Rotax Max clutch resistance

Hello everyone, first post here. This past summer I bought myself a used CRG kart with a Rotax pre Evo engine just to bomb around with at our local track. There have been the usual amount of little issues dealing with a used package but amongst them, I noticed that there seems to be a fair amount of drag when I spin the rear axle while its up on the stand. With the chain off it spins freely. I took the clutch drum off to inspect and other than some minor glazing it looks ok as does the shoe. I gave it a cleaning anyway with some brake cleaner, greased the needle bearing and reassembled. Now it seems like its a bit worse to the point that the axle is now spinning at idle where before it wasn’t. Is there anything else I should be looking at to solve this? Thanks.

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Is the chain rubbing on the clutch drum? If the chain is not rubbing against the drum, a slight amount of drag is no big deal because the clutch locks up at low RPM. I had a motor that dragged the clutch and it ran fine.

Are you using the correct size washer between the bell end and the clutch nut?
Also check if you have the bushing and rubber ring under the bell.

It doesn’t seem like the chain is the issue, more like the drum is too tight on the shoe. When I fit the clutch drum on by hand, even before any fasteners I can already feel the resistance.

As for the actual hardware used, at this point I’m just assuming it’s ok, it’s what came with the used package.

I’m wondering now if it’s ok to lightly sand or take some steel wool to the contact surfaces of the drum and shoe.

Are you supposed to grease the needle bearing? I can’t remember how the Rotax clutch goes on but I’d say grease being thrown outwards inside a clutch is the last thing you want. Do you have a manual?

Watch the rotax clutch videos this guy does if you wanna see how it’s done:

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Yes, you need to grease the needle bearing. If you have the 11 tooth driver, you need to grease the bushing prior to running for the day. You are not putting so much grease that its slung out, but you are coating the surfaces to prevent overheating and seizure.

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Not sure if you can on the non evo but try flipping the clutch bell on the shaft so the gear is on the inside and give it a spin. If it still binds then it could be the bearing or bushing have cracked.

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I’ll give that a try when I work on the kart tonight, thanks for the suggestion. Can you see anything going horribly wrong if I were to take some scotchbrite or sandpaper to the contact surfaces?

Not sure if you can switch the clutch drum around. But if you do, don’t fire up the engine. At a minimum, you’ll wreck the clutch.
Your chain, is it an O-ring or non-O-ring? An O-ring chain is much stiffer than the non. With a Rotax, using an O-ring chain is not a bad idea.
If you used a heavy grease on the bearing, clean the bearing off again and see if that helps. I used a Lithium grease without problems.
And was there an O-ring on the clutch shaft? Cleaning it with break cleaner may have caused it to swell. Pull and see what happens. This O-ring was used to prevent the bearing grease from migrating into the clutch surfaces.

Tony, I think you were right. I spent some more time messing around with the clutch and found that with the o-ring removed, everything spins as it should. I guess it got swollen over time. Thanks for the tips!

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Just had the same issue with ours. We pulled the o ring and out in the wider bearing. Rolls free now!