Alright guys, let's figure this one out. 1991 warrior, ran great last season. Fresh gas, cleaned carb, cleaned/oiled air filter (k&n w/prefilter). Installed HMF exhaust, opened airbox, install pilot jet 45 (stock 42.5) better spring on the accelerator rod, main jet 152 (rec'd by HMF) [stock main was 145], clip down one on needle, 121 psi in cylinder, new plug. Quad starts and idles fine. About 1/4 throttle it bogs all the way to WOT. I pull the plug and carbon fouled. OK, main too fat. Go down to 150, same thing-carbon fouled. Put stock main 145 back in, same thing. Move clip up to stock position to lean it out, no change-bogs sputters from 1/4 throttle to WOT and carbon fouled plug. Choke circuit doesn't seem to be stuck closed or blocked. What am I missing???

 

well im having the same sort of problem with my raptor 08' and i have no ducking clue what it could be.. so if you get it fixed please let me know..

 

is it always easy to start and the spark looks good? possible weak stator, parking brake sensor can cause something close to this but i doubt thats it, also might be your carb has got something funky going on something with the float or chunk of dirt somewhere that youll have a hard time finding. have you checked your timing to make sure timing didnt jump at all?

 

Easy to start. Plug looks good, except for the soot. Haven't checked the stator nor the timing yet. One guy mentioned that it could be the needle and seat are worn slightly allowing extra fuel to pass. Is that another possibility?

 

ooops i meant to say hows the spark look not the spark plug lol, and i guess that needle and seat wearing is possible but i doubt it i know when you buy a jet kit they give you there own needle, so that might help, its good to the kits anyways the needle actually works better then the original one, the 152 jet HMF sends is actually a little to rich, thats one reason why i just got the kit, and i installed i forget which jet but it actually ran better then with the 152, with what you mentioned it almost has to be the carb if the spark it puts out is good also and it has good compression only thing left where a problem could be i would think is the carb.

 

HMF didn't give me any jets, I had to buy them from the local shop. I'll still check the ohms on the stator just to make sure. I'll get a new needle and seat, since I've pulled the carb out about a dozen times already one more won't hurt. It just has the stock needle, any suggestions on an after-market one? I might call Steve Webb at Mikuni and see if he can help.

 

hmm HMF sells pipe kits that includes HMF slip-on, spark arrestor, pipe clamp, stickers and there 152 jet, oh well i guess they sell them separate also. the only brand i have used for aftermaket needles was Dyno-jet and it worked fine, seemed slightly better then my old one, the tip of the aftermarket needle had like a taper on it, might be why it seemed to work better, yea it wouldnt hurt to call up mikuni he might have some positive input on it, i know warrior carbs can really be a pain sometimes.

 

Let me clarify this. HMF didn't include free jets with my order. I could have purchased the jets from them, but I went thru TREMX instead (a little cheaper). I'll look for the Dyno jet needle. Yamaha OEM wants around $70. I'll see what Mikuni has to say, I'm only about 20 minutes from their HQ and I've just walked in off the street and had great service in the past. Thanks for the advice and I'll let everyone know what happens.

 

Ok, here's the update. Had Mikuni look at the carb. They couldn't see anything strange. One suggestion that they had was that maybe the coasting enrichment diaphragm might be bad, but it looks good to me. I put everything back to stock, jets, needle clip position, exhaust, covered the hole I put in to open the airbox and still no change. I checked the resistance on the stator and it looks in spec. Checked the coil and it had ohm readings all over the place, so I'm leaning to the coil as maybe the problem. The spark looks ok, there's spark, but not a big blue one, more of an off yellow/orange and sometimes blue. Haven't checked the timing or valve clearance yet. The only other thing that I can think of is that there is something blocking an air passage in the carb body, but I've cleaned that thing many times. Would the coil cause the problems stated in my thread?

 

it sounds to me like u either have it out of time or u might have a vavle sticking jus some things to check also i was checking mine today and mine has a deep blue spark all the time (mine has been missing a little at about half throttle just checking it) so u might check the stator