KR-1S.co.uk Forum

Been thinking about this 90 deg crank phasing a bit and wondered if the advantages of this format would translate in a tandem twin engine.

It should be easy enough to do on the KR250 Tandem twin since the ignition is seperate for each cylinder, and the cranks could be phased to 90 deg by adjusting the clutch/primary gears without haveing to tare the whole engine down.

Any thoughts?

No need on the tandem as there is no rocking couple(occurs on parralel twins on a common crank) as it has 2 cranks. That's not to say it couldn't do with some updating in the ignition/port/pipe/carb/disc dept. The KR should be a rocket as there is these around now.Not forgetting the Aprilia RSW and RSA that are disc valve.

http://pagesperso-orange.fr/fpe-racing/ ... rs/FPE.JPG

and essentialy the same thing

http://www.brceng.com/250fe.html
http://www.brceng.com/pdfs/BRC250FE_Tec ... Sept05.pdf

I was thinking more along the lines of the smoother drive out of corners you mentioned earlier.
I know there are a lot of upgrades the old KR250 could do with, but just thought that this would be a very easy (and cheap) mod to do on this engine.

It was one of the things I was planning for mine when I get around to it. Since each cylinder has it's own pickup coil, cdi and coil. You shouldnt even have to modify the thing, just take the clutch off and move one primary gear.

It might be a worthwhile trick, it would be easy and reverseable also.

mj43 wrote:KR has fairly large exhaust sub ports (biggest of any engine I have seen) -I can't easily make them triangular as there are inherent weakness' in the KR barrel and it would mean compromising reliability

...triangular as in tapers towards the wristpin ... not the divider downstream




NACA duct

resale value of B barrels just went up

Are those FPE or HeJa cylinders?


PS running the KR 250 in twingle firing is the go.

He-Ja
Something to try,i got shed full of B barrels

He-Ja was the only cylinder to better the Aprilia RSA power output