nikasil replating

There are a bunch of places now advertising nikasil repair.
Has anybody ever had this repair done ? By whom ?
Were you happy with the result ? How much did it cost ?

For a 1000 cc airhead BMW twin, it looks like somewhere
between $350 - $450 for two cylinders stripped, repaired
as needed, plated and brought to spec.

I just stumbled into a set of cylinders and am considering
this repair.

 

No idea, but that sounds cheap. What airhead boxer do you have, out of
interest?

(As one who has a soft spot for them)

 

Rob,

I've used Millennium Technologies for snowmobile cylinders and was very
impressed with their work. It was about 4 years ago and cost a little over
$200 per cylinder. The snowmobile is still running well.

http://www.mt-llc.com/index_home.shtml

Martin

 

'88 R100 GS.

The current cylinders have 137,000 miles on them.
They survived a badly trashed rod bearing and got
transplanted onto a new short block, so I'd say
they've served honoraby.

Over the weekend I acquired several damaged
cylinders as part of a milk crate full of bits
and pieces. I'm thinking of sending these out
for replating while I continue to run on the old
worn set.

 

The bike is an '88 R100GS.

The cylinders are the originals with 137,000 miles on
them. They survived a badly trashed rod bearing at
95,000 miles and got transplanted onto a new short block,
so I'd say they've served honorably.

Over the weekend, I acquired several damaged cylinders
as part of a milk crate full of BMW bits. The plan would
be to send these out for plating while continuing to run
on the clapped out originals.

 

<snip>

I like them. Have you uprated the front brake? I always found the
single disc a bit terrifying, but here there are billet caliper
replacements.

 

Mine now sports an oilhead Brembo 4 pot caliper
turned ass backwards and machined very slightly
to align with the disk.

This puts the larger pistons wrong way round but
improves the stopping enormously and costs
almost nothing. Total job costs were under $100,
including machining and fluids.

Having ridden a DT400 with ornamental mini drum
brakes on both wheels, I'd be hard pressed to call
anything else terrifying. The oilhead 4 pot is
certainly a nice improvement though.

I also added a taller 5th gear which brings freeway
cruising speed up by maybe 5 mph or a little better.

Having done a few long trips trying to keep up with
oilheads, brakes and top speed were the two things
I found bothersome. Both of these have been mitigated.
It's also lighter than an oilhead, which I like.

 

I didn't even know the Brembo calipers had different-sized pistons, to
be honest. That sounds like a really neat (and cheap!) mod.

OK, another question: what did you do here? My last airhead boxer was a
R100S, RS-ised (engine was the same big-valve lump anyway), but running
the 32/11 rear drive box for taller overall gearing. I didn't know you
could get a taller fifth gear.

I'd *love* to raise fifth on my K, actually. It's just fractionally
undergeared on stock gearing.

 

Siebenrock offers taller 5th and lower 1st gears.
Both are a little weird in that they involve a gear
of the same diameter with one less tooth and funny
tooth angles to make up for the missing tooth.
(think appalachia).

Top gear is pretty easy, as it's just a matter of
replacing one helical gear with another. Bottom
gear is tricker and requires that you press a whole
gear cluster apart, swap in the funny gear then
reassemble it.

I had this done when the gearbox was already
apart for new helical gears, so the extra cost
was again under $100. The work was done by
somebody else who had more clues than I do
how to repair transmissions.

Dunno if there's anything for a K bike. What about
just changing the final drive ratio ? If you could live
with a taller first, this might be easier.

 

Well, that's the thing: I do like the lower gears. The gearing on the LT
is slightly shorter than it is for the RS so yes, I could just stick an
RS final drive on it.

As it is, it's geared for maybe 135 at the redline, but the engine has
so much torque I could sacrifice a bit of top gear flexibility for a
more relaxed cruise at (say) 85-90.

My last tourer was a Triumph Trophy 1200, which was overgeared - if you
could have got it to the redline in top, it'd have been doing 170 or so.
But again, the engine was super-torquey, and so top gear was a nice
relaxed touring gear.

I'd like to have that attribute on the BMW.

 

It's theoretically possible to cut a gear that will do that and
one or more people are crazy enough to do that for the
airheads. On the airheads, a one tooth difference
bumps the top end gearing by ~ 6%.

You could try Siebenrock and/or

At Siebenrock, be prepared to wade through some strange
computer generated German->English translations.

Not too surprisingly, there seem to be lots of folks
dealing in exotic BMW parts in Germany.