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Post by gsx600racer on Nov 30, 2015 15:10:32 GMT -5
I have a Kymco zx50 that has 6300 miles on the stock crank shaft, 45 hours(2000 miles with a 70cc kit with spirited riding). The most iv ever pushed it to is 9200 rpm down hill. It likes to run around 8400-8800 @ wot.
I had issues at the end of this season with a worn crank seal(oil residue in the cvt). During inspection I noticed the outer crank bearing had some play(movement up and down & side to side) especially on the cvt side.
My questing is this, should replace the entire crank or just replace the outer bearing and re-true(if needed)? I am not looking to push it over 10,000 rpm. The big end bearing on rod seems to be in good shape.
Thanks, Don
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Post by 190mech on Nov 30, 2015 18:35:51 GMT -5
Ive read that Kymco makes a bullet proof crank,if youve been using quality 2T oil and the big end bearing has very little play,just replace the main bearings and seals..
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Post by gsx600racer on Dec 1, 2015 1:54:19 GMT -5
190mech, That is what I would like to do. My only concern is that I can slide the old bearing on and off on the cvt side by hand, no tools.(only that bearing from that side. Old bearing from flywheel side will not slide on the cvt side) My guess is that the inner race is cracked and expanded(or worn for some reason) so the old bearing slides on with ease. New bearings will not slide on by hand so that is a good sign. I am going to go for it but considering using Loctite 690 on the questionable(cvt) side. The new bearings were packed with grease, should they be cleaned and re-oiled at assemble or leave grease in them ? After 70cc build, I am running Amsoil Dominator @ 40:1 premix. Pics of tear down. Very happy with the condition. Thanks, Don
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Post by 190mech on Dec 1, 2015 5:04:58 GMT -5
If the new CVT side bearing is snug,690 shouldnt be needed..Replacing the piston pin bearing and clips are a good idea while you are in there..
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