New 250cc Vintage land Speed Record for R25/3 - 77.58 MPH / 124.85 KPH

[DanMay]

I wanted to thank everyone on this forum who helped with tips and performance information for my R25/3.  With the help of all of you, and my enigine builder Richard Sheckler in OHIO, USA we were able to set a new 250cc Vintage land speed Record of 77.58 MPH / 124.85 KPH.  This was a significant increase from our old record of 72.085 MPH / 116.01 KPH.

We did this while following the production racing rules, keeping a 100% stock external factory apperance and a maximum displacement of 250cc.

Daniel

[DanMay]

[BenW]

Congratulations, Daniel, well done!!! 

Do you mind sharing some of the 'secret' sauce (no, I am not referring to the gasoline ) you and Richard have put into your bike?

Best regards,
BenW

[Taz]

Hello Daniel.

I am deeply impressed...thanks for sharing your success with us and letting us know how darn fast these little bikes really can go

Best regards, Taz

[rolf]

Bravo!
Na Mek, die 6 km/h mehr schaffst du auch noch!

[DanMay]

Congratulations, Daniel, well done!!! 

Do you mind sharing some of the 'secret' sauce (no, I am not referring to the gasoline ) you and Richard have put into your bike?

Best regards,
BenW

I would have to say it was a lot of little things Richard did that added up to the performance increases.  Since we did many of them at the same time, it is hard to tell which ones contributed most.  I will try to list them in order of importance.

1. Perform the exhaust modifications that were described on this forum.  The reproduction muffler's do not "breath" as well as the originals.
2. Replace the R25/3 (or R25/0 and R25/2) air cleaner with an aftermarket K&N filter or the one Uli sells.  In my case, I had to be a "stock production" motorcycle, so i simply removed the metal mesh filter from inside the housing.  Not good for engine life !
3. Add a larger main jet to the carburetor after doing #1 & #2.  I was running anywhere between a #155 and #165 depending on the temperature.
4. Use high compression piston from Uli.
5. Advance the ignition timing 3 degrees beyond the “F” mark (be careful, this may cause overheating.  I added the additional oil passage to the cylinder to assist in the cooling).
6. Lightened Flywheel

Those changes above got me to 72 MPH, to get to 78 MPH
7. Added the R27 camshaft
8. Better aerodynamic handlebars and rider position
9. Synthetic engine and transmission oils
10. Even more ignition advance, 6 degrees beyond “F’ mark.  This much advance is dangerous for every day riding, it “knocks” a bit under load.

Daniel

[Rütz]

Hi Dan,
!!

In my case, I had to be a "stock production" motorcycle, so i simply removed the metal mesh filter from inside the housing.  Not good for engine life !

Once i posted a little "picture story" on metal mesh replacement for R26/27: http://www.bmw-einzylinder.de/forum/index.php?topic=1503.0
I used Moto-Cross airfilter foam and i'm still happy with it.

Perhaps a similar solution is possible with your R25/3.

Rütz

[BenW]

Hi Dan,

Thanks for the insights!
It shows that a well balanced machine with a few alterations can run incredibly fast. Not just hearsay - we now have official hard proof :
http://www.ecta-lsr.com/events/2011/Records0511.php

Cheers,
BenW

[cledrera]

Indeed,
a fine looking quick old Lady.
Good work.

Clemens

@Peter63,
108 m/s² oder wie war das neulich im Ansaugstutzen? 

[Kurt in S.A.]

Great job Dan!  And nice tuck!!

Kurt in S.A.

[DanMay]

That is Rebecca Berneck doing the riding.  She always gets about 3 -4 MPH faster than I can.  She is a bit smaller than me, and the wind drag is a huge factor on a non fairing bike.

Daniel

[DanMay]

Here are a few pictures



We are planning to try again in October.  I am going to do some head and valve work to see if we can get a few more MPH...

[Tino]

How about some really fast clothing features 
greetings Tino

[axel69]

How about some really fast clothing features 
greetings Tino

Great Picture,

The second "helmet" will at least gain 5 mph....

Axel

[BenW]

Daniel,

Be careful when going much faster. Here's Arlo's story about going 150 and what happens afterwards:


Cheers,
BenW

[cledrera]

Daniel,
BenW`s opinion ist right.
With the "evenwaygear" of the R 25/3 it is dangerous to drive faster than 200 km/h  .

Clemens

[† Knut]

Congratulations Dan, even if you gave the handlebars to Rebecca - but I guess that the acceleration and the air drag is much better with her   

Guys - for me it's really an impressive speed. Please keep in mind, that the course is only 1 mile long (1609 Meter) and the rider have to accelerate without any mistakes

Knut (taking off the hat to .... Rebecca  )

[emm]

2. Replace the R25/3 (or R25/0 and R25/2) air cleaner with an aftermarket K&N filter or the one Uli sells.  In my case, I had to be a "stock production" motorcycle, so i simply removed the metal mesh filter from inside the housing.  Not good for engine life !

Hi Daniel!

Here is the solution for the 25/3 that Rütz suggested: http://www.bmw-einzylinder.de/forum/index.php?topic=5403.msg60583#msg60583
Written in German, of cause, but I think a translator like babelfish can do the job.

Kind regards to Richard!

Markus

[DanMay]

Thank you all again for the kind remarks.  I will pass them on to Richard and Rebecca.

In regards to the R25/3 air filter, thank you for the link to the flow measurements.  I quickly learned of the importance of the "tuned" intake on the R25/3, as my experiments with a velocity stack directly on the carburetor yielded a significant reduction in power. 

I was not quite sure I understood the translation from German to English completely, but I think what you are saying is that the R25/3 air filter with the wire mesh removed will have a 490 Pascal pressure drop.  Is this correct ?  I will have to look back at my calculations, but I thought I had taken the total sum of the "triangle" openings to the air filter, and compared that to the opening of the intake tube on the R25/3 gas tank.  The "triangle" openings area exceeded that of the intake tube, so my conclusion was that there was no air restriction once the mesh element was removed.  Now I would like to add back a foam filter to remove dirt, so I would have to make sure the foam element does not reduce the air flow beyond the capacity of the intake tube.

For now, I am simple using this:


I put it over the outside of the air filter housing.  The problem is it does very minimal filtering.

Do you think there is any "ram air" effect when moving at 70 MPH on the R25/3 since the air intake is pointed into the wind ?

Daniel

[rolf]

ram air doesn't exist, it is a fake. In the late 50ty the knew it that it doesn't work.

[Tino]

ram air doesn't exist, it is a fake. In the late 50ty the knew it that it doesn't work.

http://en.wikipedia.org/wiki/Ram-air_intake

Japanese "fake technology"  



And i know what C.Hertweck wrote about ram air  
Greeting Tino

[rolf]

And I believe Hertweck!
And I belive that for normal speed AND normal carburettors (and intakes) it doesn't increase the power....I think the opposite will happen

[Rütz]

"Ram air" is a different thing.
It indispensably needs a big(!) airbox, in which the slightly increased atmospheric pressure is "stored" and calmed.

Rütz

[rolf]

WOW (your english AND your RAM AIR knowledge!)...and now you, Tino!

[Tino]

"Ram air" is a different thing.
It indispensably needs a big(!) airbox, in which the slightly increased atmospheric pressure is "stored" and calmed.

Rütz

Yes! Thats it!

But rolf wrote:

ram air doesn't exist, it is a fake. In the late 50ty the knew it that it doesn't work.

And this statement is a total negation of ram air systems. But this is not true! (see Rütz)

So we can say ram air systems are not applicable/usefull on the old bikes (absence of high speed and correct air intake system).
greeting Tino

[emm]

I was not quite sure I understood the translation from German to English completely, but I think what you are saying is that the R25/3 air filter with the wire mesh removed will have a 490 Pascal pressure drop.  Is this correct ? 

Jep!

Furthermore 454 Pascal with a bell moth and 488(!) Pascal only with the intake of the carb.

Markus

[DanMay]

You can read a recap of our runs at the ECTA (East Coast Timing Association) May meet in Maxton North Carolina here:

www.chicagovintageracing.com

There are photos and videos posted.

/Daniel

[4Taktix]

Wer's mal sehen möchte, wie eine Serien-/3 125 km/h fährt, und weil's immer wieder schön ist: