i messed with this thing again today and i tried to watch the carb as i tried to keep it running and it seems like it is trying to blow the gas out of the carb as i throttled
it. if that seems possible. would it still start and try to run if it is 180 degrees out of
time? was going to buy a new engine but they r expensive so still gonna try and get this one going.

 

Can you get the valve timing off by 180 degrees? I don't think so, but I'm not an expert in this. On a car if you get the camshaft off 180 degrees the ignition spark occurs on the exhaust stroke instead of the compression stroke. But on a quad the ignition fires on both the exhaust and compression stroke so it shouldn't matter. Firing the spark plug on the exhaust stroke does absolutely nothing, nor does it hurt anything, but it does make the design of the ignition system a lot simpler.

But I'm wondering what happens if the valve timing is off by 1 chain link? I'm not sure if the engine would start at all, but if it did it would sure run terrible. It might even blow gas back out the carburetor. I've no experience in this, so other members feel free to shoot my ideas down if they don't make sense.

Have you measured your compression?

 

compression is between 120-125

 

What did you set the valves at? Since you had the cam out of the engine...it it could be out 180 degrees..but 180 shouldnt hurt, Im not even sure how youed know if you were 180 out.(gonna think about that a bit more).. but if your off 1 tooth it could cause the symptom your describing..

 

If your blowing fuel back through the carb it's got to be because the intake valve is open (maybe only part way) on the up stroke of the piston. Things that come to mind are 1 tooth off on the timing, poorly adjusted valve clearence and bent valve stem.

 

i didnt touch the cam or valves i basically just replace rings and gaskets and put head back on and got timing details off internet but i will try to adjust the chain by
one tooth and see if that helps. i will keep you guys posted.
thanks for the replys and again it is greatly appreciated

 

You did loosen and remove the cam and then reassemble and tighten everything down again.. I would recheck the cam location.. dont move it unless its wrong.. I would also check the valves just to be sure... .004 at the TDC after the intake valves close...

 

i will check that also and thanks again

 

So does anybody have any idea on the compression of 120-125 PSI? I have absolutely no experience on this but I'm curious. From all my reading on the internet I think this is on the low side. Has anyone measured their 110cc machine for compression?

I'm really familiar with electrical stuff, but have limited experience with actual engine work. I'm sure I will get some as my quad ages, but right now mine (and my neighbors) quad just keeps running and running.

The rule of thumb for compression (in PSI) is 15 to 20 times the compression ratio. If the compresion ratios is 8.1 then the compression should be 121 to 162. These are new rings so I would think the high side numbers would be more appropriate. But this is all theory..

What's the difference between theory and the real world? Nothing! (in theory)....

 

I checked my son's 110 this morning dry it was 120.