I just checked the compression and am getting 100lbs after just a few crank revolutions. I do not have a manual, but wanted to know if this is a good reading or not? Also, I have a gas leak somewhere. I ordered a rebuild kit, but curiousity has gotten the best of me. I removed the carb and plugged off the fuel line. I let it just hang there to see if maybe I had a pin hole in the line somewhere. Nope. Next, I put the carb on the bench and took a piece of fuel line and attached a bottle of fuel to it. It has been sitting for an hour or so, and no leaks. WTF is going on? A week or so ago, I noticed fuel coming out of the overflow on the bottom of the fuel bowl. I removed the bowl and adjusted the float. It doesn't leak out of the valve anymore. I seems to start to lead after I have the quad running. Is there something I am doing wrong here? Hope someone can send me in the right direction. I am also waiting for the rebuild kit (mainly the bowl gasket), but right now it isn't leaking on the bench.

 

100 psi is the bare minimum reading. tip top bore should be around 115 - 120 PSI.
without any pressure on the fuel line there could be a small pin hole in it and when the line moves because its not hooked to the carb anymore it closes it up enough to stop the leak.

 

i forgot to post that i did replace the short line from the fuel filter outlet to the carb inlet. it did have a pin hole. i wanted to reverify that maybe the fuel filter or something else wasn't leaking. I have noticed a little fuel building up at the front of the carb while sitting. There are a series of hole in the face (inlet side) of the carb. the biggest hole appears to have the slightest amount of fuel coming out of it making the front lip of the carb wet. I went ahead and reinstalled the carb and ran it for a while to get it warmed up. so far, no leaks. i may wait to rebuild the motor. this one is for our 13 yr old son and it is his first quad. so maybe a little tired motor to start out might work out for the best. he is already bugging me to ride my vinson, but not yet. he already wrecked on his sisters lt125, so jumping to a bigger quad might be trouble.

 

like i said 100 psi is bare minimum. they will run at pressures lower than that but are usually a pain to get started. it sounds like you might have the float just a little out of wack still. or the needle valve is bad and slowly letting fuel by.

 

with it on the bench, i filled the bowl full through the inlet line with a plastic bottle of fuel and fuel line. i removed the bottle and the line was full of fuel. i next,and don't try this at home kids, blew into the inlet hose. no leak meaning the float is seating. it never did leak down. i left it sit for an hour or so.

 

best way to check the compression is stone cold engine w/ wide open throttle and crank over 5 goos strong pulls on the cord or a few seconds on the starter to get a good true reading. agreed that 100 psi is ok to run and less is no power and hard staritng. did you check the needle and seat when you adjusted the float to make sure it wasnt worn or damaged which could be letting gas seep out? imo.

 

it did show a little wear, but not out of line. i did order the rebuild kit, but i just hate leaving something sitting without exhausting every option. i hate when i have to order parts. the wait is like christmas. you sit and watch the mailman come, but nope, no packages today. sit and wait another day. i have my son's yz80 apart on the lift waiting for a clutch and new tires, but no parts. ups is supposed to bring them monday. just wondering, but where is a good outlet to get a piston and gasket set from? my neighbor's son told me to just re-ring it if the piston looks good. any suggestions? thoughts?

 

a 2 strokes nature is wear anywhere there is friction because of the limited supply of oil. sometimes you can get away with just reringing a 4 cycle motor because it has fresh oil on every stroke. on 2 strokes it wears the rings and the cylinder. if you have a bore mic you could check to see if yo ucould just rering it but the odds are it needs to be bored 1 up to get the compression back. its not a bad deal really. you can get the bore done for generally around 100 bucks and a topend kit (get wiseco pistons) around 120. look on ebay for the top end kit