The Great Debate: KA100 vs VLR

2 Stroke Kart Engine Forums
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22

Thats great! Im planning on making the switch to vlr next season!

23

I really donā€™t think you can go wrong with either. Itā€™s probably more down to support at the races you plan to run over anything else.

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24

From what I heard from someone that ran at the Biloxi race, Rok made a new header and reed valve that makes it more competitive with the KA. That was at least in the Junior class, but I canā€™t believe it wasnā€™t done for the seniors as well. The only problem weā€™ve seen with the one VLR that runs at our track, is getting parts for the motor.

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25

So just to get some convo going simply because I like to know more about eachā€¦

Since the VLR and KA have been out there long enough, whats the real world say now?

Longevity(ie rebuild times), tuning power vs each other, growth, etc.

26

Last I heard, the KA is still slightly quicker, but there are rule changes afoot perhaps to bring the VLR into the mix a bit more for places itā€™s running against the KA.

Iā€™ve also heard the KA remains the reliability champ compared to the VLR, but the VLR is cheaper initially and isnā€™t that far behind in terms of running costs.

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27

As TJ pointed out, the KA is a little quicker. Iā€™ve seen it head to head at our track. However, Iā€™ve also heard that they have new reed blocks and exhaust manifolds that are supposed to bring them close in performance.

28

More information regarding VLR vs. KAā€¦

At Rok the Rio, I was told that the best VLR finished P8. There were 4-5 VLRs in the field, the rest were KAs.

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29

This is the way I look at it when people ask me if they should get a VLR or a KA. They say all the fast guys are running a KA so I should get one. I think you see more KA up front because of the drivers. Most fast regional and national drivers run skusa. So why as a national level racer would I run a VLR when I canā€™t run it at my skusa events but I can run my KA at ROK events. I think that the only way to get an honest evaluation would be to put the top drivers in both motors and test both back to back.

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30

Agree. I was also making this assessment in my head. I donā€™t want to sh*t on the Rok the Rio drivers, theyā€™re quality, but the level at SuperNats last year was higher. I would like to see some of the front SuperNats finishers back-to-back the engines.

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31

Would ROK run a 100 grid if there were only entries for the KA? Theoretically itā€™s possible is it not?

Seems obvious to me that Vortex will have to either update their package or stop this self-defeating cross-over.

32

According to ekarting news senior was 5 VLR/14 IAME but Junior was only 1 IAME to 18 VLR. Master was more evenly mixed with 6 VLR/10 IAME. any way to see how that class shook out?

33

What is the differences between the KA100 Tillotson HW 33A carb and the VLR 100cc Tillotson HW38 carb?

34

Iā€™ve heard that some of the reason that most Juniors were on the VLR vs the KA is that in junior restriction the VLR produces up to 4 more HP. I donā€™t know if that is true, but thatā€™s what Iā€™ve heard. At the ROK race in Biloxi, they actually had an entirely new restrictor and intake for the juniors. One of the entrants is someone we normally race against, and they have both the VLR and KA, and ran the VLR at the ROK.

35

So, I figured we would all do well to see an update from this post.

There are many similarities and differences but both motors are pretty similar from what I can tell the major differences being the Reeds both in Material and Dimensions. The other major difference is the pipe between the two engines but the Carb is identical on both but 98% of all dimensions give an advantage to the KA as overall other then port size tiny bit larger on VLR but less timing by a very small margin, its has larger breathing in and out which is why ignition timing has become such a hot issue for BOP. Altho, I would say at this point both engines can get you to the front, seems like I have seen more envelope pushing on the KA at this point. The only big advantage I have seen for the VLR is the min clutch weight is like nearly 180g lighter.

When it comes to Juniors I canā€™t say much we donā€™t run that at our track.

36

Its been a while since this topic has been discussed but have any of the above mentioned VLR changes happened (header, reed valve, rules changes)? All other things being equal does the KA still have the edge compared to the VLR?

37

From what I read above, I believe the advantages we more to do with Senior vs. Junior. The restriction in Junior gives an advantage to the VLR where in Senior they are more equal.

38

I havenā€™t heard anything more on an update to the VLR in the senior spec, the KA is still the motor to have as a senior. For the junior spec, there has been some testing going on running the KA with a 25mm restrictor instead of the 22mm one. We ran the larger one at Battle at the Brickyard, and from what I could tell between those running up front, the KA was more on par, maybe even a little faster, than the VLR. Of course, a lap at the Brickyard is 90% full throttle.

39

Is it still the case today that you cannot run Rok at SKUSA but you can run the KA in the Rok series? Saw that mentioned in the thread, was wondering if that is still the case today.

40

I donā€™t think the KA is allowed at Rok Cup anymore, and the VLR is not allowed at SKUSA.

The parity between engines was not close enough (KA better in Sr., VLR better in Jr.) so I think Rok got rid of it.

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41

There are club level classes that mix 100cc engines. But as TJ said I think KA was dropped from the RoK USA events.