compression...sucks not blows?

[not2hi]

Just completed the rebuild of our 300EX with a new (used) bottom end, cylinder hone and new rings...this is a Pro-X stock compression piston, cylinder is bored .020 over

She won't start, turns over strong but won't fire...good spark, maybe too much fuel...but anyways...

The manual says to test the compression, take the plug out and ground it to the head, then put your finger over the plug hole and crank it, and it should blow your finger off...ours seems to actually suck your finger in!

what is the cause of this?

timing (though i've checked this 3 times!)?

THX

[balls2da-wall]

bent valve...atleast thats what happened to me

[dober250R]

go to an auto parts store and buy a compression tester. You have a four stroke, that could have been on a non fire stroke or somethin. I recommend a compression tester.

[Toadz400]

Timing is off, check it again.

[balls2da-wall]

180degrees off sounds like...so really your timing could be on just not on the right side:D

[400ex2072]

Originally posted by balls2da-wall
180degrees off sounds like...so really your timing could be on just not on the right side:D

Yup, thats what it sounds like to me. Rotate the engine over one more time and then reset the timing