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I'm looking for information regarding how many cc's an R90 (S or /6) is suppose to have in it's combustion chamber.
Then I'd like to know what the difference (cc's and mm's) is in the piston dome construction of an R90S vs. a R90/6.
I've done some searching but I can't find any detailed information. Does anyone have some detailed information about R90S pistons?

You have probably seen this comparison of R100 pistons with specs at the bottom. http://moragafalconers.org/bmw_pistons/index.htm

I'm not sure if you can extrapulate the dome hights down to a 900.

Perhaps MI can help.

Garnet wrote:You have probably seen this comparison of R100 pistons with specs at the bottom. http://moragafalconers.org/bmw_pistons/index.htm

I'm not sure if you can extrapulate the dome hights down to a 900.

Perhaps MI can help.

There's lots out there about 1000cc pistons, I'd like to stay with 900. I want to have some light weight Venolias custom made like R90S pistons, but with enough dome to boost it a little over 10:1. I've been quoted at $118.00 per piston. I could buy 4 for the price of 2 heavy stock 90S pistons.
I'm going to be putting in a 336 and I'm dual plugging this winter. The other challenge will be to figure out how deep the intake valve pockets will need to be on bigger dome pistons for the bigger cam.
Venolia has a very detailed order form. I don't have a R90S piston to take measurements off of, so it makes it more challenging.

Perhaps you can get someone with a CAD program to mock something up for you. Start with your head shape and stock R90 piston dome shape and then fill in till you get the desired volume.

Then you can extend the valves to determin valve pockets.
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I can already see a bunch of holes in my story, you realy need some R90S pistons or specs.

I know this comes in at over twice the price of the Venolas and you have seen these before, but there is a lot more expertise in the design of these pistons, and they will be able to tell you what to do with your head to get to your desired compresion, as well as what will be needed for valve clearance.
http://www.motoren-israel.com/products/ ... -2-St.html

PS: I love to spend other people's money.

Garnet wrote:I know this comes in at over twice the price of the Venolas and you have seen these before, but there is a lot more expertise in the design of these pistons, and they will be able to tell you what to do with your head to get to your desired compresion, as well as what will be needed for valve clearance.
http://www.motoren-israel.com/products/ ... -2-St.html

PS: I love to spend other people's money.

I like that they have a 91.5mm bore piston. Actually not a bad deal for performance pistons. That's about what Motobins charges for stock, 1975 technology, R90S pistons. They had the cheapest price before I saw this.
The only catch is that I want more than 9.5:1 compression to optimize the performance of the 336.
I'll contact MI and see what they have to say.
Do US customers have to pay VAT or any other taxes on German products?

Of course I could still have Venolia build some comparable pistons for a bit less. But I really need all the measurements or that's going to be a big gamble.

"Do US customers have to pay VAT or any other taxes on German products?"

No that only applies within the EU, so that makes those pistons about 300 Euro.