Author Topic: Gear ratios  (Read 846 times)

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Offline basketcase

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Gear ratios
« on: April 30, 2012, 03:05:06 PM »
Guys I have a gearbox here that was sold as a IT465 Box, however on closer inspection it appears to be from an earlier Yamaha. I hazard a guess to say the seller mistook the 425 for a 465? The second pinion gear is retained by a circlip and there is an oiling hole in the input spindle. If there is someone out there with a 425 gearbox in bits, perhaps you would be kind enough to count the teeth and let me know so I can identify which box I have got here.

Offline 2fITy.J

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Re: Gear ratios
« Reply #1 on: April 30, 2012, 06:13:57 PM »
The 425G shares cogs, washers and clips from earlier models, both IT and YZ....

http://www.boats.net/parts/search/Yamaha/Motorcycle/1980/IT425G/TRANSMISSION/parts.html

But my Clymer's doesn't give internal ratios to help work it out unfortunately.


Cheers,
Chris.

A bike in the bush is worth two in the shed!

BMW-BSA-Ducati-Honda-Kawasaki-Lambretta-Matchless-Norton-Suzuki-Triumph-Vespa-Yamaha.

Dirty Dozen '13 DR650SE - '90 DR650RS - '82 IT465J - '82 IT250J - '80 GT80G - '77 A100B - '76 DT100C - '76 TC125 - '75 TM75 - '73 MX80 -       '73 TC100K - '69 TC120-1

Offline basketcase

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Re: Gear ratios
« Reply #2 on: May 01, 2012, 07:26:21 AM »
Thanks for the link there, I recall seeing some diagrams like this which have the gear tooth count next to the part number. That would be gold. Yes I see what you mean, comparing the Early DT,MX and YZ boxes to the one I have is proving to worsen my predicament! Now I am sure that this could be from just about any late 70's Yamaha, which narrows it down to about half a dozen models ??? ???

Offline 2fITy.J

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Re: Gear ratios
« Reply #3 on: May 01, 2012, 07:34:45 AM »
I was hoping the part numbers can shed some light like the bolt numbers do (length is part of the part number in mm)


I am sure I have seen gear ratios for my IT250 (ie; 6th 2.075: 1. 5th 3.75:1 etc....)



Cheers.
Chris.
A bike in the bush is worth two in the shed!

BMW-BSA-Ducati-Honda-Kawasaki-Lambretta-Matchless-Norton-Suzuki-Triumph-Vespa-Yamaha.

Dirty Dozen '13 DR650SE - '90 DR650RS - '82 IT465J - '82 IT250J - '80 GT80G - '77 A100B - '76 DT100C - '76 TC125 - '75 TM75 - '73 MX80 -       '73 TC100K - '69 TC120-1