Flappy Valve - replacement link pipe

Done about 1000 miles since I fitted mine.... Lots smoother! But noisier!
My flappy valve was only moving through a few degrees: from closed to nearly closed!
Also, I seem to be getting a few more mpg. I guess it was running badly with the valve semi-closed all the time. I'd just got used to it!



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Get a pair of custom moulded earplugs and all will be well. I only got a pair a couple of months ago after threatening to get them for years.
Much more comfortable than foam plugs and the bike has never sounded better!
 
I like the Moldex Rockets ear plugs. They are not as all blocking as their "Spark Plugs" but more than enough on the bike. Dirt cheap on eBay and easy to clean with alcohol.
 
Just playing around with the design of the thru pipe, increasing the bore size slightly in order to lighten it and improve gas flow perhaps take some weight out of the collar and also change the design enough so as not to incur the wrath of the Motorworks wallahs.

Didn't really have plans to sell them, was just gonna be an exercise In penny pinching 😁
 
How about machining some dimples around the centre flange. So it looks like a perforated ring wrapped around the pipe. Or even use a next size up pipe with holes drilled through for the same effect. :)
 
Test piece manufactured but the donor billet is narrower overall by 15mm. Have maintained the collar width as per the original but the two diameters either side of it have been reduced in length to 15mm each. Is that enough to clear the clamp slots and would the clamps themselves still seal the slots?
I've not yet stripped my valve out to test.....

Rob.

 
Can increase the width of the clamped diameters by stealing some of the collar width, providing ofc that the width of the collar isn't critical. Doing so would reduce the width of the collar from 21mm down to just 7mm. Hopefully there'd be enough 'give' in the exhaust pipes to accommodate the reduction.
 
Actually looking at mine, the width of the flange does move the position of the connected pipe to the correct position, so it does need to be that wide I am afraid.
 
How about getting some stainless exhaust tube the correct outside dia to go inside the original pipes. Then cut a ring of the next size up to slip over the tube to use as a spacer. You could drill it to give a (deliberately) perforated look.
 
Just playing around with the design of the thru pipe, increasing the bore size slightly in order to lighten it and improve gas flow perhaps take some weight out of the collar and also change the design enough so as not to incur the wrath of the Motorworks wallahs.

Didn't really have plans to sell them, was just gonna be an exercise In penny pinching 😁
The finished item looks good, but why not make it the same length as standard? I think you will need to, so as to have everything line up, and it seal reasonably well.
Keep the internal bore size the same as the pipes joining to it: going bigger will not improve airflow; it will slow it down at that point and possibly interfere with any useful pressure pulses.

Wish I still had access to machine tools :-\

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Get a pair of custom moulded earplugs and all will be well. I only got a pair a couple of months ago after threatening to get them for years.
Much more comfortable than foam plugs and the bike has never sounded better!
Which custom plugs would you recommend?
I got some years ago but didn't get on with them. Can't remember the make. I found them to become uncomfortable on longer rides / multi-day trips, and didn't think they attenuated much noise either!
I've been using Lazer Lite disposables: fairly comfortable and really good attenuation.... but keep thinking I might try custom again.
Cheers

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The finished item looks good, but why not make it the same length as standard? I think you will need to, so as to have everything line up, and it seal reasonably well.
Keep the internal bore size the same as the pipes joining to it: going bigger will not improve airflow; it will slow it down at that point and possibly interfere with any useful pressure pulses.

Wish I still had access to machine tools :-\

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The stainless pieces I'm using are from trepanned offcuts of bearings that the company I work for manufacture. The material starts off life as 220mm solid stainless 440c, making them the correct length would render them incredibly expensive.
I do have the option of making them to the correct length using EN31 or ST52 steel but alas neither are rust resistant...

Pics to illustrate:-







 
Wonder if the silencer mounting bracket could be elongated; then move the silencer forward/down slightly, so as not to need the saddled section. Should be long enough to get a good seal, and be easier to make.
Envious of your skills with the machines.

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The spacer looks a really nice job but i just can't for the life of me see why it is necessary.
working on the KISS principle I just left the valve in place (stuck wide open) removing all the cables etc. and sticking them in a drawer.
 
Which custom plugs would you recommend?
I got some years ago but didn't get on with them. Can't remember the make. I found them to become uncomfortable on longer rides / multi-day trips, and didn't think they attenuated much noise either!
I've been using Lazer Lite disposables: fairly comfortable and really good attenuation.... but keep thinking I might try custom again.
Cheers

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I got mine from Specsavers - made by Minerva Hearing.

Took a few times of use to get used to them, but now brilliant.

They're now stopping me hearing the snoring of a Brit on sunbed.
 
I think a simple piece of exhaust pipe tube is more than good enough. If you want the rib around the middle then another piece next size up will fir the space between the pipe ends.

The pipe runs diagonally across the bike so you can't simply butt the pipe ends closer. The silencer would need to move forwards and inwards.

Why use a tube? Because you can drop the old valve into a jar of diesel fuel and leave it for a week or two (store it with the motor and control cables).
The valve bearings will free up, so one day you can put it back on the bike and have the bike running as standard for next to no cost.
 


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