I just purchased my first quad, its an 87 quad runner 250 4WD. I’m an auto mechanic so I know my way around an engine. Well first off when I got it the fuel pump wasn’t working, I took it apart and cleaned it, and it fired right up. Changed the oil and the diff fluid up front, put a air filter and new plug in it. Pulled the carb out took it apart and cleaned everything and put it back in. I set the motor to tdc and adjusted the valves to .001 on intake and .003 on exhaust. It stoped the rattle in it. Did a compression check with wot and it sat right on 140. What I understand is low. Well after all that it still surges and acts like it wants to bog down, having to downshift, when its held at wot it surges, like it has no power. Pulled the plug out and its solid black. Like I said this is my first quad, just looking for some pointers, and suggestions on how to get it to run properly. Thanks

 

Well I adjusted the valves again, this time the intake to .0035 and the exhaust to .004. It seems to run a bit better, but it still seems to bog down when your going up hill or have two people on it. Is that because the compression is low?

 

I just want to say, thanks for all help... its been great.
I rebuilt the carb, that solved the problem if anyone else is having similar problems.