Raleigh RM8 AV7 Rebuild - Retrofit Variator

Coulter Blackburn /

Hello moped lovers. I have just started an attempt to fully rebuild an old 1967 Raleigh RM8 (AV7) moped! The engine was seized so the plan is to fit a new engine as pictured below which comes complete with a variator pulley. The original moped did not have a variator and the engine was fixed at the top and bottom without any vibration mounts.

So my question is can I simply allow the top mount to swivel and fit a damper type spring at the bottom side of the engine to allow it to swivel as the variator operates? I have read in other posts that a 40lb (200N) damper should be suitable. But will the engine need any other support at the bottom to compensate for the horizontal forces of the engine or will the top mount be sufficient?

Also as the bike did not have any vibration mounts in the original setup, will I need to configure the top mount to add some kind of vibration mount?

All opinions and advice will be greatly appreciated especially from those that have attempted such tasks in the past. Many Thanks.

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Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

An av7 with the dimoby clutch would be the closest to stock. I imagine that is a dimoby on your seized motor....

As far as the variation, as long as it swings it will probably work. Although maybe a bit shaky. You may have to use your original head on the new engine. As for the spring I imagine that you could retrofit a standard Moby 50v spring and hook setup...

Those complete replacement engines are pretty bad quality wise, as is the variator. Pretty expensive too. You could probably buy a good used french made engine here for far less. Those complete engines are indian or Chinese made clones.

Your also gonna need a new intake and carb. As that old gurtner carb will be much harder to setup with the new engine. If you can even save it at all....a 15mm malossi shorty intake and dellorto 15:15 carb would be your best bet. Get some more power too...don't forget to buy a range of jets in the correct sizes. Don't want to seize it from running too lean

Why don't you just rebuild the engine you have? A new cylinder, Piston, crank and seals/bearings would be much cheaper and a pretty easy job.

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Coulter Blackburn /

Hi Aaron, many thanks for your helpful reply. The old engine was laying for about 47 years with no spark plug and had water in the bottom end, so I don't think it's worth rebuilding. I already have the new engine on order so I do hope that's not a mistake! Just thought I would have everything new, variator clutch, electronic ignition, exhaust etc.

Thanks for the advise on the carburettor, I have purchased a new Dellorto SHA15:15 and intake pipe to suit. I have 60 and 68 jet to start with, do you have any numbers in mind that I may require?

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

looks like the bottom of the engine is mounted with a bracket, if you want to use a variator, you have to mount the AV7 bracket+spring mount so the engine can swing about the top engine bolt. this means you also have to mount the top of the engine in a manner that will allow it to rotate, like with a nylon lock-nut without torquing down the nut. otherwise, you need to get fancy with spacers n bushings.

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Look at the raleigh rm9 ultramatic for inspiration, it's what the factory came up with to accomplish the same thing you want to do. They made new top motor hangers with the bushings in the hanger itself, rather than new bushing mounts welded on the frame like the RM11-RM12.

If it was me I think I'd try to acquire the RM9 mounting hardware (although it could be replicated if you have access to a welder), use the stock rm8 cylinder head on the new AV7, and then knock the corners off the new AV7 cylinder to match the round stock head.

Or of course you could swap the variator for a new single speed clutch and leave the thing solid mounted.

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Aww you'll be fine. I just had trouble with the one I bought. Nothing catastrophic though. I remember I wrote down what I did to mine somewhere. I'll see if I can find it and let you know what I did to fix it up. Your engine might very well be just fine ...quality control wasn't the greatest engine to engine.

68 miiight be ok, I'm thinking a little bit lean. Some one else will chime in but I think I was running a 72 on a stock av7? Regardless you will certainly need more than those two jets. I'd say buy the next few sizes up, 70, 72, doubt it would need a 74...what size is your new intake?

Is that engine a points or cdi? I imagine that you'll have to switch everything over to 12v as the new engine isn't going to be 6v....well I doubt it would be anyway.

With the way the engine mounts I would aim to keep it non variated if I was doing this myself. But you can certainly make it work...

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Coulter Blackburn /

Thank you for your reply Full Tuck. Yes that's the way that I'm thinking of going, although I'm tempted to try the gas strut idea instead of the spring as it would seem easier to mount! (edited)

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Coulter Blackburn /

Hi Saabsonettguy, thanks for your reply. Excellent idea regarding the RM9 mounting system. I didn't realise that it was so similar to what's in my head! Although I'm thinking of trying to keep the new engine complete with it's own head and make up some sort of conversion bracket to attach it to the frame. Maybe I can incorporate mounting bushings in that as well. Yes, I could just change the clutch but I do like the idea of have the variator if I can get it to work.

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Coulter Blackburn /

Thanks again Aaron. Relieved to hear that the issues with the new engine were not too serious anyway! Ok, I'll order in some more jets but I have some time to go before I will get to that stage. The carburettor is the 15.15 and the intake pipe is 15mm. All electrics will be 12v but that's only a headlight and taillight anyway. The engine is electronic ignition and requires a CDI unit. (edited)

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Another idea would be a simplified version of a parallelogram mount like this.

Not sure if those dimensions would all work for your application, but it gives you something to start from. (edited)

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Coulter Blackburn /

Thanks Saabsonettguy, that's brilliant and yes it could be a good alternative for me to consider all right. Thanks for taking the time to provide the pictures. Is that made from aluminium or steel plate? It should certainly give a lot more stability and support than the spring system. Has anyone used the gas struts instead of the spring? Many Thanks.

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

I think all those in the photos are aluminum. I think a thinner piece of steel would be ok if you had a tube welded on the big end for the rubber bushings to press into.

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Wow that's ruff, are you sure the frame is solid? That might actually be better as wall art, not to mention the rims and everything else.

Trust me I'm the king of lost causes but that just might be too rotten.

If you do want to bring it back, you can probably save the cases, and head. Find a used dimoby clutch, and put on the av7 cylinder or find an av88 that would have similar fins

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

Coulter Blackburn /

Thanks Graham, yes it looks rough all right but I have it completely dismantled now and the frame is solid. It's not worth rebuilding for financial reasons for sure but I have it for about 47 years and sill have the log book etc. It's one of those 'reliving my youth' type situations!

Re: Raleigh RM8 AV7 Rebuild - Retrofit Variator

daan SJAARLOOS /

I second Graham. Looks like a lot of holes to fill once you sandblast that frame. But anything can be fixed of course.

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