Honda-SOHC

Sounds to me like you topped it up when it had been stood a while and oil tank had drained into sump

I'm fairly convinced this is the issue if I were a gambling man..

Original not repro


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Quote from: Toko_Jo on May 04, 2023, 04:14:16 PM

Quote from: McCabe-Thiele (Ted) on May 04, 2023, 03:03:53 PM

FWIW that strange shaped B is I understand it is only applicable to the engine number casing not the headstock stamp or plate if it has one.

The odd B is on my 400 & 500 engine numbers on the upper crankcases  - my 400 has the original chassis plate and its a normal printed B on the plate.

Frame and engine fonts are identical Ted

So you are talking the direct stamp on the frame not the alloy frame plate when fitted. A bit of 50 yes rusting could soon mess up the frame - either way a Honda frame would have the right B unless you are saying sand-cast frames were different?

What Jo is saying is the stamps used on CB750 Sandcast, K0-K6 Frames and engines are the same font, height, dimensionally identical. I just used a Sandcast frame I have here to help visually explain. I’ve got plenty of other pictures somewhere showing the same ‘B’ on later K1-K6 frames. But don’t take my word for it - I’m sure other members will chime in here.

thanks for that.the plot thickens looking at pic i took of stampings it looks like they are not original factory.so need help guys what i do know it has never been restored cos it was a faded rusty tatty mess when i bought it.it was imported from usa probably sunny state cos it wasnt rotten rusty.i certainly would have checked the numbers to the v5.although the guy i bought it off seemed a really nice bloke he either didnt know or didnt tell me they were not original.so is it possible the frame was changed under warranty from a dealer which was a k1 frame cos its a late k0 and they stamped it or there was some stealing going on i put it like that cos the engine,carbs, airbox,clocks,seat,side panels etc are k0 as is the engine numbers seems a strange way round.james said they are k1 forks and hub could they have gone on a late k0 i dunno.obviously i'm a bit pi**ed off, i don't really know what it is.certainly don't want to sell it someone telling them one thing and its another.and what do you think value wise cos obviously theres a lot of money in it as your all aware. appreciate your help.

Trev - I'm feeling a bit guilty having raised this in the first place, so apologies and I know you're in a tricky spot.

From what I can see, the front fork lowers, front hub (tabs on chrome spedo drive plate are the giveaway) and front brake disc (doesn't have the square section on black boss reverse side closest to hub) are the bits that look K1. My instinct suggests it was probably rebuilt early in it's life in the US by a dealer, using a restamped factory replacement frame and new front end components that were available at the time. More than likely in the early 70's but who knows.

To make it a 'proper' matching numbers K0 you'd need to source a matching numbers K0 frame with data plate, fork lowers (the stanchions and internals will swap straight across) with correct profile, K0 brake disc, K0 speedo drive plate and chrome cover (the K1 hub will likely be the correct 'tall shoulder' hub) and then build it all into the replacement frame. Technically it should also have a single cut (rear) front fender. It's do-able, but a total pain in the arse given you probably just want a straight sale.  It's an annoying situation & I can only sympathise.

Having said all of that above, there is still value in the bike - I guess you've just got to decide which path to take and price it accordingly if you do just want to sell as-is.

Hi Ogre - nice bike, seem to recall discussing this back in 2013 when you were asking about getting a VIN plate made as yours didn’t have one?

Just to double check - does the bike have a replacement frame? Is the stamped VIN number visible on the LHS of the headstock.  Only reason I ask is because it’s quite unusual for a K0 to have the ‘hole’ on the upper frame plate under the seat (see circled below).

Be worth establishing the frame provenance before you market the bike too widely, as I’m probably not the only person who would spot / ask this (also has K1 fork lowers, front hub and brake disc, which some might spot).

Personally I’d say the price is spot on for the work / effort you’ve put in, especially with genuine the HM300’s and beautiful red foam seat etc..

She’s a beauty Ian. Can’t think of a better home she could have gone to and you’ve perfectly judged the recommissioning of this bike. Congrats

I need to up my search game, i didn't spot those at all! I'm thinking my terminology has been americanised, shameful  A search for top yolk brings up plenty local ones, fantastic! Cheers Ted

Gary I’ve almost certainly got one if you still need one. Drop me a pm.