Do I need a refresh?

KennyNUT

Well Known and Active Forum User
Non-VOC Member
Ok, its not me :rolleyes:, but rather my 1950 Comet!

The bike is, generally, in great shape as per the image below, and the engine looks good from the outside (second image). However, I have done a couple of 20-40 mile runs with a couple of mates and both have said the engine is smoking on the overrun and off the throttle riding downhill. Riding steadily, it appears to be OK, however, I have noticed it on start up occasionally, too and hate to admit that I think it needs some attention. It also seems to max out at 70 mph. I thought a comet on a good day should be able to do around 85mph. There is a small oil leak from the oil pump brass screw at the bottom of the RH crankcase and some from the valve tubes which I have reduced by tightening the valve tube screws and also occasional weeping from the inspection caps on the RHS, not a lot and not a major worry.

Looking through the history (and there is a lot with this bike), the last engine work was done in 1980 and 1981 with a host of invoices for numerous parts. I believe the work was done by the then owner who was a competent motorcycle mechanic. So, however competent the gentlemen was, I have to be realistic that this was 24 years ago and whilst the bike runs well enough, together with the other niggly items, I think it may be worth having it looked at and some fresh gaskets here and there replaced at the same time.

I am moderately competent but am not keen about doing this level of work as I reckon the valves need to be checked and it would not do any harm to look at the piston & rings. Anything else I should be thinking of?

I need some advice or a recommendation on someone , trustworthy to do a great job at a modest cost. I did come across Mike Hawthorne's name and he lives around 100 miles from me in Newcastle, however, have no idea of his reputation, though I did spot he races a Grey Flash on "You Tube"!

Also, what should I expect to pay for a strip down, check over, new valves, piston, gaskets and rebuild? I would prefer to have the work done over the winter , however, I also want to be out on the bike again in the Spring, so need a reliable turnaround time.

So, recommendations on appropriate Vincent engine specialists, thoughts on likely causes of smoking and a very rough estimate of cost would be very welcome at this stage. I should let it be known that I have only owned this bike since December 2013 and am still a relative newbie to this site, so I hope its ok to ask for this sort of advice. I would gladly tackle the work if I was shadowed by a Vincent "expert" but on my own, I don't think so.

I do want to keep the Comet in good shape and enjoy it for many years to come and have enjoyed its charm on these recent outings, though I feel there is a little more power to be gained from it. Perhaps, that a reflection of it needing some fettling.

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Something in my life that is a little older than I!

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And the engine that is on 50 B & H a day!
 

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Martyn Goodwin

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Non-VOC Member
If you want it done for "modest cost" why not do the bulk of the work yourself? You can remove the head and send it off to have new valves, valve guides and seals fitted - While at it be sure to replace the valve springs - after 30 years they will be rather tired.

You could also remove the barrel (muff and liner together) and the piston yourself , then send them off to be examined and if work is needed simply have the liner honed to a size to suit a new oversize piston - I'm sure if you spoke with Omega - the piston company, they may have some recommendation.

On reflection I reckon someone like Conways could do both for you. You strip every thing down, they do the "technical" stuff and you reassemble. Should save you heaps of dosh that way.
 

KennyNUT

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Non-VOC Member
34 years and not 24 years :eek: - maybe it is me that needs the refresh after all. Thanks, Robert.

To Martyn G, Boggler and CollingsBob, also thanks. Never thought about the valve springs. So the bottom end should be good? Some comments around the engine running is that it sounds quiet enough, ie not much mechanical noise, so should be good. So the consensus is a top end refresh and liner/piston check work should be enough. (I am afraid I don't have any indicators around the mileage. When I bought the bike it had 500 miles showing, not that that had me fooled!

All other stuff like electrics, charging, starting carburation etc all feels fine, so no worries on any of that stuff.

Thanks again. Time to get the big spanners out, a call to Simon Linford and a call to Conways.

Cheers, Kenny.

:)
 

Bill Thomas

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VOC Member
Hello Kenny, It don't sound too bad to me, As it is !, If you have only done a few short runs, After all those years, I would give it a chance. If you use thin Multi grade oil it would make it smoke !. I like a single grade, 40, If it was done all that time ago, I don't think it would have the new type Pistons, With the small clearance, There are not many Comets that are oil tight !. After some rebuilds the bike are Worse than yours !, Have Fun, Bill.
 

Len Matthews

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VOC Member
Good looking bike but I would suggest that you re-route the plug lead from the magneto. It looks perilously close to the exhaust nut. Ideally, the lead should loop right round the back of the cylinder head making sure that it doesn't get burnt.
 

Howard

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VOC Member
This is the right season to set to, but I'd be inclined to leave any serious work, it doesn't sound too bad.
First guess at smoke would be valve guides, make sure you've got metering wires in the rocker feeds, and maybe as Bill says, try a thicker oil. Try following it yourself, people used to following new vehicles panic when they see a whiffle of smoke.
Smoke on start up could be due to some sumping oil blowing past the rings until it clears the sump.
Check your breather is working properly.
Lack of performance isn't necessarily a sign of wear, I'm sure some of the hacks I've had in the past went quicker than they ever did new. It may be as simple as a restrictive silencer, there's been a lot of that about.
Oil leaks - yes it does doesn't it!
Look on the bright side - if it's leaking and burning oil the lubrication system is working. :)
Just my humble opinions.

H
 
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