I am restoring a 74 commando roadster (a real basket case), I am trying to bring it back to close to original. However I am making some personal improvements, solid state ignition, modern regulator, and an improved seat. People have told me to nix the old pipes (with crossover) and go to a standard set of pipes, my current pipes aren't that bad and I could get them re-chromed for maybe the same cost or slightly more. Was told the crossover was a bad idea then, a PIA to fit correctly, and not something I should keep. I could go either way, it does look kind of cool, but not sure if it would effect the value of the final project. For all you commando experts what do you think ? Would appreciate your advice.
Question on keeping the Exhaust cross tube on a 74
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Having welded several sets of pipes on 850's to keep them original, and going, and hearing that subsequent owners had to do it too,
I'd suggest that spending good money to get a set rechromed sounds like a really silly idea. !!
My 850 I'm percolating at the moment won't have them, although the crosslinked pipes look quite good at the moment.
I just know that won't last with any miles on them though.....
Maybe if you removed the linked bits, and blanked off the crossover, and then got those rechromed ?
BTW, the subject of how much power/torque difference those cross linked pipes actually make has been a recurring theme here,
and no-one has yet come up with before and after dyno charts to show what the difference in performance actually is, if any.
Which is amazing when you consider these appeared for sale 40+ years ago.....
I'd suggest that spending good money to get a set rechromed sounds like a really silly idea. !!
My 850 I'm percolating at the moment won't have them, although the crosslinked pipes look quite good at the moment.
I just know that won't last with any miles on them though.....
Maybe if you removed the linked bits, and blanked off the crossover, and then got those rechromed ?
BTW, the subject of how much power/torque difference those cross linked pipes actually make has been a recurring theme here,
and no-one has yet come up with before and after dyno charts to show what the difference in performance actually is, if any.
Which is amazing when you consider these appeared for sale 40+ years ago.....
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The crossover pipes WORK better. I put a NOS set on my 850 which has always had 750 pipes when I bought it and in the 9 years I have owned it. But after 200 miles on the crossover pipes, I would not consider putting 750 pipes back on it. With OEM peashooters the crossovers seem more responsive and they are a bit quieter. Frankly, IMO, there is nothing to not like about them ASSUMING they will stay together. I realize that's a big assumption!
Peter R
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mike996 said:
Mike's observation is correct that the cross over pipes put the noise level slightly down, and offer a (marginal) inncrease in power.
ASSUMING they will stay together.
Here's the catch: All aftermarket crossover systems I have had, were a very poor fit, cracked in no time at all.
That is probably why few part suppliers today still stock the balanced exhaust systems today.
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I concur with the stated positive attributes of a balanced system.
I highly suggest you do not go down the path of the (IMO) brain dead. Specifically DO NOT clamp solid the balance tube. Only tighten one bolt on each coupler. Heavily nickel antiseize the couplers.
The aluminum head and steel tubing don't expand the same and IMO the loose coupler reduces strain on the welded joint of the pipe that breaks when thermally worked.
I still buy balanced pipes and since my first balanced system in 1995 have not had one go bad yet.
I highly suggest you do not go down the path of the (IMO) brain dead. Specifically DO NOT clamp solid the balance tube. Only tighten one bolt on each coupler. Heavily nickel antiseize the couplers.
The aluminum head and steel tubing don't expand the same and IMO the loose coupler reduces strain on the welded joint of the pipe that breaks when thermally worked.
I still buy balanced pipes and since my first balanced system in 1995 have not had one go bad yet.
Except for peashooters,my owned since new '75 still has the original balanced exhaust system including the center pipe and both connector pipes. Years ago one of the headers cracked at the curve and was welded by a real craftsman. Now at around 60,000 miles, all good. Like any Commando it's had it's share of head removal for various reasons and the cross-over parts are showing their age. If I was to actually 'restore' this bike (which ain't gonna happen) I'd consider re chroming just the header pipes and buy the cross-over bits new.
I've had my 73 Commando with crossover pipe back on the road now for 8 years. No problems. Was not that hard to put on, all stock.
IMO, just polish it up and run it. If you chrome it it will just turn color on you anyhow.....assuming you could even find someone to chrome used exhaust pipes.
IMO, just polish it up and run it. If you chrome it it will just turn color on you anyhow.....assuming you could even find someone to chrome used exhaust pipes.
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I had factory crossover pipes on my '74 and they hadn't been removed or disturbed since at least 2000 and likely many years before. But when I did the isolastics in 2013, I removed them. The crossover was stuck together pretty good but I got it free after some work. When I reassembled, it was difficult to get them to seal properly so I got popping on closed throttle deceleration. I think I could have put some high-temp silicone in there to cure this, but I bought non-crossover pipes when I observed how much more thread the exhaust collars engage in the head. I did not detect a seat-of-the-pants power difference, but I do have a dyno baseline with the crossovers and there have been no other changes, so I will the bike again in its current setup and see what the results are. It is a bit louder with the non-crossover, but it's not inordinately loud and I like the tone better with the current setup.
Onder
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Found the non cross overs on my 850 louder. But a PIA to deal with the
cross over compared to single pipes.
Probably not a major worry one way or the other in terms of performance.
No idea if it matters but you are blocking some airflow over the head and
adding some heat to the airflow you do get.
cross over compared to single pipes.
Probably not a major worry one way or the other in terms of performance.
No idea if it matters but you are blocking some airflow over the head and
adding some heat to the airflow you do get.
Onder
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Found the non cross overs on my 850 louder. But a PIA to deal with the
cross over compared to single pipes.
Probably not a major worry one way or the other in terms of performance.
No idea if it matters but you are blocking some airflow over the head and
adding some heat to the airflow you do get.
cross over compared to single pipes.
Probably not a major worry one way or the other in terms of performance.
No idea if it matters but you are blocking some airflow over the head and
adding some heat to the airflow you do get.
N
nortonspeed
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+1Peter R said:
Also the balanced system requires extra special seating rings and retaining collets abating the truly needed exhaust threads :!:
True, but what that unique seating system also does is allow the header pipes to pivot around bit at the head instead of just rotate allowing for better, easier alignment of the whole system right to the tip of the mufflers with less stress at any of the floating mounting points. I would search out that style of fixture even if I were going the non balance pipe route.nortonspeed said:
dynodave said:
May we enquire then how many miles you have actually done on any one of these numerous bikes you have done ??
May we also enquire where/who you buy the balanced pipes off that have well aligned balanced pipe arrangements. ?
Also, anyone think of rechroming an old pipe should check how thick the metal is that is actually left in these old pipes.
If they have ever run leaded fuel, they are likely rusting from the inside.
And the metal is already pretty thin around where the balance pipe has been added....
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Biscuit said:
I got my crossover headers from CBM in the UK, used new collets and inserts etc. nickel anti seize everywhere and tightened it up in many stages, adjusting the system throughout the process so that nothing is loaded. Only got 2000kms on it but so far so good.
Theory has it that such a balance pipe should improve midrange torque and reduce exhaust noise, I have no base line for comparison, have to trust the engineers at NVT R&D. :|
Mr.Sparks said:
:mrgreen: :mrgreen: Who never released any dyno charts to back up what they said... :mrgreen: :mrgreen:
Maybe that statement came out of the
Marketing Dept The noise side of things I can believe, 2 smaller mufflers interconnected can indeed be quieter.
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Rohan said:Mr.Sparks said:
:mrgreen: :mrgreen: Who never released any dyno charts to back up what they said... :mrgreen: :mrgreen:
Maybe that statement came out of the
The noise side of things I can believe, 2 smaller mufflers interconnected can indeed be quieter.
Can't remember seeing factory dyno sheets for many bikes back then, maybe they were embarrased about the Honda 4 and Kawasaki 900 power figures.
Given the crossover added to production cost, they must have been able to justify it. :mrgreen:
Mr.Sparks said:
The noise side of things alone would justify it ?
Merely adding a balance tube to an entirely existing design is the simplest change they could have made.
(But when were the (removeable) mutes added into the ends of the peashooters ?).
On the subject of that rocket booster on a box kite, NASA have just tested the most powerful addition to a box kite yet. !
http://www.nasa.gov/press/2015/march/na ... QEAOCyqBW8
But we diverge....
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