400ex wont crank, Read info

[Js7bla]

ok here it is, my 400ex stripped the cylinder studs and sit for about 3 months, weill i just went and bought a new 440ex cylinder, put it on and now it wont crank, it was running perfect before it stripped the studs, i rechecked the timing its in time, checked the spark plug it sparking, its getting gas to the carb, i held the gas down trying to foul the spark plug but the plug never got wet, ive put to diffent rev boxes on it and still wont crank, i havent put a compression gauge on it yet put it sounds like it got alot of compression, i dont see how the valves could be bent as it was running perfect before the studs stripped but thats the only thing i havent checked, any help i would really appricate it, thanks

[CJM]

Cranking is the engine turning over, not firing is cranking (what you have going on) is the engine turning over but never catching (least I thinkt hats what you mean).

The plugs sparking, you have gas, and the timing is correct.

That leads me to believe the following:
-The gas is no good, replace with fresh gas and clean carb to be sure it snot all gummed up.
-Although you think the timing is good, its not. When reinstalling the cam the lobes must be face down and the cam gear must line up with the cylinder using the indicator lines
-The valves arent adjusted right.

before you go crazy trying everything, get some starting fluid and remove the air filter. Spray it in while your trying to turn it over, it fires you know the gas is bad or the carbs gummed up or both.

[Js7bla]

i have replaced the gas with good gas, i miced the valves, i timed it on top dead center with the cam lobes down, the t lined up with the line and the side cover and the lines on the cam sprocket, the moter turns over perfect it just will not catch or even act like its going to crank, idk what to do except check the valve to see if there bent but i dont think its them because it was running fine before i parked it

[CJM]

When cranking over does it make a glug glug noise, like the engine doesnt sound quite right?

A friend of mine had the timing chain tensioner go bad and actually the chain itself stretched. The motor would crank but sounded awful and wouldnt fire.

Im not sure what else to suggest as it seems everything else is in line.

[smithersusmc]

I am going to throw in my thoughts on what the problem might be.

If you run any gas with ethanol, the gas will go bad in a very short amount of time( 30 days or more).

Every quad I have worked on in the last 6 months, I have had to clean the carb. Each one took at least 1 can of carb cleaner. Pull the carb apart and take out all the jets( pilot and main) blow them out with carb cleaner till they flow freely.

Most importantly pull out the Air Fuel screw all the way and clean it and the hole it came out of. This has been the main problem with getting these things to start and idle after cleaning. Start with 2 1/2 to 3 turns out on the screw and adjust from there.

I hope that this helps. I am not claiming to know what exactly is your problem. I am not there looking at it. If you need anything else let us know we will help you.

Dave

[Js7bla]

well after many hours of looking over stuff we figured it out, if you pulled it off it crunk right up, so i went and bought a new starter and cranks right up, thats the last thing i would of thought it was, the stsrter sounded fine no noise or any thing but thanks for all the help

[smithersusmc]

I am glad you got it fixed. Happy Riding!