R25/3 Dyno run and Bonneville Salt Flats results

[DanMay]

Hello Everyone,

I wanted to share my latest dynometer run on the two R25/3 land speed bikes.



We also have just returned from the Bonneville Salt Flats, and set 3 new records on the salt.
-          Rebecca Ann Berneck ran an average speed of 77.96 in P/PV-250 (Production Vintage 250cc). This beats the SCTA Bonneville record of 69.224.
-          Craig Chawla ran 79.307 in MPS/VF-250 (Modified Partial Streamlined Vintage Fuel), with a one way run of 80.039 MPH. This also is a new Bonneville record.
-          Daniel May ran 75.504 in M/VF-250 (Modified Vintage Fuel), beating the existing Bonneville SCTA 75.350 record set on a Triumph 250 in 1996.

[DanMay]

[DanMay]

These might be easier to read

https://picasaweb.google.com/lh/photo/zl3MwTGuAJvFtL_P8NKZAlE6UxEV3UvDMaKNRa_vbmQ?feat=directlink
https://picasaweb.google.com/lh/photo/rA_DK68XehLgexCrmfqTHlE6UxEV3UvDMaKNRa_vbmQ?feat=directlink

[Taz]

Hello Dan.

Kudos to all of you...sounds like an extraordinary successful trip Its pretty impressive to learn how much potential these bikes really have...

Best regards, Taz

[mekgyver]

Just readed, thank you guys, nice to read about you guys.
You have great options in running to speed up the 250er BMWs   

reagrds and in mind, mek 

[BenW]

Hi Daniel,

Well done, congratulations, this is very impressive!!!

From the dyno printout it appears that you have used modified/custom exhausts, retarded timing, changed the main jet, as well as having mounted different carbs (60/5) to achieve peak HP and torque. Could you detail the modifications, especially the exhaust mods? Also, what else did you 'fine-tune' with the bikes? And finally: what's the average weight of the three riders (I am not asking for individual weights for privacy reasons )?

By the way, here in Europe it will be difficult to test the bikes at 78°F and 22% humidity: it is usually colder and wetter...

Cheers
BenW

[cledrera]

77.96 mph = 125.46 km/h

[4Taktix]

Hi Dan,
searching for the last hidden bit of power you could try and paint your Cylinderhead and Valvecovers black
(stock for R25/3) and also use an aluminum Gasket for the Valvecovers.
This will improve the cooling noticeable and is worth it by all means. (My opinion)
--> "heat absorption of fresh mixture"
Another common add-on for additional cooling is a finned Sleeve nut for the Exhaustpipe.
There are two versions available, one replaces the plain sleeve nut, the other one fits over it and is clamped
with a bolt. Not sure if this matches the rules for Vintage Stock or your class.
Good luck !
Sascha

[Rawost]

Ihr habt aber gemerkt, dass der Beitrag schon über zwei Jahre alt ist?

[4Taktix]

Deutschland brauchte schon immer etwas länger als Amerika 

Aber Dan hat's mitbekommen, denke ich, er war bis eben eingeloggt. Geht doch 

[DanMay]

Thanks for the renewed interest in the BMW R25/3 land speed racers.  To be clear, we raced two different bikes.  The "green bike" was run in the "production" class which required no visible external modifications.  It needed to appear 100% as the factory produced it.  The "black bike" was run in the "modified" class, which allowed us to use a larger, open exhaust and the later /5 R50/5 carburetor.

You can see all the modifications in this thread:  http://bmw-einzylinder.de/forum/index.php?topic=8512.0

[4Taktix]

It needed to appear 100% as the factory produced it.

Which is the case for a black head and valvecovers - all! R25/3 were this way.
This lead to their nickname "Mohrenkopf". --> chocolate marshmallow
Plain aluminum heads/covers were later replacements or stripped due to individual preferences.
Go to the startpage, tab: "Medien", choose "Werk-Fotos" and filter for R25/3.
http://cms.bmw-einzylinder.de/index.php/presseberichte-und-medien/werksfotos.html

Sascha

[BenW]

Ihr habt aber gemerkt, dass der Beitrag schon über zwei Jahre alt ist?

Cold start of the Year...