dps650rider
XS650 Addict
The crank in one of my engines has some end play, I measured 0.4 mm with a dial indicator. Does anyone know if there is a spec on this? I've looked and looked but no luck.
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Crank End Play
- Thread starter dps650rider
- Start date
Did you look in the clymer manual?
If not, take a look.
If so, then I don't know. Perhaps some other guys can be of help.
Personally, I wouldn't use a Clymer if it was given to me. Use the factory manual. That's what Yamaha made it for.
There's no end play listed in the manual. Since the right main is a ball bearing (to take the side loads of the drive gear), there shouldn't be any discernable side play. If there is, the right main bearing's worn.
.4mm ain't much... If it was a runner, I'd prolly keep on running it. If I was building an engine, I'd replace the mains.
Curious as to why you checked side play?
dps650rider
XS650 Addict
I checked Clymer and Yamaha service manuals and no mention of it. Somewhere in this forum I saw it mentioned that the max was 0.6 mm but I would like to confirm that.
dps650rider
XS650 Addict
After thinking about it for a bit... not sure I'd continue to run one with that much play. That's about .015". That means the right side of the crank will be flexing up and down that much. That's based on the assumption that if there's that much side play in the balls, then there's also that much radial play too.
TIR on these cranks is .002" max... and even that much makes for a motor that shakes a bit. .015" play in that bearing is way beyond that.
If the noise you're chasing is a whirring sound, that's the sound a helical gear (the drive gear) makes when there's clearance problems. Have you checked runout on that side?
TIR on these cranks is .002" max... and even that much makes for a motor that shakes a bit. .015" play in that bearing is way beyond that.
If the noise you're chasing is a whirring sound, that's the sound a helical gear (the drive gear) makes when there's clearance problems. Have you checked runout on that side?
IMO, if you're going to do a tear-down, do the full tear down. It's better knowing you went through the whole thing. I just rebuilt my XL250 engine when it destroyed a piston. I couldve just bored the jug and got a new piston, but I went and did the full Monty and replaced seals and bearings, cleaned the case, jug, head, and lapped the valves. Then painted the engine. I'm glad I went through it. Go ahead and make it a "new" engine, you'll be glad you did.
dps650rider
XS650 Addict
I just checked a used bearing with a similar amount of end play and I can't feel any radial play at all. Best I can tell with my caliper is there is about 0.02 mm radial play or about 0.0008". Still would really like to see a spec on this, the used bearing I measured feels fine and the internal surfaces look OK. It just has some end play.
That's less than a thou of play, I think you'll be ok.
