Exhaust

[Monkeypants]

Finally got a bit of time to work at fabricating the exhaust. Not fond of the usual puffy sleeved shirt look of 2" pipes grafted onto 1 5/8" stubs, so this is what I came up with. Tubing is 2"x .045" wall 304 stainless. Much polishing will happen after everything is complete.

Glen

 

[davidd]

Glen,

As always lovely workmanship. Where did you get the bends and collector, SPD? Also, how did the band saw jig work out?

David

 

[Monkeypants]

Hi David

The collector and the megaphone came from Cone Engineering in California. They couldn't supply me with 6" radius U bends in 18 gauge 2", but directed me to a Nascar supplier in Florida that had stock, name escapes me at the moment.
I remembered the bandsaw jig about half way thru the job when making an awkward cut. Somehow I managed with the adjustable quadrant vise on the cutoff saw. Oh well, next time I do this, the jig will get built first!
Glen

 

[roy the mechanic]

Hi, Glen, I have no wish to "butt heads " here but why go for such long pipes? my pal who builds wrc (world rally championship) motors assures me that 1 5/8 pipes at 33inches is all that is required to do "the job".

 

[Monkeypants]

Terry Prince's advice was to make the pipes about 37" to the merge collector, so I have gone with that(approximately). According to three different header tube size calculators provided by exhaust component manufacturers, 15/8" headers are exactly the right size for a 998 Vincent up to 6,000 Rpm. One calculator also provided the ideal length to the merge, at 36" it was almost identical to Terry's number.

1 5/8" is to 998 ccs as 2" is to 1360ccs, or very close to it. 1 15/16" would have been spot on the calculated number, so 2" was the natural choice and being a common automotive size was easy to find in the desired gauge and radius.
Glen

 

[greg brillus]

Now I can see why Davidd told me what a headache the exhaust system can be. I am not that happy with the system we have done on the racer....I will come up with something better. I originally wanted a system very similar to Reg's, but using 1 3/4 diameter pipes....so these would need to be longer than equivalent 2 inch ones, but we put in a 2 into 1 collector, and a descent sized muffler to keep the noise down. But now I think I need to run longer separate pipes into two separate smaller mufflers. Or else run an upswept system, which would give all the ground clearance necessary, but would hide the engine, which I was trying to avoid. I have looked carefully at Reg's pipes, and can see no evidence of them scraping the ground. Glen your system looks great, you are one hell of a good fabricator, Cheers.......Greg.

 

[Bill Thomas]

For me, It's good to have a collector box, But it should have an exit hole big enough to serve both pipes, Only trouble is the noise !,A standard stroke Vin', Needs to Breathe !. Cheers Bill.

 

[Monkeypants]

Greg- Sorry to hear that the cross under system is causing you problems. I originally had planned a cross under system something like yours, however the megaphone would have exited right where the kickstand is welded to the swingarm, so that was out.
Bill- After the merge connector the diameter increases to 2.5 inches and continues at that right thru the megaphone, which is not really a megaphone but a straight thru with stainless wool packing around the outside. I have read in various places, including the 'racing' section in the Riders handbook, that megaphones do not work well on Vincents.
Here is the exhaust all tacked up and ready for final welding& polishing.
Glen

 

[Monkeypants]

Had to shrink the photos to make it work

 

[Bill Thomas]

Looks the Biz' Glen, When I did mine, I had a Brother in law work out the area of two 1 5/8" = Big !!.That was the outlet pipe. The thing with two pipes like Reg's, You can have two silencers, So you don't have too much restriction, But I think Reg's would be too loud for racing in the UK, We all have to do whats best for us. I just bought a silencer for my road comet, I wanted a chrome one, No strawing!!, But it had a baffle right across the hole, The stainless one, Nice big hole !, So stainless it is !!, Not too loud at tickover gets louder the faster you go, But not too bad. All The Best, Bill.