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Ron

RAF Royal Enfield

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My WD/CO is from the RAF contract C14219. I completely rebuilt the engine about 350 miles ago which included a +40 thou rebore and installation of a modern dome top Bullet piston which raises the compression from 6.1 to 7.1 and just gives these bikes a little more pulling power. Unfortunately the bike vibrates a bit more than I would like and is especially pronounced because of the lack of  foot rest rubbers and handlebar grips.

It's always bugged me because my engine is from an earlier Army contract, so I decided I'd rebuild my engine again, including balancing of the crank assembly if only  I could find some engine cases to match my contract. Within moments of asking, Jan put me in touch with a very nice guy, Leon in the Netherlands who had the engine cases I needed.  I local friend who visited the Arnhem event last week collected the cases and I picked them up from him this morning. I've already cleaned them up and transferred my new main bearing races and bronze timing side bush from my old cases. (God knows how the drive side bearing had a big chunk out of it?)

My crank assembly is with my engineer Ainsley who tells me that the heavier piston I fitted is producing a balance factor of about 45%, where 55-60% would be more normal for this sort of bike. He'll now proceed with drilling and lightening the flywheels accordingly to alter the balance factor. 

I'll post updates as I proceed.   Ron

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PS. Some people think that these engines are 'wet sump' like a car. It's not the case. They are 'Dry Sump' like all the rest. It's just that the oil tank is part of the crankcase. Ron

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Glad to see that I've been able to help you reunite your bike with a correct pair of crankcases Ron! Keep up the good work!

Jan

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Indeed it is Jan! I had my suspicions and marked that disc before I let the bearing fall out in the oven. So put it back in the same location and it's well and truly held by the new bearing and its thrust washer now. Will seal the crack with JP weld or something. 

There's no need to knock these bearings out! In fact there is nothing to hit. I have a small electric oven in my workshop and at 220 degrees the bearing was laying in the bottom of the oven. 

Some butchery must have taken place beforehand as the old race had a big chuck broken out???Ron

Edited by Ron

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I collected my crankshaft from Ainsley today. The outcome is that when he first checked it, he calculated the balance factor at 43%. After drilling the flywheels at the big end area, he's achieved a balance factor of 58%.. I've ordered new gaskets and small parts from Hitchcock's, so I can proceed with the engine build tomorrow. Ron

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Crankshaft end float clocked and adjusted with different thickness thrust washers. Bottom end built and back in the frame. 

Ron

 

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😃😃Especially needed for failing eyesight for the tiny dots on the pinion! 

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Always a lot easier and more accurate to do the ignition timing whilst the head is off!

All the Royal Enfield WD models are the only ones I know of that have a slack wire cable advance. Actually a better idea! Adopted by  other make after the war. Ron

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You’ve got a Burman Gearbox engine plate there Ron, I may be wrong but I think Jan mentioned that after the CO/B contract, the Burman plate became standard to even Albion fitted bikes.

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I didn't know that Chris, I've never given it a thought, but of course it makes sense that there would have been different plates for the Burman box........As it happens, the crankcases I;ve just replaced were from the Burman contract.  Ron

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The WD/CO has been made with a Burman gearbox (contract C/13870, also known as the WD/CO/B) and an Albion gearbox (all the other contracts). The difference between these gearboxes is obvious, but a less known fact is the change in engine plates and footrests that was needed to accommodate the Burman gearbox in the WD/CO frame.

The contract C/11081 motorcycles had two identical engine plates, a long footrest bar with spacers on both sides and two identical footrests. But the right hand engine plate on the WD/CO/B had a cut out to accommodate the bulkier Burman gearbox, and the long footrest bar was in the way of the inner and outer kickstart cover. So the footrest bar was shortened, and a longer footrest was fitted. This footrest couldn’t have the same shape as the original one, as the angled section would still touch the gearbox, so the footrest was forged with a 90- degree bend instead. For an unknown reason the right hand spacer wasn’t removed from the spare parts list, although it was now obsolete.

Although there was only one Burman contract, all the post Burman contract parts lists still showed the same setup as the WD/CO/B: a right hand side engine plate with a cut out and a modified right hand footrest. It is currently unsure if all these later motorcycles were also equipped like this...

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It's all in the report😣 Mine has always been fitted with the plates this way round and it looks neater on the side you can see, so i'll leave it like that.  Cheers Jan.

 

Ron

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I finished my engine installation today and it started second kick (I don't think I'd tickled it enough first time) . The wind, rain, and inevitable 'Sunday, garden center Muppet's' precluded any attempt at a test ride today!

I'll give it a try on the next available dry period to see if the vibration has been eradicated or at least improved on. Ron  

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Also it's occurred to me, that the fitting of the Burman engine/gearbox plate to the off side would possibly iron out the last kink in the clutch cable........But too late now!  Ron  

 

 

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Today I managed 2 x 7 mile test rides which included some 45+ MPH duel carriageway. The first run proved that the engine vibration was vastly improved and would probably be completely eradicated with some non regulation rubber foot rest and handlebar grips. However I must have disturbed the carb as the engine wouldn't idle properly and wanted to stall at traffic lights etc.....So back on the bench to remove the carb for a strip, clean and poke out those tiny drillings with thin wire.  

The second run was much more enjoyable with only a noisy tappet to re-adjust when home and back on the bench again.  

I must admit though, I am completely spoilt by my Model G/WD which is essentially the same, but  a much smoother ride with its  heavier crank shafts, rubber foot rest and handlebar grips,  and rubber mounted handlebars.  Ron

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