R100GS exhaust balance pipe - essential or not?

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RobG

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My 1989 R100GS has a balance pipe to connect the two exhaust pipes before they go to the collector box... I need to replace the pipes and have a pair from motorworks but without the balance pipes...

Does anyone know if I can just install these and forget about connecting them before they enter the collector box - would it affect the running?

The Ohlins rear shock is installed BTW and is fantastic - what a difference!

Any advice much appreciated.

Rob
 
Ain't got one on mine - from memory the replacement s/s items do away with it. By also doing away with the collector box with a y piece you undoubtably get more coughing and farting but not sure if significant performance effects, probably levelled out by freer flowing. The collector box weighs almost 1.5 tonne on it's own though and creates a large object for clouting so I'd not worry about losing anything on the weighty pipe system...in fact...tonight it's off with the silencer - far too weighty ! :P
As Para say's it's obviously there for a reason, but like most of the carb setting I'd guess it's mainly for emmission regulation.
Balance tighter emissions leading to more fuel use versus less restricted and less fuel - which creates more pollution in whole world cost terms...please discuss.
There are settings in the carbs that can be modded to give as good performance, and more mpg, but they break emmission regs - more b*ll*cks from the legislators. :confused:
 
I had the same question when I bought a set of new stainless pipes fro Motorworks 6 months ago. They pointed out that the diameter of the new pipes is greater than the originals (fair point) and that would reduce the back pressure (which is the reason for the balance pipe.

I agree with Fritz that the best thing you can do to get a free breathing lighter bike if to fit a y-piece instead of the balance box.

The lack of a balance pipe seems ok on my bike ('90 R100) - but I don't do high speeds on it. the unbalanced pipes have advantages in that they dont need to be disconnected when taking off the pipe on one side (occassional consideration) and they clean up much better - I bet you rreplaced yours because of corrosion around the balance pipe area.

My advice - fit them and don't worry.

Simon
 
Thanks for the advice, I'll try these ones I have. I did try to get the proper ones from Motorworks but this is the second attempt and they keep sending ones without a balance pipe.... maybe they're Ok because ther're wider inside?

As to the resaon... well there is a fair bit of corrosion around the balance pipe... but the main and pressing reason for replacement is a lamp-post sized dent in the left side pipe which restricts it to less than half the correct size...

The carbs are due for a tune anyway so I'll let you all know how it goes!

Cheers,

Rob
 
Balance pipes

They are used for changing the wave pattern reaching the combstion chamber, and thus helping volumetric eficiency (also carburetion is improved - the carbs get better pulse feedback).
Was also used in Harley sportster and than removed because it doesnt look "cool" enough.
miky
 
IIRC the balance pipe is there to aid scavenging on the non firing cylinder at high revs.

had the same dilemma when fitting stainless pipes on my le mans, which should also have a balance pipe.
in the end i decided to go with no balance as they are very much easier to remove, clean and are cheaper :P

can't tell the difference.

edit: i didn't post this to disagree with miky's post above. i didn't even see it. he's probably right. who knows :confused:
 
cookie said:
IIRC the balance pipe is there to aid scavenging on the non firing cylinder at high revs.

can't tell the difference.

edit: i didn't post this to disagree with miky's post above. i didn't even see it. he's probably right. who knows :confused:
Click to expand...

It's the same thing - the negative pressure wave geting into the exhaust port at the right moment to draw spent mixture out and aid to start filling the combustion chamber with fresh mixture. this same wave is felt by the carb as at that moment both exhaust and intake valves are open.

I dont think you can feel the difference while riding, it will be present if you'll run the engine on a dyno.
 
cookie said:
IIRC the balance pipe is there to aid scavenging on the non firing cylinder at high revs.
Click to expand...

I always understood it to be to increase low end torque. :confused:
My Tiger has them also. So they must be a good thing! ;)
 
In the very late sixties to very early seventies some of the racing car tuners helped with some of the exhaust systems on the new multi cylinder motorcycles. Rocket three, Trident and the CB750 4, especially when they were being inserted into sidecars for competition purposes.

One of the known things from the car world to improve multi cylinder 4 strokes, was to have a set of equal size (volume not always length) header pipes running into a collector box. The general idea was as stated previously, to help with the scavenging and general sucking out of the gases more efficiently.

This did work and I witnessed in January 1970 a CB750 engine in an outfit being raced on Saturday with a set of four pipes and then on the Sunday with a Four into wunzon exhaust system. The rider and his passenger noticed a cleaner low to mid range pulling ability and they did improve their position by one placing relative to the Saturday race. The race placing could have been just one of those things.

If you are running a large twin cylinder bike and you have a crossover pipe fitted you should notice smoother idling and possibly very low end clean pulling compared to a set of straight extractors on each cylinder.

Mick.
 
Very interesting thread.I followed the advice of early posters and fitted the pipes without the balance pipe. I have to say the bike runs brilliantly now... but it was running on one pot pretty much before owing to the left hand pipe being dented and restricting exhast flow;)

Here's another one? Why is a y-piece said to improve things over the standard collector box?
 
RobG said:
Here's another one? Why is a y-piece said to improve things over the standard collector box?
Click to expand...
This is contrary to how I was informed by none less than Jim Cray of Cray Engineering. I was running with th y-piece and was recommended to find and re-fit with the collector box.

I have a Cray Stage 1 Fast Rode tuned bike and the collector box in place give better mid range and sounds far better :thumb
 
and who supplied the collector box -- another satisfied costumer


:D :D
 
Para,

I have a scrap (leaky) R100GS para shock that I'm abouty to throw away, if that's any good to you?

Rob
 
Paragon said:
- i was hoping that Steptoe might bring one to the Andover do.


Cheers


Para
Click to expand...

Blimey guvner, i doff me hat to yer, you being a gentleman an all, your going to the hog --


( for 10 mins on sat afternoon )

i can read between the lines on this one Bill, not so sure if others know you as well .

:D
 
Steptoe said:
Blimey guvner, i doff me hat to yer, you being a gentleman an all, your going to the hog --


( for 10 mins on sat afternoon )

i can read between the lines on this one Bill, not so sure if others know you as well .

:D
Click to expand...
He'll be there long enough to suit his personal interests and go before he has to pay I bet.
 
Para,

I'm in Godstone on the A25, let me know if you want it, I can send it if you want... Be glad to be rid of it!

Rob
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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