Not much… still a 3/8" spacer on each side of the front seat mount is all that’s left. I can remove it to see if that’ll give me enough additional front weight. Already took one set of 3/8" spacers out and still needed that much weight (~8 lbs) to get to just under 43% on the front. The kart overall is at 393 lbs with ~1/4 tank of gas.
Thats a lot of weight to In front of the front axle.
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I’m working on other possibilities to move weight forward. Now sure what’s going to work tho.
I understand. Any weights bolted under your thighs? Or on the floor pan?
How big of gas tank you got? Fill it all the way. You mentioned only 1/4 full. You can get some
Weights taken of then.
Yea that is what I heard. I just got one, I just want to have more steps between the softest metal bar and no bar for testing this weekend given how much front end was in the kart during the first practice sessions last week.
That chrome round bar’s stiffness in bending is about exactly the same as the flat rectangular bar very close to vertical. In the bending deflection calcs I did, all the metal bars range between 0.008" and 0.018" (I used a 100 ft lb moment, free ends) where the solid round delrin bar is around 0.09", and the bladed one ranges from 0.04" to 0.15" depending on the setting.
Keep in mind those are arbitrary deflections, they just give me a easy way to visualize the relative stiffnesses.
I generally like how most chassis feel with no front bar, but that can get flimsy feeling in a shifter, so a “super soft” option like this has worked for me in the past. My home track has some gnarly curbs too, and a more compliant front end is fairly popular there, everything stays more settled.
Behold. Took me way too long to get the measurements right. 8mm incline on the seat. Only thing I could not get right was the top of the seat to the axle measurement. My seat literally wouldn’t go down far enough without messing up the other measurements. But quite proud of it.
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I’ve been trying to get the front weight up to ~43%. It was at around 35 - 36% IIRC. I’ve been struggling with understeer/flat tight and am trying to free up the kart. I’ll try adding gas and moving the seat up to the brackets (3/8" spacers there now) and move the existing nose weight as far forward as I can and saw what happens when my partner in crime stops by.
Nothing to the floor pan, I took the weight that was under the front of my seat near the gas tank brace out to try and move weight forward. I’ll try adding gas, moving the existing front weight as far forward as I can and moving the seat 3/8" forward and see what happens.
New bearings for the crankshaft and the countershafr installed. New countershaft readdy to install but its that comment we need to true up our crankshaft before close the cases
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Its so odd that the bearings need to installed with the caged profiles looking outside of the inside nest of the crankcases . Its the complete opposite f4om what the rotax asks for their engines in their workshop manuals …
Strange world… 2 strokes …
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I would like to formally thank everyone who snapped me back into reality on this seat. To my surprise, instantly more comfortable in the kart than i’ve ever been. Supported by the new low profile Odenthal mount and the 10 degree wheel shim. This is pretty close to perfect.
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Now we’re talking. 
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Proper positioning now! So glad we can help!
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Gotta love brand new everything. Running in the engine and chassis tonight! Gonna sweat hard in the heat.
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Let us know what you do to decrease the sensitivity
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- Replaced OTK front rectangular bar with Delrin blade bar I made, oriented horizontally. Bar is 5-10% of the stiffness of the OTK bar horizontal bar
- 4 clicks (2 forward bottom, 2 back top) of negative caster. Adjusted such that camber is unaffected and is still neutral. May use some negative if I want to further dull the turn in feel
- Moved tie rods to upper holes to reduce Ackerman
- Toe set to zero with me in the kart (was 2mm out on each side)
Gonna test this Sunday, I will report back after
TJ do you have a link to that setup video you made a while ago? I thought I saved it but I can’t find it. It was really helpful
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Tested the 401rr TM KZ kart today. It was great, everything I changed worked more or less as I expected. For the track conditions and weight it was the quickest I’ve been around orlando (green track, used levantos, 410 lbs).
I did get the headshake thing one time going into turn one, but I backed the bias off a touch and ran the 4 quickest laps of the day right afterwards. I guess these brakes are really sensitive about having the bias set dead on the money if you’re gonna go deep. Overall the kart is badass and the TM R2 engine absolutely rips. Can’t wait to race it this weekend.
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