Britbike forum Forums Buy & sell - private adverts only! Garage sale - The private buy & sell board Wanted, BSA siamese exhaust

Looking for a A65 or A10 siamese exhaust or 2 into 1 aftermarket pipe is any condition so long as the pipes before the junction are not dented..Thanks

I think classic British spares carries them

I may have a set or 2....i'll look this week
Bill in OHIO

Thanks, do let me know, Tony

Went to the Warehouse found the main pipe NOS...but the short pipe looks too long..send me your email or ph # I'll send 2 pics 419-466-7444
regards Bill

PM sent

Bill,
If you have another set I would be interested
Thanks,
Richard

what is the advantage, if any, of siamesed pipes in this application?

Less parts....Some claim more power, some say less, some say no difference.....

Don't know what he's building but a good tuned set of 2 n 1 headers can do wonderful for the bottom end pull and mid range. Great fun for the eighth mile dirt, worked well for me on A65 anyway. but retired the pipes few years ago and just kept for memories.

nice collection. how do u tune them?

Didn’t mean to alter the thread; but the headers are made to exact equal dimensions. Then you pick your silencer and just jet and tune the bike to match what you want. What you have coming in and what you have going out have to be in proportion with each other. That’s what I was taught anyway and it always seemed to work well for me. Though I do tend to run my old bikes a little rich now these days.

i run 1-5/8 inch open pipes on a T120, and tune them with extensions

the bare pipes are 32 inches and i can clamp on tubes that make them 34, 36, 38, and 40



on this machine th ebest length is 34, which is way shorter than even ordinary TT pipes

wouldn't know what to do with a muffler though. that introduces multiple complexities, like a megaphone.

Eddie Dow the known BSA tuner liked the unequal length siamese pipes on the A10....That was then and more is known about exhaust tuning...
Like Kevin I have found a 34 inch pipe to make the best speed, but 1.5 diameter .....Our bikes are very close in performance
but have different carbs, cams and so on but like the same pipe length
Current thinking is the intake, cams and exhaust must all work together, each requiring adjustments.....
The A10 I am building is just a fun back road bike, no need fror maxmum power

the unequal pipe thing may have been to broaden the power band by peaking the cylinders at slightly different rpm

like tuning ignition, exhaust, and intake 500 rpm apart. they don't give you the highest peak but it spreads out more

dunno how vibration would be affected

leo goff told me to use 1 5/8-inch pipes. i have some standard TT pipes to experiment with, 1 3/4-inch and whatever their length should be. i think the length was pretty much stadardized by years of flattrackers.

[quote=kevin]the unequal pipe thing may have been to broaden the power band by peaking the cylinders at slightly different rpm

I like that line of thinking......