total compression loss

[Oldshell4481]

i finally got my recently purchased rebuilt 12:1 compression motor and within the first mile of testing it, she just bogged down, cut out and i lost all compression. it felt just like kicking it without the spark plug in it when i was trying to kick it over,(wouldnt turn over at all of course) what could this be, i dont think its the head gasket, although the only way i ever know the head gasket is blown is if there is leakage around the contact seems of the top end pieces. could toasted rings cause loss of compression??? any other thoughts??

[MTS]

Pop your valve caps and see if they valves are moving when you kick it over, also take the plug out and look in the hole with a flashlight see if the piston is moving while kicking over....if the valves are moving then your piston/rings are Fryed, if they dont move you could have busted a timing chain, what kinda gas did you run in the motor?

[Oldshell4481]

i ran supreme... probably stupid but i didnt think it could hurt for a test run, race gas is hard to access, and if the rings are fried im going to switch over to stock compression.

[Howdy]

Might have just blowed a head gasket. The head gasket could be blowed out inbetween the cam chain and the cylinder.
Howdy

[Maine_Triker]

Might have just blowed a head gasket.
Howdy

That's blown , but yes it does sound like a head gasket to me.

[Oldshell4481]

this is a motor you rebuilt for 90nut by the way howdy.. how do i check for a blown gasket without having to replace my other gaskets (i sound wicked cheap), cuz i really aint looking forward to having to put any money into a 350 dollar motor that was s'posedly freshly rebuilt.

[slothminx]

Another guy on here had a 200x that had just been rebuilt. did that exact same thing, cut out. It was a stuck valve he had to buy a new valve and was up and running again.

[chris200x]

Another guy on here had a 200x that had just been rebuilt. did that exact same thing, cut out. It was a stuck valve he had to buy a new valve and was up and running again.

If I'm thinkin about that same 200x? And really feel bad about that one. Blowfishct bought my 200x that had 0 miles on a rebuild motor. He got it home and in less than a week the valves went on it. I would pull the caps and look there.

[slothminx]

Yep, were thinking of the same 200X. If I remeber right, he couldnt tell it was stuck by taking the valve adjusting caps off. it was head off to see.

[Oldshell4481]

i opened the inspection caps and the rocker arms still pull the valves up, the only thing i can think of is toasted rings or head gasket..

[Howdy]

this is a motor you rebuilt for 90nut by the way howdy.. how do i check for a blown gasket without having to replace my other gaskets (i sound wicked cheap), cuz i really aint looking forward to having to put any money into a 350 dollar motor that was s'posedly freshly rebuilt.

I check for compression leaks using a air hose. I turn the motor over to TDC on the fire stroke and hold it there ( I have various tools and ways to do this ). I then use a set up I have to put 100PSI of air into the cylinder via the spark plug hole. If you have a air leak anywhere it will come out. If air comes through the carb it's the intake valve, Air comes out the exhaust it a exhaust valve, Air comes out inbetween the head and cylinder its a head gasket, and if air comes out the crank case then it's most likely a piston / ring issue.

FYI, I do know it ran good for Cody.
Howdy

[Oldshell4481]

TDC is when the piston is at the top of the cylinder right? ill take my machine up to my friends compressor and see what i can do, could the rocker arms still be closing but the valve be staying stuck open?? or vice versa lifting but the valve still be staying closed??