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New bearings or not!?

D

Denmark

New member
Hello from DK, and sorry if my spelling sucks a bit.

Have one BJ25IRLEIE all apart for sort of an economical restoring(rings/seals etc). Never heard it running. I do have farly large proffesional automotive repair eksperience BUT never worked on 2 strokes.

Question: how do i determite if the roller bearing plus the 2 other needlebearings on crank should be replaced? There is no "endplay" or "wiggeling" no real marks and no discolour.

BUT the bearings sort of make noise when i fit the crank and spin it with my hands. Is that just normal 2 stroke bearingnoises? Are Johnson known for problems "down There" ? Or is it what i hope just plain old BULLETPROOF:p

Any sort of answers would be great, remember its an economical build i am doing.

Kris
 
Replace the bottom bearing.-------Put 2 drops of oil on the other 2 bearings.-------Spin it again.------------Those bearings were not changed at the factory for many , many years.-----So not a weak design !
 
It is allways alot more economical to put it together right the first time! Check for piston clearance at the skirts. Be sure and get a nice crosshatch to break in the new rings. Is the bearings making noise dry you want to add a little engine oil on the bearings and see if they quiet down. You do want a little end play on the crank it just takes a couple drops of oil to lube the rollers and ball bearings they should be nice and smooth, if you cleaned them with gas they do make noise once completely dry.
 
Roller bearings should look perfect---no flat spots, pits, rust etc. Some discoloration is normal, but not turned blue from heat. If they pass those tests, they are fine. BTW, that goes for the journals and con rod bearing surfaces also. Those areas are part of the bearing.
 
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