Hi all, I recently took on the task of tuning up a quad that the LAUSD uses to drag chainlink around the baseball infield. I have experience with these quads cause I have bought them for my kids over the years and if you own one you become familiar with the usual problems associated with them... I have bought 3 (2 110cc and 1 125cc) this is the first one Ive worked on with an auto choke. It cranks, but won't start. I can start it with starting fluid and it runs good when warm but as soon as it cools off, again, won't start. I have dismantled the entire carburetor and cleaned the jets, new fuel filter while I was there, it gets gas, gets spark. Suspiciously though, when it's cold it doesn't matter how long I crank it or give it gas it won't flood... spark plug is dry as a bone. What do you guys think? Bad electric choke?

 

Electric chokes usually are made to give excess fuel unless the alternator is producing power, so you would expect too much fuel all the time if the choke went wrong. A blocked jet is the most likely thing, though the excess fuel device stuck shut is a possibility. Bad starting can be due to low compression, often due to incorrect valve clearances, so check that too. A 150cc bike would seem an odd choice for towing, a circa 300cc utility machine would be better.

 

I agree about the size of the cc's for towing but it was what the school was offered. Since my post I have installed a new PD24J carburetor. Right now it sits with the valve cover off and the flywheel at TDC. I adjusted the valves 3 times last night to .004 intake and .005 exhaust... Strange thing is when I crank the flywheel by hand and recheck the clearance, I can no longer fit the feeler gauge between the stem and the rocker... am I doing something wrong?

Thank you for your response,

 

The valves must be set at TDC on the compression stroke, on the exhaust stroke TDC both valves will be slightly open. How to tell, turn in the direction of rotation, by hand, until inlet valve closes, then the next TDC is compression, or feel the compression rising as you turn by hand, again this TDC is the right one. Has the new carb done any good?

 

Ugh!!! Performed a leak down test today and um well the results were less than promising. I ran compressed air at 55psi and my leak test revealed 8psi. I could feel the air coming out of the exhaust pipe and it hissed and leaked from just about everywhere. I purchased a complete new engine for $365. I know I could have just rebuilt the top end but I removed the CVT cover and found one of the clutch spring had come loose and bounced around causing some damage, plus the starter was questionable +++. So instead of trouble shooting one at a time I just replaced the whole thing. I'm going to put it in today and post my results. Thanks for your help Merryman