fresh rebuild, but sluggish in low RPM

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#1
Well as the title says Ive got a freshly rebuilt 91 KX125. I've been riding it for 3 days now and its a bit sluggish through the lower RPM's..When it gets in the power band though it will get it! One issue I know of is that my clutch doesnt engage all the way. When i click into first before i take off it will want to lurch or die, unless i give it some gas. Im thinking this along with jetting will fix my sluggishness. Im thinking of just getting a new clutch kit, but i want to try cheaper options first...I dont think its the clutch cable because i opened the clutch at the tranny case and still had the grabbing as if it were in gear...All the fluids are new, so what do you suggest for tranny fluid that may help me alleviate this problem....sorry for the long post.
 
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#2
Any time I hear of a bike that rips on the top end but is slow on the bottom after doing a top end rebuild, it's almost always an improperly set up power valve, stuck open in this case. Go back over all of the linkage to ensure it is properly engaged.
 
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#3
As for the clutch most likely the fingers in the clutch basket are worn and do not allow the clutch to operate smoothly. You will need to pull off the clutch cover and take a look.


There are many aftermarket clutch companies that you can buy a complete basket disk sprint, etc setup from.
 
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#4
It's pretty standard for MX bikes to want to lurch or die if you drop them in gear without giving it a little throttle (especially while the transmission is cold). As easy as it is to inspect the clutch, go ahead and do that anyways, but I doubt you'll find any problems.
 
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#5
well I opened the clutch last night and found that the tang on my plates was severely worn..11.8-12mm is standard and mine were 11.1mm. I ordered a new clutch kit, but no basket..The basket was worn too, im thinking ill smoooth it out with a dremel or something before i get a new one..ill see what the plates do for now...I also refilled the clutch with automotive ATF. Will this mess things up?..It seemed to be easier to shift with and without using the clutch.....As for the the linkage to the powervalves I have no idea..I didnt do the rebuild, I just bought the motor after a buddy let it sit for over 5 years...I pieced the bike together from 2 separate bikes that came in a box....Ill have to refer to my manual.

Thanks for the help....any tips for the powervalves would be appreciated!
 
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#6
If you smooth the basket out with a dremel it will wear out again very soon. You can pick up an aftermarket basket for around 140 and that will solve your problem for good.
 
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#7
What places did you have in mind...I found a new one on **** for $165, but i would prefer to buy from someplace else..
 
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#8
Performance engineering makes a clutch basket and you can usually pick up from an online retailer for around 139.00
 
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#10
Well i just spoke with them and the only ones they have are for 94-02. You guys know what years' parts will swap with the 91 H2 125?
 
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#11
mkelly04 said:
If you smooth the basket out with a dremel it will wear out again very soon. You can pick up an aftermarket basket for around 140 and that will solve your problem for good.

It's worth a shot, I filed the notches out of mine 25+ hours ago and they haven't started coming back yet. Don't use a dremel, though, use a file. It will make a flatter surface.