predator no compression help??

[Latent]

ahhh thats unfortunate!

 

[93notch408]

nothing a lil hone won't fix and a new set of rings

 

[youngengines]

I still dont think it should have had no compression. It wouldnt crank? Better check everything.

 

[Stephen115]

^ I agree, I burned up a rod and burned the crap out of the stock piston. No cylinder damage and I still had compression.

 

[125ccCrazy]

I agree^^^......... that's pretty scored up but if it ran before you swapped heads then the cylinder isn't the main problem....I've seen pistons alot worse than that and the engine still ran...

 

[Stephen115]

Have you tried putting your stock head back on? If so excuse my question
I suggest you get in touch with the person that did your head, its more than likely a leak.

 

[Latent]

Defiantly agree with the posts above me, its most likely compression leaking your cylinder head some how. Turn the engine off pull the cord and try to feel for air pressure leaving the cylinder.

 

[93notch408]

I put the stock head back on it and it did the same thing so I dont kno

 

[cheezy1]

Check the case bearings, a seal could be leaking. have you taken out the stock low oil sensor bolt and replaced it with something? that could be causing leaks. I agree with the post above, just feel around for leaks, you'll be able to feel them.

Crazy question...what does that have to do with leaking compression?

 

[Stephen115]

Crazy question...what does that have to do with leaking compression?

true, I wasn't thinking haha.

 

[cheezy1]

true, I wasn't thinking haha.

:laugh:....I was curious to your answer.

 

[125ccCrazy]

Crazy question...what does that have to do with leaking compression?

big issue on 2 strokes but mostly a mess on 4 strokes...:doah:

 

[cheezy1]

big issue on 2 strokes but mostly a mess on 4 strokes...:doah:

I know that:laugh:..but I meant the issue at hand with no compression above the rings area.

 

[clintonior]

your Pic is alittle grainy but. here goes pointing out the obvious but where are the two upper piston rings? did you take them off for the photo? got a cigar use smoke to find the leaks old trick.. that scratch would clean up with steel wool/emery cloth I don't think that piston looks that bad mabye its the pic ? just looks like it got scratced when the ring draged across it when someone removed it. I have a RM250 it runs mint on an used ebay top end came with the used piston 50+ horse gas isn't gonna care. fuel, air, compression, spark your missing one... take some 180 and put a crosshatch on that piston go diagonal from two 45 deg angles for oil retention and put the rings on it correctly or get some new ones. put that head on insall the spark plug an try it before you put in the rockers. put a teaspoon of oil down the plug hole put plug back in and try it again.

 

[93notch408]

FIXED!!! i put some new rings in it and ran a ball hone thru it and it seals now thx for the help guys!

 

[125ccCrazy]

I know that:laugh:..but I meant the issue at hand with no compression above the rings area.

LOL I know...just commenting..

FIXED!!! i put some new rings in it and ran a ball hone thru it and it seals now thx for the help guys!

Hard to believe the rings were leaking bad enough that it wouldn't run unless the gaps were lined up..... it didn't look too extremely terrible.. :shrug:

did you put stock rings or file fit back in it?

 

[93notch408]

rings

stock...and i put the stock head back on it with the hunter roller rockers and chromo pushrods it could been the head but since it was apart i over hauled it anyway lol

LOL I know...just commenting..

Hard to believe the rings were leaking bad enough that it wouldn't run unless the gaps were lined up..... it didn't look too extremely terrible.. :shrug:

did you put stock rings or file fit back in it?