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Boozebag
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This is the write up for the Rokon:

I aquired a Rokon prototype 340 back in 1989. It is one of two rotary powered experimental bikes built in Keene,N.H. The other was powered by a 13 horse sachs, and mine is powered by a 33 horse Sachs KM24 engine. As far as anyone knows, the other no longer exists. The build date was sometime in 1974.

It is basically a 340, with some unusual modifactions. The goose neck angle has been altered, so the serial number has a weld going through it. It now reads RT3-08. It has the yellow glass tank and the mag wheels. The rear brake rotor was spaced off the wheel for some reason, probably to make the caliper contact better.

There are many parts sourced from other bikes, the fenders are Kawasaki, headlamp is Suzuki, Honda tailamp, BMW muffler, Bettor air forks, clip on street bars, Carlisle flat track tire.

Currently, it is registered and insured, and I ride it regularly. It causes a scene wherever I go, particularly at shows, and Harley bars.

I couldn't attach the picture, it wouldn't transfer over. I'll see if I can find one.
 

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Boozebag
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349803

Crap picture. I'll try and find a better one.

At least you can see the BMW muff, Honda tail light, Kaw fenders and clip on bars.
If you've ever seen an Arctic Cat with the KM24 Sachs Rotary, you'll recognize that too.
It also has a VDO speedometer, Mikuni VM24 carb, no battery and pull start!
I was thinking of restoring it, but it is all original. The Rokon group guys suggested leaving it alone.

This pic was taken in Albany, NY - 1998. You can see one of the State buildings in the background.
 

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1991 Irregular Cab Short-Short Bed
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287 Posts
Discussion Starter · #403 · (Edited)
$ome new part$, YAY!!
Ridetech 3-way coilover $hocks and Eibach $prings.

350132



Gonna have to fab some stuff and make some parts so it will fit in here.

350133
 

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I always tell people if they have the skills to cut off the spring pocket and flatten the frame. Mount the C/O on the outside and improve your spring ratio immensely.

Regardless of what you do I'm sure it will be well thought out. Looking forward to more results.
 

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1991 Irregular Cab Short-Short Bed
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287 Posts
Discussion Starter · #405 ·
I always tell people if they have the skills to cut off the spring pocket and flatten the frame. Mount the C/O on the outside and improve your spring ratio immensely.

Regardless of what you do I'm sure it will be well thought out. Looking forward to more results.
Yeah, with the extended control arms my spring ratio is 3.1:1
I'll have to think real hard for a while about doing that. I'm losing enthusiasm for major chopping and fabbing...
I'd like to get a lot closer to working on making it run (which is still a L O N G way off).
 

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Very cool. We have an extra 4 door 2nd gen bed we want to throw on a reg cab for fun. Plan is to lift it though.
 

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Yeah, with the extended control arms my spring ratio is 3.1:1
I'll have to think real hard for a while about doing that. I'm losing enthusiasm for major chopping and fabbing...
I'd like to get a lot closer to working on making it run (which is still a L O N G way off).
Can always bolt on the C/O as is for now, get the engine running, and you might find your motivation again. Or just enjoy it and get back to it after tearing up the road for a year or two.
 

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Discussion Starter · #410 ·
Can always bolt on the C/O as is for now, get the engine running, and you might find your motivation again. Or just enjoy it and get back to it after tearing up the road for a year or two.
This is likely what I will do for now. As you say, I can chop it up later if the big ratio turns out to overpower the shocks.
The Eibach springs in the photo are 1100 lb/in. 🐘
 

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Discussion Starter · #412 ·
Cool. How fancy you plan on going? Sequential fuel and spark? Coil on plug?
Fuel and spark - Yes.
Coil on plug - Yes.
Knock detection. Maybe eventually traction control.
Sequential? Possibly. I have to learn more about pros and cons of batch fire or sequential. It's been a few years since I dived in to the Megasquirt world. I have to re-learn whatever it was I learned back then. It seems like with batch fire and coil on plug wasted spark ignition I could eliminate the need for a cam position sensor.
 

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Discussion Starter · #413 ·
I always tell people if they have the skills to cut off the spring pocket and flatten the frame. Mount the C/O on the outside and improve your spring ratio immensely.
It's looking like I may have to do this anyway. The fingers that locate the top of the stock spring are in the way of the upper end of the coilover spring. Cutting them out will be a big PITA and even then there may be a little bit of interference due to the inside shape of the frame. Plus, the ugly frame would mostly hide my beautiful, expensive shocks!

I can see that mounting the coilovers outboard of the frame could change my spring ratio from 3.1:1 to somewhere around 1.8:1. Maybe less if I angle the shocks out at the bottom a little.
Also the fabrication of the lower coilover mount can be much simpler.
 

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Horsepower Addict
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Cutting the inner spring seat is not that bad. Took me about 1/2 hr to do both sides, using a carbide cutter & cutoff wheel.

350179


Keep in mind, if you angle the coil over, you also reduce the effective rate of the shock & spring.

Shock Angle Angle Correction Factor (ACF)

10°………………………………….. .98
15°………………………………….. .96
20°…………………………………. .94
25°…………………………………. .91
30°…………………………………. .87
35°…………………………………. .82
40°…………………………………. .77
45°…………………………………. .71

Formula: ACF = COS∠A°
 

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1991 Irregular Cab Short-Short Bed
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287 Posts
Discussion Starter · #415 ·
Keep in mind, if you angle the coil over, you also reduce the effective rate of the shock & spring.
Yes, but it makes a good trade off by getting the bottom of the shock closer to the wheel. Especially since my control arms are extra long.
 

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1991 Irregular Cab Short-Short Bed
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287 Posts
Discussion Starter · #416 ·
How to make a nice flat plane of a cut in the odd shaped bulge of the spring seat?

Break out the laser!
A laser level and a paint pen make it a lot easier than eyeballing it with a grinder.
350185


Cut on the dotted line
350186
 
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