A group of us locally have started doing regular trackdays and occasional races at our nearby indoor go kart track. We have been doing this through the winter the last couple years. The track specifics: .20 mile indoor track Polished concrete Minimally heated (indoor temperature ranges from 10F-50F depending on the day and the point in the winter we are in) I am running Mitas tires on my KLX143 (Super Soft Front, Medium Rear). I have been experimenting with pressures in an attempt to find better grip. My typical starting pressure is 16F/20R psi cold. I have been focusing mainly on the rear as this is where I am struggling the most with traction. I have experimented with going up in PSI (28PSI hot max so far) as well as down (20PSI hot min). In the case of this last weekend, ambient temperature was approximately 45F. Tire temperatures measured via probe pyrometer were 87F at 24psi, and 82F at either 28 or 20PSI. I'm hoping anyone can give any tips/direction on what direction to go with the pressures. Based on the temperatures measured it doesn't seem like up OR down was an improvement in temperature/grip. *Subjectively* when running lower pressures it feels like there is more "pumping" during throttle application. I think the ideal working temperature for these tires is ~170-180F, so we are well short of the ideal. I assume I will have to drop way down in pressure in an attempt to get to these temperatures, but I was hoping to get some feedback from people who may have run mitas tires in similar environments. PS the tires stick great outdoors, where the attached picture was taken. But just can't come to terms with them on the polished concrete inside yet...
That photo makes you look fast. When I rode Nick's 143 at K2K, it had the medium rear. It slid every time at initial throttle application. Whether it was setup, pressures, etc., I'm not positive - but I'm going with a soft rear, to start out.
I have low confidence that going Soft or Super Soft would help in this case, just because my personal experience is that the SS front doesn't stick uniquely well either!!! At least i'm not alone in slippery Medium Rears. Next session i'll try going lower, like 11-12PSI cold and check my temperatures and see if that builds any more heat. But I think it'll just lead to the sidewall collapsing a lot...we'll see! I've been told that picture makes me look slow, because I look like i'm just laying there next to the bike haha. I even kind of agree after someone mentioned it
Agreed, it is somewhat of a moot point, in the winter there. We'd play around with pressures high and low and there was only so much you could do. Like you said, too low wasn't good either. Grip was always a limiting factor, but great practice.
Savas MC31s? IIRC they say to go UP in pressure in cold or wet, WAY up to increase point loading. I remember having giggle inducing traction on MC31s at 38psi in a warm rain with 1 to 2 inches of standing water on parts of the track. https://www.ooracing.com/tyre-sava-mc31-120/80/12-race-soft-s-racer.html INSTRUCTIONS FOR USE OF SAVA RACING TYRES (Recommendations) tread patterns MC 16 / MC 18 / MC 29 / MC 0 / MC 31 note: dry surface tyre pressure front/rear pressure warm weather rough surface MEDIUM 1,7 bar - 25 psi 1,8 bar - 26 psi warm weather smooth surface SOFT 1,7 bar - 36 psiSOFT 1,8 bar - 26 psi cold weather rough surface MEDIUM 2,5 bar - 36 psi 2,7 bar - 39 psi cold weather smooth surface SOFT 2,5 bar - 36 psi 2,7 bar - 39 psi When seeking the optimal pressure values the rider's weight must be taken into account. It is recommendable to increase tyre pressure gradually by 0.2 bar until the ideal tyre pressure is reached. WARNING Different pressures in tyres can cause tyres to react differently in case of skidding: - in case of higher pressure reactions are harsh and abrupt; - in case of lower pressure reactions are more soft and temperate.
Wow, 36/39 is high! I think the Mitas and the Savas are more or less the same tire? Seems like I may be off on the compound (medium vs soft) for smooth pavement. Hopefully that doesn't make too much of a difference. Considering our track temperatures are never above 50-60F, I think even a warm day at our track would be considered "cold". An outdoor event with track temperatures of 85+ degrees may start to count as a warm day. So next time out we'll jack the pressures way up and see how it feels. Thanks for that piece of information Kurlon. Hopefully it helps. Eddie, pretend you never saw this. Need you chasing pressures on your KLX so that the rest of us have a chance. While you're at it, buy a hard compound
Damn, and I thought the Hard compound on my 150r was slippery. I tried the medium last week and it was a god send. I usually run around 25psi. That's in Colorado winter btw, so usually about 60 degrees and sunny
Our typical running conditions are ~32F and indoor, so no sun. We've had a couple days in the single digits for ambient temps. Its like riding on ice
The sava/Mitas are a strange tire I run much higher pressures on them than I did the dunlops. It's kind of nice cause you don't have to worry about pinching a tube as much. Not that my new bike has tubes but the older ones do. With the dunlops I stayed around 18-20 psi with Sava/Mitas I'm 25-28 and they seem to work till the cords are showing, were as the dunlops lasted a long time they started sliding more and more past half tread depth. I don't have much experience indoor I have only ridden indoor once and the tires were brand new so half the day was spent trying to scrub them in. Eddie the oil all over the bottom of the engine might have been part of the issue with the rear tire. I think I have that figured out. (New o ring on the filter cover, new drain crush washer, and a vent on the crank breather bottle(not sure why it was not vented in the first place I did not build it).
It has been phenomenally good training to get used feeling what the bike is doing underneath you. I look forward to trying to put it to use at STT days this summer. Although I have gotten into the habit of just muscling the minis around. I think the big bikes may want/need a bit more finesse
I would run the MC 35 in a higher pressure and run a softer rear on a cold smooth polished concrete track as well. We recommend starting pressures around 22 due to the softer carcass of this model tire.
I experimented some more this weekend with higher tire pressures. Track temp was ~50F. Started at 36F/39R cold. This eliminated my troubles with "pumping" however once I reached the "limit" (or should I say my limit) of traction, I would get severe chatter on both tires. Recorded tire temps were ~95-97F max on the rear, and about 10 degrees colder on the front. Then rest pressures to 36F/39R hot. Chatter was reduced slightly, but far from eliminated. Tire temps were still in the high 90 range. I also tried a back to back comparison using my dad's CRF50 and my own (with 10" tires obviously). His bike has Mitas 3.5x10 (SS front, MED rear) and mine has the 90/90x10 (SS front, SFT rear). We set his bike to the previously recommended pressure (16F/20R) and my bike to the high pressure (36F/39R). Results after a 15 minute session were that the tires achieved more or less the same temperature, about 120F in the rear. We split the session in half, swapping bikes at the 7 minute mark. We both ride more or less the same pace, but this should eliminate rider influence. Subjective feedback from both riders was that the lower pressure bike felt better. So at least so far the very high tire pressures feels like a failed experiment. But i'll continue to try pressured in the 20-30 range and see what works best for me
The grip outside was decent, to say the least. Corner speeds on the infield section of our supermoto track were noticeably higher with the KLXs than the 250/450s
Some feedback here. I ran MC35 Soft front at 20psi cold and the tire wore too quickly. Ambient temperature around 60 degrees and fairly grippy pavement. It's down past 50% tread life only after a couple of day's worth of riding.
So for the MC35, follow that same chart for the MC31 et al? I have the mediums 25/26 cold pressure on warm day; 36/39 cold pressure cold day? on asphalt
