RichardW's Velocette rebuild

[CitroJim]

I'm intrigued to know what's in the box Richard

Timely as I'm currently reading a book on vintage British motorcycles Fantastic bedtime reading...

I thought I knew my vintage bikes well but last evening I discovered a manufacturer from the vintage period that was new to me - Martinsyde...

That Model U sounds good... I could smell the smoke just from watching the video

[Zelandeth]

Seeing this thread has reminded me I meant to reply ages ago.

I heard back from my contacts in the bus world and they sadly don't reckon they'd be able to help with regards to your cylinder machining issues. Their kit has been set up with bits for machining the cylinders for the very specific engines they usually have to work on - usually Leyland 510s in Nationals I believe. They don't think they'd be able to handle something as small as this. It's pretty rare they have to do that sort of work anyway...usually dropping in another engine is simpler! Obviously not so simple in your case.

[RichardW]

Not much has occurred in the interim, but this box arrived the other day



More when I've got it opened properly....

Finally got around to looking at this! In the box was the barrell, which Vintage Engines in Lancaster have sleeved. Here is the inside, much nicer, you can just see in the ports where the sleeve is:

Unfortunately whilst there it had some more 'History' added to it it escaped from the clamps and broke a couple of the fins on the head. They welded them back on, and repaired the missing bit, and then refused to charge anything for the labour for doing the sleeve (or the head repair) so it only cost £70 in the end.

Dark evenings now so on with trying to get it back together and running. I have until Easter next year to beat 70 years since it last ran. Hope I make it!

[CitroJim]

Am excellent bit of resleeving Richard and top marks to the company for owning up and very adequately compensating you

Looking forward to tne next instalment of this slow burner

[RichardW]

Engine reassembled, ring gap adjusted - bore is tighter I had to take some off the end of the rings to get a 0.3mm gap. And...



Hmm. Ran a few strokes on easy start, then spits back through the carb still. Progress of sorts, that's more than I had out if it before. I think too much advance, I did try reducing it by holding the advance ring down but ran out of leg (had Covid last week...). I think I need to strip the carb again and check it's not blocked somewhere. After that, might need to try Mike's trick with a gas supply.

[RichardW]

I re-stripped the carb, all clear. Fitted the tank so I could get proper level in the carb. Still no go. I looked back over the thread, I've already double checked the timing, and my thoughts 3 years ago are the same as now! I was getting some smoke, but only from the LH exhaust which is the one where the decompressor is. I'll have to look at it again...

[RichardW]

It has run!!!! 69 years, 7 months, 7 days since it last did (roughly!)

3 or 4 times for about 30s a go, but got throttle response. Then the flywheel came loose and stopped play thought I had broken the crank to start with

Seems I was on the right track with the decompressor, fiddled with it a bit to get a better seal, was enough to get it going.

No video as I was so surprised (and on my own)!

[xantia_v6]

Congratulations

[CitroJim]

Excellent!

[mickthemaverick]

Well done Richard!!

[moizeau]

That's great. Can you get hold of a compression tester to see if there is a difference between the cylinders? Might need to spin the crank off a drill.

[CitroJim]

That's great. Can you get hold of a compression tester to see if there is a difference between the cylinders?

The difference will be zero Despite the two exhausts pipes it's a single cylinder engine...

It looks smart and and gives the bike a nice balanced look and a nice sound

[moizeau]

I thought it was but then somehow forgot that slightly important fact when Richard mentioned only one exhaust was showing signs of life.

[RichardW]

Yes, single with twin exhaust. The significance of the LH port is that that's where the decompressor routes to.

I reset the flywheel/ timing and got a slightly longer run out of it, but something is not right in the bottom end. If I crank the flywheel down hard it locks up, and then when it was running the crankcase seal plate was rattling / fluttering in and out with the crankcase pressure, but when I tightened this up it also caused crank problems. So need to get it out again and have a look. Can't think what is supposed to gap it from the crank - witness marks on the cover suggest it has been tightened down in the past I wondering if the bottom end bush is a bit long on the flywheel side causing it to jam up when tight. Might have to take it off properly.

It's also evident that the play in the big end (which I was ignoring!) may cause quite a lot of rattle.... It might have to be re done, not sure on the construction I think the inside of the con rod is white metalled then bored to suit the rollers.

[xantia_v6]

I would not have expected a roller bearing in the big end of that engine, more likely a bronze bush or white metal running on the crank.