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KTM 50 Clutches SUCK!

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I remember when I bought my son's KTM a year ago, I had hear some advice that told me to be careful with the KTM clutch since problems with them can look like carb problems instead.

Well here's the situation... I have the carb as dialed in as I can get it. I've worked on carbs for over 15 years and haven't dealt with a carb that was more finicky than this little De' Lorto. It's a complete pain! Well I got it to where it seems to run ok (not great, just ok) and as my son rode it, the rev was about as choppy as can be. After thinking about it for a while, I remembered that early advice and figured that if the clutch is engaging improperly, then I'd get that choppy sound.

I took it and and sure enough, the pads were pretty loose on the block. I repositioned some of the washers in the stack to hopefully make them engage in unison, but after putting it back together and running it, it's not much better. I know I've heard that blipping will cause the washers to wear faster but DAMN!!! I think my son had had a total of 5 rides before they were worn out!

Tomorrow I'm going to replace the washers and hopefully a softer stack will help him get over the blipping (though I'm not confident in that).

Has anyone else found that the little De' Lortos are as touchy as it seems to be for me? I mean if I adjust the idle 1/4 of a turn less that where it likes to be, it dies. It really seems like this bike wants to idle higher than normal. Also, any advice on a stack that will enable a smooth engagement at a little lower RPM but still enable him to have a little fun at WOT?

New stack is (()) (()) () () () // .654"

Also, it's a 2001 Sr. Pro 50 LC.

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Man do I feel your pain. But I myself am a gluttun for punishment and thoroughly enjoy "garage time". I crack open a beer and get my micrometer out. Put on some pandora and go at it. As of now, I have mini adventure springs in the clutch. It keeps the clutch cooler and offers a low engagement speed. It will get up to top speed as well. May take a bit longer to get there, but not by much.  It is a great change from doing washer measurment/replacements. It is also great for trail riding. Not so much for motocross, but will be good for practice weekends. I have a great cheat sheet that I built off of ktmtalk.com. It took alot of hits and misses.

 

Also I do feel your pain on the damn carb. There seems to be two settings on these things. Cold and warm. I just fiddle with it alot during runs at the track. How you set it up in the garage will be totally different than when you get it running and hot at the track. Don't get frustrated, do alot of reading at the KTM site and just keep fiddling with it. You will be so happy when you get him onto a 65, but you will someday miss the days of running the mini bikes.  Good Luck.

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I feel you elpato! I swear the bike needs choke to start after 20 minutes of sitting. It's a bitch! As for the springs and the racing bit. I'm actually considering that since I don't anticipate my son being the racing type for at least a few years. He's got a healthy fear of getting hurt and until health care is free, I'm glad he's in no hurry to get himself wrecked ;-)

As for the carb, you are again correct. This thing is so clean, the Pope could bless it, yet the idle is all over the map. I actually find that I have to play with the idle just to get it to start, then drop it when it gets warmed up. I'll tell you what... It sure makes me appreciate my Yamaha and how reliable IT is! I guess I want to get this thing dialed in for a could reasons. 1. So my son can enjoy riding it until he outgrows it rather than enjoying dad working on it and 2. So when I sell it, I don't have to scare the new owner with what a PITA they are. I mean, if parents truly knew what they were getting into with these little bikes BEFORE they bought them, they'd make their kids keep riding the PW50s of force them to take a couple years off! Unfortunately like you guys, I'm too far in to back out now. Any recommendation on the springs? My boy is a good rider but no racer. If he can go fast but doesn't get there NOW he would be ok with that.

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Yep you have described mini bike ownership to a "T". I'm guessing you have gone up and down on the jetting as far as the hard to start when warm is concerned? I don't really experience that problem, I mainly find that when cold it will slow idle and then when hot the idle is just under engagement. As far as spring recommendations they are simply the mini adventure springs with one washer under the bolt side. This causes early engagement (before it comes up on the pipe). Keeps the kids from getting that "hit" when it revs up. If you aren't planning on doing any racing I would recommend at least trying it and see what you come away with. I have an '08 version, so I must admit I am not familiar with the '01 models per say. And as far as the tomar clutch they are a good alternative to the three shoe set up, but I am a poor Sailor and couldn't afford it.

 

Have you read and researched on KTM talk yet?

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I actually used to spend a LOT of time on KTMtalk but apparently the main admin is still rebuilding it or something.

As for being a "poor sailor", I'd have to imagine that parents of these bikes would have to fall into 2 categories. Poor enough to have to DIY or wealthy enough to have someone else do it. ;-)

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Hop over to Cobratalk as well.  Same admin, several of the same guys posting there.  To me, it sounds like you're running a bit too rich if you're idle is all over the place but I've run into some of the same types of issues with the Del 'Orto on the Cobras as well.

 

Where's your air/fuel mixture screw set right now?  I've had to lean mine out to about 1 1/2 turns.

 

There are 3 things that will kill these clutches quick - Heat, blipping and gearing.  We have a set of gearing that we use at home and then I've recorded different gear sets for each track.  We're racing dirt track, but it still makes a huge difference if he's geared too high.

 

What type of riding is he doing?  Is he really ever riding flat out?  If not, try picking up the next size down front sprocket along with a range from 34-39 rears (if he's racing that is).  Running dirt track, I have 12-16t fronts and 24-39 rears.  At home, we always run 12/34 since we've only got about 225 ft straights.

 

Heat is definitely the worst factor on them.  Rides should be kept to 10-15 min max.  Any longer than that and it will really start breaking down the fluid and the materials on the clutch.  Blipping adds a lot of heat and unnecessary clutch slippage, so that's why they suggest keeping it to a minimum.  At the track I'll warm the bike up for a min in the pits, have him ride it up and shut it off and it stays off until the other race is on their checkered flag lap.

 

Now if I could only figure out the starts on these little 50s, we'd be all set :)

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Right now he's got an 11/48 sprocket setup and when he rides he goes for a while though I've never timed him. For the jetting, he runs a 50 pilot and 85 main right now and that's after dropping the pilot from 52 because I got no change with screw adjustment. The last test ride we did wasn't long enough for me to do an accurate plug check but it is still coming out a little wetter than I like. For all I know I'm not testing the bike long enough to get the plug check right.

Mainly the riding he does is track, but no racing. He likes to ride for fun and he does blip a LOT. I'm trying to teach him throttle control but it's just taking time is all. He only hits the power band when we are riding around our neighborhood because its a straight shot. When he rides track, he's pretty conservative and seems like he revs and rides (blips) rather than just going all out. I'd like to get him out into trails, but I don't think this bike could handle any serious time riding without having a meltdown since it wants to be a dainty little race bike. I'd like to get it set up more for trails than racing, but if I can't get one element dialed in, I have no idea where to start with the other.

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My buddies always ran Tomar clutches and the kids rode track and trails... One of my buddies sold me one and we only used it for an hr or so before he got a newer bike which the tomar doesnt fit on.... Dammit!

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I am just getting started with a 7 year old on a KTM 50 sx 2007.He's starting to race flat track and I need to get info on sprokets for 1/8th mile, 1/4 mile and half mile tracks as the series races on all three. Currently the bike has 10 / 44. I believe the rest of the bike is also stock. Any tips or info would be great. Thanks

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