poor quality repop silencers

[timetraveller]

The position of the Y junction should be just about level with the big end quill. There should be lots of photographs to show this.

 

[Gary Gittleson]

Good news! Bill Thomas hit the nail on the head. Yes, the angle of the flange is critical. The rear flange, the one that Armour's made, was off. After reading Bill's comment, I examined that carefully and could see that the gasket in the rear cylinder was only being touched on the outer edge. The pipe was being forced inward by the nut. With both pipes connected, when I was able with much difficulty, to get the rear nut threaded in the rear pipe was fouling the head under the valve adjuster cap. I think I saw someone on this thread mention trimming the head at this spot. I didn't want to do that!

So it was back to hammering, filing and working the edges of the flange with a Dremel. After three or four sessions, the thing went together. The silencer and pipe brackets lined up with the bolt holes. The pipes no longer foul the engine, albeit with just enough clearance.

It all makes sense, once I think about it. A millimeter (I mean .039 inches, this is the USA) of difference on the rim of the flange will be greatly magnified at the end of the pipes. Still, it's amazing how far off it all was, in all sorts of directions for a very small change at the flange.

So I can say that with only small reservations that I can recommend Armours, at least for the stainless setup. I took a 40 mile ride so far with it. Despite the straight-through silencer, the exhaust note is somewhat deeper in tone but not annoyingly loud at all. The two down pipes do have the expected golden hue, just down to the Y and not beyond.

Thank you all for your suggestions. I admit to getting panicky at the thought of laying up the bike for a few weeks to get this all sorted out.

Gary

 

[Martyn Goodwin]

Well I made a huge mistake, it seems. I ordered a complete exhaust system from Armour's. It cost 80 pounds for shipping to the US. Their price for the system is fair I thought, so no problem.

But yes, there's a problem. I don't see any way this system will fit. Both pipes will fit individually (I do have a twin -- a D Rapide) but when together, after a lot of fussing, trials and errors, I finally got both nuts threaded in. I didn't spin them completely home, just enough to see where things meet up.

The front pipe fouls the front cowl. (I do have a C-type cowl. The bike came with that when I bought it in 1976). The pipe itself points upward like a modern crotch rocket and there's no way the silencer will go on. The bracket on the rear of the pipe is about two inches too high. With the front pipe alone, there's no problem with the rear bracket. When both pipes are installed, the rear pipe forces the front one upward in the rear. It seems that the "Y" connection is in the wrong place, maybe at the wrong angle and maybe the curve of the one or both of the pipes is incorrect.

I emailed Armour's just now. Let's see what they say about this mess.

Perhaps some of you fine chaps might have some suggestions. I'm pretty sure this system can't be used without some serious bending and welding. If I could get this setup to work, I'd be fine with it but I think I'll be knocking out the flange and putting the nut back on my old system. That system is fine except for the chrome, which is in bad shape. This is the wrong time for the bike to be laid up, dammit.

Gary

I have fitted a few "new" pipes to Comets and have found that if you flange the pipe at 90 degrees so there is a straight entry into the head (which is what it it supposed to do) the resultant pipe is a dogs breakfast and points anywhere but where you want it. On most I find I need to flange at an angle so the pipe follows the 'proper' path along the bike.

The root cause of the problem is the bottom bracket that holds the nut captive. If we could do away with that - somehow - then getting the entry into the head straight and the line along the bike would be easier.

 

[Bill Thomas]

Magic, Gary, In the old days, Blokes were called " Fitters ", But it takes a " Mechanic ", To over come some Problems.
Just had Fun with my Comet, I bought the Downpipe a year or two ago, They said they would do the Flange,
But I would have to supply them with the big nut, But I said I would do it, On my Old Comet, The pipe went down at the back, Only a bit, But it did not look right, So I wanted to get this one good.
Cheers Bill.

 

[macvette]

Magic, Gary, In the old days, Blokes were called " Fitters ", But it takes a " Mechanic ", To over come some Problems.
Just had Fun with my Comet, I bought the Downpipe a year or two ago, They said they would do the Flange,
But I would have to supply them with the big nut, But I said I would do it, On my Old Comet, The pipe went down at the back, Only a bit, But it did not look right, So I wanted to get this one good.
Cheers Bill.

In oil,gas and petrochemical industry, the guys who erect piping are pipefitters. On piping which connects to machinery ( turbines, compessors
and pumps etc), the LAST flange to be set and welded is the one connected to the machine(s) in question. Now these are large diameter, subject to wide temperature variations and have sophisticated pipe supprt systems to avoid stress on the machine. Nevertheless, the last flange is precisely aligned across it's diameter in all directions.
Given that the twin front pipe is fabricated solid and using the priciples above, the front head joint and lower bolt determine the orientation of the rear head pipe and its flange which means its flange will need adjusting in three planes not necessarily at right angle to the pipe axis, I start with the front pipe and adjust it so that it can be fitted solidly with the nut just more than finger tight with the lower bolt, silencer and its support in the final position. This means adjusting the flange first followed by the lower bolt either by enlarging its hole and or adding spacers and maybe bending the support tab to get the kickstart and gearbox clearance correct.
The rear pipe is tricky and may need several trial fits to get the flange to seat properly. I find this is easier if the front pipe is expanded where it is slotted to allow easy in and out adjustment of the the rear pipe. It is returned to standard on final assembly.
Norman is right about the accuracy of CNC pipe benders in that the pipes would be consistent, however, this would not address the inherent inconsistency in one Vinnie to another so as Bill says it comes down to "fitting"

 

[greg brillus]

It is quite normal for the front main header pipe to be actually longer than is necessary so the alignment can be sorted to the individual bike. The front flange when made is often not square to the center of the pipe, thus the rear of the flange may not be the same height as the front, this is what Mac is referring to in his post above. the fine tuning of setting up new pipes is not an easy job, but must be done with patience or else you can and possibly will end up with damaged exhaust port threads. Several years ago I installed two sets of new Armors pipes to a C Shadow and a B Rapide. The ones on the Shadow were extremely difficult to fit, I had to linish alloy off the front head near the inlet tappet inspection cap to allow clearance for the rear pipe, and it was touching the mag cowl as well........I really had to carry out a lot of painstaking work to fit them...........The second set on the B Rapide went on with minimal fuss at all......... The trick is to be patient and think carefully about what you are doing, measure twice and cut once............

 

[Bill Thomas]

I remember doing the same as Gary once, And the rear of the pipe kicked out and up !, And I thought , This is never going to fit !, Like a lot of jobs on a Vin'.
I should have asked Armours, If they had any "Send Backs " Going Cheap !.
The other thing I have found, Is on a Comet, The Silencer bracket, Likes to go behind the pillion plate.
Cheers Bill.

 

[Bill Thomas]

I don't know why, But my Comet down pipe was about 2. 1/2" too long, If I didn't take it off, It touched the inside
Baffle, So the Silencer could not go all the way on, Also if left a little longer than the stub, It might coke up and be hard to get off in years to come ?. Cheers Bill.

 

[Gary Gittleson]

What I am now wondering is whether it makes any sense for Armours to flange the rear pipe. Maybe it would be best left to the installer. Given the uncertainties on the never-standard Vincent, how could they ever know the correct angle?

There's one more thing I didn't mention. Their attempt at a flange was quite crude. The flange was very wide and flared out like the mouth of a trombone. Just to get it to go into the opening, I had to trim quite a bit off the rim. Upon doing that, what remained was not at all flat. There were several hammer divots as well. I had to flatten that and then trim some more. I was then able to try the installation. That got me the foothills of the real adventure.
Gary

 

[Bill Thomas]

The trouble is some people don't have the tools or garage to make a flange.
Must be hard for them. Cheers Bill.