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ScottaKR · Post by **ScottaKR** » Fri Jan 30, 2009 6:27 am

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?

TwoStroke Institute · Post by **TwoStroke Institute** » Fri Jan 30, 2009 7:27 am

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

ScottaKR · Post by **ScottaKR** » Fri Jan 30, 2009 7:56 am

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.

Sheik Yerbouti · Post by **Sheik Yerbouti** » Fri Jan 30, 2009 12:30 pm

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.

TwoStroke Institute · Fri Jan 30, 2009 10:13 pm

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

KR-1R · Post by **KR-1R** » Wed Jul 31, 2013 4:31 am

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

TwoStroke Institute · Post by **TwoStroke Institute** » Wed Jul 31, 2013 2:20 pm

Are those FPE or HeJa cylinders?

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

dave32 · Post by **dave32** » Wed Jul 31, 2013 10:27 pm

He-Ja

Something to try,i got shed full of B barrels

TwoStroke Institute · Post by **TwoStroke Institute** » Thu Aug 01, 2013 9:44 am

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

KR-1S.co.uk Forum

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