sudden compression drop?

[cubinzkid]

I was riding along, and all of a sudden my shee dies. Top end has maybe 10 hours on it. Cleaned the carbs about 3 times, removed tors, have spark, could it be compression? Where could I get a compression tester? and if the new topend was needed, wouldnt it be just rings and gaskets?

thanks guys.

[cubinzkid]

also, every 4th kick it like sputters like its starting, but it wont turn over.

[shustack]

I got my compression tester at Advanced Auto, $20 bucks well spent

[cubinzkid]

okay, whereabouts should I be running?

[HolySheet]

120 or higher. Less then 110 rebuild.

[cubinzkid]

Okay, and what about it trying to start every 4th kick?

[WINDYCITYJOHN400]

On a fresh re-build......I can't tell you how many flywheels I've heard of that came loose.....

Just pointing out something to check on.

If you lost compression in 10 hours.......you forgot to mix oil in your gas.

I'm betting it's not compression.

[trickedcarbine]

120psi +

[So Cal Suspension]

Have you checked your reeds? Sounds like a broken/missing reed petal.

[cubinzkid]

I have 29 PSI, of compression in cylinder A, and 30, in B. I've been running a 32:1 with Lucas Oil Semi Synthetic. I tested it with two different testers. I also pulled my reeds, no issues there. Should I pull my cylinders and check them out? Or order a flywheel puller, and go down that road?

[cubinzkid]

Is it a possibility that one of my bolts came un torqued?

[Top Fuel Bender]

wayyyyy too low

either hole in both pistons/cracked rings (unlikely) or blew headgaket

which head do you have?

doesn't take much to pull the head (coolant, plug wires and a few nuts)

 

and/or pull the carbs and reeds and check the pistons 

but I'd start with the head 1st

[Top Fuel Bender]

in the 1st 10hrs of running did you check your plugs at all?

 

who did the "top end" and what all was done?

I'm assuming compression wasn't checked after overhaul

[hercalmighty]

Before you tear down the motor do a leak down test. If you have an air leak you will smoke the motor in no time.

[cubinzkid]

I pulled the head, before I read your post hercalmighty, but 3 of my studs came with my bolts. I'm gonna go get a good set of cometic gaskets and 3 new studs from the shop tomorrow. I just put new plugs in 2 hours ago. Pistons and cylinders look good, and the rings are still expanding. When the top end was done, the cylinders were bored and honed, by a professional, with new pistons and rings and gaskets. I think it was my headgasket.