98 Bayou 220 Carb question?

[krp44994]

A friend asked me to look into running/performance issues with his 98 Bayou 220. Starts and idles cleanly, On acceleration, and pushing the throttle, it hesitates and cuts out. Today, for kicks, I actually ran it with choke on and it ran great with no hesitation on hard acceleration and at speed. Of course it would not run at idle with choke on. I am guessing that the main jet is either clogged or not set properly and the idle jet is good to go. (Hence it running great at idle) Therefore running with the choke ON enriches the air/fuel ratio such that it runs great. My plan is to disassemble the carb and clean/inspect and re-set everything. I purchased the Haynes manual and I am very mech. inclined with cars/equipment - but this is my first bike/4 wheeler effort. Can anyone give me some good advice on cleaning and set-up, good diagrams,what to look for, etc before I tear the carb down? Many thanks in advance!

PS: Per the owner, the carb was recently "rebuilt" by an expert friend who said it had to be the head gasket. Which I just replaced at the owner's insistance - made no difference in performance.

[99prairie400]

Sounds like a classic clogged carb. Get a spray can of carb cleaner and make sure it has the small plastic hose taped to the side of the can before you leave the autoparts store. Remove all of the rubber from the carb and spray it down paying very close attention to the pilot jet passages both on the inlet side of the carb and under the pilot jet itself. Make sure of the needle setpoint if it's adjustable (don't have a bayou 220 so not really sure) because that surely will cause it to lack acceleration.

Did the "expert friend" do a compression test on the quad? That would tell you (and the owner) alot about the condition of the rings/piston/cylinder/headgasket and would diagnose head gasket failure.

No compression test=no diagnosis.

[krp44994]

Your point on compression test was well-made. Unfortunately, my compression gauge only has a 14 mm x 1.25 fitting, the Bayou needs a 12 mm x 1.25 fitting for the plug hole...so against my better judgement, I went ahead and replaced the head gasket without doing a compression test. I have an adapter ordered that will at least tell me the state of compression post-gasket install....I will tear down the carb and clean everything up and then post back on progress.

[krp44994]

Well - completely disassembled the carb tonight for soaking/cleaning. Upon initial inspection I found the air/pilot screw (on bottom of carb) set at 7.5 turns out.....(I have read that initial set-up is 1.5 turns out) Can someone please confirm that? And if everything else checks out, would this be enough to cause the bayou to run irregular?

[RCW]

It is a wonder it even would start and idle, let along run at any speed other than wide open at 7.5 turns from the bottom. The carb has to be pretty plugged to allow it to even run at that setting.

Set it at 1.5 to 2 turns from lightly bottomed, after the carburetor is fully cleaned and the passages inspected. Then adjust from that point for the best sounding idle once you have it idling.

If you look up my posts you will find the procedure for power tuning the pilot jet air screw for maximum performance and economy.

[krp44994]

Thanks RCW for the information on setting up the pilot jet air screw. Got all the metal parts soaking in carb cleaner tonight....will dry and install tomorrow.

On a slightly different subject, when I replaced the head gasket, I noticed that the head has two "openings" just to the right of the exhaust manifold?!? A little bit of oil appears to radiate from this point onto cooling fins? Don't see this referenced in any manual or cut sheet....what is the purpose of these "holes"?? Thanks in advance.

[krp44994]

The two holes are just to the right of the exhaust manifold.....I reassembled and reinstalled the carb today. Started at 1.5 turns and worked out to 5 in 1/2 turn increments.....would make an adjustment, then drive the 4 wheeler, then come back and make another adjustment. not sure what type of screwdriver would allow you to get underneath to adjust without turning the carb AND burning your hand (even with gloves on) - please explain.....REALLY FRUSTRATED that cleaning the carb did not make any difference on performance coming off idle to about 1/4 to 1/3 throttle.....hesitates and stutters.....now if I turn the CHOKE back on after I get rolling, it runs without a single miss....there is something here that I am missing....obviously, it is too lean coming off idle 1/4 to 1/3 throttle.........if anyone has any ideas, I am open - really bugs me that I have not found a "smoking gun" but again CHOKING it off idle makes it run great (again, once you get rolling a bit) HELP.......

[99prairie400]

Adjusting the carb isn't something that's supposed to be done on a daily basis so convenience wasn't exactly on their minds. As a matter of fact, most new quads have a brass plug in the pilot jet hole because except for a total rebuild, you shouldn't need to mess with the pilot jet at all. For the purpose of getting it running this time, burn your hands a few times but hopefully you won't have to mess with it again.

I'm not sure what you're referring to when you say two "holes" to the right of the manifold. The only holes that should be on the front of that motor are the two stud holes for the exhaust flange and the two bolts for the valve inspection plate.

I'm thinking now you should splurge on the fitting for your compression tester in order to diagnose your problem. 5 1/2 turns out on the pilot jet is WAY too far for everything else to be ok. You're leaking oil out onto the cooling fins which is not normal.

Just an idea, but I have seen it before... What kind of physical condition is this quad in? Any missing bodywork? Real beat-up? Some quads have a stock "snorkel" built into their bodywork and sometimes the end of that snorkel has a rubber ring on the end of it to increase vacuum and keep the slide working properly. Usually if there is a ring on the end of the snorkel it's held in place by some part of the bodywork but if the bodywork on the quad is damaged it's possible that the end of that snorkel has dislodged. If the carb doesn't have the proper amount of vacuum it will snap the slide open violently causing the engine to run lean (a problem which can be compensated for by partially choking)

Check your compression to make sure you don't have a timing/valve/piston ring issue, look into the leaking oil, take the carb back off one more time and spray it out with a can of carb cleaner with the little hose on the end to make SURE you got every single little passage in there cleaned out REALLY well, and look into where the pipe that comes out of the airbox (the non-filtered side) goes up to.

[Mark BT]

Have a Bultaco that does that when ever the carby is loose, or has a perferated intake pipe, big bears have a hose that comes from the top of the carbie that seem to be some sort of breather, if that gets blocked they do the same thing.......just a thought

[krp44994]

I will take a pic of the two small "holes" in the fins.....oil appears to be seeping out here.....as for the compression tester, I concur that I have to break down and buy the right reducer and then get the compression tested to confirm or rule out rings, valves, timing etc. I also will check tomorrow the O-rings and intake manifold BETWEEN the carb and the head for leaks. Gonna set the pilot screw to 1-1/2 turns out and leave it. Can I assume that since the hesitation goes away with choke, that the problem is NOT ignition module related?

[krp44994]

One more thing:

I am gonna check the carb fuel level as well (did not do that as part of the rebuild)..One more question: The parts diagram on Kawasaki.com shows what appears to be a check valve on one of the "drain tubes" coming off the bottom of the carb. My bayou has no valve. Is it possible to be drawing air from this potential waste line?? Please advise and thanks!

[86klf300guy]

hello..

did you use compressed air to clean out the carb after soakin it.to clear all the passages out and blow out all the jets?and could you see day light through all the jets ?there is one jet in the carb that has multiple holes in on the barrel of the jet those get gummed up so bad you have to 1 replace it or get cuttin torch cleaner kit and clean um out.

did you bye a aftermarket rebuild kit for this.it should have come with new jets,float needle.bowl gasket.oring and washer for the air flow mix screw,new screw and spring (for the air fuel mix)and a new pilot needle and a couple other little orings.

or did you just take it all down soak em and clean em up?cause if so im goin to test your memory here.while the air fuel mix screw was out did notice a sharp point at the end of it?iv seen them break off in the passage and get stuck from over tightin it,or age ,so you can adjust that screw all you want and its not goin to do nothin to the air fuel mix.that 7.5 turns out when you first took it apart sounds fishy no bike should run with it out that far

also do you have the air filter hooked up and the box closed up?

and have you change the spark plug with a fresh ngk yet?

thems there sum ideas hope they may help you figure out whatsa goin on with you machine.-corey-

[86klf300guy]

hello..

did you use compressed air to clean out the carb after soakin it.to clear all the passages out and blow out all the jets?and could you see day light through all the jets ?there is one jet in the carb that has multiple holes in on the barrel of the jet those get gummed up so bad you have to 1 replace it or get cuttin torch cleaner kit and clean um out.

did you bye a aftermarket rebuild kit for this.it should have come with new jets,float needle.bowl gasket.oring and washer for the air flow mix screw,new screw and spring (for the air fuel mix)and a new pilot needle and a couple other little orings.

or did you just take it all down soak em and clean em up?cause if so im goin to test your memory here.while the air fuel mix screw was out did notice a sharp point at the end of it?iv seen them break off in the passage and get stuck from over tightin it,or age ,so you can adjust that screw all you want and its not goin to do nothin to the air fuel mix.that 7.5 turns out when you first took it apart sounds fishy no bike should run with it out that far

also do you have the air filter hooked up and the box closed up?

and have you change the spark plug with a fresh ngk yet?

thems there sum ideas hope they may help you figure out whatsa goin on with you machine.-corey-

[krp44994]

Hey thanks for all the responses...did not get to work on 4 wheeler tonight but here are some answers to some of the questions:

Did not buy a rebuild kit because owner told me that he just paid "~$350 for a complete rebuild".....I did tear the entire carb down and soak all metallic parts in Sea Foam over night, then blew everything out with compressed air (main jet, pilot jet, choke, etc....inspected every port, hole, orifice with a lupe (powerful magnifying glass for those that may not know) Everything was clear. Replace the O-ring on the main jet as it came apart when I removed with a dental pick (so much for "complete" rebuild - it looked dry-rotted) The pilot screw does have a needle like point on it and - yes - it WAS out 7 1/2 turns. I am going to tear down intake manifold tomorrow.....looking for leaks.....and also check fuel level in bowl.....and buy 14 mm x 12 mm reducer for compression tester if I can find one!......this should rule out a few things...and yes there are two small holes in the head cooling fin area just to right of exhaust manifold - weird?! Also - I do have the air filter installed and the cover on it.....if I plug one side of intake filter cover (two slots at back of cover) with a rag, it runs a little better (IE - richer - again it is running lean - this I know - just do NOT know why!?!?)

[MrGiggles]

Originally Posted by krp44994

Hey thanks for all the responses...did not get to work on 4 wheeler tonight but here are some answers to some of the questions:

Did not buy a rebuild kit because owner told me that he just paid "~$350 for a complete rebuild".....I did tear the entire carb down and soak all metallic parts in Sea Foam over night, then blew everything out with compressed air (main jet, pilot jet, choke, etc....inspected every port, hole, orifice with a lupe (powerful magnifying glass for those that may not know) Everything was clear. Replace the O-ring on the main jet as it came apart when I removed with a dental pick (so much for "complete" rebuild - it looked dry-rotted) The pilot screw does have a needle like point on it and - yes - it WAS out 7 1/2 turns. I am going to tear down intake manifold tomorrow.....looking for leaks.....and also check fuel level in bowl.....and buy 14 mm x 12 mm reducer for compression tester if I can find one!......this should rule out a few things...and yes there are two small holes in the head cooling fin area just to right of exhaust manifold - weird?! Also - I do have the air filter installed and the cover on it.....if I plug one side of intake filter cover (two slots at back of cover) with a rag, it runs a little better (IE - richer - again it is running lean - this I know - just do NOT know why!?!?)

Like Corey said if the pilot screw doesn't have a needle tip on it is broken off and needs replacing. I don't know how you could get the old tip out though. That would explain why you can turn it all day long and it does nothing. On the throttle plunger, there is a needle. It is held in by a C-clip and a retainer sort of thing. Remove the plunger, and take it off the throttle cable. Push on the needle until in pushed the retainer out. The needle has different slots for the c-clip to sit in. Move it to the middle slot to start out. If it is already there, move it down one.

[ThatDrummerDude]

KRP is there anyway you could keep me informed on your progress? Its like I was reading my own post. I've done almost everything I can think to do with it to get that "dead spot" out. If you find the "miracle cure", please fill me in on what remedied this. Thank you.

[krp44994]

Ok - so I broke down tonight and bought a new compression tester (to get the required 12 mm adapter). The result: 151 psi consistently - factory spec....so I can now rule out compression.....Did a lot of reading today on Mikuni carbs and carb 101 in general. Now have a MUCH better understanding of how the various circuits work and interface with one another. More and more convinced my problem is the pilot circuit....mixture screw......Tomorrow will confirm correct bowl fuel level and also will pull the pilot screw again. It does have a tip but not sure if this is supposed to be a sharp tip? Please see ATTACHMENT pic of spark plug (white electrode) looks lean to me....and also pic of phantom "mystery holes" in head to right of exhaust manifold....Also gonna pull the inlet manifold to check O-rings and boot tomorrow......May move jet needle clip down one position to effectively open needle jet a bit to see if this helps the issue from idle to 1/4 to 1/3 throttle......thanks for any feedback.....

[86klf300guy]

good compression!!!

them holes in your head there that looks like some one shot at it with a .22 lol

i had never seen holes in a head like that before. i dont see any purpose for them bein there.

is it leakin oil from them hole?

j/b weld may be your freind to plug them holes up if its leakin oil.

as for the tip of the screw it should be a point thats sharp.

movein the needle clip down one only if its in the middle or higher up will help you.but if the clip is allready below the middle circle then raise it up one. this is a playfull game off huntin the right settin of that clip and adjustin the air fuel mix screw.

as for your plug yep that would be lean on fuel just a tasteplyin with that clip and air mix screw should get you back up and runnin correctly

-corey-

[99prairie400]

Ok, those holes don't look like a factory option...

The only way I can see that those may have been formed is if the top timing gear fell off and crunched the case from the inside. Is there any evidence of this down inside the timing cavity?

Spark plugs don't lie... that machine is still running lean. I think you're on the right track questioning the tip of the pilot jet/air passages. There has to be something crazy going on because the needle shouldn't be 7.5 turns out and the plug shouldn't look that white.

[krp44994]

OK GOOD NEWS! - I checked the float/gas level in the bowl and determined that it was at -12/14 mm below bowl flange versus spec of -5 mm to +1.5 mm. Disassembled the carb again, completely cleaned and blew out every orifice again (just to be sure) and made and adjustment on the bowl float. Set the pilot screw to a little under 1 5/8 turns and put everthing back together. Also disassembled the intake manifold and inspected the o-rings, flanges etc. The hex bolts were a little loose when I disassembled. Put everything back together, checked my bowl level - it was ~ -5.0 mm. Fired the ATV up and IT RUNS GREAT!! No bogging, hesitation, backfiring at all!! I did inadvertently break the plastic choke cable nut at the threads when I initially assembled but I glued with 2-part epoxy and let it cure overnight just so I could verify that that the bike runs well. New nut is on order of course from local Kawasaki dealer. Gonna "try" JB Weld on the two mystery holes in the head fin area....not sure what else to do other than new head.....and owner will not want to pay that at this time. A little oil appears to be the biggest issue although it seems that this could also be a significant source of contamination for the crankcase?!?! Comments on that? Anyway - want to thank everyone for the posts/suggestions etc these past few weeks. This is a great forum!