1982 European R100RS

ghlubik · Aug 3, 2015

Does anyone know for sure what the compression ratio is on the European version of the 1981-1984 BMW R100RS ?

USA is 8.2 and am thinking Euro may be 9.5? or 9?

If you own one, do they have any special problems beyond the valve seats?

Thanks.................................George

lkchris · Aug 4, 2015

It's 9.5. Needle jet position is one click higher than on USA models, otherwise same carbs. Rest of engine is identical save for head ports for the air injection. No air injection means a little less heat around exhaust valve, but otherwise same materials.

ghlubik · Aug 4, 2015

Hello Kent,

Thank You, now I know for sure it is the 9.5...............George

brook.reams · Aug 5, 2015

Minor Typo ??

lkchris said:
It's 9.5. Needle jet position is one click higher than on USA models, otherwise same carbs. Rest of engine is identical save for head ports for the air injection. No air injection means a little less heat around exhaust valve, but otherwise same materials.

Just a minor nit, but I think you meant the "jet needle position ..." as the needle jet is kinda fixed in place

Best.
Brook Reams

ghlubik · Aug 5, 2015

Do these have 38mm or 40mm exhaust ports?

Should it have a kick starter, or was that optional?

Darryl Cainey · Aug 6, 2015

The exhaust on my European 1984 R100RS was 38mm and it came with a kick start.

lkchris · Aug 6, 2015

ghlubik said:
Do these have 38mm or 40mm exhaust ports?

Should it have a kick starter, or was that optional?

40 mm exhausts were only on the earliest R100s. The dual crossovers on the Nikasil engines made that redundant.

1982 European R100RS

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