KA100 engine question

looking for the best KA100 engine for JR class, my friend has a Woltjer and a Comet and the Comet performs better, we have used Woltjer in the past with the mini swift engines and were always happy with performance, although some of our Woltjer engines did perform much better than others. It may be more about the engine than the builder. Looking for opinions.

Woltjer will no longer be working on KA engines. He will be focusing on his gynormous Swift business. You’ll get split opinions on the value of an engine builder. I value having “the best” builder, because I’m not a small engine specialist, and I’ll go after every tenth I can get. We were a Woltjer customer this season . . .

Any of the top builders are capable of putting out top-notch engines. Not all engines are created equal. Usually engines will require some fine tuning with carburetion in order to dial in to specific atmospheric conditions (even if a builder provides a baseline). Most drivers aren’t capable of maximizing an engine’s potential, and 0.5 HP won’t make a difference to their finishing position.

I’d recommend developing a relationship with a builder and they will be able to help you get the most out of your engine.

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The way I look at it is by asking the question “who can help me get maximum performance on the day, at the track”.

This is going to come down to who has the most presence at the races you’re running and/or is most available to you to help dial thing in.

A fast engine has limited usefullness if you can’t get the most out of it during a race weekend.

This x1000

Except BBS actually makes the fastest KA’s… I’m completely kidding here but I do have a great relationship with Brian and he’s been great to work with. We’ve had engines from Woltjer / BBS / Comet and what Evan says is true…there are very few secrets in the way these things are being setup based on the rule set in play and the manufacturing process leaves very little variance from engine to engine…dare I say the biggest difference in how they perform is in the way each builder is setting up their carbs and even that isn’t MUCH of a difference at all.

Your ability to learn to tune the carb will have a bigger impact on race day performance than which builder you choose in my opinion so pick one that will help you with that, answer your questions and be able to best serve you based on logistics of getting them rebuilt.


Yeah I feel like proximity to builder and relationship with builder is a more important factor than who builds the “fastest” engines with KA tolerances being so close already. Having a builder that can dyno and tune the carb for you is probably more important than their building capability. just my 2 cents.

Thank you for the advice, I guess we are a little cautious coming out of mini swift, sounds like the KA engines are more forgiving. You told us what we wanted to hear. Mike

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Maybe not forgiving but consistent. In senior at our track we see several builders and none have shown dominance. I think fresh top ends up till about 8 - 10 hours are all very similar.

i’m praying mine makes it to 20 before a top end

It will likely make it but there is a drop in performance and your builder may need to remove more material to get the cylinder round vs doing an earlier rebuild.

yeah i know im definitely going to get a performance drop but i dont plan on competing anywhere but locally my first year in a 2 stroke. especially since i dont have anyone or know anyone locally that works on these types of karts, this year is just going to be me figuring everything out. hell if it wasn’t for this forum i probably would barely be able to get track time with the initial problem i had with the engine where the kill switch was causing no spark at the plug.

I’m not familiar enough with the KA to know the upper end of the service interval, but I would absolutely advocate for rebuilding sooner than later from the standpoint of preventative maintenance. You’re better off to pay a few hundred bucks for a rebuild than to have a piston/ring completely fail and ruin your engine.

You’ll make it there as long as you’re using the right mixture. I have one with over 25 hours on it, and it’s still serviceable as a practice motor. There’s just a small drop in performance, but when we’re not racing at the front, more time can be made up from the driver right now. However, with all that said, the motor IS going in this winter for a rebuild. As Evan said, it’s for preventative over having a new anchor.

As for best builder, find one you trust and like. Some people will also opt for a builder that is closer to them so that shipping costs are cheaper. I personally send my motors to P1 Engines. Jesus is very knowledgeable and is always willing to help me at any time I need it. I can email, text, or call him and get the help I need.

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