Open/mix 100cc class does it work

I have read about tracks trying open 100cc class. Ka100, KT, Kpv, ROK . Any suggestions on making this work at a club level

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Imo you can reliably run kpv and kt100 together but would be difficult to mix in the newer 100cc engines without a major weight handicap or reduction for the older engines.

Simple to make a weight difference to even them out but does anyone have any kind of numbers on weight to even out the newer 100cc. Motors where I run we don’t have enough people to run a specific engine

We have a few topic on it here, I’ll try to dig them up…
Do you have a sense of what the engine mix looks like?

Are number of members is limited so we always have a mix of . KT,KA, KPV, and we run in the mix of 125 tags. The structure I’m looking for is 100cc class only not the 125 in there

This topic is worth I read for you I think.

Good read…thanks . Sounds like we will just need to test what we have and what works for us …

Based on feedback here it sounds like KA vs VLR could be pretty easy to get a balance of performance, but the Yamaha is going to need a fairly big weight break or a really aggressive pipe to be competitive.

My home group runs KA and KT in separate classes. Yamaha runs on the SR-Y pipe which was the spec senior pipe for WKA before they went back to can.

KA races at 360 lbs
KT races at 345 lbs with SR-Y pipe.

Last weekend on a course with a 40 second lap the KA was right at a second a lap quicker than KT. That’s the same driver running both classes so in my mind that’s a great comparison.

Good place to start. Being same driver/track. 100cc piston port motor might run with them around 320 pounds… need to figure out a weight for running the kid kart motors also … Honda and comer.

You’d need a driver weight of around 155 to get a yamaha to that weight. You’d almost have to add weight to the other to make it to where you can find a driver light enough to still try the Yamaha.

I’d think 340 for Yamaha with spec pipe and 380 for KA…still think the KA has a slight advantage at those numbers but it won’t be a huge gap.

The problem is that 380 is almost TaG Masters weight. I weight 140 and run KA100, my kart’s heavy enough as it is without running an extra 20 lbs. on the seat, if I even had enough space for it.

Unfortunately the reality is that a 30+ year old piston port Yamaha won’t be competitive with KA, it’s just too different of a motor. At my home track you’re looking at a 49.0 vs. 51.5 for the track records for KA vs. KT. That’s 2.5 seconds you would have to find with a weight break or some other type of advantage.

yea maybe never on a regional level Could you mix them but club racing on a 25 second lap track we can mostl likely find a place for a piston port motor. To compete if the driver can’t come in light enough guess he can just get a Ka or vlr .just looking for any kind of numbers to start with

Unfortunately we just don’t have the kart count to have a class …we do good with are run what you brung class right now there is no weight limit. So anything might help even everything out

Personally, I would just run a 100cc open class. Standard weight of 360 to start and adjust weights as necessary for say KA vs. VLR but not Yamaha or KPV, and any 100cc motor is usable. Then, score a sub class as 100cc Piston Port for the Yamaha and KPV drivers since they’re at such a disadvantage versus the new reed valve motors.

And yes, an FA/FSA engine would be allowed. It would whoop the field and be badass and anyone that complains about that just doesn’t know how to have fun.

Is that a “piped” KT time or can?

It is a can time, I haven’t seen a yamaha pipe go around Badger in probably 4 years now. It never picked up out here so that’s all we had. I think the pipe is about a second quicker so only a 1.5 second gap which is still significant but not as terrible.

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That’s why I wanted to check. A can is going to get crushed for sure. In cases where the engines are mixed, the KT with a pipe is what’s being used.

I do wonder what (If anything) could be done inexpensively (say sub $300) to pep up a KT.

Head volume? Larger carb? @Rapid1 ?

The old Yamaha Pipe class from the early-mid 2000s was pretty similar in times to KPV at the time. I can’t remember the weight it ran at, might’ve been 340 with the two KPV classes at 320 and 360. Most tracks they were within a few tenths.

Any post on here about time bracket racing maybe that would work for are small club. Have a slow class and a fast class ?

You could group them by induction type. Piston port in one group, TaG reeds in another. That would help with weight grouping too with KT and HPV being somewhere manageable to get close.

You could run together, score separately or grid them with piston port behind the reeds.

The need to do this might depend on entry numbers though.