2 stroke crank seals, what r the signs....

**boyoboy** · 05-06-2008, 10:33 AM

good day, can anyone tell me the signs/symptoms that a 2 strokes crank seals are going/gone? please feel free to debate, i would like several opinions.
thanks all.

**RonnieRev** · 05-06-2008, 10:37 AM

The most common sympton is the clyinder with the bad seal wont fire at idle, at higher rpm the cylinder will kick in.

**bitzz** · 05-06-2008, 10:38 AM

Lousy idle, screams at top end, plugs show lean after screaming at top end.

The BEST sign that your seals are gone is failure of a leakdown test.

**boyoboy** · 05-06-2008, 10:41 AM

Originally Posted by bitzz

Lousy idle, screams at top end, plugs show lean after screaming at top end.

The BEST sign that your seals are gone is failure of a leakdown test.

leak down test!that costs money. and this backyard mechanic has a cheap gene. lol. keep the opinions coming-but i see the two first are quite similar so ....

**bitzz** · 05-06-2008, 10:54 AM

Originally Posted by boyoboy

leak down test!that costs money. and this backyard mechanic has a cheap gene. lol. keep the opinions coming-but i see the two first are quite similar so ....

A couple of plates and a $3 pressure gauge is too much money?

Anything else is speculation.

**nokturnal** · 05-06-2008, 12:38 PM

what kind of bike?

I know on an RZ350 if it is a leaky right side (clutch) then you will suck in tranny oil and your right pipe will smoke like a mother.... If it is the left side, then a high idle (or top end screamer as above)... or a locked rear wheel at 80mph, followed by a lot of swearing (then crying).

TRY THIS TEST AT YOUR OWN RISK, I HAVE NEVER TRIED IT ONLY READ ABOUT IT ON THE NET-

when idling, use an unlit propane torch, and try sending some unlit propane behind the flywheel, if the idle goes up, you're sucking in air.

I would imagine you could do the same at the intake manifold.

... or you could just do a leakdown test.

http://atv.off-road.com/atv/article/....jsp?id=190479

**RonnieRev** · 05-06-2008, 01:15 PM

boyocoy, What are the problem(s) you are having with your bike?

**boyoboy** · 05-06-2008, 02:20 PM

actually, its not my bike. its a bike i may consider for purchase. older 125cc dirt bike, 70's, rare, honda, and i just wanted to inform myself before going to check it out.

how much would a shop charge to do a leak down test?

and thanks all for letting me pick your brains - great information!

**boyoboy** · 05-06-2008, 02:27 PM

Originally Posted by bitzz

A couple of plates and a $3 pressure gauge is too much money?

Anything else is speculation.

hmmm $3....now your talking my language! any chance you know a website that could instruct me on the procedure, and how to interprAte the results?

**RonnieRev** · 05-06-2008, 02:35 PM

you could do a google search and see what you come up with. its not really a leak down test you want to perform, What you want to do a crankcase presure test.
Let us know what you find.

**BrianZ** · 05-06-2008, 03:28 PM

Originally Posted by boyoboy

actually, its not my bike. its a bike i may consider for purchase. older 125cc dirt bike, 70's, rare, honda, and i just wanted to inform myself before going to check it out.

how much would a shop charge to do a leak down test?

and thanks all for letting me pick your brains - great information!

If it's a 70's dirtbike, and it hasn't been rebuilt in some time, then you are better off replacing the seals regardless. Parts are getting harder to find for old Elsinores and you don't want to trash the motor only to find you can no longer get parts. An engine seal kit is not too expensive, and although it will take some time to install, it's worth the piece of mind.

P.S. If you decide against purchasing the bike drop me a PM. I know a guy who is keen on first generation CR125's.