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engine blowby

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Snakeoil
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Post by Snakeoil » Sat Sep 04, 2010 3:59 pm

Well, there is always the old Bonami trick. Don't think they make that anymore, so it could now be the old Comet trick.

regards,
Rob

mike1969
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blowby

Post by mike1969 » Sat Sep 04, 2010 7:37 pm

Teazer,I found "Dan's motorcycle leak down test"on the internet yesterday.

My compressor only puts out 75 lbs. so I applied that to each cylinder and got some hissing from both cyls. at the oil fill hole and from the engine breather hose. Dan's info is the same as your's, the air is getting past the rings.

I didn't de-glaze the cylinders so it looks like i'll have to do that and have them properly measured
and take a closer look at the rings.

Sure wish I hadn't cut corners the first time,would have saved me a whole lot of work.

Live and learn.

teazer
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Post by teazer » Sat Sep 04, 2010 11:52 pm

I g\figure that every experience to learn something new is a good day and most of us learn from our mistakes. None of us were born knowing everything.

The way I see it, is that the barrels have to come off of a spare pair has to be honed at least to take those new pistons, but there's no rush if it runs OK. Except of curse you'll need new rings to go with the new bores.

Summer is almost done, but the best riding season is fall, so I'd wait until it gets much colder - unless you're in CA or FL in which case do it whenever you feel like it.

mike1969
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blowby

Post by mike1969 » Sun Sep 05, 2010 11:50 am

My business is really slow due to lack of rain so I have a lot of extra time to fart around with the bike.
I'm getting really good at removing the engine and cylinder head! Less than 1 hour.

I bought a caliper and measured the cyls. they 2.355 in. and 2.354. repair limit is 2.366.

Will be taking both pair of cylinders to the machine shop tomorrow to see what can be done with them.

Something strange I found on one piston. It has a clean spot on the dome edge 1/4" wide and about an in. long. All the rest of the piston has black carbon and the other piston dome is all black. Anyone know what could be up with that?

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Snakeoil
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Post by Snakeoil » Sun Sep 05, 2010 1:33 pm

Is the carbon soft? Can you rub it off with your fingers? If so, it might be gas dripping down from the carb if the float valve is not seating well or the float is set a little too high, and washing off the carbon.

regards,
Rob

jensen
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Post by jensen » Sun Sep 05, 2010 2:58 pm

hi,

Very sharp observation, never would have thought about that.
Should be visible on the rear side of the intake valve too,

Jensen
assembly of Japanese motorcycles requires great peace of mind (Pirsig)

mike1969
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blowby

Post by mike1969 » Sat Sep 11, 2010 6:33 pm

Got my cylinders back from the machine shop today. All that was needed was honing and was were within specs.
I'm waiting for the new head gasket to come in.

Will keep you posted.

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