Clutch engagement question

I'm not familiar with the 50 Jr clutch, but the ones on the CR50SLC (the liquid cooled 50) wear rather quickly. consequently they need fairly frequent adjustment.

Wolf,
The clutch on your bike is not the stock clutch. the JR came with a 2 shoe stock. If you can take a pic of it and post or e-mail I can probably tell you what it came from. Possibly the SR.
But these clutches are designed to "free wheel" until the bike hits 4000rpm or so. The Stall speed can be changed by adding or removing shims. If someone used the Cobra clutch you'd be set. Its vary straigt forward and does not require all the re-shimming the KTM clutch does. Just new washers every once in a while and your OK.

Absoloutley Key on all the Mini's is to change the gear oil OFTEN. In Arizona we changed it as much as after every Moto. Usually only once a day though. We used $4 a gallon ATF from wal-mart. It lubricates fairly well and was designed for Auto clutches. Also Stuff like Cobra clutch milk works well.
We need to determine if your clutch is actually slipping. If the RPM's reach 4K RPM and the bike does not go then you'r probably slipping. You can remove your shoes and buzz the glazing off with a dremel tool and a sand barrel. Then remove one of the bottom washers that are "spooned" together. Like (( Washer stacks usually look something like ()()()((( for a cobra. KTM uses more washers but the same ones.

If your stall speed starts to come down and the clutch hits earlier then you will develope a bog. Once your around a while you'll get to notice how different it sounds. The washers wear out and sometimes crack. This leads to bogging. I usually remove and inspect clutch washers every week. Some call me a little anal though. I actually measure their thickness and toss some and reuse others. Most just replace washers when they really start to notice the clutch hitting too early.

If you have any questions just give me a call. You can find my number on my web page.

Sorry I don't know the Husky well enough to tell you where the vent is. I know on the cobra and air cooled morinin motors it is under the carb. Directly behing the rotor should be the crank seal and it should not leak. But maybe inside that same area they worked out a vent for the trans area...Im not sure.

$4 a gallon ATF fluid from Wal-Mart huh? My dealer recommends Golden Spectro 85W two-stroke gearbox oil. Maybe that's why we're going through clutches so fast (different post). Are you using the Super Tech stuff or something different?


Actually Jeff Sexton, NOT Sean. I think I'll let the air out his tires before the next race.

Wolf...I've gotten your emails and responded. not sure why your getting bounced.

Yeah the supertech stuff. Its like $4.64 a gallon. I just change it often. Rich Rohrich has posted several times in the other posts about how ATF is suitable for 2 stroke use. I've used it in other big bikes too.
I have found a lot less crud in the cover when I do my inspections using atf over other oils such as maxima mtl and such. I've found that even after one moto those oils are dark black and leave crud. The atf is dark after one moto but a lot less sludge. And I have found in customers bikes that those with ATF are more prone to keeping up on oil changes. When paying 6-15 bucks a quart they tend to leave it in longer and run in to problems.
We have a King Cobra that was Jacob Fox's. He was #2 at the world Mini's last year. He is from Phoenix AZ where race day temps are over 110ºF during the summer. He rides HARD on a 50. Well from new his dad used strictly ATF. The cheap stuff not synthetic. But he is super anal about changing fluids. Even logs hours on the bike and compression. After every practice or race day he changed the fluid. Then my son rode for another 3 months not quite as hard as Jacob. Then while testing out a new tool I over pressurized the bottom end and blew out a crank seal. So I figured I'd tear the bottom end apart. The 2 smallest bearings called the precision transmission bearings has some slop in them but the other bearings were OK. Typical for other motors I have seen that used only synthetic oils.
So if a guy pulls up in a $400K motor home and wants me to change his plug asks me what Oil to buy I suggest $6.25 a pint synthetic stuff. If he pulls up in a beat up pickup I reccomend ATF. Either way their motors still need attention about once a year if ridden hard.
Try it. Use ATF for one race day then pull the clutch cover and see what it looks like. Then the next week try something else synthetic. Then pull that cover and see what you see.
The only thing that has made me think about using the synthetic oils was an experiment using and infra red thermometer. After 4 laps we checked cylinder temps and using ATF they were about 10º higher than with the maxima. Now this was not a super controlled experiment with a control fluid and its hard to make 4 laps the same with a 7 year old rider...but just so you know.