Brooking850 2:1 fitting

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The noise testing probably doesn't mean much anyway. Most sound meters don't measure impulse noise very well and some of that is what is emitted by two strokes.
 
acotrel said:
The noise testing probably doesn't mean much anyway. Most sound meters don't measure impulse noise very well and some of that is what is emitted by two strokes.
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Noise testing means A LOT when you're the guy trying to get your bike passed by the tester before being allowed to race!

Difficult to win races if yer bikes stuck in the paddock !!
 
I have the same ideas about the dyno being used for setting up a data base as well, might as well use all the tools in the shed!!!
Regards Mike
 
Fast Eddie said:
acotrel said:
The noise testing probably doesn't mean much anyway. Most sound meters don't measure impulse noise very well and some of that is what is emitted by two strokes.
Click to expand...

Noise testing means A LOT when you're the guy trying to get your bike passed by the tester before being allowed to race!

Difficult to win races if yer bikes stuck in the paddock !!
Click to expand...

Yes this is the irony, passing a noise test is critical to your race weekend, but the noise test itself doesn't mean much other than a figure recorded in the given conditions by the given equipment.

Savvy entrants can 'improve' their test results, clumsy ones can degrade theirs. Tests conducted in ideal conditions can only give an indication of the merits of one solution versus another. Any testing of the system designef for a machine type is only an indication of potential subject to many variables: fitting the Maney style system to machines varying in bore, stroke and valve timing will give varying results in both noise and power delivery.

Most of us are focussed on power delivery and accept the noise levels we get, testers don't: you gambling when you arrive for the test. To improve your chances you over do the muffling! and as a fall back may have a 'db killer' in your back pocket. There is even then no guarantee that the atmospherics and test site on the day won't lead to a fail.

Then you are reliant on the tester on the day who may notice a general offset from typical results and apply an adjustment.

By preference, warm the whole machine thouroughly, make sure you are between the tester and the inlets/other noises to reduce the contribution of these, and only make small throttle changes until the required engine speed is achieved....and don't forget to smile nicely and be polite!
 
My Roadster with peashooters (no baffles) is noisier than my race bike with the 2 into 1 and I still get a WOF for it(MOT)
Im going to test both and post results
Regards Mike
 
I haven't raced at a meeting yet, were there was a noise meter, because the last couple were two plus four - cars plus bikes. However if I ever go to Broadford, I would expect trouble. The cam timing I use with the 2 into 1 gives excellent torque, but it is LOUD ! The thing about this is that nobody can see VALUE in our nostalgia trip, the noise was always an integral part of motor sport in the old days. What we are doing now is RETRO - RACING. What sort of idiot would ever fit a muffler to a 500cc Manx Norton ? Next they will be fitting mufflers to Spitfires and Lancaster bombers at air shows.
 
Back in the old days, the only twin cylinder bikes with siamesed pipes were Triumph Trophies and the Matchless 650CSR - neither had much top end performance. Amongst road racers, siamesed pipes did not become common until we made after-market exhausts for Japanese super bikes - a bit later than when Peter Williams was doing his thing. My Seeley 850 is eligible for historic racing, but in the strictest sense the 2 into 1 exhaust system gives the lie to that. The bike is not what it would have been in the era. When I raced my 500cc Triton in the early 70s, it was the only twin which had a 2 into 1 pipe.
I agree with the comment about top end power for large circuits. In effect I would never take my Seeley anywhere near a large circuit because I would have to change it too much. With my Triton, I could choose where I would lose a race. It badly needed a 6 speed box and a disc brake. It was all top end and it would go faster forever on a big circuit. It is unbelievable how fast a 500cc bike can go when it is set up to produce all top end power. My friend originally built that bike in the mid 1950s and rode it at Bathurst. At the end of Conrod Straight, it was going far too fast to stop, so he had to choose between the escape road and attempting to go around the corner. One choice was as bad as the other, so he chose to go around - and succeeded, but crashed at the top of the mountain and broke an arm and a leg. What can you do with a bike which, whenever it comes on song, it goes sideways ? - 4 inch megaphones on separate pipes - try it with your Commando.
 
'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.'

All you have to do to stop a 2 into 1 pipe from working properly is make the tail-pipe too small in diameter. It is not obvious.
 
Alan and your point is?

On a performance motor, the results show a gain of torque throughout the rev range when swapping to a 2EX1 system from 2 x single pipes with hollow peashooters.
Due to the type of racing we do here in NZ, there is no need for extended long periods of wide open throttle in top gear, it is only a matter of seconds on the longest straights.
Torque is the master in this case.
Not sure why you keep comparing Triumphs in these instance, I would rather hear about your achievements with your Seely Norton.
Regards Mike
 
SteveA said:
Yes this is the irony, passing a noise test is critical to your race weekend, but the noise test itself doesn't mean much other than a figure recorded in the given conditions by the given equipment.

Savvy entrants can 'improve' their test results, clumsy ones can degrade theirs. Tests conducted in ideal conditions can only give an indication of the merits of one solution versus another. Any testing of the system designef for a machine type is only an indication of potential subject to many variables: fitting the Maney style system to machines varying in bore, stroke and valve timing will give varying results in both noise and power delivery.

Most of us are focussed on power delivery and accept the noise levels we get, testers don't: you gambling when you arrive for the test. To improve your chances you over do the muffling! and as a fall back may have a 'db killer' in your back pocket. There is even then no guarantee that the atmospherics and test site on the day won't lead to a fail.

Then you are reliant on the tester on the day who may notice a general offset from typical results and apply an adjustment.

By preference, warm the whole machine thouroughly, make sure you are between the tester and the inlets/other noises to reduce the contribution of these, and only make small throttle changes until the required engine speed is achieved....and don't forget to smile nicely and be polite!
Click to expand...

And do not blip the throttle too agressively in case the wire wool gets blown out !
 
Alan, as has been discussed before at length. Mikes pipe is a copy of the Steve Maney system, which must be the most widely used race system on Norton twins today. The basic Maney design was alos the basis of the NRP system (which I understand has subsequently been modified).

It’s a race system, and with a race type cam, gives big benefits. My own tests showed 5bhp peak gain and even more in the mid range.

When I tested it back to back against peashooters, the dyno mans words were “whoever designed that 2:1 certainly knew their stuff”.

However, my own experiments seeemd to suggest much less gain with softer cam (less duration).

Perhaps I should copy paste this reply in readiness for the (inevitable) next time you post this question?
 
acotrel said:
.......My Seeley 850 is eligible for historic racing, but in the strictest sense the 2 into 1 exhaust system gives the lie to that. The bike is not what it would have been in the era......
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Frankly that is tosh Alan. Back in the '70s when I ran my Rickman in it's first incarnation I ran separate pipes based on works dimensions. It was faster than I was and faster than pretty much any other twin.....but

Of the other Nortons racing I would recall about 50/50 2 into 1 to separate pipes, there were plenty of 2 into 1 designs about and they were a popular choice on Seeley framed bikes. Indeed I experimented with both over time. Separate pipes worked on my motor, which had a lot of ex-works parts in it! 2 into 1 didn't, but even then I judged the collector implementation to be restrictive. Pipe work is generally executed to a better standard these days. I agree with one point, Thruxton, who had unlimited dyno access, used separate pipes, they did know something, including everything there was to know about their aims and the total spec of the motor. Who is to say that to some degree exhaust choice did not drive other choices?

My reading is that Steve Maney's design is better than the 2 into 1s around in the '70s, he was successful with it, others have been successful with it as well and like a lot of race parts, it became a 'fashion accessory'. Not many people who have invested £1000 in a 2 in to 1 system have back to back tested their motors with an 'equivalent' separate pipe system.

I don't knock the Maney design (or Brooking execution of it) because I know it works.

In software rather than on a dyno, the system on my bike has been modelled and compared with the Maney design, they are comparable but the indications are that each has an edge at different rpms.

However the Maney system without additional silencing tends to fail noise!
 
The only reason I use a 2 into 1 pipe as opposed to separate pipes with megaphones, is you don't get that boot when the pipe comes on song. With separate pipes, if you are halfway around a corner and lose revs, megaphones can cause the motor to drop off the pipes. Then you have a choice - you can slip the clutch to bring the motor back on song or you can ride the situation out and just allow the motor to do it's thing. Either way you get a kick in the pants which can crash you if you are on the limit. With the 2 into 1 pipe, traction is smooth and strong from the bottom to the top of the rev range. It probably doesn't matter too much on a power circuit but even Daytona apparently has some slower corners in the infield. You don't win races by ending up on the ground. Even with the best tyres, if you are going fast enough being smooth is essential.
 
In Australia, noise testing is supposed to be done from the side of the track as the bikes pass during testing. Using a sound meter to get accurate and repeatable results is not an easy process. I doubt that noise testing is appropriate for something which is essentially a nostalgia kick anyway. I would have thought the UK laws would have waivered the requirement at historic events. Their whole approach to tourism seems to be creation of a sense of history.
 
Brooking 850 said:
Alan and your point is?

On a performance motor, the results show a gain of torque throughout the rev range when swapping to a 2EX1 system from 2 x single pipes with hollow peashooters.
Due to the type of racing we do here in NZ, there is no need for extended long periods of wide open throttle in top gear, it is only a matter of seconds on the longest straights.
Torque is the master in this case.
Not sure why you keep comparing Triumphs in these instance, I would rather hear about your achievements with your Seely Norton.
Regards Mike
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In Australia, in the early 70s very few Norton twins were ever raced - most over-500cc bikes were Triumphs or Tritons and in 1973 Z1 Kawasakis were king.
Everything is relative - a Commando-based bike is not a modern bike. It can only be rationally compared with what was being raced when Commandos were being produced. I was racing back then and I know the comparisons. An H2 Kawasaki two-stroke with chambers is usually slightly slower than a Z1 Kawasaki on most race circuits. It takes an extremely fast Triumph 650 to beat either one, even using nitro.
I don't usually make promises, but I will make you one. A bit later this year, I should be able to get my bike back onto Winton. I will do some on-board video, so you can see what I have been talking about.
 
Just a thought , had anyone expereince of using silencers other than peashooters on 2 into 2 systems?
 
Brooking 850 said:
Alan, will keep you to that
Regards Mike
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I have had doing on-board video in mind for quite a while now. I've got two cameras, all I need are the funds and the opportunity. The weather has cooled off and with luck, might stay that way for a while. My only real problem is that over the last year, I have become a doddering old fool, so I need to get my head straight again. I'm pretty sure that I can still ride OK, but it is just the effort of getting everything together which is difficult for me. My main helper died in a car crash a while back - died at the wheel and veered into the oncoming traffic.
 
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