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Old 07-30-2013, 08:42 PM   #91
trustme OP
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Rings arrived Work is going ballistic

I'll find time somehow
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Old 09-07-2013, 04:15 PM   #92
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Apologies , I'm away 6 nights a week so get very little time to work on Winston or talk shite on the interweb
There has been progress , the motor is back together & back in the frame. The wife picked Winston up from the exhaust man on Sat arvo . Here's a few pics , I will paint the new 1 3/4 " headers while I am away this week. There is a testing day at Taupo on Oct 10 should be achievable. 1 good day will have it finished .
I'm toying with the idea of narrower bars with less rise, common sense says 'yes', common sense is so boring.



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Old 09-07-2013, 05:22 PM   #93
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pipes look awesome - Griso like
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Old 09-07-2013, 09:55 PM   #94
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They look beautiful. How are they connected to the head???

Must have been an old triumph owners club run to Golden bay this weekend. There were a few being trailered & vanned back. They don't like the Huns do they not many waved back
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Old 09-07-2013, 10:58 PM   #95
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Fat pipes? Triumph reduced the dia of the pipes in the mid '60's for a reason....
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Old 09-08-2013, 12:46 AM   #96
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Fat pipes? Triumph reduced the dia of the pipes in the mid '60's for a reason....

Cheaper?
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Old 09-08-2013, 04:08 AM   #97
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Fat pipes give slow gas speed, they reduced the pipe dia to speed up gas flow - you can see the step down from the clamp to the pipe on say a '69 Triumph. Bikes from the '50's had the fat 1 3/4 headers.

Fat pre unit.



Reduced dia pipe on '69.

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Old 09-08-2013, 12:21 PM   #98
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Fat pipes give slow gas speed, they reduced the pipe dia to speed up gas flow - you can see the step down from the clamp to the pipe on say a '69 Triumph. Bikes from the '50's had the fat 1 3/4 headers.
Motu, they did that on BMWs as well. My RS has 40mm pipes. The stock GS has 38mm stepped down to 36mm. It's partially to improve bottom end responce. Racer compared to Tractor.

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Old 09-08-2013, 02:28 PM   #99
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Faster gas speed? My understanding is flow speed is an irelevant factor
Back pressure is used to change the engine performance matrix.
Pressure is not caused by speed of flow, it is caused by restriction of flow Thus smaller dia pipes
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Old 09-08-2013, 06:09 PM   #100
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Pressure is not caused by speed of flow, it is caused by restriction of flow Thus smaller dia pipes
Dunno about that one. Mechanics of compressible fluids is a bit over my head but I do remember that with incompressible fluids in pipes pressure drop rises in proportion to the square of the velocity.

...plus, big pipes look phat

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Old 09-08-2013, 07:15 PM   #101
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Bigger pipes mean the oil can get out quicker than normal.

I've been looking at making a 2 into 1 for the BMW, research that I don't understand has the 38mm headers stepping up immediately to 41mm then a collector at 26" . No balance pipe and a 'muffler' starting at 50mm.
Place here sells the bits.http://www.chase.co.nz/
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Old 09-08-2013, 11:28 PM   #102
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My understanding of it is all about pressure waves.

Where a pipe ends or enters a muffler the exhaust gases make a pressure wave that travels back up the pipe which will hopefully bounce off the exhaust valve just before it is closing on the overlap which will then go back down the pipe causing a suction through the exhaust valve making a vacuum in the combustion chamber which will suck the fuel air mix out of the inlet port when the inlet valve opens. It is a slight supercharging effect that only works at a certain rpm and is tuned using amongst other things the exhaust header length.

Or summit like that.
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Old 09-08-2013, 11:56 PM   #103
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Quote:
Originally Posted by innathyzit View Post
My understanding of it is all about pressure waves.

Where a pipe ends or enters a muffler the exhaust gases make a pressure wave that travels back up the pipe which will hopefully bounce off the exhaust valve just before it is closing on the overlap which will then go back down the pipe causing a suction through the exhaust valve making a vacuum in the combustion chamber which will suck the fuel air mix out of the inlet port when the inlet valve opens. It is a slight supercharging effect that only works at a certain rpm and is tuned using amongst other things the exhaust header length.

Or summit like that.
I see, I see, so the gas wave pressures the valves into sucking the vacuum chamber to supercharge the header pipes and allow the fuel to mix with the inlet port....pretty obvious when ya think about it
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Old 09-09-2013, 12:23 AM   #104
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Originally Posted by Micawberism View Post
Faster gas speed? My understanding is flow speed is an irelevant factor
Back pressure is used to change the engine performance matrix.
Pipe length is used to tune resonance, pipe dia for gas speed, around 300 ft/sec at max rpm. When people talk about back pressure they are really talking about gas speed - not enough back pressure, slow gas speed, too much back pressure high gas speeds. To increase gas speed you need to restrict the pipe (carb venturi, fluid dynamics etc), to slow it down, open the system up. That's what a Supertrapp does, fine tunes gas speed.
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Old 09-09-2013, 12:34 AM   #105
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Pipe length is used to tune resonance, pipe dia for gas speed, around 300 ft/sec at max rpm. When people talk about back pressure they are really talking about gas speed - not enough back pressure, slow gas speed, too much back pressure high gas speeds. To increase gas speed you need to restrict the pipe (carb venturi, fluid dynamics etc), to slow it down, open the system up. That's what a Supertrapp does, fine tunes gas speed.
Yep bet me to it.
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