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Ok didn't have much time this aft but got the air box off and.......ya full of oil.


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OK, so the source of oil is the dipstick tube. She's flowing out the top pretty good. Does that indicator point to anything in particular?

Stekay wrote:I'd start at the beginning. Compression or preferably a leak down test. Check condition of the plugs as you pull them. A hard run at high RPM could've hurt a piston or rings, or burned a valve. Wishing for the best that it's a clogged breather or something simple.

As Stekay said a compression test or preferably a leak down test. This may help what is causing the excessive crankcase pressure you seem to be experiencing and hopefully rule out Jim's suspicion of washed out cylinders.

Have you pulled and examined the spark plugs yet?

Definite problem with one of the cylinders. Oily and showing signs of backfiring damage

edzz wrote:

Stekay wrote:I'd start at the beginning. Compression or preferably a leak down test. Check condition of the plugs as you pull them. A hard run at high RPM could've hurt a piston or rings, or burned a valve. Wishing for the best that it's a clogged breather or something simple.

As Stekay said a compression test or preferably a leak down test. This may help what is causing the excessive crankcase pressure you seem to be experiencing and hopefully rule out Jim's suspicion of washed out cylinders.

Have you pulled and examined the spark plugs yet?

Ya compression test is next. One plug is a real mess.

Just picked up a compression tester kit, will be working on it this week or weekend. I pulled all of the plugs (had to buy a generic 13/16 lawn mower tool to get them all out). 2nd cylinder is the only one producing an oil soaked and damaged spark plug. The rest look good and uniform.

I will check out the compression numbers on all cylinders and post up results.

tx Dave

Ok, she slept for the winter, but is slated for compression testing this weekend, Saturday I figure. Wish me luck.....

Ok, so compression test done, #1 - 135, #2 - 0, #3- 125, #4 - 135.

So #2 has a serious problem! Anyway, going to get some compressed air in there and see where the leak is from (under the guidance of my mechanic brother in law, of course).

Parts order from EI coming by the end of next week I'm sure!

tx Dave

ok, so as previously mentioned, the second cylinder from the front was 0 on the compression test. We put some compressed air in there and had a lot of bypass coming out the oil filler tube and nowhere else. Pulled the head and cylinder and voila! A nicely F'd piston.

So, when replacing the piston and cylinder (I know I can hone the cylinder, but for arguments sake, lets say I'm replacing both), does it matter if I use a 92MM, 92.5mm or 93mm, as long as the piston and cylinder match? Do I need to match them to the remaining 3?

tx Dave

Here are the pics of the culprit

Also, I'm guessing that I need to buy a tool to remove the piston, is there are common variant?

I wonder what would cause a failure like that? Did a part of the piston break off and hammer the cylinder?
You should go with the same size piston and cylinder as stock to keep the engine in balance. The piston/rings and rod assemblies should all weigh the same, so if you go with 92.5 or 93 mm pistons you could have vibration problems or bearing failure eventually.

Thanks, yes, I've established that I need 92mm and have ordered that. As for cause, still trying to figure that one out. looks like the piece of the piston did detonate, not sure the cause. Valves are all good, so heat is likely not the issue. Oil is fresh and in good supply. :?: :?: :?:

No special tools to remove the piston. Just remove the retainer and slide the pin out, you will have to remove the #1 piston to remove the bad #2 piston. If the pin is stuck, use a nut and long bolt through the pin and pull it out.

Jim LaGuardia wrote:No special tools to remove the piston. Just remove the retainer and slide the pin out, you will have to remove the #1 piston to remove the bad #2 piston. If the pin is stuck, use a nut and long bolt through the pin and pull it out.

Thanks Jim, I was wondering if I had to remove any other pistons. A great help as always!