Help ID'ing some transmission parts please?

[JonW]

A mate of mine bought these as LC parts, but saw quite quickly that they are not LC at all, but what are they?
(I can do more pics to help understanding of course, let me know what you need to see)

He tells me thet the guy he got them from also had a bunch of older Honda stuff he was into, some sort of old CB250 or something and he thought they could be from that, but... to me the output shaft has a very Yam nut on it, Honda usually has the twist/bolt lock plate I thought. The Yam nut looks very like the LC/YPVS nut with the recess to pull the shaft tight, I dont think anyone else used this?

What I will say is that they are in really nice condition and look to have been carefully stored, but I cant identify em at all

I initially thought AC RD, maybe 400?

The pins in the shift selector forks made me think that, but since nothing seems to fit the LC cases... hmm... pics included... also the kicker spindle has too big an OD to fit the LC case 'ole.

I also hoped that the giveaway might be the selector drum end, which has removable pins and a floating sort of lock out tab thing held captive, maybe thats to stop it rotating forever... I just dont know, but looks AC to me... who knows nothing about ACs, just looked at parts books lol

They look like matched parts to an engine, but... maybe the output shaft is from one bike and the input another? I say this as the gears across the shafts dont really line up with 'small/large'... but they could have been just pushed back on the shafts for safe keeping in the wrong order of course.

Its also weird that one shaft has bearings and the other doesnt, tho they are captive on the output shaft of course.

The output shaft almost fits the LC cases, but the input seems less of a good fit, but that could be the gears pushing it out n away...

I keep looking at parts books and think its some kind of RD400, but Ive read (on here) that they differ quite a bit over the years.

Anyway, he wanted to find out so he could move em on. I didnt know he had em until I asked about an LC transmission and he said that maybe this would fit...

Happy to hear what you think, I know we've all got different histories with bikes on here but I didnt recognise these parts at all but i rarely touch 70s stuff... or non yam lol

















not a good fit in the LC cases...











He also had this tacho drive shaft in the same box, it fits the LC case, but as you can see the YPVS one I show here has a different end... shame, my old YPVS version is ugly in comparison lol

[dusty350]

Look very much like aircooled to me.
The spline ends changed between models - I think the earlier shafts had more splines - Reedpete will know for sure. Kick start mechanism looks aircooled and differs in size to Lc, and another clue is the gearchange fork shafts - the circlip grooves at the very ends of the shaft are like the aircooled - Lc/Pv sit further in as the circlips sit inside the case whereas on the aircooled they are outside of the casing behind rubber bungs by the front sprocket. This is 400e;

20200216_164207 by dusty miller, on Flickr

20200211_200920 by dusty miller, on Flickr

20200211_214638 by dusty miller, on Flickr

Hth

Dusty

[JonW]

Super info Dusty!

Yes, defo looks like what youve shown.

[4l04ever]

The gears look like an air cooled gearbox I was looking at last week, but my selector forks looked more like LC ones.

It must be a later gearbox as YDS7 only had 5 gears and 3 selectors.
www.ebay.co.uk/itm/334497575740

The gearbox he has will use 4 selector forks as it has 4 selector grooves, so he is missing one.

There are usually numbers on the selector forks. See what they are as that may give another clue.

[reedpete]

Looks like early Aircooled RD the fine spline on the clutch input shaft dates it as ‘round tank’ .. 73/74… and it’s obviously 6 speed so not YDS7/YR5

[JonW]

Aug 9, 2023 8:51:55 GMT 1 4l04ever said:

The gears look like an air cooled gearbox I was looking at last week, but my selector forks looked more like LC ones.

It must be a later gearbox as YDS7 only had 5 gears and 3 selectors.
www.ebay.co.uk/itm/334497575740

The gearbox he has will use 4 selector forks as it has 4 selector grooves, so he is missing one.

There are usually numbers on the selector forks. See what they are as that may give another clue.

Thanks Rob,

Selector forks are all '328'.

[JonW]

Aug 9, 2023 20:31:08 GMT 1 reedpete said:

Looks like early Aircooled RD the fine spline on the clutch input shaft dates it as ‘round tank’ .. 73/74… and it’s obviously 6 speed so not YDS7/YR5

Thanks Pete.

I hadnt noticed the fine clutch splines, til you and Dusty mentioned then. Good spot!

Does this relate to any specific engine size of the era do you think? RD350? or is it a 200 or something? I'd like to know as I can help him sell it off (or even trade for LC tx and case innards etc) if can work out what it is, no sense it sitting a cupboard in his garage as neither him nor I will ever use it.

I really have no idea bout AC models, sorry... my world begins when Yamaha discovered water.*
* - I might have to use that in my forum sign off lol EDITED: done!

Is this the sort of thing or am I barking up the wrong tree?

[JonW]

One thing I did notice when looking at the parts books for the 73/4/5 models is that the idler is a two gear design,



The one fitted to the gear clusters in my pics is just like an LC / YPVS version... or has that been retro fitted incorrectly?

Interestingly the 200 of those years have something more like whats in my pics... but have totally different selector forks... of course im assuming the selector forks Ive shown originated with the clusters...

I reckon im overthinking this to start worrying its all from different bikes as there is no reason its not all from one bike considering the condition etc.

Hmm.... does the idler help narrow this down I wonder?

[dusty350]

The twin gear was fitted up till the D model 250/400 I think. E/F had the revised Lc type idler, Cdi ignition too. Earlier Ac's had a Bendix type kickstart gear - later are more Lc in design

Dusty

[reedpete]

As with LC, Ac 250 and 350 have the same clusters.
Agree about the idler style, there’s not an obvious explanation for that except as dusty’s suggestion that it was changed at some point. Maybe even full set of late gears on early shafts…
But to be absolutely sure of what you have, see if you can see the engraved numbers on some of the gears.

[JonW]

Aug 10, 2023 9:07:24 GMT 1 reedpete said:

As with LC, Ac 250 and 350 have the same clusters.
Agree about the idler style, there’s not an obvious explanation for that except as dusty’s suggestion that it was changed at some point. Maybe even full set of late gears on early shafts…
But to be absolutely sure of what you have, see if you can see the engraved numbers on some of the gears.

Will have a look Pete, I assume on the sides, not the teeth or anywhere else and engraved like the basket/drive numbers Im used to with Yams watercooled bikes?