Honda Spree and Elite 50 Forums

Had low compression and bike wouldnt start so I replaced the rings and gaskets so why am I only getting 70psi compression? I did the compression test right and I carefully honed the cylinder and cleaned off the gasket surfaces and torqued everything down to spec. I dont understand what could have happened.

put a little bit of oil in the spark plug hole and test again.

The cylinder could be out of round or beyond wear specs, did you mic it before honing? how much material did you remove? A ring could have snagged a port and broke, or a ring could be sticking in the groove if not cleaned properly.

Put a little oil in the cyl and see if the numbers come up. Are you doing the compression test with the carb attached? if so open the throttle completely. A fresh engine will not have perfect compression until the rings seat. 70 psi should at least start, try some ether.

Did you ever have the bike running before replacing the rings? Could be another issue altogether.

Make sure the tiny marks found on the rings by the gap are facing up. Sometimes a flashlight makes seeing the marks easier.

Did you hone the cylinder before you installed the new rings? Did you oil the cylinder walls, piston and rings with 2 stroke oil BEFORE you installed the piston in the cylinder?

tricolour wrote:I carefully honed the cylinder

Yes he did bear.

I don't thing I ever heard the term "I carefully honed the cylinder" before. Honing is a semi haphazard process. Did he break a ring while doing the install?

Bear45-70 wrote:I don't thing I ever heard the term "I carefully honed the cylinder" before.

it doesn't seem like he's going to reply

I took the head and cylinder off again and rings are not broken and they are installed the right way up. Yes, everything was oiled up before assembly. The only thing I can think of is that the cylinder is worn out. I don't have a micrometer to test with. I may end up putting the bike up for sale. Surprising thing is it ran great until I put it away for winter 2009 and never started up since.

just curious did you ever try to start it up after you put the rings in... as long as it runs right and making sufficient power who cares what some gauge says

bc117 maybe on to something here. With a fresh hone and new rings (AKA unseated rings) the compression could be low but as long as the engine starts then the seating process begins and the rings will seal better. Question, when you did the compression test, did you have the throttle at WOT?

The initial compression test was around 70psi. When I added some oil to the cylinder, compression jumped up to around 120+ with WOT. It still won't start and run though. It just barely runs with the starter engaged but quits when the starter stops. Throttle position doesn't matter. Still can't figure it out.

For start up with a cold engine the throttle must be closed. Change the plug.

Greetings:

The next thing to check is the crankcase itself. A leaky seal at either end will be obvious as oil misting or leaking from the crank end. If that looks OK, sometimes a cracked reed valve will give low compression and hard starting. Finally the crankcase halves may be leaking from a gasket issue (SE/05) or failed HondaBond. (SA/16)