i redid the whole motor new crank, crank bearings and seals, new top end with new cylinder, new starter and new battery. battery is fully charged and with the spark plug in it will trip the starter after about a full rotation of the crank. it cranks over just fine with no spark plug in it. it seems like it builds so much compression that the starter cant crank it over which its one i got off ebay and its bigger than the stock starter on the quad. also i got a new petcock and it dont have the prime on it its just an on/off/reserve style and blocked off the oil injection and all the hoses that are not needed on the carb. im at a loss on what could be going on here so any input would be appreciated

thanks kirk

 

Check your battery voltage while cranking, should stay in the high 11's ie 11.8
Does it get better with a boost battery on it. Do any of the wires get hot while cranking?
Also measure your voltage at the starter.
Jack say the starters are usually quite robust on these and turn the hi compression race motors just fine.
What is the compression level, stock is in the 125 or 130 range
If

 

Welcome to the forums Kirk.
If after checking the previous reply's recommendations and all is well, I think you may have a bad starter.
I've had a few of the china starters and I have had 1 bad one.