How is the piston life looking for our KA100 racers in the US.
What kind of time are you guys putting on pistons (and or rings) before swapping them out? I’d be curious to know the fuel, oil and ratio you guys have been running too.
Did 4 weekends last year without doing a piston.
I’ve heard reports of guys just beating on the engine and pounding hundreds of practice laps without changing pistons. Every time they take the engine apart the piston still looks new.
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Any body else want to share what there maintenance schedule looked like for an entire year at Gopro or USPKS?
@tjkoyen did you have another other issues with the motor over the year? Clutches, starter, wiring?
Zero issues, zero rebuilds for a full season at USPKS.
We rebuilt the carb once or twice because we raced in the rain. But other than that, we literally didn’t touch or fix anything on the motor all year. Starter worked great all season, clutch looks brand new still, same with the wiring.
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Thanks TJ. Wanted to see if the issues the guys down under we’re having showed up here too.
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I think many of the issues that the Aussies had when the engine came out was with the original carb that we never had to deal with. The Tillotson carb has been trouble-free. Maybe someone from down under can correct me if I’m wrong.
The Issues “us Aussies” have had with the engine were mainly political, and nothing to do with the engine.
@tjkoyen is correct about the Carb, but only with the motor in restricted format.
Otherwise it has been the best change in Australian karting.
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Adding to this old topic to report after another year of running KA.
After two full seasons at gopro and a season of Man Cup… my observation is the KA is an awesome engine. It’s been low maintenance and has great parity.
Tips and warnings/rumours from the pits:
- If you spin it high (15k+) then replace the reeds often. Check to see if they’re sealing after each race day.
- 10-15hrs between top end rebuilds if you don’t spin it high? Absolutely.
- There have been reports of some older piston ring pins coming out and allowing the ring to spin. The results aren’t pretty.
- After 5-6 hours you’ll have a sputtering top end if you don’t put a carb rebuild kit in.
- Clean the clutch at the end of the day.
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Can you say why this is the case? Inlet needle isn’t sealing, or something else?
Assuming by spluttering you mean it’s running rich…my guess would be it’s needle not sealing, from oil accumulating on it over time. The metering gets messed up and more fuel gets dumped into the metering chamber.
… not sure on the reason. I normally do a carb rebuild much sooner than that. When I’ve heard people say they were “sputtering on the straights, rebuilt carb, and sputtering stopped” they’ve gone 5+ hours before the carb rebuild.
My hunch is the diaphragm gets hard and stretched so it’s not pumping enough fuel to sustain 14-15k rpm for long.
How long you let it sit with fuel in it is a big factor too…
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I would like to report we got 50-60 hours out of a stock engine only did 1 carb rebuild kit and the last race it did was only a tenth of pace seemed to lack speed out of the corner. Failure at 60 hours was piston ring snapping and losing compression in engine. Not disappointed at all
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That’s awesome.
I’ll be back in KA at the end of this year. I forgot how big of a hassle X30 is and also how not-sharp I am for that class at the moment.
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I wish we had a KA100 class in my area of the PNW, but we don’t have the field classes, or the ability to not be political to support it. (Cry)
I’d be surprised if the VLR isn’t every bit as good. Is that an option?
I’m starting to wonder if x30 is worth it. Yes it’s a fabulous engine but jeez, now that I’m a bit better at this, keeping this baby fresh is stupidly expensive. And I needs it on point.
Rotax/VLR/KA is looking pretty attractive right now.
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Are you finding it’s losing power, or is it more down to preventative maintenance?
I meant that to keep it truly in its happy place is relatively expensive compared to rotax and, from what I’ve read, the 100cc packages.
The engine itself (X30) isn’t the thing that breaks the bank for me… It’s the other stuff like the extra brake pads you go through, the tires, and then crash parts.
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Can you elaborate a little more on the differences in maintenance/cost/hassle between KA and X30?
How often are you changing plugs, doing carb kits, top ends, etc on each engine?
I’m considering a move to X30 at the end of this season, but one of the things I like about KA is that it is relatively simple.