Wednesday, March 30, 2011

Notes on the KTM clutch conversion

I am far from done tuning this thing, but I wanted to write a bit about the things I ran into getting this clutch to work before I forget any of them. I don't think that most of these things were covered in the original post on MA, seen HERE.

Soooo. I got it working on the first try. Shimming the bell was a bit hard, but luckily Treats has lots of thicknesses of Shim's. The first day of testing, it was nearly impossible to start, so I had to reopen it and add another washer to the starter plate pin, making it protrude more. After that, I realized I was still approaching this clutch like a Puch clutch and was using WAY too thin oil. KTM recommends 20w40. I'm currently using Mobil synthetic 15w 50 and getting better results, so I think I might go thicker.

The next day I had the issues with the clutch staying engaged. One of the shoes was dragging. I had to reopen the clutch, retorque, and locktite the shoes AGAIN (do it before install!!) This time I did it with stronger (red) locktite.

Despite all this stuff, the biggest issue with this clutch is how much it heats up(!) It's really a for-race only mod, but I'm still trying to make it last as long as possible, by attempting to control the heat in a couple of ways... 1) I'm running the springs from the KTM Junior Adventure instead of washers, which decreases the gnarliness of the engage. (specifically my set up is one spring and one flat washer per shoe).
2) I'm running way more clutch oil, so that it is able to reach the smaller (higher up in the chamber) clutch and bell. Filling up your clutch case with as much oil as the drain bolt allows, will leave your bell barely skimming the oil. Over-filling the case with as much as I'm talking about using (5 or so extra Oz.) will leave you spraying oil out of the bleeder hole and all over your back wheel... SOooo I had to put thin fuel line in the top to essentially make the bleeder higher up too. 3) The minarelli bell doesn't come with ANY holes in it for oil to move in and out... only the space between the plate and the bell. SO, I added a couple, but just small ones like the stock Puch bell has. 4) "2 Cool" additive was recommended to me. I have yet to get it/ run it, but it claims to lower temps by 20 - 40 degrees.

If anyone else is running the KTM set up and has some more tips, please chime in in the comments section. I'm getting good results so far (it takes off like no Puch clutch ever could) but I don't claim to have this set up worked out by any means.

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