Author Topic: Oversize Gudgeon Pin for Honda  (Read 191 times)

Offline AshimotoK0

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Oversize Gudgeon Pin for Honda
« on: September 13, 2019, 02:44:20 PM »
Just found out that Honda did a genuine 0.1mm oversize gudgeon pin for the CB72/77 ...idea is to ream out little end and piston to fix little end play. Anyone heard of this practice before ? I have an S90 crank that has zero big end play but about 1.5 thou of inch  play in the little end. Obviously, pin is smaller on S90 so I don't know if anyone does an oversize pin of that diameter pin.
« Last Edit: September 13, 2019, 07:50:23 PM by AshimotoK0 »
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Offline Bryanj

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Re: Oversize Gudgeon Pin for Honda
« Reply #1 on: September 13, 2019, 06:31:11 PM »
Don't remember anything like that mate

Offline AshimotoK0

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Re: Oversize Gudgeon Pin for Honda
« Reply #2 on: September 13, 2019, 07:19:37 PM »
Don't remember anything like that mate


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“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Bryanj

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Re: Oversize Gudgeon Pin for Honda
« Reply #3 on: September 13, 2019, 07:30:47 PM »
72/77 was before i started working on Hondas so thats probably why i never saw them. Dont remember anything like that in the parts books for the 70's bikes but then Honda started doing piston "kits" for some of the fours but those numbers were never in the nooks either!

Offline AshimotoK0

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Re: Oversize Gudgeon Pin for Honda
« Reply #4 on: September 13, 2019, 08:29:06 PM »
If it was good enough for Soichiro  .. then t's good enough for me .. I wonder which other bikes those 15.1 mm CB77 pins would fit .. certainly would fit a CB250K series. Doesn't help with S90 though as that's a smaller diameter of 14.0 mm
« Last Edit: September 13, 2019, 08:53:01 PM by AshimotoK0 »
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline AshimotoK0

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Re: Oversize Gudgeon Pin for Honda
« Reply #5 on: September 13, 2019, 10:23:40 PM »
Interestingly, a NOS S90 pin is ID 10mm  OD 14 mm and a CB350K one is also ID 10 mm but OD 15mm  so I am considering getting a 15mm pin ground down to 14.1mm ... Anyone know if the standard Honda gudgeon pins are the same hardness thoughout or surface hardened?
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Online hairygit

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Re: Oversize Gudgeon Pin for Honda
« Reply #6 on: September 13, 2019, 11:03:13 PM »
Ash, I can see you obviously want to use as much of the original parts as possible, but from what I can see it's cheaper to get a new rod. By the time. You have paid someone to grind down a gudgeon pin, and ream the little end and piston, you may as well but a rod kit and fit new parts. Conrods for all 6volt ohc 90 engines are the same original part no 1320 102 8000, now superseded to 1320 102 8010, and shown as in stock at CMS and available to order at DSS. Also good quality pattern ones out there. After all, is your little end wear small enough that 0.1mm will sort it? And of course, it means an irreversible mod to the piston too.

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Offline AshimotoK0

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Re: Oversize Gudgeon Pin for Honda
« Reply #7 on: September 14, 2019, 12:26:59 AM »
Ash, I can see you obviously want to use as much of the original parts as possible, but from what I can see it's cheaper to get a new rod. By the time. You have paid someone to grind down a gudgeon pin, and ream the little end and piston, you may as well but a rod kit and fit new parts. Conrods for all 6volt ohc 90 engines are the same original part no 1320 102 8000, now superseded to 1320 102 8010, and shown as in stock at CMS and available to order at DSS. Also good quality pattern ones out there. After all, is your little end wear small enough that 0.1mm will sort it? And of course, it means an irreversible mod to the piston too.

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Know where you are coming from but sounds to me like paying and trusting somebody to strip and  re-align the crank would be quite costly/risky and too-ing and fro-ing in post kind of puts me off. I can get the engineering done for free (lots of people owing me for electronics work I have done or them for free  ;) ) Clearance on little end on my crank  is about 1.5 thou " , 0.1mm equates to 4 tho " ...so should be OK with 0.1 oversize pin.
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Offline Johnwebley

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Re: Oversize Gudgeon Pin for Honda
« Reply #8 on: September 14, 2019, 10:10:41 PM »
I was looking through the Haynes manual for the CB200. and they claim that 0.1 over sized pins are available

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Offline Bryanj

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Re: Oversize Gudgeon Pin for Honda
« Reply #9 on: September 15, 2019, 08:31:13 AM »
Probably same pin.