GS550ES Pistons

[86GS550ES]

I am wondering if anyone knows if there is a Suzuki piston that will fit in my 86 GS550ES. I have blow-by issues and I have a hunch my cylinders are starting to wear. My biggest problem is that nobody seems to have any pistons for this engine. Any help will be greatly appreciated. Thanks!

[Nessism]

Suzuki sells oversize pistons and rings, although they are not cheap – about $100/hole. You might be better off finding a low mileage cylinder/pistons off ebay and then installing new OE rings.

[tkent02]

Go with a 650 top end.

[almarconi]

I have blow-by issues and I have a hunch my cylinders are starting to wear.

And how did you determine that? Did you take any measurements or do any tests??

[Nessism]

Go with a 650 top end.

Good idea except we are talking about the second generation 16v 550 here.

[86GS550ES]

I do like the idea of the low mileage piston/cylinder approach. I checked at a Suzuki dealership here in Mankato, MN, and pistons are discontinued. My bike is pulling oil through the pcv tube into the airbox, plus it will lose 1 quart of oil every 450 or so miles. I know a little oil in the pcv tube is normal, but losing that much oil when it doesn't leak anywhere else to me means the rings don't seal properly. I could be wrong, the rings might just be bad. After all, the bike is 23 years old. Things wear out. I just need to find a compression tester that will work with my metric plugs. What is the cylinder pressure supposed to be on these bikes?

[Nessism]

I think you need to find a new dealer. Pistons and rings are showing as available on-line.

[tkent02]

I could be wrong, the rings might just be bad. After all, the bike is 23 years old. Things wear out.

Unless it is well over 100,000 miles I would guess it never sealed due to taking it easy on break in, but that would only be a guess.

How is the compression?

[Steve]

I just need to find a compression tester that will work with my metric plugs.

Did you by chance realize that virtually ALL spark plugs in use today are metric?

Yep, they are either 10, 12, 14 or 18 mm.

In the NGK plugs that so many of us use, the first letter is the thread size:
A = 18mm
B = 14mm
C = 10mm
D = 12mm
J = 12 mm

.

[86GS550ES]

I didn't know about the metric spark plug commonality. Thanks for the info! I don't know my compression right now as I currently have no way to test it.