What's this all about ?? Aftermarket CB750 bearing shells for sale on Amazon?

[AshimotoK0]

https://www.amazon.co.uk/INLIMA-35-75mm-Motorcycle-Connecting-Crankshaft/dp/B0C9JVJ6QZ

[McCabe-Thiele (Ted)]

The INLIMA brand have quite a few types of bearings listed on Amazon for other makes & models.

[Bryanj]

That would mean you could regrind a crank, does anybody know if the journals are hardened cos i dont

[AshimotoK0]

This was from the USA site ! Wonder if Oddjob is following it ... he had an obsession with collecting shells 

Quote from: MauiK3 on May 17, 2024, 04:07:29 pm
"I would not risk an Sohc four crankshaft to unknown bearings."


Reply from me:-

I agree but interesting that someone other than Daido would tool up to make shell bearings for a model 40 years out of production. People fit cheapo Cruzinimage pistons and rings,  so who can say that these are rubbish. Who is going to be the guinea pig though?
When i first got my K0750 there was an Australian firm selling undersize shells to fit a reground crank ...not sure on the depth of the hardening Brian. I have a scrap '69 K0 crank ...I could give it to Graham Curtis to determine the depth of hardening.

In the 1990's I designed a solenoid switch when I worked for Fenner (now SPX) fluid power based in Rockford Il. that we had made in Shanghai.. I chose some expensive precious metal contact tips made in France but the boss man found some at a  fraction of the price of Chinese domestic manufacture. I poo poo'd the idea of using them but the boss told me to make ten samples up using them and test them to destruction ... amazingly they passed all of the qualification tests.

I have often wondered if Daido would sell these shells direct as they are still in business supplying Honda etc.

HONDAMAN  ..had this to say :-

"The OEM bearings were (and still seem to be in the ones I've bought in the last year) Babbit alloy, both for the SOHC 750 and 550 I just rebuilt.
These bearings originally came from a Mitsubishi engine (rumored to be in a forklift engine made back when), Honda didn't invent them, nor their sizes. Honda made their cranks to fit commercially-made bearings, both the needle, roller (like CB450) and SOHC4 plain types - circa 1960s!

My local machine shop said they could probably find some bearings for these cranks even if Honda quit supplying them: they said they appear to be a common size, whatever that means? Someday I'd like to investigate that."



I always assumed they were made by Daido but i do know Mitsubishi made Honda valves ... Perhaps Trigger will know.

[K2-K6]

That would mean you could regrind a crank, does anybody know if the journals are hardened cos i dont

If needing treatment after grind, process like this available https://aalberts-st-heat.co.uk/tufftride-qpq#:~:text=The%20Tufftride%C2%AE%20process%20of,the%20characteristic%20black%20surface%20finish. Suitable for materials that can't accept nitride treatment.

[AshimotoK0]

That would mean you could regrind a crank, does anybody know if the journals are hardened cos i dont

If needing treatment after grind, process like this available https://aalberts-st-heat.co.uk/tufftride-qpq#:~:text=The%20Tufftride%C2%AE%20process%20of,the%20characteristic%20black%20surface%20finish. Suitable for materials that can't accept nitride treatment.

My mate Graham Curtis refurbishes Honda cranks of the pressed together variety  (must have done at least 100) and I asked him about the depth of hardening on those. He reckons it's around 2mm on the crankpins  ... yes I know it's not a plain bearing crank but gives an indication.  He told me the crank parts are copper coated in areas where the parts are not hardened as part of the hardening process.

[K2-K6]

Yes, you'd definitely need a "depth" hardened surface to run rollers or balls on, thats in comparison to plain bearing arrangement.

[AshimotoK0]

Interesting that bikes like the DOHC 750 and CB400N used the same size shells as the 1st CB750 and also for the DOHC that there is an extra size available  'Bearing E ... Blue'. I always knew that CBX1000 shells fitted the SOHC fours though.

[K2-K6]

Very interesting within Honda, is that they've built so so many different types in configuration and application, all good to compare design traits etc.

The three mentioned above all allmin the same area in regard to bhp per cylinder, more importantly loading (torque)  and speed all being close to specify a bearing for use in.

The detail in your thread about prototype 750, the small original big ends suggest it either started as a roller bearing crank or sized upward 8f origin in plain bearing, to control crank twist perhaps. 
Around that time were the car engine 4 cylinder too, with roller bearing crankshaft.