Crank Info

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gregorious77
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Crank Info

Post by gregorious77 » 03 Jan 2018, 13:53

As I have a couple of expired cranks (1 LT rebuilt and 1 original) I am venturing down the route of disassembly and inspection to find the origins of the rod etc.
I have cut the rebuilt big end pin in half and salvaged the rod intact.
Measurements are as follows:
Small end Diameter 22mm width 17mm
Big end diameter 31mm width 17mm
Centre to centre 131.7mm

I may well cut up the OEM crank too to see how it compares.

I will also measure the Honda piston vs TRX piston pin to crown to see if there is a difference there when time allows.

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Re: Crank Info

Post by gregorious77 » 03 Jan 2018, 14:14

Its very close but not quite the Hot Rods 8111 for 1990 - 1999 KTM 250 EXC:
Small end Diameter 22mm width 16.9mm
Big end diameter 31mm width 16.9mm
Centre to centre 132mm

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knackeredMk1
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Re: Crank Info

Post by knackeredMk1 » 04 Jan 2018, 09:16

This is what I found in 2012 and is listed in FAQs -

'Mk3 conrod dimensions to the best of my measuring abilities (I strongly suspect all CRM250s are the same):

Little end
Internal diameter - 23.0mm
Width - 16.5mm

Length between centres
132.5mm

Big end
Pin 25.0mm
Internal diameter - 32.0mm
Width - 16.5mm

Washer width - 1.0mm

Please someone tell me if I have measured wrongly


I've found something very close to original spec.

KTM 250/300 90-99

Wiseco WPR135 (no made any longer but still around?)
PROX PX03.6310 (I believe but please check specs as I can't find)

Little end
Internal diameter - 22.0mm
Width - 17.0mm

Length between centres
132.0mm

Big end
Internal diameter - 31.0mm
Width - 17.0mm


Whether this is actually the same centre to centre I'm not sure but could it be mounted on the crank with a 0.5mm off set given the smaller big end?'

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Re: Crank Info

Post by gregorious77 » 04 Jan 2018, 15:36

Interesting that the LT rebuild crank has a 131.7 Ctr to ctr though.
Rod is non branded too with no markings at all.

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Re: Crank Info

Post by knackeredMk1 » 04 Jan 2018, 19:02

The KTM specs that I listed above are off the Wiseco web site.

LT, or rather the workshop they use to put the crank together may offset the bottom end to allow for tiny differences in centre to cetre lengths between the original and the option.

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Re: Crank Info

Post by gregorious77 » 04 Jan 2018, 21:10

I will press the pin halfs out when I get time to see if its a special pin.

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Re: Crank Info

Post by gregorious77 » 04 Jan 2018, 21:43

Image


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