KTM 50SX Pro SR running horrible

[mxracer2000]

We have an older PW50 and a 2000 50SX Pro SR. I was working on both bikes getting ready to put them away for the winter and figured I would take each one for a scoot around the block. I was surprised to find out the PW accelerated way quicker and had better power throughout its powerband. The KTM was sluggish off the start and seemed to sputter and want to cut out at wide open throttle. The bike has a R+D clutch with the dual fiber disks (newer style Dominator clutch), and a bored carb, as well as other mods not effecting H/P. I'm wanting to set up the powerband similiar to the PW. Hits hard off the bottom and keeps pulling without cutting out. I attempted to adjust the air screw but it didnt seem to really make a noticeable difference.

 

[cr25096er]

could the carb be dirty? air filter? replace the plug?

 

[Jasle]

If its sluggish off the start I'd suspect the clutch was hitting too early or jetting on the pilot/air screw off.
But the sputtering up top could be plug or I have seen these exact symptoms caused by a bad stator. The stator would ohm out correctly but i found a crack on the back of the epoxy and it was arcing only at topend. It got better if I jetted really rich but still popped on topend.

 

[mxracer2000]

Are you familiar with the settings for this clutch. When I contacted the dealer he suggested adjusting the 3 hex bolts between 8-10mm. With it at 8mm I'm getting a really sluggish start. I had the clutch detuned when we got it because it took off like a rocket ship. Unfortunately over the summer the hex bolts worked themselves loose and the bike was starting to move forward when idling which is why I was messing with it in the first place. I would like to have it set up similiar to when I got the bike but I dont have the specs. Its my understanding that if the air screw doesnt make any noticable difference than its likely the pilot jet that needs to be changed. I cant remember if its supposed to be bigger or smaller. For the top end Ill try the spark plug first. Its been awhile since I changed it and who knows maybe that might also look after the hard starting problem.

 

[Jasle]

I don't know the setting of the KTM clutch. its different than the Cobra one. go check out www.ktmtalk.com and look under the mini's section. there is a bunch of info about the clutch. If you bike is getting hard to start then your probably due for rings. Thats a real good sign of needing rings on the F Morini motor. Approx how many hours riding since you did a topend? One thing with beginners on these bikes is with the blipping and clutch slippage the bikes get hotter than normal. Everything wears out quicker than normal this way.
Your cylinder should either be chromed or nikasil...I'm not sure about KTM. A 2000 Cobra came chromed but either way you should be able to get away with just rings or rings and pistion if its been a really long time.
Usually you need to go bigger on the pilot to correct a bog. You might get away with going down one with the needle clip?

 

[ktmdad]

If it's an air cooled motor, contact Andy at EG Racing. He seems to have the moto morini motor figured out.

Also try Todd @ TH Racing.