IAME KA100 Reviews and Feedback

I think we leaned the carb out a bit when I noticed the temp drop. It still wasn’t ideal but closer to where it should’ve been. We ran it rich initally at NCMP and that helped get a bit more top end down the straights and I kept it there since the motor ran really well at Badger afterwards. I didn’t touch it after that and then we went to RA where I found the motor struggling

When you say you didn’t touch it, do you mean at all?
I have found with mine that if i don’t wind the jets in and back out every so often they will “gunk” up a bit and affect the tune.
Just a thought.

Oh I never knew about that. I just left it as it was for a few weeks, perhaps that was part of the issue.

I have also noticed that with the carb. This engine does not like to leaned down(to a point). For the most part I have found that the engine likes to be run rich(especially on the top end). I am talking minutes though. I have noticed that the engine can be boggy if carb is kept clean.

I also had a big drop off in rpm during my 4th weekend of racing RA. I ran a 10/77 ratio to 14.5 the prior week and ran 10/78 to only 14.2 last week. Im going to tear it down this week to investigate, but I was thinking that I had a bad crank seal versus a bad piston. If your crank seal is bad, it’s going to run leaner.
Now I don’t know why, but I’ve been struggling with my ka. For some reason I can never turn near the same rpm as other people I talk to. My second weekend on the engine, I ran 3 different sprockets 10/79, 10/78 and 10/77 with peak rpm between 14.5-14.7, where others were running in the 15’s.

What are you getting for EGT, and what are your carb settings at?

@BubbaRP Your rpms are a little low. You should be about 15,000-15,300 on a 10/77 or 10/78. Make sure that there is nothing on the kart that could be dragging engine down. Such as a bad chain, driver gear, or brakes being stuck. Aaron is on to something with egt and carb settings. We have seen that the carbs are very picky as is. They need to be cleaned every now and then.

@tjkoyen Any issues with the engine over the weekend? ( Even though you dominated and won both days and areprobably drinking a well deserved cold one right now🍻)
Any carb issues? Tuning? Gearing?

Have you been able to compare rpm traces with others?

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No issues with the engine, she ran flawlessly (and fast) all weekend.

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O.0 I haven’t dared spin mine over 14.6 or so, as the limit in the manual is 15k! So it is interesting seeing you all revving it that high.

I ran my kart on Bridgestone YLR’s at 10/74 the other day, peak rpm at 14.1. Couldn’t race due to officiating but was turning times that would have put me 2nd on race day. I think I have roughly 1 hour run time on the engine, perhaps slightly more.

I have twisted mine to 16,000 with no issues. Engine only has 5 hours on it. Mg reds for tires.

@Aaron_Hachmeister_13 I’ve been getting around 1050 for egt and I’ll swing my low needle from 1-1.1/8 (turns) with the hi needle from 57-65 (minutes).

@KartingIsLife I haven’t overlayed anyone else’s rpm trace, I have only compared peak rpms at the track.

That sounds about right for what I have been running on my engine. I would overlay data at this point and see if it comes from how you’re exiting the last turn. It’s a tricky one and I’ve seen a lot of people take it wrong or at least not optimally while I was watching

With out knowing the kind of tracks some of you guys are racing on, and I say that because US tracks in general seem to be higher revving from my anecdotal impressions, I would say that 16K is too high.
The peak power of the KA100 is at around 10.5K rpm and by the time the engine is over 14K the power curve is really starting to drop off, meaning it might be making noise but its not really going faster.
In my area, racers generally tune for the low revs to be around 7K and the high revs to be less important but not too far over 15.
I have seen racers with peaks in the low 14k’s. But again at some tracks the engine can be at peak rpm for so little of the lap that sacrificing top end for better low end seems to work best.

I did try to get to the high 15K’s and it didn’t suit me. I try to aim for high 14 to low 15 and work on my corner exit to get better rpm at the end of our straight.
Do what works for you, no one in this sport has all the answers, but I would keep in mind that your engine life will suffer at the high end of the RPM scale

I think I stated it earlier in the thread, but as @Jacedownsouth just mentioned, anything above 15.5k and you’re just making noise. The power drops fairly quickly once you start getting up there. The only reason you would run that would be on a tight track to over-rev so you have some bottom-end grunt.

I ran mine to 15.8k out of the box when breaking it in when I first got it, because we didn’t know the gearing. Didn’t hurt it at all.

Never go by the manual on RPMs, it’s almost always 1k too low on it’s recommendation. The pre MY-09 Leopard manual used to recommend like 15k, and we routinely spun them 17k or more.

I’ll let everyone in on my secret, that I was running 14.1k max at GoPro last weekend and it seemed to work pretty good there. :wink:

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Ran a KA for the first time last week at USPKS. And coming from the camp of “the KA is the answer to the question that no one was asking” I have to say it was fun and easy. Other than missing a little on carb settings initially (put the junior header on a Senior engine and didn’t adjust the carb) it was super easy to set-up and tune. The only maintenance we had all weekend was putting it back together after Rick tore it down in tech after we won both days. :smiley:. It really didn’t like carb changes and gear changes were nearly irrelevant. You pretty much bolt it on, free the kart up and go see who has the better combination of balls & brains.

Just a quick shoutout to USPKS tech on these engines. As it was a new platform for me, I was intrigued to see what they would check. Rick was very thorough and had a host of gauges and tooling to do the job properly and professionally. As he explained the processes to me that they were putting in place I couldn’t help but be impressed by how hard they were working to not have another Swift debacle. Well done.

The only downside is that it looks like a dinosaur. And not the cute cartoon kind of dinosaur. It’s just kinda unsexy, particularly compared to the new Vortex 100cc package. But if cool looks was the driving factor, Rotax would have never sold 50K engines… :stuck_out_tongue_winking_eye:

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I can’t imagine 16k being stressful mechanically. Sure things will wear more, but it’s all within tolerances. Remember the max recommended RPM is going to be way on the conservative side.

The Rotax DSD formula A motor has a max recommended RPM of 15k or something. 15K with that motor would last a long time but you would be crushed in lap times.

On tracks where you have a high ratio in speed between tightest turn and longest straight you are going to see more peak RPM (or longer sustained max) as you gear for punch between those turns. Like anything, it’s a balance and the stopwatch tells the story.

Luckily these current generation 100cc motors really do run out of puff at high RPMs, so the point of diminishing returns can be found without pulling pieces of connecting rod from your suit :joy:

Ran Ka this weekend at Route 66, had no issues twisting the motor to 16,300 and it was still pulling!Carb settings were not touched all weekend. I had many issues and the engine was not one of them. Egt was never higher than 1180. I did notice that the engine was starting to struggle in the middle range on Sunday. That may also be carb as the air was different from Saturday to Sunday. I love this motor #Ka100life

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I’ll add on, I had no complaints with my motor all weekend, although I know Dakota Pesek was struggling with his down the main straight, I don’t know why though. I ran it up to 16,300 as well in the draft and was getting EGT just touching 1,200 °F. I think the top 6 were all within 2 tenths of laptimes at the end of the race.

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