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Thread: Nikasil Cylinders - R65

  1. #1

    Nikasil Cylinders - R65

    Hi All-

    Iím back in the airhead game after a number of years away, closed a great deal on an Ď81 R65. From what I can tell, Ď81 was the first year of the nikasil cylinders for this model. The odometer states 38k, but cannot verify those all accurate (hoping it isnít 138k). This is my first airhead with nikasil cylinders. The bike has not been used since 2012.

    My question- how durable is the nikasil plating, especially after 38 years, and with the bike sitting for 7 years? With my other project airheads, an over-bore was always necessary due to either miles or from sitting too long. Before I open it up, any feedback on what I might find given reasonable service over the years? Has nikasil cylinder plating been reliable and trouble free?

    Thanks for your feedback!

    Tom

  2. #2
    Absolutely!

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  3. #3
    Registered User STEVENRANKIN's Avatar
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    Run it

    Nikasil is very durable.

    If you have got it tuned up as in valves adjusted and such, do a compression test. If it is reasonable, run it, don't bother rebuilding it.

    In my experience, my exhaust valves went long before the cylinders needed be-building.

    Unless you had water in the cylinders while it was stored, you should be OKAY.

    Not sure what the specifications are but if you really believe you need cylinder work, check the piston ring gap. The rings wear out faster than the nikakil coating. Again, if you have good compression, run it.

    Nikasil cannot be bored out like cast iron. So there is no over-boring if out of specification or the walls are damaged.

    If you need to rebuild, you can do like I did bore out the nikasil and install cast iron sleeves, buy new cylinders and pistons, or, and I am not sure of this as it something new, there are shops that will bore and reline with nikasil. Had I know about this when I rebuild my R80RT, I might have used this service. As it was, I was far cheaper to bore out the nikasil and put in sleeves than to buy new cylinders.

    Ah yeas final note. I rebuild my bike at 125K when the piston rings wore out and I started to get piston skirt slapping on the inside of the cylinder. It that case, I had to redo/replace the cylinders. St.

  4. #4
    Registered User AntonLargiader's Avatar
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    Sitting for years, in the wrong conditions, can trash the Nikasil. I've seen it (and it was on an early R65, too); it seems that moisture gets under it somehow and corrodes the base aluminum, blistering the Nikasil off.
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  5. #5
    Registered User STEVENRANKIN's Avatar
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    Moisture damage?

    Anton, would a person be able to see this damage with the naked eye? Or, would it show up after the bike was running agin?

    Am I correct to think that if there is damage to the nikasil, the compression test would show it provided the valves/valve seals were good?

    Or maybe there would be a big bunch of noise when running? LOL

    I also have heard the first year 1981, for nikasil was not entirely successful?

    Isn't there an upgrade kit for R65 engines to upsize to R80? Something else to think about. St.

  6. #6
    Quote Originally Posted by AntonLargiader View Post
    Sitting for years, in the wrong conditions, can trash the Nikasil. I've seen it (and it was on an early R65, too); it seems that moisture gets under it somehow and corrodes the base aluminum, blistering the Nikasil off.
    Anton is absolutely right, but this is a rare condition. Normally the Nikasil surface on the cylinders by far beats a cast iron cylinder. That is why BMW uses it.

    My experience is that at more than 300K miles I could still see the factory cross hatch on the cylinders. This is typical. Do a compression test. Do a leak down test. Do a visual inspection. Than get on with it.
    Paul Glaves - "Big Bend", Texas U.S.A
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  7. #7
    Thanks for all the comments. This is coming more interesting as we go along..

    So my bike was sitting 7 years. At some point, fuel leaked past the carbs (float stick) and at least a couple quarts ended up in the oil sump mixed with the oil. So besides the concern for the nikasil, I am concerned for bearings, etc, that could have been damaged due to the gas oil mix. The bike was not run this way, but I would be interested in comments about this situation and how the internals May be affected. . Again, bike appears to have 38k original miles, and in reasonably good condition by appearance.

    Thanks for feedback!

    Tom

  8. #8
    Registered User AntonLargiader's Avatar
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    Corrosion would be visible if you have the top end disassembled. Not sure that it would show up in a compression test because the location might depend on where the piston was sitting.

    Fuel in the oil is not a problem if the engine wasn't run that way. And plenty of engines do run that way briefly without problems, too.
    Anton Largiader 72724
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  9. #9
    Registered User STEVENRANKIN's Avatar
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    gas in oil

    If there was not any water or moisture in the oil AND the bike was not started or run on the contaminated oil/gas mix, I would wager there is no damage to the engine and changing the oil with fresh is all that is needed.

    Moisture/water is the killer. I have seen bikes which have sat for years destroyed by the seasonal heating and cooling of the garage they were stored in here in Upstate NY.

    The cause of death has always been moisture in the engine. Nikasil is a great improvement over the cast iron bores. It takes a lot to damage it.

    When you drained the oil which had been in it during storage, was the oil milky or did it show any signs of moisture?

    Inspect the cylinder walls for obvious damage. If none is found put in fresh oil, fire it up.

    Aside from obviouly visable damage due to any corrosion, bad bearings will make themselves known soon enough.

    If there is no damage from sitting, the bike will run like an Airhead BMW and you will be having fun with it. St.

  10. #10
    Thanks everyone for your comments!! Greatly appreciated!!

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