

Did you finally check the level inside the bowls as per post 59?

[n4mwd]

As far as I know, failure of the CDI or pickup is extremely rare. I've seen several people change it out only to discover the problem was something else. There is a hotwire security feature of the CDI that disables it if its hotwired, but that wouldn't be the case here if you're getting spark at all.

The Ninja uses a waste spark so it fires twice per cycle - once per revolution per cylinder. If the spark timing were bad, it would normally cause backfires and things like that. I don't think its ignition timing.

Now valve timing is another thing. It sounds like its time to start thinking of doing a valve adjustment. When was the last time you did one? Next time, set the valves to the max gap and not the middle. That makes it idle better - to the point where the choke isn't needed anymore.

[emoyer]

THE BIKE IS RUNNING!!!

my son finally got it to show some life with ether by covering the ports with his hand after spraying. i guess it richened it enough or something.

then we put the carbs on & tried more ether & it showed a bit more life.

the only thing we could think of to do next was try fuel so i threw the airbox & tank on and tried it a little, but it seemed to flood. i drained some fuel from the carbs & tried again, playing with throttle & choke, and finally it caught.

so i still need to put everything together properly & set the idle and idle mixture, etc, but it was SO GOOD to hear her running again! and like chris said a couple days ago, we still dont know if the midrange is any better out on the road. but its progress.

btw the valves were adjusted 700 miles ago, to the loose end of the spec.

my thanks to you all. i may be pestering you more before this is all over.

[emoyer]

Originally Posted by Motofool

Did you finally check the level inside the bowls as per post 59?

i want to do this but the tubing i have is too big to fit the drain bibbs. i intend to get some smaller tubing and do this, because i would like to see what it is doing. its a very good idea, it seems to me, especially because i dont really have to take anything apart.

(general comment: i am grateful for all i am learning by doing my own bike repairs/maintenance, but i must say that sometimes i dont really enjoy it. im not real mechanically inclined to begin with, and bikes add a level of frustration by how tightly everything is packed together. oh well.)

[emoyer]

final report -- so ive put 250 miles on the bike since getting it back together & it most definitely runs much better. possibly still a minor issue with idle mixture adjustment but i think its close.

so im glad i did it, even though it was a bit of an ordeal at some points. learned a lot.

thanks again.

[thumper64]

I ordered generic stainless washers off eBay and jets off jetsrus, the $8 generic ones, and they work fine. There's no reason to not try rejetting your bike. It's been established that the bikes come jetted too lean from the factory, and running lean makes motors less responsive, and run hotter. The relatively small investment was well worth it to a friend and I.

Are you missing the snorkel for your airbox? It will make it run lean, but you already looked and saw it's jets are chewed up, so...

A lot of people remove their rear fender or trim it down, or just install pods. I tried a few different adjustments on my bike after modifying the stock mufflers, and I'm still not content.