95 speedster compression problem

[seadoobie]

I took a compression test today, and the results are...first engine: cyl. #1 @ 150psi, cyl. #2 @ 240psi......second engine: cyl. #1 @ 150psi, cyl. #2 @ 150psi.

Needless to say I'm worried about the cyl. pushing 240psi. I did spray wd40 into the cylinders & spun them around a few times before the test, but the others are coming up normal. From what I know both engines were rebuilt, started & run for awhile 2 years ago with no problems, then winterized & stored. So I'm probably looking at tearing down a engine here and making that cylinder right. Any ideas or advise appreciated!!

 

[Dr Honda]

You can't get real compression numbers with "Wet" cylinders. BUT... if it has been sitting for a while... oil could have wept past the center seals, and filled that one jug. Pull the spark plugs out, and crank it, to clear out the extra oil. Then... start the engine, and let it run for 30 seconds or so, to purge out any extra oil. Then check the compression again.

 

[seadoobie]

Yeah I did try spinning it over a few times but nothing but wd40 came out. I retested all the cylinders to make sure it wasnt the gauge as well, and got the same numbers. I was planning on starting and running it ,then see if it clears up. 1 question though..is the high psi cyl. in danger of meltdown if started?

 

[Dr Honda]

The spec for that engine is 150 psi. The only way it can be up at 250 PSI, is if that jug is full of oil. It needs cleared, and started to get it out.

If it's cranking over, and the piston isn't physically hitting the head (internally) I would start it. Once it runs for 15 to 30 seconds, you will burn out the extra oil and WD40... and you will get a real compression number. Even the WD40 will give you false numbers. It will help seal bad rings.

A compression check needs to be done on a cold, "Dry" engine... with the throttle held open.

 

[Dr Honda]

Also... if ANYTHING came out the sparkplug holes at cranking speed... then there is too much junk down in the crankcase. The only way to clear it is to run it.

 

[seadoobie]

Yeah alot of oil/wd40 & some carbon came out the plug hole ,and I'm able to turn it over with the plug in it now, before it wouldnt. I have to wait to fire it up since I have to drain the oil tank & lines. (I have no idea what type of 2 stroke oil is in it.) I was thinking of putting a squirt of gas down the carb & spinning the engines again to break the oil up some & clean what excess I can in the mean time.

 

[seadoobie]

So would it be safe at this point to pinch the oil lines off & run some pre-mix through the tank to get it going now & blow the rest of the stuff out? and is a 4:1 ok ratio to do this? (4oz. of 2 stroke oil to 1 gallon gas). Also if its leaking past the center seal ,how long do I have till it needs to be replaced?

 

[seadoobie]

So I got them started today & alot of oil flushed out the driver side exhaust. There running ok at idle, but when I throttle up the engines bog down.
Its probably still really loaded up with crap, and I'll have to run them more to clear it all out before taking it out on the water.
So will the center seal re-seat or do I need to get a new one put in it soon? I would hate to have to go through this again every few weeks!