Spanking the Cow- The continuing saga of an R100GSPD at the Races

[Airhead Wrangler]

Originally Posted by Stagehand

I also did a down and dirty measurement of the R100 paralever and the GS1150 I have in the barn, and the 1150 was 2.5 inches longer. Pivot center to axle center.

I'm saying if the rear is 100mm longer it can get more travel than if its 50mm longer.

I remember somebody saying that 100mm longer was a fair number to aim for, but it had no data backing it up. Just a number compromising additional travel and an over-long wheelbase.

Another one from the guys at SWT:

[Koos]

Originally Posted by Airhead Wrangler

Another one from the guys at SWT:

I think that bike needs one of those maroon Husky tanks with the shiny spot on....

[Dmaster]

So, what happened to Stagehand?
Secretly building his new Air-head rally bike?

[Gone-Native]

Originally Posted by Dmaster

So, what happened to Stagehand?
Secretly building his new Air-head rally bike?

Shhhhhhh......... It's a secret

[Phreaky Phil]

After riding the Rally Beemer in Ausie he just cant face gettin on the big old heavy GSPD anymore.

[Stagehand]

Originally Posted by Phreaky Phil

After riding the Rally Beemer in Ausie he just cant face gettin on the big old heavy GSPD anymore.

Man there is some truth to that!

I do love the old girl, though, and have finally gotten it back into road-running status... minus the bash plate, though....

The poor thing is really bent so that even when I yanked on it the vice for a while and sort of straightened out the REALLY bent parts, it still doesnt quite line up with the holes in the new oil pan. Much tweaking will be required, but theoretically I could commute on it right now, if I wasnt such a wuss. Its only 35F.

ANd I'm stupid busy at the thee ater.


I also still need to take off the pannier frames and bend them out properly.. still kinda caved in from the CAnada crash. ANd I have no pannier system thats not just strapping the bent Zegas on. Its very Ghetto, but might be fine

Motor still runs solid. Charging system is ok. Forks are awesome

So I'm thinking about the lower shock mount bolt on the FD. Dont know how to make that bigger.


Ok- here's the real issue facing the Airhead Rallye team. I would love to build a BM sort of like the Rooney special, and figure out how to race it in the MEx 1K and other events. Problem is I already have a project thats going to be fun, if I could ever get around to it. Its wrong for Rallye, in fact, I know its the wrong engine and frame for what I intended to do with it in the first place, but what the hell.

I'd rather not make the same mistake with the new bike.

What to do.. what to do.. .the New bike will budget out in the 15K region. Thats a years worth of racing, financially, sort of. Depending on teh racing schedule. And barely any love for any of the other bikes... it would eat everything for a long time.

MAn thats tough love... I have to finish the bike I have and ditch it or keep it or whatever but get it in running condition and THEN look at maybe a rooney frame, and an R65/850 with cool forks and a long swingarm.

R65 engine, R100cylinders machined down, and custom pistons: ANybody want to take a $$ Guess?

then add a $1K shock, and maybe $1K in swingarm work, and $2K for powerdynamo igniton and maybe some DRZ front end. Need to mate a hub to an 18" wheel. Thats probably expensive.

Lets not leave out frame. Long as I'm dreaming I might as well go all the way and get a Rooney frame.

Thats a retarded amount of money for an old vintage brand new bike I plan on banging into the ground.




woe is me but it sounds like a perfectly awesome idea.


Sandblast Rally has moved the date a month back to first of March. Might take me that long to bend the bashplate straight again ah.. thanks for listening to the ramble.

[Rucksta]

Originally Posted by Stagehand

woe is me but it sounds like a perfectly awesome idea.


.

you know you want to

how about a rolling chassis and become very good at engine swaps?

[AntonLargiader]

Originally Posted by Stagehand

R65 engine, R100cylinders machined down, and custom pistons: ANybody want to take a $$ Guess?

I have an R65 bottom end and I suspect I have some cylinders. I know I have iron ones to play around with. But is it worth giving up 130cc for?

[Beater]

Originally Posted by AntonLargiader

I have an R65 bottom end and I suspect I have some cylinders. I know I have iron ones to play around with. But is it worth giving up 130cc for?

I have an R65 bottom end as well ... and I know your address. Very tempted.

[Rucksta]

Originally Posted by AntonLargiader

I have an R65 bottom end and I suspect I have some cylinders. I know I have iron ones to play around with. But is it worth giving up 130cc for?

The configuration has some advantages.
- faster spin up
- narower
- lighter. a bit
- maybe a bit more chuckable from side to side


When I ran my mild 980 against an 860 in a similar chassis there was not a lot in it.
The 980 was easier across the paddock in slow going .
Once the revs were up to low 3000s there didn't seem to be much performance difference
The 980 was stronger 5000 - 6500 but the 860 carried what power it had further into the rev band past 7200.
Peak power was probably similar in the low 70s and the 980 clearly had more area under the curve.

Lots of vibration from the 860.
For a dirt race bike is probably a very good choice.
AW certainly seemed to get some pretty credible performance out of the one he rode.

Did you miss the grunt of the 980 under race conditions?

[Airhead Wrangler]

Originally Posted by Rucksta

AW certainly seemed to get some pretty credible performance out of the one he rode.

Is there another AW on here now? Do I have a doppleganger? It wasn't me.

[Stagehand]

I was wondering the same thing!

I personally couldnt tell a majotr difference between my R100 and Paul's bike--


WHen I say I couldnt tell a difference, I mean of course I could, they were amost Entirely dis-similar but i mean that i did not miss 130cc by a long shot.

The engine pulled long and hard, for as long as my courage held out.

And it seems shortsighted to simply put up with the extra two inches of width and whatever extra weight came with the R100 motor, even if it is easier.

Hows this for an idea:

SInce the short width of the R65 stems from the short con-rods, and one is required to shave the cylinder bases down anyway, is it feasible to simply put short con-rods in an R100? With short headed pistons, (JP's?) one should be able toget he same volume out of the jug... I doubt it, I bet the conrod bores are the wrong size, it would be a custom con-rod deal. Maybe thats ok?
Then there's making the pushrods do right. Use R65 pushrods?

Paul is not unenlighted to solve for the lightest combination possible. Everything we talked about, he was stressing lightness.

[Airhead Wrangler]

Originally Posted by Stagehand

SInce the short width of the R65 stems from the short con-rods,

Are the rods much shorter? I thought it was mainly just the shorter stroke of the crank that made it a narrower engine.

[Rucksta]

Originally Posted by Airhead Wrangler

Is there another AW on here now? Do I have a doppleganger? It wasn't me.

Finger fault or brain fart not sure which.
Sorry AW and appologies to SH no intention to discount your achievements in the Safari. great effort.

[Rucksta]

Originally Posted by Stagehand

I SInce the short width of the R65 stems from the short con-rods, and one is required to shave the cylinder bases down anyway, is it feasible to simply put short con-rods in an R100? With short headed pistons, (JP's?) one should be able toget he same volume out of the jug... I doubt it, I bet the conrod bores are the wrong size, it would be a custom con-rod deal. Maybe thats ok?
Then there's making the pushrods do right. Use R65 pushrods?
.

SH

15mm shorter conrods are available from a number of sources including Carillo
Not cheap and neither are std BMW con rods.
30mm overall width reduction and the changed intake characteristics look appealing.
The modification is not unusual on road race airheads.

I've also wondered if short top / short skirt pistons designed for a longer rod combined with a shorter rod an cut down barrels would result in a 60mm or better than 2" narrowing.
Whether the piston skirt extends past the end of the barrel at BDC and the increased angle of the conrod clearing the barrel end at half stroke wouild seem to be important.

Once upon a time I might have tried it.
I find the width of the 980 motor not so much of a burden that I want to throw $$ at it just to slim it down. It is rare that I need to be one inch closer to the edge of the track and the inch less still doesn't get the bike flat enough on the ground to get it under the gates they use on forestry tracks around here to keep the 4x4s out.

Maybe at rebuild time when I need to replace barrels pistons and conrods I will also feel like adding an amount equal to the parts cost to do the mods to slim it down. I'd be looking at $4.500.00 - $5,000.00 plus new headers and some more for unexpecteds.to have Paul Rooney or Ray Peake do the work using new parts.

I believe I could have picked up Rays 860 motor complete for under 5.

It may be cheaper where you live.