440ex not running

[saul069]

I have an 03 400ex that I just got done doing a 440 kit to. 11:1 piston, port and polished head with over sized valves, hotcam stage, 2 yoshi carbon full exh, hotrod crank, and sparks racing rev box. I can't get it to start not even a pop. I have spark and gas on the plug and have checked cam timing 3 times now. Do I need to run a different spark plug with higher compression. any help would be great.

[AR15 guy]

If you are getting good spark and gas then the only thing missing is compression.

Or installed the kit?

[Wheelie]

Did you check cam timing or ignition timing? Check the flywheel key--see if it sheared. Check the cam timing and valve clearances.

FYI--In my stroker w/11.3:1 comp I run a NGK DPR9Z--one heat range cooler than stock.

[Groundworx]

I am really not familiar with the internals of a 400EX, but the guy I bought mine from put an 11:1 piston in it. He said he couldn't get his it to start after he installed it. He told me he ended up taking off the compression release on the cam and it has been fine ever since. I don't know if you have that since you have an aftermarket cam, but that is what he told me. He had gas and spark, but couldn't get it to start.

[GPracer2500]

Originally posted by Groundworx
I am really not familiar with the internals of a 400EX, but the guy I bought mine from put an 11:1 piston in it. He said he couldn't get his it to start after he installed it. He told me he ended up taking off the compression release on the cam and it has been fine ever since. I don't know if you have that since you have an aftermarket cam, but that is what he told me. He had gas and spark, but couldn't get it to start.

In that case, it wouldn't start because he neglected to install the auto-decomp spring and plunger in the head. The stock cam needs those pieces for the auto-decomp to work properly. Without them the engine will not start and they are sometimes overlooked. Since saul069 has an aftermarket cam without the auto-decomp (I assume) then that shouldn't be his issue. Good idea though...

Saul069, if you have a timing light--that's an easy way to check that the ignition is operating normally (i.e. timed correctly). I'd check the compression too. Try spraying starter fluid through the carb and see if anything happens.

[saul069]

Thanks for all the help guys. the bran new spark plug that I had bought was bad. Tried another new plug works great.

[Groundworx]

At least it was something simple :p