Need some help on oil seals?


I have a CH80 2 stroke bicycle engine that has a bad oil seal under the magneto.  Here are my problems, the seal size is 11.8x27x3.8 and after talking with someone who just sells seals he tells me that I would have to buy the seal from the guy I bought the engine off of.  He no longer sells these engines.  Even if I could find the same size seal I still haven't figured out how to take the old seal out of the engine.  Any help???

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I may be wrong but I think a CH80 is a Honda right? You should be able to take the serial # off the bike or the engine ( get both if you can, it may save you a trip home to get it). You should be able to take those numbers to a Honda dealer and they should be able to get the seal.

If you don't care for OEM parts, you may be able to source a seal locally. Where I live there is a large machine shop we get some of our seals from. I believe that the seal will be metric as that is what japanese (honda) bikes are. Those measurements are the ID x OD x Height so you may be able to find a 11.5 x 27 x 4(or 3.5) .

To remove the seal, I usually end up taking a flat head screwdriver and sticking it between the seal and the shaft and then prying out the old seal (look at this video around the 9'45" mark). There is also this method http://www.youtube.com/watch?v=ri8xnBnF4yk (but be careful of drilling to far because you can drill into the bearing).

When you install the new seal be sure to install it evenly and straight (i usually do it with a socket so that it is hitting all parts of the seal evenly)

If you have any more questions, feel free to message me
birdmannn101 (author)  cerberustugowar6 years ago
Thanks digitalbrad, That video was great. Now I should be able to get the seal out. I knew as soon as you said, "Isn't a CH80 engine a Honda" that you were the one to give me the best answer. This engine is not a Honda but a cheap Chinese bicycle engine. Thanks again for all your help....Dan
Burf6 years ago
When you and I were kids, most engine oil seal gaskets were made of cork. Just regular old cork pressed into sheets. I'm pretty sure you can still get cork gasket material at many auto supply places. Measure the thickness of your rubber gasket and get a slightly thicker sheet of cork, make a pattern from the engine block and cut out the gasket with a single edge razor blade. Put a light coating of automotive silicone sealer on the mating surfaces and put it back together.
The cork gasket seal will last many years if done properly.
As an alternative it may be possible to find and purchase an oil proof rubber-like material that would work the same way as the cork.
birdmannn101 (author)  Burf6 years ago
Thanks Burf, These are metal seals with rubber coating pressed into the engine shaft. I think the engine would blow out the cork....Dan
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lemonie6 years ago

Try cereal-box card, it's been known to work. With a bit of instant-gasket.

L
iceng6 years ago
At 63 yrs you are probably sol on a replacement seal even if you could get it out.
Seals are high temperature rubber material maybe an auto site has a repair kit.

A