this is going to change f125 if it's legal

Andrew. james

I saw this in the roadracing forum and its got me thinking Rotax for f125.
I think that if this is legal it will completely change f125.

http://karting1.co.uk/continuously-variable-transmission-for-karts-test.htm

Vernon Head · Posted: Mon May 22, 2006 10:09 am Post subject:

Andrew:

Here is what the rulebook says:

"Other Engines: Engines must be either a) mass produced
single cylinder two-stroke engines not to exceed 125cc or b)
mass produced single or twin cylinder, four-stroke engines
not to exceed 250cc of total displacement. No prototype, preproduction,
“works type” motors or road race engines are
allowed. Shifter or gear-box type motors are prohibited."

I think a CVT is considered a gearbox.

Ryan D Thompson · Posted: Mon May 22, 2006 10:16 am Post subject:

I'm not sure if this would qualify as a gearbox or not though. It looks kinda of like a variable gear. It doesnt look like its part of the motor. I think the regular single drive works, but the "cvt" is connected to that.

Vernon Head · Posted: Mon May 22, 2006 10:20 am Post subject:

It performs the same function as a gearbox. What's worse, it does it even better by eliminating shifting altogether. A CVT is a transmission. Gearbox is just another word for transmission.

Andrew. james · Posted: Mon May 22, 2006 1:02 pm Post subject:

I'm not so sure this is explicitly illegal with out current rules. It is not part of the engine. For example if I put this on a cr125 would it be illegal?

Vernon Head · Posted: Mon May 22, 2006 2:17 pm Post subject:

The rulebook says no transmission, so you can't have one either internally or externally. If in the future the SEB decides to allow CVTs on Rotaxes or any other TAG, believe me, it will say so.

The wording may look a little ambiguous. But in any case (especially where performance is enhanced) where it doesn't specifically allow it in the rules, then you run the risk of losing the protest.

Larry MacLeod · Posted: Mon May 22, 2006 2:35 pm Post subject:

David Hedderick · Posted: Tue May 23, 2006 12:16 pm Post subject:

would this be cost effective on a motor making less power than a built 125? Sort of an alternative? Or not likely?

David

Andrew. james · Posted: Tue May 23, 2006 4:04 pm Post subject:

Rick Brown · Posted: Wed May 24, 2006 4:39 pm Post subject:

Vernon Head · Posted: Wed May 24, 2006 6:57 pm Post subject:

Rick:

I like your thinking. However, this probably wouldn't fly either. It says "Shifter mechanisms must be manually operated", and a CVT's purpose is to change ratios and it's not manually operated.

I could be wrong, however. Maybe you could ask the Kart Advisory Committee for a ruling.

Brian Garfield · Posted: Fri May 26, 2006 7:02 pm Post subject:

I'd say it's not legal, but you might as well write a letter for clarification.

Brian

Daniel Morency · Posted: Mon Jun 05, 2006 6:45 am Post subject: create your own local class...

As you all know individual clubs can create classes for almost anything... They just are not supported beyong your own club.

Our club @ www.CumberlandMotorClub.com allows CVT's on karts and has for the last 4-5 years. I developed my own setup using a jackshaft system and a comet TAV system. It still uses a #35 chain final drive.

This system was used by my family for 3 years running the Briggs Raptor based classes. My children could spin the tires upon takeoff.

As you all know these engines are very HP limited. 6 HP out of a Box Stock engine at 4500 RPM and 8.5 or so out of a WKA "blueprinted one at about 7200 rpm. We found great advantage in corners but limited top speed. If the course is tight and slow the torque converter was a HUGE advantage, however when faster courses were setup the inherant losses due to the additional mechanical losses caused lower top speed capability. I found about 3-5 MPH was lost over a properly geared standard setup with an unlimited distance to gain speed...MY STREET! Smile

Remember a standard clutch locks up and has little operating losses a cvt has the mechanical losses from sliding parts and additional bearing losses etc...

On short, tight courses we were able to get FTD 3 - 4 times with briggs engined karts. This is running vs some pretty good autocross cars...

I think that with the two strokes capability to pull speeds beyond those in an autocross it would be a terrific system.

The UK company should however add a third bearing support at the end of the crank to reduce the crank loads.

If I could find a stock system to fit the crank of my Yamaha KT100's I'd be working a similar system right now, they drive so different than the bog and rev standard kart clutch setups.

BTW our chosen gearing with the CVT... 3:1 to .9 from the CVT and 5 on the chain for effective gearing from 15:1 to 4.5 to 1 with more RPM available you could choose gearing to make burnouts possible with a two stroke and still gear for say 70 -80 MPH on an autocross course! WOW

Dan

CMC kart chair

Larry MacLeod

Daniel Morency · Posted: Mon Jun 05, 2006 6:49 pm Post subject:

Larry, you are correct re the existing F125 class, that would not stop a local region from forming a class allowing a 125 TAG with a CVT... They would be about as fast as a shifter more than likely. (but much easier to drive!) We call our "Open" class Formula Super Stock (FSS) We have a modified Briggs Animal running, used to have an Open Briggs Raptor and have various TAG motors beyond the Yamaha Can motors that all run under that class. Recently an IAME Tag 120CC and Rotax have run... (A Yamaha with a pipe would run there too...)

Our independant club doesn't use the same SCCA insurance carrier, but we are very cautious re speed potentials and would not allow a 250 shifter for example.

We do however allow a modified Tecumseh Star or a 270CC Honda that is modified... Our rules evolved based on what our members wanted to race.

For instance we also allow Volvos with Ford V8s to run in SM2 (Engine swap from another mfg)

If the club membership sees a need and can agree on a class.... If our bord of directors and the membership deems it safe... why not.

Dan