Here is the full story of what is going on. I just purchased this quad on Saturday. I didn't get to ride it when I bought it, but it did startup (I got it really cheap so I wasn't asking too many questions at the time). I got it home and it started really hard, but once it started I was able to ride it, it bogged in the low rpm range, but had great power at the top end. I figured this was a jetting issue, so I pulled the carb and checked it out. The only thing not stock for jetting was the main jet was a 160, so I figured it was too rich, but now knowing the pipe is an HPD, it may or may not be right. After I put it back together this morning it started fairly easily, and I was able to ride it again (ran the same as before), but after getting back, and shutting it off and restarting it, the bogging is worse, and actually kills the engine so I can't get it rolling at all. It is still that way now. It starts quite easily, and idles fine, but if I advance the throttle more than about 1/8 to 1/4 it's travel and it bogs so badly the engine dies. I am really hoping to figure this out so I don't have to resort to taking it into the dealer, but I may have to.

Thanks,
Bruce

 

This morning I pulled the carb from my Trail Boss (known good), and mounted it on the Trail Blazer. I still have exactly the same problem.

The part I am not getting is why there is suction at the intake at idle, but pressure if I advance the throttle. It is almost as if the carb airflow reverses.

The only thing I can think of at this point is the check valve. Is it possible for a malfunctioning check valve to cause something like this?

Bruce

 

sounds like ur gonna have to tear the engine apart. dont no if this would be it but maybe the piston is backwards if the person did a rebuild or the rings are getting stuf causing it to bog at lower rpms

 

to add to what tbsleeper said and i dont know if it will change anything but maybe the rings are upside down. i cant remeber off hand what side goes up but im am pretty sure that its the number side of the ring that should be up. good luck, hope u can fix it. by the way look for cracks around the cylinder and stuff, i dont know if any of this would cause your problem but im just throwin ideas out. scott

 

Thanks for the tips. I can see the piston is in properly (the ports are visible through the intake), but I will have to pull it apart to check the rings.

Bruce

 

It could be the limiter same thing happened to me. I unplugged the reverse limiter and it ran fine maybe you should try that. Does it rev fine in neutral?

 

my guess is throttle problems, call your dealer or A DEALER or someone with knowledge on the ETC and explain the problem to them.

 

I decided to compare the pistons on both the Trail Blazer, and my Trail Boss by looking through the intake. On the Trail Boss I can just see a solid sided piston skirt, but on the Trail Blazer I see two ports cut into the side of the piston skirt. Unless they changed something between 1992 and 2000 on the 250 engine, I am now assuming the Piston is in backwards. Am I correct on assuming this?

Bruce

 

no the trailblazer has two intake wholes that are seperated by a divider thing

 

So the Trail Blazer and Trail boss use different pistons?