Brooking850 2:1 fitting

Chaps,

I fitted up the new Maney copy 2:1 system from Mike (Brooking850) today. Here's some pics:

General fit and finish is fabulous. The ceramic coating is very good, the heat shield fabrication is very professional, the end can and polished end cone look great:



Same overall lines as the Maney system, but designed for a road going Commando. I think I'll have to paint the small joining plate on the front tubes black though:



It has been designed to comfortably clear the stock side panels. The original Maney system did not clear it at all:



Very neat front tubes. The exhaust roses I asked Mike to use are not the ones he will use on other systems:



I don't quite know why, maybe Mike uses thicker gauge tubing than Maney used? Maybe its because it has been ceramic coated inside and out? Maybe Mike packed the (very small) silencer very well... whatever the reason... this thing sounds magnificent!!

Don't get me wrong, Mike won't be getting any praise from the Noise Abatement Society that's for sure! But the Maney system had quite an unpleasant sharpness to it which is not present on Mike system. It sounds angry, its deep and loud and sounds like it wants to go hunting for Tridents...!!

That's a great looking system. I do have one question that you can probably answer, having ridden the bike. The original Maney design put the heat shields in a position that protects the riders leg with rear sets and clip-ons. It looks to me like there may not be any heat protection for the legs with the stock pegs. Did you have any problems with that? I'm hoping not, but if that is an issue, it looks like there would be no real difficulty in extending the shields forward a bit.

Ken

lcrken said:

That's a great looking system. I do have one question that you can probably answer, having ridden the bike. The original Maney design put the heat shields in a position that protects the riders leg with rear sets and clip-ons. It looks to me like there may not be any heat protection for the legs with the stock pegs. Did you have any problems with that? I'm hoping not, but if that is an issue, it looks like there would be no real difficulty in extending the shields forward a bit.

Ken

Click to expand...

Well spotted Ken!

Yes, you are quite right and Mike has already mentioned to me about doing a different / extended guard for use with stock foot pegs. I intend to fit rearsets, but may also ask him for an extended guard so I have both options to play with!

Beautiful exhaust!

It looks like it's been (re) designed to fit better with a street bike around the front of the motor and give good side cover clearance, etc.

Looks the dogs bollocks.

How about posting a short youtube video with sound?

Damn fine looking set of pipes! :mrgreen: I know it might be sacrilegious for me to say this, but I'm not a big fan of the traditional peashooter exhaust system seen on most Commandos.

Fast Eddie said:

lcrken said:

That's a great looking system. I do have one question that you can probably answer, having ridden the bike. The original Maney design put the heat shields in a position that protects the riders leg with rear sets and clip-ons. It looks to me like there may not be any heat protection for the legs with the stock pegs. Did you have any problems with that? I'm hoping not, but if that is an issue, it looks like there would be no real difficulty in extending the shields forward a bit.

Ken

Click to expand...

Well spotted Ken!

Yes, you are quite right and Mike has already mentioned to me about doing a different / extended guard for use with stock foot pegs. I intend to fit rearsets, but may also ask him for an extended guard so I have both options to play with!

Click to expand...

And for your pillion?

Freefly, I'll try and post something soon on YouTube.

Gortnipper, the pillion pegs are going to be removed... And the solo Corbin seat re-fitted... Time to get serious...!

I always prefer the 2 into 1 exhaust to go UNDER. That loop in the header pipe on the left is always a problem getting the lengths right.

Is there a performance related reason to mount this exhaust or is it primarily just something that is done for the asthetic appeal??

Fast Eddie, thanks for the feedback.
In answer to the Q about the steel gauge, it is 1.5mm
The headers are volumetrically measured and come out at less the 20ml difference between the 2
The HPC coating is by default on the inside as well, so maybe a reason for the change in tone.

Re performance, on a performance motor, the midrange torque and power are increased as compared to a standard set of headers and peashooters.

I am sure Fast Eddie will provide us with his dyno figures. I posted some for my race bike sometime ago when I first fitted the system.
Regards Mike

Nigel,
If your bike runs half as well as it looks you should be ecstatic.

Mike,
Real nice job on that exhaust.

Pete

The two big question for me are...
What is the cost of this tubular lovelyness?
An could you post some pictures of yourself sat on the bike showing how close it get to your leg on standard pegs and rearsets (if you have some) just to give us a rough idea of their warming potential ?

One left nut. But, most of us are finished with ours anyway...

In answer to the performance question: yes!

When I put it on the Dyno, back to back with stock pipes, it have nearly 5bhp peak and an even bigger gain in the mid range.

It does require jetting changes, so just bolting it on by itself will, most likely, make the bike quite rich, gains will only be realised when its leaned off somewhat.

Also, when fitted with rearsets on simplified hangers, the whole operation saves quite a lot of weight.

I haven't got the rear sets on yet and am still fiddling about with it, so pics and vids will have to wait a little.

I suggest you will find the 2 into 1 exhaust works better if the cam is advanced a bit. If you change the exhaust in any way, even with separate pipes, you probably need to re-jet the carbs. An increase in back-pressure will make the engine run hotter, an increase in extraction will also affect carburation. I have broached 3 keyways randomly into the cam sprocket on my motor, so I can get within a couple of degrees of any setting I think might be appropriate. And once I have got my bike set up, ignition and cam timing, I do the re-jetting last. You will find the whole thing is probably an optimising/balancing act. I always try to make the motor pull harder and I then increase the overall gearing so the bike goes faster at the ends of the straights without over-revving . With the 850 cam, I now have advanced the cam 12 degrees to compensate for the 2 into 1 pipe. It is essential that the outlet of the collector and tail pipe do not represent a restriction. So the pipe is loud but effective.
My bike is quick enough to be useful against some pretty fast opposition.

I believe the 2 into 1 exhaust on my bike is different to the Maney items in that the tube IDs of the headers exactly match the IDs of the stubs in the head which have no internal tapers. So the header pipes are skinnier. The tail-pipe ID gives exactly the same cross-sectional area as the sum of the cross-sectional areas of the two header pipes.

Maybe a little background info on this design would be of interest here. Mike's system is basically a copy of Steve Maney's design, but with some improvements. Steve's orginal systems were hand bent, and looked like this:





He eventually went to machine bent pipes, and the design changed to look like this:



Mike's system is more like Steve's later design. The earlier hand-bent system had a tighter bend for the right side pipe, but a larger radius bend for the left side pipe. It also had different overall pipe lengths between the left and right sides. The later machine bent pipes were closer to equal length, and Mike appears to have made sure in his design that they are effectively equal length. I've only ever used the hand-bent system, and liked it because it did give a good mid-range boost over the Axtell twin megaphone system I had used for years. I never had it on a dyno, so can't really say much about top end horsepower. I didn't notice any difference, but that doesn't mean much. In theory, the 2-into-1 should help the mid-range power, but loose a little on top end, compared to a twin pipe racing mega system. But it would still be a noticeable gain at both mid-range and top end over a stock peashooter exhaust. When I first tried Steve's system, I speculated that the unequal length pipes might actually give a broader torque curve than the equal length pipes, but at the expense of some top end power. Never really had the chance to verify any of that on the dyno. The dyno measurements of Mike's system that have been posted here on the forum certainly demonstrate a real gain over the stock system throughout the rev range. It's clearly a great exhaust mod, whether one of Steve's old systems or Mike's new one. Mike has done a real service by making it available again.

Ken

There has always been a lot of emphasis on top end power. A good 2 into 1 exhaust usually makes a bike much more user friendly, so you can get the power down better. When I first started racing, my 500cc short stroke Triton had separate pipes with 4 inch megaphones. It was all top end and impossible to ride well - I learned some very hard lessons. I am convinced that good handling and smooth, strong power delivery are the way to go with a Commando-based bike. A big top-end power figure might give you bragging rights, but that is probably the only real benefit.

I'm worn out tonight from working on the bike all day, so it's a good time to ramble on a bit in response to Alan's comments. Here goes.

Actually, the best solution is trying for both good mid-range and top end power. Starting with a stock bike, you can enjoy the fruits of increasing both up to a certain level of performance. But at some point, you have to trade off some of one for more of the other. Depends a lot on where you race too. It's really great to be able to drive past your competitors coming out of a corner by virtue of a wide powerband, but does you no good if they fly past you on the next long straight with top end power. I think Alan's exclusive emphasis on mid-range torque is fed by lots of racing on tight, twisty circuits. In vintage racing in the US, the situation is quite different. We have our share of those sorts of tracks, but also very high speed tracks like Daytona. My local track, Willow Springs Raceway, has a couple of short, twisty circuits, where a broad power band is really useful. Unfortunately, we don't get to race on them with AHRMA, just with the modern bikes in local club races. The long track there is what we use for vintage races, and it rewards top end power, as do several other of the tracks we race at. My experience is that for the fast tracks more top end horsepower (at the expense of a narrower power band) will make for faster lap times, as long as you don't get carried away and build something that makes giant high rpm power, but has such a narrow power band that it's not really rideable on the track. Ask Jim Comstock about that some time :lol:

If you look at the factory Norton racers, you will notice that they are almost exclusively twin pipe systems. The only 2-into-1 that I've seen is the Commando 750 Formula Racer kit exhaust that was available for a while. I have some of the data from the other race exhaust systems the factory developed, and they are all twin pipe systems. There's probably a reason for that. I know they experimented with 2-into-1 systems, but I don't have the data from that. If they could have been faster with a 2-into-1 pipe, they would have used it.

In any case, I agree that something like Mike's system should be really good for a street bike, especially if used with some head work, a bit more compression ratio, and a little more cam. I'm probably sticking with the peashooters and stock style pipes for my current build, but only because I just like the look. I must be getting old! Maximum top end horsepower is no longer the holy grail for me (except at Bonneville).

Ken