Crank shaft play .

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c&b745XX

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Nov 26, 2001

76

0

• Feb 23, 2008

• #1

I have ran a search and it seems that the play that is within spec. is said to be 0- .00? something . The reason I ask during a top end rebuild that I'm attempting to do , checking other tolerances while I'm at it . I grabbed on to the flywheel and noticed alittle ,what I believe to be called axial play and maybe a touch of radial play . I know this is a hard way to check this out . So if I had a dial indicator set up on the fly wheel in the proper technique , what would the tolerance be ? . Every thing turns very smoothly and seems fine , don't want to split the cases if I don't have to . I probably have a good season on this ride ( whats this mean? , I don't know ) , I'll be sure to place a hour meter on my ride after the rebuild . Thanks. (06 RM 450Z )

 

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BigRedAF

Member

Jan 9, 2005

739

0

• Feb 23, 2008

• #2

4 Stroke cranks hold up pretty well, specially at our age. :rotfl:

I think your referring to connecting rod deflection. That's when you grab the small end of the rod and wiggle it back and forth. If so, that limit on a 06RMZ 450 is 0.12

Connecting rod big end side clearance is 0.04

Crank shaft run out, (wobble) set up on V blocks and checked with a dial indicator should be .003 or less.

 

whenfoxforks-ruled

Old MX Racer

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Oct 19, 2006

8,129

2

Merrillville,Indiana

• Feb 24, 2008

• #3

Now I know 2 people who need a shop manual. A recent mishap with my sons 250f got me an inside look at the honda. The double bearing set up they use leads me to believe there may be an acceptable amount of play. Normally I would split the cases without question when the crankends moved up and down.

 

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BigRedAF

Member

Jan 9, 2005

739

0

• Feb 24, 2008

• #4

The numbers I posted came directly out of the 06 RMX shop manual. The 0.12 number is side deflection against the top of the rod. Not movement up and down. Any up and down movement on the rod is bad!

 

whenfoxforks-ruled

Old MX Racer

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Oct 19, 2006

8,129

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Merrillville,Indiana

• Feb 24, 2008

• #5

Well, do they have any up and down deflection numbers?

 

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BigRedAF

Member

Jan 9, 2005

739

0

• Feb 24, 2008

• #6

No, and to be honest I can't think of a way to measure that with any amount of accuracy. My opinion would be that if you can feel any up and down free play it would be a bad thing.

 

whenfoxforks-ruled

Old MX Racer

~SPONSOR~

Oct 19, 2006

8,129

2

Merrillville,Indiana

• Feb 24, 2008

• #7

Yup, same here. Any play up and down on the rod or main bearings means its case splitting time. Motosports has some pretty good deals on engine kits complete.

 

C

c&b745XX

~SPONSOR~

Nov 26, 2001

76

0

• Feb 29, 2008

• Thread starter
• #8

Thanks all , when in doubt rip it out ..........

 

whenfoxforks-ruled

Old MX Racer

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Oct 19, 2006

8,129

2

Merrillville,Indiana

• Feb 29, 2008

• #9

Non-catastrophic 4 stroke engine rebuild, 500 dollars and up.