This is Me and Molly going to get the engine when she is still looking very much the puppy. The VW lump was a bargain at something like £25 from Ebay as a local sale and I couldn't leave it there.
The next problem was how to get it into a bike, I had a Dnepr frame left over from a dismantled sidecar project that was ready for for scrapping and after much thought and pondering decided to use that as a donor bike. The only part of the bike of any worth is the BMW rear wheel and drive shaft I had grafted into it some years ago. The main project idea is to slightly tilt the engine to the left side so it will miss the (raised) spine of the frame. Balance is maintained by bringing the bottom of the engine over to the right and conveniently in line with the drive shaft of the swing arm. Drive will be achieved by simply connecting the clutch to the drive shaft resulting in one gear ratio.
The faithful spread sheet tells me it will be doing about 12 mph at 500rpm and about 70 at 3000rpm. I'm guessing I'll have to slip the clutch to just above 12 mph or 500rpm where there should then be good torque from the engine and hopfully enough to drive in most road conditions. Although I doubt its capability of successfully getting up the steep side of the Applecross pass in Scotland!!
If you were wondering the VW lump actually weighs slightly less then the V Twin diesel in my other project.
]Oh and I spent a lot of time double checking the direction of rotation so I'll be very surprised if that is wrong.
This is the engine mocked up in position, you can see the half built V Twin in there but ignore that for the moment. I'll only have to alter the top spine of the frame so helpfully as the frame is not significantly altered I'll get away with the same paperwork for it.
The first problem straight off was the clutch and flywheel. Two problems here. The first is that the clutch is operated by a push rod down the centre of the main shaft and this is simply not possible to utilise this in the set up I want. The second is that the starter motor was fitted to the original gearbox and that I am not using and I am not going to be using any part of the aluminium bell housing to hold it. I also want the bike to be narrow at this point so my legs and knees will fit in so want the starter on the engine side of the flywheel and the crown gear is fouled by the flywheel mass. So the only answer is to use a different flywheel.
After removing the flywheel I spot that the bolt pattern on the output flange are not even which gave me sinking feelings about finding a easy replacement, but it was off to the breakers to see what could be found.
Another £25 later and I have a flywheel that both fits the main shaft flange and has the crown gear on the correct side and is not operated with a push rod in the centre of the output shaft.
The first real job was to fit a starter motor. I obtained a starter from a 1.9 Diesel engine (I forget which just now) that spins in the correct way for this mounting orientation. Some mocking up was done to check it was actually going to fit, several starters were rejected in this process and I 'm glad I went to the friendly breakers for this where they are interested in odd mad projects.
The bracket was made from 4mm plate. A blank was and bolted to the engine on the gearbox mounting bolt holes so measurements and marks could be made.
After some careful measurement the plate was taken into the garden shed and trimmed down with an angle grinder so the starter bolted on with the gear teeth meshing up nicely.
You can see that the crown gear is mounted on lugs. This is because the original crown gear was to small in diameter and I couldn't get the starter to mesh with it as the body of the engine got in the way. I used the gear ring from the original flywheel which was larger diameter and surprisingly spaced correctly on a handful of M6 nuts!! Now that the starter is mounted alignment will be checked and the lugs / crown wheel will be welded permanently.
Then it was on to the heart of the project as without this being successful there was no way progress could be made.
This is the input shaft of the VW gearbox and in my hand is the output flange of the BMW bike gearbox. What I intend to make is some kind of Frankenstein monster from the two that will allow the VW clutch to connect to the BMW bike drive shaft.
This is it, the FrankenCoupling (Yet to be drilled) Made from the cut down shaft and a blank turned up on a friends lathe. The flange and shaft are not only two grades of steel but the shaft is hardened and finding information on how to weld them together was a nightmare. The blank was eventually welded onto the shaft using a high nickel content stainless steel grade wire, close to but not eutectic dissimilar matching grade specification. I heated both bits up in the oven for a hour and immediately after welding dropped them into a steel bucket of unused engine oil. This was for two reasons firstly the hope I'd restore some kind of hardness to the metal but mostly to stop the heat from rising up the shaft and softening the spline that will take the torque from the clutch.
The other bits that needed to be made are the support bearing housing that will hold the coupling steady.
This will hold a bearing that will allow a lever to depress the clutch spring.
A collection of odd sized bearings to make the whole thing work and tricky to track down as I had limited space and needed narrow variants of common sizes and the shaft was an odd but thankfully metric diameter.
The coupling and attachments mocked up in position. The next job is to make up supporting bracketery to hold this bit in place. The coupling support bearing bit will be bolted in place to allow easy disassembly in the expected frequent clutch plate exchange.
Spend to date is about £65 and I hope to keep the budget for the rest of the project just as low.
Call me a pessimist, but are you convinced that the engine will tick over as low as 500 rpm at idle?
