Rotax Senior Max - Losing time out of the corners

Hi everyone,

I pretty new to Rotax Senior and it’s my first 2 stroke kart. I have a lot of time to still find but I am realising that I am slow out of the corners and that is where a lot of my time is being lost. I have done some searching around and have found that the throttle makes a lot of difference with how you apply it which helps with getting out of the corner quicker especially with the rotax

Could anyone advise me on what I should roughly be aiming to do with the throttle, any tips, and tricks, or just general tips to help maximise exit?

Thank you

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Imagine the pedal is a wet sponge and you’re squeezing the water out of it. When you jump from rentals to 2 stroke it’s hard to train yourself not to mash the gas.

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Rotax bogs funny if you hammer it at low rpm, correct? Different than x30?

Still some but not the same extent. Still better to be progressive on the gas

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Rotax requires very smooth throttle application, and it requires you to carry good apex speed to keep the kart rolling and on the pipe.

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Might want to check to see if your carb is setup correctly with the right main jet and Clip 3 on the needle. If it’s too lean it will bog out of the corners.

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Don’t think it as a throttle in terms of traction. Think of it like you’ve got a carb on that’s way too big and have to modulate the amount of fuel going into the engine, especially if it’s the pre-evo model.

I tend to be very lazy on the throttle for most of the day, and that always seem to work driving a MAX, as much as they breaks me from an emotional perspective :slight_smile:

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Is it a non evo or evo?

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Roll on the throttle after you are done braking if you just mash the pedal coming off the corner you’ll just bog and lose a lot of time. Find that sweet spot and try to hit that coming off the corner where the Rotax pulls almost feels like Vtec in a Honda Civic. Jetting is also pretty important just download the Rotax app and it’ll give you the right jetting based on the weather by grabbing your current location on your phone.

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Is rolling the throttle on critical if above say 8000 rpm?
What RPM can i go full throttle?

I have just moved from restricted to open and against the X30’s i was getting gaped.

The X30 will likely kill you out of the slow stuff. The Rotax is best when the track is mostly mid range.

The way I used to apply throttle was to just to open the throttle just enough to stay a bit ahead of the RPM of the motor.

Quite the opposite I believe. Rotax has banging low and mid but drops off at the end vs the x30 which really starts punching at mid all the way to high.

Peak rotax @ 9500 rough vs peak X30 @ 11000 - Hence rotax geared for 14000 vs X30 16000

Might be different for restricted though.

Where are you located? What changes have you made to the package going from restricted to open - exhaust restrictor, sprocket changes etc? What kind of tracks are you running at - long flow or tight technical etc? Are other rotax drivers suffering the same problem? If not have you compared data against other rotax drivers to see where you are losing out?

With regard to throttle application i’d suggest just rolling on power when required. You shouldn’t ever be stabbing the pedal straight to full throttle from no throttle anyway, especially in a rotax. I’d suggest just turn laps and through trial and error you’ll pick up throttle timing.

Possibly check your carburetor setup. Is this an EVO? Either way, if you’re not getting off the corners without bogging down, you might find improvement by stepping down the needle clip 1 or 2 positions, and/or adjusting your float lever height, or jetting, to richen your mixture for more bottom end.

This is absolutely spot on, for example Al Ain Raceway - designed for Rotax. If you run against them with an X30 there you feel like wtfffff why am I in reverse? RAK Track conversely X30 designed, Rotax don’t have a hope there against X30.

X30 doesn’t have a power valve like the Rotax does, it’s power delivery is pretty linear - with Rotax as far as I know and experienced before defecting you have to keep that power valve thing open by keeping the revs up. Slow corners it closes and bogs, apply throttle progressively or you kind of flood the chamber exacerbating the bog.

The track has both tight and open sections so is hard to drive/setup. Video attached. These 2 guys have been racing open for a while but still felt at a disadvantage.
Was 1 second off on a 48 second lap. My best was 48.8, one guy did a 47.8 other guy did a 48.4.

Also first time on a grippier tyre. Gone from Dunlop DFM to Lecont SVB which caused a world of hurt being over gripped. Made a few changes this week which i will hopefully test on the weekend rain permitting.

Its a EVO. Doesnt fell like it bogs ever.

Float is set correctly. We are at sea level around 1020 pressure, 60% humidity, 20-35 degrees through the day here in Australia. Had a 122 main on clip 3. Plug was perfect. Engine guy said i could have been 1 clip to lean on the needle.

Bottom RPM was 6900, top was 13900. Took 2 teeth off rear going from restricted.

Have no other data on rotax at the moment. Will set my go pro up to film my right foot hopefully this weekend.

The Rotax is going to be worse on the bottom and top compared to an X30. Rotax makes all it’s power in the mid-range, and the X30 is a bit more linear.

Looks to me like you’re a little late to the throttle in a lot of those corners. I would try rolling into the throttle a little sooner but more progressively, as stated the Rotax dislikes harsh throttle inputs.

I know i was definitely late on the throttle. Kart would Hop quite bad if i tired to pick it up any earlier. Actually put my kart on scales and moved weight bias forward from 39% to 44% plus a few other changes to test out again.