classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: Oggers on May 16, 2022, 03:36:58 PM
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As well as a small leak from the kickstart housing, I appear to have a slightly more severe weep from the bottom of the timing cover. I have since removed the cover, cleaned up the mating surfaces, and replaced the very thin gasket with a thicker one cut from flexitallic fibre sheet - about 1mm thick - along with a smear of Wellseal both sides. However, I have since found that one of the 3/16 screws - one at around 7 o clock - near the base of the cover where the leak was - does not tighten, indicating that the thread is stripped within. Another PO bodge had been made with some PTFE wrapped around the existing screw. The cover looks a much tighter fit and it is quite possible that the other screws will be adequate, but any thoughts as to what could be done here? I am well aware of helicoils, but anything else a little simpler - and at the risk of another bodge - a self tapper perhaps? just to obtain a bit of a clamping force in the vicinity.
Many thanks
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Whatever you do, don't use a self tapper as it will make sorting it out later much harder. I would use a helicoil (or similar).
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Ian
Yes appreciate the comment. I'll run it and see if it leaks again. If so, helicoil perhaps. Can you obtain such a small helicoil?
What about re-tapping thread perhaps?
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Your repair alternatives will largely depend on how much 'meat' there is surrounding the stripped thread. Is there enough remaining metal to safely install an insert? There are various tyles and types of thread repair inserts, "helicoil" is just the common term to cover a variety of methods.
You say the scrrew is 3/16" diameter but don't mention how many tpi. Absolutely no bother getting inserts down to 3/16". They are available in much smaller diameter than that. Your main concern is what thread type?
Installing an insert is quick and easy. The trick lies in fitting the right one first time.
Good luck,
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I'd use a helicoil type rather than timesert or similar as there isn't a lot of meat round there (from memory).
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Me too. Small Helicoil kits are cheap enough on Ebay, but 3/16 sounds small. From memory those screws are 1/4 BSF and that is (or certainly was) a common Helicoil size.
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Gents
Thanks for all the advice. The thicker gasket and the other screws appear to be sealing things. I cannot feel any trace of oil at the base of the cover after a run so here's hoping the thicker gasket has worked. Naturally I now appear to have drips from the pressed steel chaincase - and therein is a whole other story of course! Quite why such a prestigous marque as Velocette went with that deeply flawed design is beyond me!
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Hence the common saying "You have to be an engineer to own a Velo". Actually, I agree there is quite a lot to be desired in a number of areas - but they are very nice bikes to ride and are very pretty. I think they're overpriced for what they are.
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I’m shocked Oggers. Don’t you know those subtle oil leaks you complain about are a classic example of the BART preservation system in action? It was practiced across the whole industry with varied success but all factories employed it.
You’ve not heard of BART? That famed British Anti Rust Treatment process? Have you ever known of any British bike to have rust problems in it’s underpinnings? Or any problems with winter salt on those parts protected by the BART? I would suggest you examine your bike much more closely and consider how you could expand the whole BART process with a judicious loose screw or two or possibly a torn or misapplied gasket here and there.
Cheers,
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Ian
I am an engineer, and in my humble opinion, a pressed steel chaincase which is liable to warping and made in two halves to hold lovely permeating warm oil is about as far from sound engineering practice as a chocolate teacup. Yes Velos are pretty, nice to ride, and the engine is remarkable for a single, but in some other respects, a little flawed. Mind, I had a Matchless G9 which leaked oil like the Exxon Valdez. Dynamo seal, chaincase, head, bottom end, to name but a few points of hydrocarbon incontinence. Eventually I just gave up on it and sold it....
My 46 Ariel VB600 has - as far as I know - not leaked at all in 8 years of ownership. Superb old SV thumper. Pig to start sometimes though....
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"Sound engineering practice" is usually tempered with "but we need to make a profit though".
Tin primary covers have leaked oil ever since the first ham-fisted tw*t over-tightened the screws and produced localised high spots in the cover, meaning that every other ham-fisted tw*t since thinks he needs to whang up the torque even more to get it oil-tight.
Worth bearing in mind though that it (and the bike) have survived far longer than the makers ever intended, and that bikes' ability to not leak oil wasn't an over-riding and essential quality 50/50/70 years ago.
Rather like the dummies who love the "Lucas Prince of Darkness" jokes and never fail to trot them out when electrical failure has happened (even 60+ years later) all these designs are well-past their sell-by date and most recognise that there's no comparison with current products.
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Isn’t that why we love and ride’em? “There’s no comparison with modern products.”
I ride ancient stuff because it provides an experience that modern and efficient stuff doesn’t. Sometimes that experience isn’t to my expectations but the more I know them the less that happens.
Cheers,
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It's certainly why I love 'em, anyway.
If I wanted total reliability, oil integrity and all the other stuff modern riders take for granted, I'd buy another Kawasaki, just as I did when I needed a daily pounder for work for decades.
As various philosophers seem to have said, it's the journey not the destination for me now.
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I am not convinced that poor design such as a pressed steel chaincase can be forgiven on the altar of misty eyed nostalgia. The Ariel has cast covers, proper gaskets and adequate fixing screws around the peripheries, and most Ariels are pretty basic workmanlike machines and priced accordingly. As far as I know it has never leaked oil - despite me removing/replacing them several times.
I agree that other traits of old classics are about the experience and the delight in riding and maintaining such venerable machinery, but for me, the pressed steel chaincase is a poor design rather than a mere characteristic or foible, and one is left with incessantly trying to make a silk purse from a sow's ear.
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I think one problem is that Velocette were always on the margin of viability and like Norton spent a huge amount on the racing machines. Although this meant that much good stuff did percolate down to the bread and butter bikes it also had the result of limiting investment. The Velo clutch, for example is just a refined / bodged (take your pick) of the original which was fitted to a lowly 2 stroke.
The persistence in running the final drive outside the primary, although having some racing advantage in giving a narrow stiff crankcase and ease in changing final drive ratios, was not that useful to the road rider and indeed given the number of people unable to read and understand the manual led to incessant problems with clutch adjustment. You only have to join the Velo "forum" to see a lot of new owners struggling..... https://velocette.groups.io/g/main/topics (https://velocette.groups.io/g/main/topics)
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Ian
I agree that Velo clutch adjustment is not straighforward. However, I find that if it is done right, changing gear can be just sublime. My MSS is near perfect. The Viper has yet to attain this peak of peeling perfection as I have the leak on the kickstarter housing to address first!
I would have thought that a flanged cover at least instead of the useless banded cover would not have been that more expensive to produce. Certainly the Velo club recommends these as being a great improvement, and I am tempted myself. Pricey though....
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My Venom had the cover with tiny screws all around it which was better than the band but still not good. The fact that the inner cover is already liberally supplied with holes doesn't help....
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Ian
Well quite.. why Velocette and others could not emulate Ariel and heaven forfend - Triumph - in providing a proper cover goodness only knows. Penny wise and pound foolish springs to mind....I wonder if such an arrangement put folk off buying them back in the day? As an aside, there is a school of thought which suggests that not putting in any oil in the chaincase at all and simply spraying the primary chain with lube every now and then may suffice. After all, that is what is done with the drive chain.....
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There's a lot of debate about doing this for Nortons which have a slightly better oilbath chaincase. Some people who've tried it report reduced chain life, and of course the oil lubricates other things like the clutch bearing.
I had an odd hybrid for a while - Norton ES2 engine / box in an Enfield frame - and because of the close coupling of the engine and box only an outer cover over the primary chain. Despite frequent oil can applications the chain wore very quickly.
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Well I now have a new band seal to fit around the chaincase. I'll also give some thought to pouring in some warm tallow to help seal the base of the joint - as one handbook advises - or some modern equivalent perhaps? I really do loathe the things! Never seen a truly oil-tight banded seal yet.....
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When I had my old MAC I used a book called "Norm's Technicalities" as a guide for maintenance tasks etc and it was particularly good for explaining how to set up the clutch. When you get your head around how the clutch works it's a far simpler design (and easier to adjust) than the usual 3/4/5/6 spring things as used on most old bikes.
That's one of things so endearing (hoho) about Scotts...they use the release mechanism design of the Velo and Vincent, along with a six spring clutch as used on most British vertical twins of the 1950s. :-\
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I had a Matchless G80 with a band seal and there was a special seal available - called the Buckingham seal IIRC? Anyway it seemed to work much better than the standard one. I have a word copy of the "reliable" manual which may or may not be the same as Norm's technicalities if you would like it. It has a long section on the clutch.....
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Opinion is divided over the effectiveness of the "Buckingham" seal. More importantly perhaps is the condition and flatness of the mating faces and obtaining an even gap all round. I have tried several times with varying results, but silk purse from sow's ear springs to mind all too readily.