Enrichening the Fuel Air Mixture?

[Scattcatt]

Pretty much what the title states, I strongly believe my ninjette has a cold and is running lean again. I looked into this a bit yesterday, and I've come to somewhat of the conclusion that it all deals with the needles in the carbs, but these threads also seem to be heavily weighed towards the low end of the power curve, I notice my mixture problems on the high end, in sixth gear, on the freeway going about 83 indicated on the speedo (so 75 ish) but also in a few of those DIY videos regarding carbs, they also mention a mixture screw. I pulled out my service manual and tried to track down that screw with no success. Why can't these be as easy as planes lol? We have a big ugly red knob to change the fuel/are mixture at will "Increase throttle to 1800 rpm and lean mixture for maximum performance" <--- straight from my old run-up section of preflight lol. Now I know ninjettes are not planes... But still, I'd imagine that mixture screw would exist and it couldn't be too terribly hard to find.

Symptoms: Severe loss of power after riding approx 10-15 mins on the freeway at night keeping very steady speed due to lack of traffic. You can throw the choke on during this event and she'll get tiny little spurts of power back (leading me to believe it's a mixture problem) but definitely not rideable still. This is a somewhat rare event, it happened before and I took her down to a local bike shop where it took them 4 days to fix my mixture... I don't want to wait that long again. Now it's only happened once since I took her down, and I don't know if she's doing it again as a fluke, because I did a valve clearance, or synced the carbs. None seems like a reason for her doing this again, but I could be wrong.

Hey Alex, sorry if this one exists already, I searched a little bit, but probably could have done a better job, I guess I could always just delete this if someone points me in the right direction, no worries. I thought my very first post here was regarding something about this, but that must have been on a different site, I was just going to bring that dead one back to life and save ya the trouble lol.

Thanks all!

UPDATE: This morning I was on my way to do a 400 mile round trip to Utah and back, she started up with me again on the freeway. I made it the 5 or 6 miles to the meet up place with the other guys that were going too, and I made it roughly 15 miles after that on the freeway, but then she just started dying again. It starts off subtle, very slight variations in the power output at a given throttle twist, like it's choppy, but in no time I'm dealing with a full on 1/3 or so power loss. I was in the 80's indicated on speed again, the problem never occurs unless you're over roughly 8.5k rpm's. Once it happened, I pulled over and shut her off. She came back to life just fine after I let her sit there for like 10-15 seconds (could have been longer, I was under a decent adrenaline rush). Power was normal for the first few seconds, until I got back up to the higher rpm ranges, then the throttle became very choppy again.

Finally after making it back to the surface streets she was doing a little better getting out of the high rpm's, the throttle was still very choppy though along with the power loss through the entire range of rpm's. I still think this is a mixture problem, but please do let me know what you guys think it is too. The local bike shop was closed when I rode by, might be a good thing since I'd rather fix this myself anyway

Oh and a final note for today's encounter, the choke really didn't do too much today when I was fiddling with it under the choppy throttle on the way home

(jotting more stuff down as I find more related threads)

-She had a full tank, just filled her up, the needle was probably at the line just under FULL when this happened, I don't think it's a fuel issue because when it happened before it happened at all fuel levels.
-Fuel venting issue? Perhaps, but I don't really think it's this one either considering it rarely happens, and once I got the mixture fixed last time, I didn't have a single problem with her until now
-She's got new spark plugs, did the 7500 service myself, she now has 8700 on her.

AFTERMARKET PARTS RELATED TO PERFORMANCE (I didn't put any of these on, they're all what the previous owner put on her, maybe something in here is causing the trouble):
-Full carbon fiber Yoshi exhaust
-K&N air filter (the box is removed, I think the snorkel is too)
-Larger rear sprocket (found that one out through you guys, actually, so I have slightly higher rpm's at speed than a stock ninjette)
-Been told she has a jet kit, not sure what kind though (dynojet I think...)

I think that's it, at least that's all I've discovered so far.

[LoD575]

Need to get a jet kit. Seem to be running way too lean with the full exhaust installed and air box removed.

[Scattcatt]

Originally Posted by LoD575

Need to get a jet kit. Seem to be running way too lean with the full exhaust installed and air box removed.

Forgot to add that one too, I do believe she's running on a dyno jet, anyway to check? (adding that to the top by the way)

[LoD575]

I would remove the carbs, check needles, check jets, and drill out the mixture plugs and adjust.

Here is a DIY written up by Vex mixture+screws

[Cuongism]

To actually check the jets, you have to remove the carbs (possible to do so without removing the carbs if you know where everything is, but it's tight). Have you tried opening your gas cap whenever this occurs? It sounds like a vent problem many people have.

With pods, you definitely want larger jets since a lot more air is introduced. The Dynojet Kit that's sold does not have large enough jets unless it was a custom kit.

The mixture screw you're talking about are the idle mixture screws which are capped off from factory.

http://www.ninjette.org/forums/showthread.php?t=10246

[Scattcatt]

I saw that one earlier during my search, I kind of discarded it for now since he states it's good from idle to about 5k rpm's. I've already got the bike stripped down though so I don't see any harm in doing it, I suppose anything like this could fix my problem anyway, right?

[Scattcatt]

Originally Posted by Cuongism

To actually check the jets, you have to remove the carbs (possible to do so without removing the carbs if you know where everything is, but it's tight). Have you tried opening your gas cap whenever this occurs? It sounds like a vent problem many people have.

With pods, you definitely want larger jets since a lot more air is introduced. The Dynojet Kit that's sold does not have large enough jets unless it was a custom kit.

The mixture screw you're talking about are the idle mixture screws which are capped off from factory.

http://www.ninjette.org/forums/showthread.php?t=10246

I actually haven't tried opening the gas cap this time around, but I did try that the last time this was happening with no results. Is there anyway to confirm whether or not I have the Dynojet kit? I'm not sure what brand, I was only told by the previous owner "yeah, she's been jetted" so I really have no clue. Reading through Vex's DIY for now, I'll commit to it here in a sec after I finish reading it

[Cuongism]

Yes, the jets will have their sizes on them. I have extras in my car so give me a few minutes to take pics.

[Cuongism]

Sorry, my camera is dead so here's a phone pic. The size is lightly engraved on top (size 108 in the pic). The regular Dynojet Kit comes with a pair of 96, 98, and 100's. With pods, you want larger jets such as DJ 106-110.





The only other caveat is that each brand of jet uses a different numeric value for sizes. Dynojet 106 is different than Keihin 106.

[Scattcatt]

Lol so then it really won't benefit me much anyway even if I do find the size without knowing the brand. Hmm... I'll still keep going just to take a look. Thanks for the pic! At least now I know what I'm looking for

Hopefully for Christmas I can convince someone to get me the EFI kit and get away from carbs entirely haha... We'll see! So then I only have to keep her running for another couple of months!

[Cuongism]

Knowing the size will give you a pretty good idea if you're lean or not. Here's the conversion chart from our jetting database.


Here are some main jet conversions between manufactures-

Width------Keihin # -- DynoJet # --- Mikuni #
0.0350---- 92.5--------- 92----------- 86.3
0.0360---- 95----------- 94----------- 88.1
0.0370---- 97.5--------- 96----------- 90.0
0.0380---- 100---------- 98----------- 91.9
0.0390---- 102.5------- 100---------- 93.8
0.0400---- 105--------- 102---------- 95.6
0.0410---- 107.5------- 104---------- 97.5
0.0420---- 110--------- 106---------- 99.4
0.0430---- 112.5------- 108--------- 101.3
0.0440---- 115--------- 110--------- 103.1
0.0450---- 117.5------- 112--------- 105.0
0.0460---- 120--------- 114--------- 106.9
0.0470---- 122.5------- 116--------- 108.8
0.0480---- 125--------- 118--------- 110.6
0.0490---- 127.5------- 120--------- 112.5
0.0500---- 130--------- 122--------- 114.4

Chances are it's not Mikuni since those jets aren't very common and you can eliminate it if it doesn't have a decimal. The common sizes for pods are DJ 106-110 which converts to Keihin 110-115. If you have any of those numbers, you're not in too bad of shape. If it's less than 106, chances are you're running lean. Best way to check is to look at your spark plugs.

[Scattcatt]

Originally Posted by Cuongism

\ Best way to check is to look at your spark plugs.

My spark plugs? For carbon or burning? I mean I can yank them out, but they're pretty new, changed them both out at 7500. I gotta go get me one of them handy dandy offset screw drivers and I'll get to work on those needles. You also mentioned you just had them sitting in your car? Do they come in packs or something? Or do you have to order them individually or something?

[DaBlue1]

Have you considered maybe you are bogging due to being too rich. Around 8-10.5k the Ninja is naturally rich. Adding a jet kit (even with POD filters) increases the richness in that range. Just a thought.

[Scattcatt]

I saw a similar chart earlier (maybe even the same one) but totally overlooked the bottom portion of it, I was unaware of that rich portion. It could definitely be the problem, but if that was the case, wouldn't putting the choke on make things even worse?

ALSO I took her up to the mountains yesterday, it's 2200 feet here in the city, and I took her to well over 7000 feet. That would have enrichened the mixture like crazy, but she didn't give me any problems at all, even at higher rpms

[Cuongism]

Looking at the spark plug color can give you an idea if you're running rich or lean. When I got pods, I ordered multiple sizes from Dynojet to see which size was best. They're like $2 a jet so figured order a bunch and test them out vs guessing a size and having to order multiple times if I'm wrong. I ended up using 106's so the 108's are just chilling in my car.

[Scattcatt]

Okay, I'll pull the spark plugs, I'll also take a picture of the old ones too. I don't really know what I'm looking for regarding to the color, give me like 5 mins to get those up

Okay, first pic, the old ones are on top, and the new ones on the bottom. The second pic, the old ones are on the left, and the new ones on the right. The old ones I'm assuming were on the bike from the start, so those have 7500 miles on them, the new ones only have 1200 miles on them

This thread helped out a little bit about the spark plugs, so I'm thinking that they're okay, but a second opinion would be cool http://www.ninjette.org/forums/showthread.php?t=27260

[Scattcatt]

Originally Posted by Cuongism

Chances are it's not Mikuni since those jets aren't very common and you can eliminate it if it doesn't have a decimal. The common sizes for pods are DJ 106-110 which converts to Keihin 110-115. If you have any of those numbers, you're not in too bad of shape. If it's less than 106, chances are you're running lean. Best way to check is to look at your spark plugs.

BOOM baby!! Those say 100 on them! You freaking rock Cuong!! I gotta get me some new ones now!

As far as brands are concerned though, Keihin vs DynoJet, it doesn't really matter right? Just as long as you get the proper needle size correct?

UPDATE Looks like my decision is made up for me anyway lol, the bike shop only has Keihin and Mikuni, I'm going to get me some Keihin's. Hopefully turn her back on in a couple of hours and tear up the freeway tonight to test her out!! Thanks again man! I'll keep you updated with how she runs!

Or not, they don't have the right sizes, so now I need to order them lol...

[greg737]

It starts off subtle, very slight variations in the power output at a given throttle twist, like it's choppy, but in no time I'm dealing with a full on 1/3 or so power loss. I was in the 80's indicated on speed again, the problem never occurs unless you're over roughly 8.5k rpm's. Once it happened, I pulled over and shut her off. She came back to life just fine after I let her sit there for like 10-15 seconds (could have been longer, I was under a decent adrenaline rush). Power was normal for the first few seconds, until I got back up to the higher rpm ranges, then the throttle became very choppy again.

I'm not saying the jet change isn't the fix for your problem, but if you make the jet change and it doesn't fix the situation you may have a simple fuel delivery problem.

Here's a possible senario:

Your posts indicate that the problem doesn't manifest until you've been at higher RPMs for a while. This could mean that fuel just isn't feeding from the bike's tank to the carbs fast enough to keep up during high-demand riding phases, like highway riding in the 80 mph range.

When the "choppyness" and the power loss occur you naturally back off or stop or get off the highway. While you're stopped or coasting or on neighborhood streets the fuel delivery is adequate so the bike feels "back to normal", but then when you get back on the throttle in a sustained high-demand situation (back on the highway) the problem re-occurs.

Possible causes: 1. lots of crap in the fuel tank blocking the petcock screens, or 2. the tiny factory fuel filter that's in the feed line is full of garbage and mostly blocked, or 3. there have been cases where guys have installed aftermarket in-line fuel filters that don't allow enough flow, or 4. some other fuel line problem like a kink in the line or something pressing on the line, constricting it.

Here's a write-up on aftermarket fuel filters that includes some information on the factory filter. It's tiny and most people don't even know it's there. http://faq.ninja250.org/wiki/How_do_...fuel_filter%3F

[Scattcatt]

Greg, I'll definitely rip her apart and take a look just to be on the safeside, but would it make sense for this to be a rare event if these were the causes?

[greg737]

Originally Posted by Scattcatt

Greg, I'll definitely rip her apart and take a look just to be on the safeside, but would it make sense for this to be a rare event if these were the causes?

Well, it could be a rare event if most or almost all of your riding was done in a way that never overtaxed the fuel system's ability to deliver.

Maybe I misinterpreted your situation. It sounded like every time you take it out on the highway it does the choppyness and power-loss thing.

Also, the situation could be getting worse, i.e. the filter getting more and more clogged, so the symptoms are getting more noticable.

I was just giving you a "what if" in case the jet change didn't do the trick.

[Scattcatt]

Oh no lol, didn't mean to give you that impression. I do plenty of freeway riding, when this happened before it would happen about once every 7 or 8 times under those conditions. This time around, I've logged probably somewhere around 1400 miles on the freeway between the first incident ending and it reappearing again now. No worries though, like I said I'm still definitely going to check it out, I'm willing to check anything out if it means getting her back into shape!

[kiler]

New plugs look like you're running lean. Old plugs look better, but it depends on how you're riding it when you pull them.

[Scattcatt]

Originally Posted by kiler

New plugs look like you're running lean. Old plugs look better, but it depends on how you're riding it when you pull them.

Then that puts me a little bit more at ease regarding going up on the jet sizes. Where did you guys purchase your jets from? Went to 2 motorcycle shops an neither of them carried the sizes I need. They all start too big

[Cuongism]

http://www.dynojet.com/jetkits/jetassortment.aspx

I called to order from them and received them next day. They are located in north las Vegas so doesn't hurt to call to see if you can pick it up in person if you're close by.

You're looking for DJ style main jet.

[Scattcatt]

Originally Posted by Cuongism

http://www.dynojet.com/jetkits/jetassortment.aspx

I called to order from them and received them next day. They are located in north las Vegas so doesn't hurt to call to see if you can pick it up in person.

haha yeah I JUST saw that! Definitely going to give them a call tomorrow, I thought that was an amazing stoke of luck, they're like just a couple of miles away!

I ended up buying 104's 106's and 108's. Might have to go back to get 110's, didn't even think about those ones for some reason, but we'll hope for the best with these

The 104's seemed to work best for me, the 106's I had some bogging on the low rpm range, particularly noted before 5k rpm, I threw 108's on it for the heck of it afterwards, these ran very strange, the idle was very difficult to maintain, she actually ended up dying while I had the clutch pulled in on multiple occasions, the throttle also hung for a while too, like it took a very long time for the rpms to drop from 5k down to idle. What little bit I actually did ride it though, I could notice quite a bit of power off of these, but I never did make it out of first or second gear. To keep the playing field level, I resynced the carbs after every jet swap, some of the oil that I was using actually entered the vacuum tubes on the 108's while I synced them though creating a fairly large amount of smoke. No matter, she pounded right through it just fine and the smoke cleared in no time. That may have accounted for my weird experience with the 108's, but I'm definitely going back down to the 104's tomorrow.

One more thing you guys might be able to help me out with though, I noticed on the other threads, in particular the jetting databases, they speak a large amount about washers, seeing as I wasn't the one who installed this jet kit, I have no idea what the washers are or really what they do. Do any old washers work? Or do I need to make another trip down to Dynojet an pick some up? Also how do they affect the performance? Thanks!

[Cuongism]

IF there was a Dynokit installed, you should actually have their custom needles in them which uses e-clips. Easy way to tell is that it has two e-clips (washers with an open end) and two washers that are fully closed. The washers should be in the third position to start with.

I don't have a pic of the DJ needles since they're installed, but here's a pic of stock needles with washers at the end. You can get the washers at many places (radioshack, ACE, etc). They're 3 mm washers or SAE #4 washers. If you have DJ needles, they have grooves where those washers are in that pic.

[Scattcatt]

And that needle is what these main jets are going over right? Like you take the main jet out and it's that little silver guy in there? Just pull it out gently? I'll get to work on it tomorrow, hopefully professors will let us out early lol.

Thanks again Cuong! Alex, you should like give this guy a medal or something lol

[Cuongism]

The needles are actually easier to reach and don't require removing the jets or carbs. You actually get them from on top of the carb.

Shimming Carbs

But also be careful with the diaphragm because it's fragile and the screws that hold the top of the carbs on aren't phillips, but JIS.

http://www.ninjette.org/forums/showthread.php?t=49003

[Scattcatt]

Okay so this is my needle from one of the carbs, you mentioned that it should have 2 E-clips if it was DJ, I'm pretty sure it's a DJ after looking up some pics on Google but should I be concerned that it only has 1 e-clip? The other one only has 1 e-clip and it's missing both washers entirely... These are 3mm washers? I guess these are notoriously hard to find here in Vegas lol... Went to Radio Shack, Home Depot, and Lowes to try and find some, none have had anything smaller than 4mm so far. Going to try Ace Hardware tomorrow.

Few more questions:
-3rd position from the back of the needle? or the tip of the needle?
-Which direction moving the clip controls what? (like toward the tip = richer, or leaner?)
-Did you mean to say 2 e-clips? The images from google showed only 1 so I wasn't sure...

Thanks!

UPDATE: I moved the e-clip to the 4th position from the top (there are 6 positions for me to choose from). I haven't played with the mixture screws or anything but she seems to be running much better on the lower rpm's higher rpms sound and feel fine, but she didn't seem to wanna get up to speed as quick, quite possibly from aerodynamic characteristic (no fairings or anything, just a nekkid bike) tonight should be the moment of truth when I take her out on the open freeway and let her go for a while

Also, took a look at the fuel line and stuff, turns out I have no fuel filter period lol... So I owe you a thanks, Greg, for making me check that out too. Idk why that would be missing, but it is. Gotta go check into some good flow gravity fuel filters now.