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Author Topic: Crank play  (Read 10505 times)

Offline Polonda

Crank play
« Reply #30 on: July 25, 2013, 11:19:15 PM »
No problem Joe.  Let us know if you need anything when putting her back together!

Offline fearlessfred

Crank play
« Reply #31 on: July 25, 2013, 11:29:29 PM »
I learned some things On this post ,so thanks joe

Offline mx250r91

Crank play
« Reply #32 on: July 26, 2013, 08:15:35 AM »
I just installed new OEM Honda 88-89 250R 8 Ball bearings (aka CR500 bearings) this spring and noticed right out of the bag the inner races could be tilted slightly by hand with respect to the outer race. I knew this would translate to some side to side play in the crank once assembled, which it has. But I think it is ok to have a little bit of end to end free play in the crank, it is the up and down movement you want to be tight, like the rod bearing. The slight end to end movement will allow the crank to find its neutral center position to the bore when running. If the crank were tight it could be in a bind and this is when things could break. Don't forget Neil's trick of relieving the preload on the crank after you install it by giving it a whop with a mallet on the clutch side, it should spin a little more freely then too. Also I used a hot rod stroker crank and sanded down the right bearing journal with emory paper carefully until it measured the same OD as an old Honda crank I had laying around. This allowed a slip fit with the bearing since I don't have a press.

Offline JoePA

Crank play
« Reply #33 on: July 26, 2013, 10:19:41 AM »
Frank, thanks!!! The side to side was a bit excessive as it would clunk when you did it. If it was just a little then ok but I had up and down movement on the stator side as well. So its keep it snug on the clutch side but a slip fit on the stator side?

When's your next race? I see you ran line mountain...that's one heck of a course.

Offline Polonda

Crank play
« Reply #34 on: July 26, 2013, 01:30:15 PM »
Factory is slip fit on the clutch side.  However some do the opposite with the hot rods cranks.  Not sure it really matters.

Offline mx250r91

Crank play
« Reply #35 on: July 26, 2013, 09:11:52 PM »
Quote from: JoePA;5829
Frank, thanks!!! The side to side was a bit excessive as it would clunk when you did it. If it was just a little then ok but I had up and down movement on the stator side as well. So its keep it snug on the clutch side but a slip fit on the stator side?

When's your next race? I see you ran line mountain...that's one heck of a course.

Slip fit is on the clutch side, stator side stays interference fit like stock.

Yeah line mountain was fun but it is rough, lots of rocks! I got first in the 2stroke class and 9th out of 73 quads and bikes overall so not a bad day for the old R. That might be my last race for a while its crunch time now getting ready for the little one to come around Labor Day! I do plan on going to the 2 stroke shoot out at Sleepy in September to watch, that race is getting bigger and better every year and I'm hoping their pro national team will be there too.

 

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