Crankshaft Blues

S

seaguy

Joined

May 19, 2009

Messages

271

• Aug 5, 2009

• #1

My local machine shop kept my 750 crank for a week and a half before deciding they couldn't turn it. I took it to them seperated because I read somewhere that it had to be turned that way. Shop said bolt it together and they could turn it then tell me they can't. Anyone know of a real machine shop in America. Guess I'll have to ship it somewhere. It is top to bottom 1 .7485 " and mid throw is .749 Got to go to .010 under I guess. Sure wish they made -.001 shells.

 

J

JimC

Joined

Oct 12, 2007

Messages

2,904

• Aug 5, 2009

• #2

http://motorcycle.memphismotorwerks.com/

 

C

chris plant

Joined

Nov 6, 2008

Messages

502

• Aug 5, 2009

• #3

hi seaguy, is the difference between your two measurements 1/2 thou

 

S

seaguy

Joined

May 19, 2009

Messages

271

• Aug 5, 2009

• #4

chris plant said:

hi seaguy, is the difference between your two measurements 1/2 thou

Click to expand...

I believe that is correct. Best I can remember top to bottom (where the work is done ) was .7485 and halfway up the stroke was .749 I copied the specs from the Norton shop manual, took the readings with a mic (no caliper) and showed it all to a machinest here at work and he said I could probably get by but would lose some oil pressure. Thats why I took it to the machine shop. Didn't want to put it back loose since I had it apart anyway.

 

C

chris plant

Joined

Nov 6, 2008

Messages

502

• Aug 5, 2009

• #5

hi seaguy, if thats the case then i dont think you need a regrind,

 

S

splatt

Joined

Jul 14, 2008

Messages

1,131

• Aug 5, 2009

• #6

1.7509/1.7504 is the standard size, so your crank is nearly 0.002'' down on size and really should be re ground.

 

R

rond944

Joined

Nov 4, 2008

Messages

89

• Aug 6, 2009

• #7

I concur with JimC . Leo Goff is the man when it comes to all things Norton and Memphis Motorwerks has state of the art equipment .

 

S

seaguy

Joined

May 19, 2009

Messages

271

• Aug 7, 2009

• #8

Check this out. My crank was laying in the back seat of my rice burner and ambient was about 102F. I mic-ed it once again and the smallest measurement was 1.7503" go figure. I know that engine will run hotter than 102F so I'm going back with standard shells. My son can turn it when he gets it. :wink:

 

S

splatt

Joined

Jul 14, 2008

Messages

1,131

• Aug 7, 2009

• #9

If you put the micrometer in the frezzer it will measure even bigger :idea: :idea: