RichardW's Velocette rebuild

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Zelandeth
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Re: RichardW's Velocette rebuild

Post by Zelandeth »

Nothing much to say really, but watching this threat with a great deal of fascination...

It's always fun seeing period repairs on stuff from this era. A friend of mine had an early Austin 7 at one point which had always suffered from a seemingly incurable engine vibration. Not bad enough to really be a problem, but moderately annoying.

A few years later we stripped the engine down when the oil consumption started to get a little excessive, only to find that at some point the crankshaft had broken. What was the really interesting thing was the fact that it had been very obviously crudely brazed back together to get the car back up and running. It was visibly bent at the join.

If laid flat on the table the crankshaft would sit a good 1/8" proud of the surface at the flywheel end...how it didn't snap or utterly destroy the block we've no idea. The bearing surfaces weren't even in bad shape as I recall! This wasn't a bend that you needed a run out gauge to spot! We reckon there must have been half a pound of brass stuck around the join too.

Despite that it had run for goodness only knows how many years (my mate had been using it regularly for 10+ years before the engine got stripped down to the extent this was obvious) like that without any outward symptoms beyond a moderate vibration above 2000rpm...

We did fit a new crankshaft during the rebuild, but made a point of keeping the old one as it was a great talking point at shows. Sure I've got a photo of it somewhere, I'll post it here if I manage to come across it at any point.
RichardW
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Re: RichardW's Velocette rebuild

Post by RichardW »

That's bodgery par-excellence, Zel! Today's yoof don' know they're born, running around in brand new lease cars that never break down.
Gibbo2286
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Re: RichardW's Velocette rebuild

Post by Gibbo2286 »

Broken crankshafts on Austin 7s was quite common especially on the early two bearing ones.

Brazing was often used to fix bits that were difficult to weld, I recall our foreman brazing the threaded end of rear axle pinion back on on a pre war Standard 8 after it sheared off and dropped the propshaft on the road. (During the war he was a shipyard welder)
RichardW
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Re: RichardW's Velocette rebuild

Post by RichardW »

Engine assembly!

I got the circlips fitted to the gudgeon pin yesterday (just a slight injury to one thumb from slipping screwdriver!) so the piston was reconnected to the conrod. In the evening I made gaskets for the cylinder and carb
gaskets.jpg
So, then I could insert the piston into the cylinder
cylinder.jpg

Ready to fit to the crankcase. I had the crankcase back in the frame, but then looking at it I remembered that it was difficult to get the nuts on the mag bolts with the engine in the frame - in fact it's impossible to get on the rear bolt, so crankcase out, mag fitted and back in.
casein.jpg

Then I dropped the cylinder on, so I could refit the rollers in the big end
bigendrollers.jpg
Some of these are in better conditions than others....!

However, soon becomes apparent that all the rollers need to be fitted to the crankshaft before the con rod is dropped over, that's going to be difficult with the crankcase in, so out it came again.... Easy enough to fit the rollers and then the conrod once on its side on the bench
bigend.jpg
Then back in the frame - unexpectedly it needs to go in from the nearside (the cylinder is off set to the off side) as otherwise it fouls on the mount for the gearchange. On with the flywheel and mag drive chain, then I could set the timing. I eventually found my feeler gauges to set the points gap, but they're metric, so had to work out 10 thou equivalent! I was wondering how I was going to get the very small nuts undone, but whilst looking for the feelers, I found this spanner set
spanners.jpg
I didn't know where it was, but turns out it's on the Isle of Man, now I have never been there, but I know Grandad went plenty of times to see the racing, so almost certainly they came from his house - fitting!

Setting the timing - no computer required here, the essential tools are masking tape, a bit of old wire, and some tissue paper (not having any fag papers!)
timinggear.jpg
timingflywheel.jpg
Was unsure what advance to set but I found some info on the web that it should be set to 2.7" on the circumference of the flywheel. This seems to be 35 or so degrees, which sounds like a lot, but it's full advance setting, so we'll see how it goes.

Final job was to fit the oil control
bugger.jpg
Bugger, said Dougal! Will need to lift the barrel again to get it in, but should be enough room to do it without having to disconnect the big end - which would mean taking the crankcase out again :evil:
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myglaren
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Re: RichardW's Velocette rebuild

Post by myglaren »

My old geography teacher would have been appalled, I knew not that Snaefell was IOM. Thought Iceland :(

Coming along well now.
RichardW
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Re: RichardW's Velocette rebuild

Post by RichardW »

I had to look it up....

Just realised that the aforementioned gear change mount may prevent lifting the barrel enough to get the oil control in, so the crankcase may have to come out again - knew there was a reason I didn't bolt it up this time!!
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Mandrake
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Re: RichardW's Velocette rebuild

Post by Mandrake »

Love the way the engine just bolts onto the chassis using U-clamps. :rofl2:
RichardW
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Re: RichardW's Velocette rebuild

Post by RichardW »

There's a plate mount at the rear of the engine as well, but yes, NVH suppression was not high on the list!!
RichardW
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Re: RichardW's Velocette rebuild

Post by RichardW »

Only a small amount today...

Got the oil control fitted
oilcontrol.jpg
This allows you to vary to amount of oil the engine sucks in (along the crank shaft bush, and out to the big end - all rather clever!). It says on the plate Off / Slow / Fast - which I rather suspect equates to Engine seized / plenty of smoke / Bond-esq smoke screen! I thought at first there wasn't enough room with the cylinder on, but then realised you can tilt the cylinder forward so it clears the gearchange mount, then pull it up to give enough room to drop the control in.

Then I was looking at the throttle, but this is not proving so easy. The brake lever is mounted on the bend on the bars, and is quite a long way from the bar, so unless you've got fingers like a gorilla, the twist grip needs to be right up next to the corner - but if you do this, then it causes the throttle to bind up. Not sure where to go with that, may just have to go back to the original internal scroll one. To get it running I guess I can just move it along the bars to the straight bit, will allow me to control the carb for the initital runs.
throttle.jpg
RichardW
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Re: RichardW's Velocette rebuild

Post by RichardW »

Gearbox filled, oil tank filled, kick starter fitted, plug lead fitted, pushed outside, carb bowl filled and...



Most anticlimatic video ever... :roll: :cry: headless man tries and fails to start vintage motorbike!

It's sparking, the timing looks to be where it is supposed to be, and we've got compression, so it it's something to do with the carb, too much or not enough fuel? Don't know. Will try some easy start.

The bolt in the crankcase is not oil tight, and the carb is leaking all over the shop, although I am not sure where from yet.
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xantia_v6
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Re: RichardW's Velocette rebuild

Post by xantia_v6 »

My dad often had to resurrect old two-stroke motorcycles with unknown faults, and when they refused to start, he had 2 strategies, the first was to spin them over with an electric drill and socket on the flywheel nut, which would usually eventually get them going if the mixture and timing were approximately correct.

The other technique, often needed with Vespas that had flooded was to shut off the fuel supply, and feed the air intake with a gas/air mix. butane/air or even acetylene /air, with the correct mixture determined by the appropriate blow-torch tip. Then when the engine had run on the gas mixture for a minute or two, he would turn the fuel back on and see if it would run without the gas.
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moizeau
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Re: RichardW's Velocette rebuild

Post by moizeau »

If the carb is leaking and the crank isn't oil tight, then it's not air tight, making the mixture leaner? To test the engine spin it faster, if it's close it'll go. Then back to basics with joints.
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moizeau
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Re: RichardW's Velocette rebuild

Post by moizeau »

Just noticed..no exhaust, very important with 2 strokes
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Mandrake
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Re: RichardW's Velocette rebuild

Post by Mandrake »

Is it possible to turn it over with a power drill as a starter motor to get a better idea of whether it's rich or lacking in fuel ?
RichardW
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Re: RichardW's Velocette rebuild

Post by RichardW »

Away for a week now, so progress will stall....

Will try some easy start, and also retard the spark a bit - it should be possible to wedge up the mech on the end of the mag to get the spark retarded a bit. I don't fancy turning it over by the flywheel, as the nut is not the best and it's RH thread so if it does fire, likely to unscrew itself!! We live on a hill, so if I rigged up the rear brake (!), clutch and chain I could try bump starting it.... :rofl2: