4 Stroke to 2 Stroke - KA100

After completing my first Karting season starting in LO206 (5 races) and adding in World Formula (2 races) I’m finding myself wanting more speed.

I have chatted with some of the local Racers and they have said the tuning and maintenance isn’t that much more than the world formula. I do understand it will be more expensive with it needing rebuilds relatively often and of course race fuel.

Would like to hear things I should consider in making the move. Is the learning curve much steeper? I’m not an expert tuner so hoping for minimal tuning. Anyone regret making the move?

Ultimately I’ll still keep my 4 strokes and still race on occasion as those will be priority.


What’s the power of WF? Lo is like 9hp I think?

Seems like going from Honda gx270 to gx390 sorta. The extra 5hp is very significant but it doesn’t drive differently. I’m curious to see what folks say.

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Evan we have talked a little. But I have done my research. And have one whole test session on a 100cc. But I’m here to see what people say as well


One of the best guys I raced this year in KA jumped over to our class from 206 half way through the year and was immediately fast with very little test time. If you have the principals of karting down, my impression is the adaption should be very quick.

Setups are a little different, but you’ve got a 2-stroke OTK kart from RPG right? put the baseline setup in that thing, mount the KA and let it rip.


I apologize, I thought you were wondering about the switch from LO to WF.

The difference between my x30 driving and rental racing (4-stroke) is significant but I don’t think you need to adapt your driving exactly. It’s a different thing in that the lack of power and grip in 4 stroke makes you drive carefully. 2-stroke makes you feel like you can get away with being a bit more ragged because it feels so much more responsive. But, that’s just an illusion. Drive it like your WF. End of the day quiet tires and correctly timed inputs wins.

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206 to KA shouldn’t be that tough if you’ve got the basics. Based on the coaching session we did Evan, I think you’d adapt quickly enough.

KA is about as fool-proof and straightforward as you can get for a 2-stroke. There’s a reason it’s so popular and my favorite engine package at the moment.


WF is 13-15 hp depending on regulations. Ive seen one make 18 but it was blueprinted

Its not relevant to the topic, but Ive been interested in some kind of coaching next season. Do you have a website or something where I can look at options or whatever?


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A KA100 is faster than a WF, but not that much faster. Now if you want more, just put on two WF!


Glorious! Would love to hear what twin 4-strokes at sustained top end sounds and feels like.


Our machine wasn’t that glorious at top end - sound wise. We had the RLV mufflers pointed at the ground and they were between the bumper/tire/bearing change area. Probably the quietest kart on the track. Sounded kind like the Jetsons car going by! We have a couple more in process that will have RLV “Out the Back” pipes on them. Should sound a little more fun. Kart is just a little faster than most sit-up TAGs and just behind good shifters (Road Racing).

Oddly, I kind of like the sound of 4-stroke. Yah it’s quiet, relatively speaking, but still, it gets under your skin.

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To be fair, the 4 stroke driver your talking about has a wealth of driving experience including TAG from years past.

We ran with NCK at Speedvegas last weekend. Kart ran well, still had few racing issues. Here is a video from one of the races. Enjoy! https://youtu.be/-0G9sb5Cj6c


#18 lay down looks so cool!

I’ll chime in quick and just say the transition will be quick but difficult to get used to for a little while.

I do the opposite, I hop into a 206 from KA every once in a while. It’s really tricky to remember I’m not entering the corners as quickly so I can go way deeper into the turn before braking, and I also don’t need to roll onto the throttle with the 206. Then I’ll hop into my KA again, just mash the gas and hit a big slide for a couple laps. The driving style is different by a good bit, but you’ll notice pretty quickly what you need to change.

One thing I’ll point out is that “race fuel” could be 93 mixed with 5 oz/gallon of Mystik Sea and Snow JT-4 oil ($5/quart), giving you a fuel that costs about $4/gallon. It’s not a significant cost.

If you’re not planning to race a 2-stroke regularly, why not spend less than a new KA100 would cost, and buy an old Rotax? It’ll be inexpensive to run.

Evan, I have zero experience with 4 stroke, unless you count time pushing the lawnmower, but I find it interesting about your comments on the learning curve. As have given some thought to trying 4 stroke after 4 years running 2 stroke and feel the same way as you do about switching.

What I will say is the KA is about as easy as it gets for 2 stroke. Out of the box they run great, there is almost nothing to do to the clutch and really the only “tuning” is off of the baseline setting on the carb. An EGT will help with that, but isn’t required. I find a little rich on the high needle is the way to go. As for rebuilds I had the top end done on mine at 12 hours and honestly it could have gone longer.

I’m sure the driving technique will be different, but as other mention, if your technique in 206 is good you will be fine with KA.

Give it a shot. Even if it doesn’t work out for you the demand for used KA’s is high and you won’t lose much on your initial outlay.

Whats the rebuild cost on the KA-100? Both on a bottom end, and a top end? I know zero on this subject, but anyone moving from 206 to KA-100 it would be a factor to consider . . .