When you say 2 white 2 black on red slide, are the 2 blacks and 2 white springs for the clutch while the red is for the carb?
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You got it. Personally we havent done a ton of testing with different clutch spring setups because we still hsve so much to gain on driver and chassis changesā¦
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I wonder where people get the idea that youāre going to tear up your equipment doing the bathroom scale up against the wall procedure??
Hardly a weekend went by when we didnāt test the clutch engagement RPM on our Yamaha. Never burned up a clutch, never never never! If youāve never done it, how can you evaluate it?
As long as Iāve been talking about it, Iām sure there must have been people who have tried it. Have you ever seen a post talking about how somebody tore up their equipment using my suggestion??? lol I havenāt!!
When doing the bathroom trick do you set the scale in between the wall and the kart and drive into the scale while in contact with the scale and record the reading on the scale? What numbers would I get?
What other methods are there to calculate peak torque?
Torque is not calculated, itās measured!! Horsepower is calculated.
I hope you were joking about driving into the scale.
Calculate the torque?? I suppose, if we assume the engine is making 12 foot-pounds of torque, (assuming the clutch is holding the engine at peak torque) with a 4 to 1 gear ratio, you would likely see somewhere in the neighborhood of 48 foot-pounds of torque. Just a wild guess. Lots of variables to include in the calculation.
I didnāt quite mean backing up and then driving into the scale. 
I meant like if the the kart was already against the wall and the scale and then drive forward. Is that what the bathroom scale trick is?
Exactly. Tell me how it goes.
Ok Iāll try, Iāll list the steps and see if its right
- set the scale against the wall
- position the front of the kart until it is in contact with the scale
- sit in kart
- go full throttle for 2-3 seconds and measure the numbers shown on the scale
- repeat a few times and use highest number to find highest torque
Did I pass the test? 
You have it right. Good luck with yourClutch testing.
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Yes!
I would read the rpm that I get at the highest reading and then set my springs as close to that rpm as possible, right?
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I think you are supposes to adjust the springs up or down until you reach the peak force applied to the scale. The idea being, if the springs are too weak, the clutch will engage prior to peak torque and the engine will bog (small force). If the springs are too stiff, the clutch will slip excessively and you will overshoot peak torque (small force). When you have it just right, the clutch will grab at or near where the engine reaches peak torque and the more pressure will be applied to the scale (max force). It should be a Bell Curve in terms of force applied to the scale where the best engagement point is close to peak torque. Engine RPM is coincidental to wear the engine makes peak Torque. Shooting for highest RPM may put you over the mark for peak torque, because the clutch is slipping too much before engaging preventing it from applying the most force to the scale.
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Ah dang just when I thought I got the hang of it!
So I know there are different color springs with different strengths. How do you know when the clutch is engaging prior to peak torque or slipping?
So should I shoot and try to set the springs at 200-300 rpm under the highest rpm? Like letās say I do the bathroom test and conclude my peak torque rpm is 3000 RPM, would I use 2 blacks and 2 whites to get 2800 RPM? Or if itās at 4000 RPM, Iād use all blacks to get 3800 RPM?
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The readings on the scale will start to drop off on either side of peak torque.
I would suggest slightly under peak torque. That way as you come off the corner, the engine stays in the sweet spot for as long as possible as it revs up. Too far below peak and the engine will struggle, too far above and you will limit the time in the sweet spot. Gearing will affect duration of acceleration as well. Get them both right and you should be able to pull strongly almost all the down the longest straight.
Because the engine and the clutches youāre referring to here are nothing like what is commonly run in late model karts.
It doesnāt take much to overheat a low stall, stamped drum, dry clutch. They donāt take anything like the abuse of their multi disk and or wet types used more commonly in the past.
The upside is that a kartsā performance is not as reliant on tuning of the clutch. Really itās only the 206 clutch that has any adjustment anymore, other classes (KA100, TaG, Rotax) have a spec engagement RPM.
Conscious choice for mechanical simplicity.
No!! Why would you want to do that?
If youāre gonna put the nose of your kart against a scale against a wall, go ahead and order new shoes to put in it after you destroy the ones youāre abusing. Be ready to rework the inside of the drum, too.
These crappy fun kart clutches wonāt hold up to such nonsense. You can barely make it out of a rear rolling direction in a spin without toasting them.
Three second bursts (Max) with cooldowns in between will be fine, but I think it helps if you have mechanical sympathy, you definitely want to tread carefully.
Or we can stop telling new people to do pointless nonsensical things to a 206 when everything is already well documented and easily accessible.
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I donāt disagree, but it does beg the questionā¦
If itās well documented and easily accessibleā¦ why hasnāt Eric and others found it already?
Man, that question isnāt gonna make me a lot of friendsā¦
Self-sufficiency is a lost art. Itās all easily Googlable(?) for anyone that puts in the effort to pop open a search tab. Some of the top results even point right back to previous discussions here.
That also provides further evidence that a relationship with your local kart shop or engine builder is a key component of building a successful future in the sport.
āHey, Gary, Red Slide, Flame Clutch, what springs?ā Bam. Heāll give you who, what, when, where, and why.
(A guy named Gary does not build or prep my engines, but I hear heās great.)
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