It just wont run right...I've tried everything

[warrior dude 82]

Hey guys I got a good one for ya. I have an 87 warrior with the J.E. 366 10.5:1 piston, stage 1 hot cam, cluth cover oil cooler, and all the bolt on goodies. I love this quad but a couple months ago it started running bad and I cant figure it out.
It has 200 psi compression, valve timing is correct, valve clearance is correct, even checked ignition timing with a timing light, I have had 3 different carbs on it and it runs the same every time, stator checks out ok and woodruff key is not sheared off, I have also had 2 different cdi boxes on it and 3 different ignition coils and it still wont run good.
It runs really bad but idles great, the only way i can describe it is a horrible mis-fire at any throttle opening it almost feels like a V-8 car running on 4 cylinders, it pops and bangs and wont accept throttle at all. The plug looks rich and I have ran it with the air filter off and it ran the same, Actually it runs like its got a plugged air filter but I have cleaned it and also drained the fuel and refilled with different thinking i got bad fuel.
I consider myself a good, professional technician I have worked at several automobile and motorcycle dealership service departments and I really cant figure this thing out.
Please help me out guys

 

[1998yamahawarrior]

Have you gone thru the wiring. Is the parking brake and clutch sensors bypassed?

 

[buzzy613]

is the carb clean?

 

[DeadLastRacing]

Carb boot rip/tear?

 

[jasonp]

Have you gone thru the wiring. Is the parking brake and clutch sensors bypassed?

+1.

Sounds to me like something electrical.. if it idles great but doesn't take throttle and acts like the limiter I would say it's a parking brake limiter that is coming on.

Edit: I've also had my bike do this with a bad stator pickup coil. The stupid thing checked out ok as well.

 

[1998yamahawarrior]

Edit: I've also had my bike do this with a bad stator pickup coil. The stupid thing checked out ok as well.

+1 there the stator I originally got for the yellow one was like that. Tested good for a week and then showed its true colors.

 

[MotoArts]

200psi compression? Holy shizz! I don't know exactly what it's supposed to be, but it sounds a bit high. Especially for an engine with a performance cam (extra valve overlap should bleed off some static compression compared to a stock cam).

Has the valve lash ever gone way loose?

Is it hard to start, as in does the starter motor have a tough time turning it over on first compression stroke? Mine had a wiped stock cam and rockers, and even though the lash was OK it seemed like the starter or battery was weak. Replaced it with a good used stock cam and now all is well.

Even though the valve lash has been checked, I'd probably take a peek at the cam lobes themselves just for fun. Just a wild guess, but if lobes are wiped it may contribute to that 200# deal due to lack of lift and overlap.

Otherwise, I like the bad electronics/grounds/parking brake diagnosis.

 

[Neverdone]

mine was doing the same thing.......

I never found the actual cause, but I did get it to go away. When you had the timing light on it, did you throttle up and watch it? That is how I found my problem. When I throttled it up the spark started dropping out like it was hitting a rev limiter.

All I did to get it to quit was took apart all of the electrical connections, ALL OF THEM. Used a good electronics spray and cleaned them out. Then took a small file (torch cleaning tips) and scuffed them up in case there was something on the contacts. Then put contact grease on all connections and plugged it back together and viola the problem was gone and it has been running great for the last week since I did it.

Hope that helps......

 

[duneracerweston]

Had a warrior do exactly what you say its doing and everything checks out fine but on the wiring harness were it comes out the stator rubbed a bear spot on the frame and the fire wire to the coil was grounding out on the frame wen it was above idel duck tape or electrical tape fixed it fine

To check and see if that's your problem have sore one stuff there hand in there and move the wires enough to keep the wires from touching the frame and it it will revv then that's ur problem

You will have to pull the rear fenders off to be able to get to it to fix it but that's what it sounds like to me

 

[jasonp]

200psi compression? Holy shizz! I don't know exactly what it's supposed to be, but it sounds a bit high. Especially for an engine with a performance cam (extra valve overlap should bleed off some static compression compared to a stock cam).

Has the valve lash ever gone way loose?

Is it hard to start, as in does the starter motor have a tough time turning it over on first compression stroke? Mine had a wiped stock cam and rockers, and even though the lash was OK it seemed like the starter or battery was weak. Replaced it with a good used stock cam and now all is well.

Even though the valve lash has been checked, I'd probably take a peek at the cam lobes themselves just for fun. Just a wild guess, but if lobes are wiped it may contribute to that 200# deal due to lack of lift and overlap.

Otherwise, I like the bad electronics/grounds/parking brake diagnosis.

For the JE piston 185-225 psi is what I've seen.

I have about 200 psi with my mega .450 cam.

One thing you can try is unplug the charging side (3 white wires) of the stator plug to make sure it's not a rectifier