poor quality repop silencers

[Bill Thomas]

That's what happens when I try and use Logic !,
Anyway, I had a spare "C" one, The last of my bits !, And think they look the part.
Plus if I had to make one, It would have looked like a Pigs Ear !
The steel one to me looked cheap. Cheers Bill.

 

[macvette]

Nice Bike, I think a good set of pipes can make a Bike,
If you have enough good thread on the front, Maybe use 2 sealing washers, Which might bring it away from the cowl A nats ?. I would use a bit of car Ex' sealer on the joint ?.
Funny you have a "C" cowl, I am just building a "D" 500, Using one of those, Always thought I would have to have a "D" one, But it must be needed for the Big type front mudguard ?.
Cheers Bill.

My bike came with a new repro silencer which I fitted during the rebuild. It's a D like Gary's. After running in, it struggled on accerarion from 80 mph and up. After many carb and ignition resets it was still the same. I had read about the tests on the original spiral baffle silencers ( the repro is spiral baffle) so when the Spares Co made their repro, I got one. It had a significantly larger central pipe than the one I had fitted originally, was louder but not signficantly so.
That cured the reluctance to pull strongly from 80 upwards. At the same time I replaced the kickstarter shaft with a longer one which gave more clearance from the exhaust. The bike has a C cowl and I managed to fit the exhaust system with clearance (albeit not much) all round. I'll post some clearance pics, sorry they are not brilliant, it was dificult to get my phone in good positions.

 

[Bill Thomas]

The front pipes should fit with an Alloy cowl, I don't think there were different pipes for the "D" ?.
You may be able to weld a small extension where the flange goes ?, Not sure with Gary's Bike !, Stainless,
I have never welded Stainless.
I had some really bad stainless pipes, Years ago, Very bad graining, Not polished well, Looked Rusty to me !,
Put up with it for years, Then got offered these pipes that were miles out, Had to have a go at fitting them, For the price !, They made the Bike look so much better. Cheers Bill.

 

[macvette]

The front pipes should fit with an Alloy cowl, I don't think there were different pipes for the "D" ?.
You may be able to weld a small extension where the flange goes ?, Not sure with Gary's Bike !, Stainless,
I have never welded Stainless.
I had some really bad stainless pipes, Years ago, Very bad graining, Not polished well, Looked Rusty to me !,
Put up with it for years, Then got offered these pipes that were miles out, Had to have a go at fitting them, For the price !, They made the Bike look so much better. Cheers Bill.

Here are some pictures. First is rear silencer bracket. 2nd is rear pipe/ valve cap. 3rd is gearbox/ exhaust pipe. 4th is front exhaust to cowl. Altough they dont look much, they are min of 1/8 of an inch. D pipes are the same as C ( within fabrication tolerances)

 

[Gary Gittleson]

First of all, I live some 15 miles from a saw mill. I buy oak boards from them on occasion for use as flooring for horses. I have lots of trimmings from that. Great stuff.

The front cowl was always very close to the front fender when the fork was fully extended. Still, it never fouled. But now the bike has the JE/Timetraveller steering head, so there's comfortable room. What the picture doesn't show is that I used one of Michael Breeding's knobs for the nut on the rear of the front fender. It sticks out a bit but still no problem.

I looked more carefully at the clearance. There's some ten thou between the front pipe and the cowl. I may leave it, although the suggestion of a second gasket is a good one. The rear pipe may have clearance for a piece of typing paper. Still, I don't think it's going to move.

Thanks for the complements, coming as they are from a very knowledgeable group.
Gary

 

[vibrac]

Yes I have no doubt a modern pipe bender would make new pipes within thous trouble is all the Vincents are different!

 

[timetraveller]

Just how different Tim? The reason that I ask is that many years ago one of my chums bought a new exhaust system for his twin and it would not fit. Being new to Vincents he assumed that it was his problem so he asked me to help. I could not fit it either so we put his engine/gearbox unit in the car and took it to the manufacturer. He could not fit it either and told us it must be a 'build up of manufacturing tolerances'. So we slackened off the cylinder head nuts, the push rod tubes and anything else which might be stopping any potential movement and tried again by moving everything around as far as it would go. Total movement on heads etc was thous. The cylinder holding down studs act as locating dowels and even with the heads loose there is very little potential movement. Of course all Vincents are different and it is difficult to measure the respective positions of things like exhaust ports etc but when things do not fit by one quarter to one half an inch then I doubt that is manufacturing tolerances. Remember that Vincent test riders had their own sets of pipes to be used when testing out new bikes. That would not have worked had there been the kind of mismatch which we see sometimes.

 

[timetraveller]

Just heard from Bob Culver, who has been using the original Vincent jig for years to manufacture exhaust pipes for twins and singles. It seems that what I wrote above in #138 about the jig being worn out is not correct. It turns out that a worm and worm wheel in the jig which is used to drive the tube through various formers was worn out but the parts of the jig, weighing hundredweights, which locate the ends of the pipes to ensure that they should fit the bikes are still in good order. The worm and worm wheel finally failed some time ago and have now been replaced with new parts so in the future the pipes should be easier to make and still fit. One thing that Bob did say, and this comes all the way from people who worked at the factory, was that were occasionally pipes which needed to be forced to fit but after a few weeks of heating and cooling the imposed stresses worked themselves out and then that set of pipes was good for years. This tip might be of use to some people who have trouble with some modern pipes. Apologies to Bob for any confusion.

 

[vibrac]

Just how different Tim? The reason that I ask is that many years ago one of my chums bought a new exhaust system for his twin and it would not fit. Being new to Vincents he assumed that it was his problem so he asked me to help. I could not fit it either so we put his engine/gearbox unit in the car and took it to the manufacturer. He could not fit it either and told us it must be a 'build up of manufacturing tolerances'. So we slackened off the cylinder head nuts, the push rod tubes and anything else which might be stopping any potential movement and tried again by moving everything around as far as it would go. Total movement on heads etc was thous. The cylinder holding down studs act as locating dowels and even with the heads loose there is very little potential movement. Of course all Vincents are different and it is difficult to measure the respective positions of things like exhaust ports etc but when things do not fit by one quarter to one half an inch then I doubt that is manufacturing tolerances. Remember that Vincent test riders had their own sets of pipes to be used when testing out new bikes. That would not have worked had there been the kind of mismatch which we see sometimes.

I was particularly thinking of packing under barrels, and the fact that there are numerous lengths of push rods which may indicate there are variations not just confined to cam lifts and an old Vincent employee told me at a H&B section one night that there were a few sets of pipes available for road testers. I know one of my Comets wont accept the flash style push rod tubes because the angle is to acute to screw the 'collar's on

 

[Gary Gittleson]

It looks like the cowl and front intake to exhaust clearances on my bike are about the same as the above pictures. I think I'll worry out something else and leave this as it is. I took a longer ride today of about 140 miles. No problems.

By the way, Davidd theorized that the cowl might have been changed on the D to accommodate the distributor. Nope. His first guess is probably more to the point. It was a cost-cutting change. My bike still has the distributor and there's no problem with the cowl.

Here's another theory. The D has the center stand, so doesn't need the side stands. That makes the cost cutting even bigger. And for what it's worth, it's nice to have both side and center stands.

Gary