wrist pin bearing

[unclefista240]

went to put new rings in my 1995 rm 250 and now the wrist pin and bearing are too tight to fit through the crank. the piston moved freely at dissambley but i believe it was the piston moving on the wrist pin. the crank had small indentions from the needle bearings so i tried to clean them up with a dremel. i used a puller to remove the pin, id didnt seem too difficult. im gonna buy a new bearing and pin and try to clean up the crank. this is the first set of rings since all new top end. never seen this happen before. i dont have any bore guages, i did use an inside caliper and a digital caliper but its not as precise. i need it to last so...... maybe new conn. rod.could it have ran with just the piston moving? the plug looks fine and theres no play on the bottom end of the rod. now i just need a new wrist pin and bearing.

 

[Ol'89r]

the crank had small indentions from the needle bearings so i tried to clean them up with a dremel. now i just need a new wrist pin and bearing.

If the needle bearings have worn into the small end of the rod, you need a new rod and crankpin assy. You can't just clean up the rod with a dremel. This has to be a precise fit.

 

[spark250]

You made a big mistake if you took a dremel to the small end of the rod. You should put a crank assy in it.

As far as using calipers to measure the bore? You might as well be using a tape measure, it won't tell you a thing.

 

[unclefista240]

fixed

put a new pin and bearing in. bought bore guage set, along with most of the other tools, ill need to do a total overhaul. except for a few bearing tools.it actually cleaned up really good and i got it to measure within spec. went ahead and polished the conn rod also. new rings. figure ill get some gaskets ride it for a few times then take it apart and see how its wearing.