Worn crankpins - is there a solution ?

Phil-UK · Post by **Phil-UK** » Thu May 16, 2013 2:38 am

I am trying to put together enough bits for a friend to build a CB77 ( he had several at University ) and sent a C72 and CB77 crank to a leading UK crank specialist in the hope that we could get a good 180 degree crank out of the bits. Unfortuantely they say that the cranks are not usable as the crankpins are too badly worn.

This make 4 U/S cranks left after getting the one I'm running now rebuilt. My understanding is that Honda never sold crank parts only complete cranks, so has anyone ever found a successful way to reclaim or replace worn crankpins ?

Couldn't they be repaired with metal spraying and then machined or somehow sleeved ?
What about an alternative big end bearing with a smaller ID and machining the pin ?
Anyone ever had replacements made ?

A friend of mine bought a freshly made crankshaft for his BSA Gold Star last year at an affordable price and I'm sure Honda made more Dreams/Hawks/Superhawks so is there a market for these bits ? Otherwise we're all running on borrowed time until the supply of usable cranks runs out and the bikes become static exhibits.

Any ideas or experiences ?

Phil

G-Man · Post by **G-Man** » Sat May 18, 2013 1:12 am

Phil

I bought some crank parts from CMS a while back. I have been pondering the same thing as you. I think that it would be difficult to metal spray or hard chrome the pin as it is part of the web on one side. A better solution might be to get someone like Alpha bearings to make a replacement pin and machine the existing one away, making the new pin interference fit in both crank halves.

I have been buying up cranks on my US travels and now have some NOS cranks (at great cost) as well.

http://www.hardchromeplating.co.uk/services.cfm

G

jensey · Post by **jensey** » Sat May 18, 2013 2:43 am

Hi,

Like Graham, I'm always searching for cranks.
I found and bought a few NOS, as well good used ones.

Cranks are becoming hard to find, because most people are not aware of the crank vulnerability. I see people pounding small end pins out with a hammer, pounding on stators's etc.

On top of that, these cranks are very sensitive too lubrication faults.

Jensen

G-Man · Post by **G-Man** » Sat May 18, 2013 2:58 am

Hi Jensen

Great to hear from you. Have you considered using an available pin / rod from something like an RD250? I know it's not as simple as that but just using as an example. There are a lot of rod kits out there for two-strokes (maybe not great quality) and even some of the Honda singles.

Here is what CMS has left.....

http://www.cmsnl.com/honda-c72_model743 ... ml#results

I have a hydraulic press so I am going to press one apart soon and take a look.

G

G-Man · Post by **G-Man** » Sat May 18, 2013 2:59 am

Hi Jensen

Great to hear from you. Have you considered using an available pin / rod from something like an RD250? I know it's not as simple as that but just using as an example. There are a lot of rod kits out there for two-strokes (maybe not great quality) and even some of the Honda singles.

Here is what CMS has left.....

http://www.cmsnl.com/honda-c72_model743 ... ml#results

I have a hydraulic press so I am going to press one apart soon and take a look.

G