250 Rebuilding KX250

AdamRides87

AdamRides87

ossagp:
Usually is when I find it. The gears are trying to push themselves apart under power. The end of the crankshaft flexes over. If you find it on the magneto side you usually have a bent ignition rotor. Exception for lack of oil etc.
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Okay. Thank you for all the knowledge. I really like learning from you guys!
 
Mihylo33

Mihylo33

Rules of thumb:
Always use a manual
They make torque wrenches for a reason
dont take shortcuts or the cheap way out.
If the part is questionable, it's not. Replace it anyway.
 
2strokesteve89

2strokesteve89

adamrides646:
View attachment 28049
How should I go about pulling this crank bearing from the case? Should I pound it out with a socket and a hammer, or should I use some type of puller?
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Puller is best, try using propane to heat the case around the bearing first. It may make it easier to pull. I've heard others say they've had the bearing kinda just fall out with heat alone, but I've not personally had this luck before.
 
O

ossagp

Torch it or put it in the oven at 350 for about 15. Get welders gloves etc and smack it face down on a phone book. Presses and slide hammers work too. I always heat them if they don't fall out cold.
 
Redordead89

Redordead89

ossagp:
Torch it or put it in the oven at 350 for about 15. Get welders gloves etc and smack it face down on a phone book. Presses and slide hammers work too. I always heat them if they don't fall out cold.
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A few hours before you do it put your new bearings in the freezer, once the old ones out drop the new one in while you got heat at hand and still in the casing!
 
Mihylo33

Mihylo33

ossagp:
I like the way that works on suspension. I don't usually like using any force, but the rockers have so much interference for those little bearings and I don't like getting them very hot.
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I don't ever remember having an issue installing crank bearings. A little red grease and in she went. Head set bearings however..... Grrrrrr
 
O

ossagp

They get exposed to some pretty high temps when the rig is running. you have a fair amount of time to get the cold bearing in after slipping the seal in. You won't get the lip of the seal warm enough to hurt it if the case is preheated. 400 degrees won't hurt the case or the frame of the seal. 300 is probably plenty warm enough to cool down to the point of an easy droppin.

Just make sure you have everything planned and layed out and practice the moves a few times. The gloves you want etc. have you got something you like for driving the seal in?
 
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