have gone 5 years with really no major problems. last weekend I changed the oil,plug and cleaned the carb. Went out for a ride and it stalled cause I see after hitting a bump the carb poped off. i must not have had it on correctly (no glasses at the time). I let out on the winch a few feet and towed it back a few blocks with my golf car then put the carb on and rode it into the shed. went back a few weeks later to make sure it was on right and now it won't start.I have 2 of these quads and they start up always with no problems. I have cleaned the carb, adjusted the valves and the compression seems good. I also have swapped plugs ,swapped to the original carb,swapped coils and cdi's. i can get a little rumble but that is it. i have tried the test from old post (Lynn Edwards),with a volt meter and they seem fine. The only thing i see is maybe a week spark cause it won't even go with starter fluid sprayed in the spark plug hole. I'm thinking maybe the stator or rectifier? Not sure what they really contribute to the spark. The winch I have used before, not for long periods but didn't think that it would hurt anything?
Any help would be great
Tim

 

Whether or not you have weak spark is somewhat subjective. Different people can look at the same spark and come to different conclusions. You have an advantage since you have two identical quads side by side that you can use to compare.

So the question is whether you have weak spark or not. How does the spark compare between your two quads? When you're doing these tests be a skeptic. Imagine you're a consultant hired to determine if the sparks between the two quads are the same or different. If they are different, exactly *how* are they different? If someone were to mix the two quads up and you then were only able to look at the spark (with all the other stuff covered with tarps so there are no other visual clues), would you be able to tell which quad is what? Would you stake your reputation on it?

The stator has 3 separate systems in it. The battery charging system (including the rectifier) has nothing to do with spark, or with starting up your quad unless the battery is so dead the starter doesn't turn fast enough.

The stator also powers the CDI (if your CDI is AC powered), and it always triggers the CDI. The trigger signal is all or nothing. If you're getting spark at all, then you don't have a problem from your trigger pulse coming from the stator. The AC power (if your CDI is AC powered) can be measured. Your said it was "fine", but posted no actual values. I'm a skeptic, as all engineers should be .

Running the winch will only run the battery dead at it's worst (after a lot of winching). If you charge the battery back up promptly (measured in a day or so - not minutes) this is not the issue either.

 

I have had a little time to work on this bike to no luck. It will run for about 15 seconds or so then shuts off. I have a compression reading of 180,have spark(brand new plug),I bought a brand new carb. i have adjusted the valves and even checked a second time to make sure it was right. Not saying that I know alot but I have had these two quads for 5 years and never had any problems with either of them till now. I have adjusted the carbs before but now it is really hard since it doesn't stay running for long. Also drained the tank and put in new gas. I am even killing the jumper box thing from trying so much! Any ideas would be graet.
Tim

 

When it runs for 15 seconds does it rev through the entire RPM range, or does it just cough and sputter for a while near idle?

After sitting a while does it start up quickly again for another 15 seconds and then die?

Have you tried cranking the starter with wide open throttle? If you have too much gas being delivered by the carburetor this will help lean it out.

 

At first it started right up and was actually surging forward for a second then died. Any starts after that were short lived. For some strange reason and this may be that I just had never tried it before but the starter cannot turn the engine over with the throttle open. I had tried while cranking to open the throttle and it will almost stop cranking, then if I let go it will speed back up again. Also this is in just short burst so the starter doesn't over heat. Can't do much with it till Saturday.
Thanks Tim