this mechanic is COMPLETELY stumped... help

[dirt_humper88]

ok i put a simple 440 top end in my 400ex. should have been an easy job, well its all back together and will not start, will fire slightly but not run... every revolution it just goes "plop, plop, plop" just one small ignition of fuel. ive checked the timing probably 8 times, have tried it one tooth advanced, one tooth retarded, no difference. WTF good spark and fuel but i dont just dont get it.... the only thing i seen maybe wierd is the decompression mechanism on the cam, would that have anything to do with it?????? it turns over slow now with a full charge battery, only 10.5;1 nothing to crazy
anyone????

[gojk]

Originally posted by dirt_humper88
ok i put a simple 440 top end in my 400ex. should have been an easy job, well its all back together and will not start, will fire slightly but not run... every revolution it just goes "plop, plop, plop" just one small ignition of fuel. ive checked the timing probably 8 times, have tried it one tooth advanced, one tooth retarded, no difference. WTF good spark and fuel but i dont just dont get it.... the only thing i seen maybe wierd is the decompression mechanism on the cam, would that have anything to do with it?????? it turns over slow now with a full charge battery, only 10.5;1 nothing to crazy
anyone????

What kind of compression are going getting out of it?

Could def be the decompression device. Are running the stock cam? Did you put the spring and plunger back in the head if you had it off?

[dirt_humper88]

10.5 : 1 comp.
stock cam for now, yea i had it oof, which spring/ plunger you tallkin about? dont remember seein anything like that

[gojk]

There is a tiny spring and plunger that goes in the head. More than likely it fell out and that is causing the problem.

And by compression, what PSI(measured with a compression tester), not what CR.

Numbers 4 and 5 in this pic are the spring and plunger. Which you remove if you put in an aftermarket cam. Kinda essential with the stock cam.

[dirt_humper88]

m\ok yea unfortunately i tried gettin a compression reading earlier but i dont have the adapter for a 12mm spark plug, only the lager 14mm i believe... and as far as the plunger goes, i know what your talkin about now, they did fall out and i didnt realize there was a spring and i just put the plunger in the hole, i wasnt sure exactly what it was or did, ut i guess ill look for that spring, thanks a lot, you think thats my problem then?

[dirt_humper88]

hey thanks alot, i searched forever and found that spring on my garage floor and put it in, the damn thing ired right up!!! thanks again man!

[gojk]

Originally posted by dirt_humper88
hey thanks alot, i searched forever and found that spring on my garage floor and put it in, the damn thing ired right up!!! thanks again man!
NP, glad I could help.