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Replacement pistons for R51/3

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EuroIron
Posts: 367
Joined: Mon Apr 23, 2007 12:38 pm

Replacement pistons for R51/3

Post by EuroIron »

I don't know how much originals cost but I highly recommend contacting Keith Black and pricing appropriate blank pairs even of their HyperEutectic low expansion pistons and then Total Seal for their mighty fine Gapless RIng sets.

I know for a fact Total Seal has rings that will fit the stock pistons and they are cheaper than OEM, amazing sealing qualities and easy to find 2-4% leak down with no extraordinary preparation...... stock in good shape does well to leak down any less than 20%

The Gapless rings work very well.

The KB pistons set up with 0.0005" - 0.0015" skirt clearance and have worked phenomenally in every engine I've used them in, especially the vintage ones

If you will post the critical dims, I do have the Internal Engine Parts catalogs which list pistons by their physical dimensions and ya never know when a modern piston out of a semi-universal Japanese or whatever engine may just all but drop in place

I think the last time I crossed some over I found some Alfa pistons, think so anyhow, that worked in a Bevel Drive Duck Twin with only a bit of massaging

saved about 500 bucks

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comet
Posts: 156
Joined: Fri Oct 27, 2006 3:00 am

Replacement pistons for R51/3

Post by comet »

A few years back John Landstrom at Blue Moon Cycle sold, I believe, Fiat pistons that worked well in the pre 55 BMWs. You might contact him.........Comet

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VBMWMO
Posts: 1322
Joined: Sun Aug 23, 2009 7:49 pm

Replacement pistons for R51/3

Post by VBMWMO »

Hi. I am starting to think seriously about an engine overhaul and would like to know if there is a possibility to use an other substitute for the pistons, i.e. a matching piston from a modern vehicle or, at least, a more common one. The original pistons are very expensive. Thanks and regards, Michael.
Dedicated to the Preservation of Classic and Antique BMW Motorcycles.

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