[Just some guy]

Hey guys,
I recently picked up a fourtrax 300. It was running a week ago. It has compression, it has spark, it has fuel, it has a new plug, and valves are where they need to be. It still won't run. I am at a lost. I don't know what else to check. Can someone PLEASE HELP?

 

[fishfiles]

Maybe the timing jumped from a worn chain

 

[Just some guy]

I was thinking that or a sheared flywheel key. If I can ever get the dang shift lever off I was going to remove the stator cover and look. I kinda got a glance at timing chain through the valve inspection cover. How much play should be on the chain with a properly working tensioner. I know more about cars than four wheelers so I'm kinda learning on the fly.

 

[Goober]

No I would think oil overheating system or CDI first. Do the diagnostics in the manual
Download the service manual and check parts links in my signature block below

 

[fishfiles]

How much play should be on the chain with a properly working tensioner.

You take out the chain adjuster , that will let it spring out, then you put the adjuster back into the hole it came out of , there should be a about 1/4 -3/8 inch gap between the base of the adjuster and the jug , if the base of the adjuster touches the jug , either the chain is worn or the adjuster bad

You say you have spark , fuel an compression --------- can you feel a suck and push with your finger over the spark plug hole

 

[Just some guy]

No I would think oil overheating system or CDI first. Do the diagnostics in the manual
Download the service manual and check parts links in my signature block below

If I'm getting a good spark how could it be the CDI?

 

[Just some guy]

You take out the chain adjuster , that will let it spring out, then you put the adjuster back into the hole it came out of , there should be a about 1/4 -3/8 inch gap between the base of the adjuster and the jug , if the base of the adjuster touches the jug , either the chain is worn or the adjuster bad

You say you have spark , fuel an compression --------- can you feel a suck and push with your finger over the spark plug hole

Thanks for that information. Yes, I put finger over the hole and it about wants to suck it in there then blows it right off.

 

[Goober]

Oh i read it wrong i thot you didn’t have spark.

is your plug wet with fuel or no?
Have to tried shooting a squirt of starter fluid in the carb and then try to start?

 

[Just some guy]

I have tried carb cleaner, ether, and gas in the cylinder and nothing. That's why I believe the timing is off or the flywheel key is sheared. I have gotten a couple back fires through the carb but that's it.

 

[Andy Bauska]

Na the timing chain could not jump off, and have good compression. The timing chain slipped of the cam gear in my '93 300 and it had next to no compression, later I found out my exhaust valve was bent. Try cleaning the carb. I really don't think it is timing. When it ran did the chain slap? also is the tensioner all the way in?