Crank Bearing Play

[thealmightytaco]

Into the NSR motor now, and all three main crank bearings have play, the 2 end ones not so much but the middle one about double what the end ones have. And the big end bearings on the con rods seem to have a bit.

Just wondering how much play is bad for a bearing and how to properly test them for play, pure radial movement of the races or axial or twisting or what.

Any info much appreciated.

[Ixion]

H'ya go, crank bearing wear specs for NSR250

http://tech.nsr-world.com/nsr/mc21/crank-specs/

Oh, and the good news, the crank is supposed to be non serviceable. You buy a complete new crank . Bugger that for a lark, should have bought a Yamaha!

[thealmightytaco]

H'ya go, crank bearing wear specs for NSR250

http://tech.nsr-world.com/nsr/mc21/crank-specs/

Oh, and the good news, the crank is supposed to be non serviceable. You buy a complete new crank . Bugger that for a lark, should have bought a Yamaha!

Cripes, I was just there lookin' at the full rebuild section. And I saw the bearings were impossible to get now, so fark it they're stayin'! But handy to know, cheers Ixion.

Mines an MC16 btw but I aint worried, even harder to get bits for if anything.

[Brian d marge]

yes I was looking at that crank to looks like the crank pins are pushed in from the outside and the inner bearing stopps any form of removal
There would be money there for those who couldreplace that inner bearing , as the Nsr is quite popular !!

Stephen

[Motu]

Bloody Honda's,it was a bit of a shock when I went in to buy my first Honda bigend....like,hello??!! It doesn't pay to buy a worn out Honda.

[thealmightytaco]

Thank goodness, I was sittin' starin' at the crank goin' "how the farrrrrk?!?!" but if even Motu can't fix 'em...

It's just goin' back in then.

[Brian d marge]

you must remember that bikes are made for production efficiency. and to that extent , the NSR crank it a good crank. It will be pressed up in a jig. ( oh and if it does go bang , you buy a new one ! win win for Honda !)

we were talking yesterday about the rear shock piston rod being 18 mm and we reckon it so that they can run losser production tolerances by using a bigger rod ...Very smart thinking

there will be a way of repairing the crank ,,,we just dont know it yet !

Stephen

[Ixion]

Main bearing wear on a two smoker is often self limiting, because worn mains cause crank whip which buggers the crank seals. So engine won't run , before mains fail catasthropically.