Fast Eddie
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How can it rotate if it’s clamped tight ??
JS exhaust port fillers
- Thread starter Carl H
- Start date
I know when I did mine, I cleaned the head surface and used Grey silicone. I can see how they might move when tightening. So If I was to do the job again. I would take an extra day to do it.
I would use the Rose nut to clamp the port filler down with out the Exhaust pipe installed , that way you could see the location and angle to align it didn't move. Then after allowing the silicone to cure 24 Hrs. Install the pipe and finish up..
I guess that would be too much drama for some, But, being a very skilled race bike mechanic, it is much more important to do it right than to worry about how long it took. My riders deserved the best and not everyone gets into Victory Circle like we did.
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If the exhaust nuts are tight its not possible for them to rotate. And the tip of the floor is pushed down on the port so it will not lift. Just slide the pipe straight in and tighten the nut.
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O.K. , now I understand better . Thanks .
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The same way any exhaust system can develop a leak. When the pipes move the tend to loosen and wear the threads in the head. On my bike, the exhaust system is 2 into 1,and the bits that fit into the head are stubs, sleeves and springs. But it can still loosen . If the inserts mange to rotate, the bike would probably go backwards very quickly. However I am still going to try them - on my motor with that exhaust system, I think they might be superb. It really cops a big blast with the valve timing I use.
Everything I have done to my bike has not really been about racing. Racing is just my way of testing it.
I never thought the 850 motor could work properly in a race bike. To my mind, my set-up is a very strange combination. Sensibly, any sports bike with an 850cc four stroke motor should perform as well as any other which is somewhat similar, regardless of the number of cylinders.
If you ever install them , then you might understand the issues fully. They don't move when they are fully tightened, they can move while your tightening.
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It was the " while you are tightening " part that had me concerned .
MK 111 running well , using the flared end pipe with the MK 111 spherical collets system , smothered in high temp copper silicone , including threads .. Can't much say I notice any real difference . But I'm a road rider , no racing .
Carl, many thanks. Christmas is a’comin’ !
Well, that is why you need to be concerned. Just the large change of idle speed blew my mind.
Jim, what happens when the exhaust rose nuts shake loose, which they often do on a Commando? It seems to me that your method of fixing the inserts relies too much on "good fortunes".
- Knut
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You simply have to pay attention to your exhaust nuts. Its a big deal if they shake loose and destroy the threads and it can happen to anyone - at that point the ex shoe is the least of your worries. I try to pay attention and even so one came loose on me but I caught it just in time. I was able to save it by expanding the nut a few thou to tighten up the threads. My solution was to use springs to hold in the pipes, sleeve the nuts and cinch them down semi-permanently with silicone and now they don't seem to loosen since the pipe is no longer vibrating against the nut (the nut stays tight). I still check the nuts just to be sure.
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If the insert is rotated, how is the performance affected?
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I have been running these daily for the last few months. Varied conditions long road rides, and commuting. If your exhaust nuts are tight they will not rotate.
Additionally say hypothetically your exhaust nuts fell off and they they were to loosen or rotate there is a very limited range which they can rotate due to the port shape.
I have done multiple checks on these to make sure that my exhaust nuts are not loosening, and I have yet to run into an instance where I have found them to be backed off. I was checking once a week or so, and I stopped checking a couple months ago now. A check just now show they are still tight.
That all said the tip should have some slight pressure into the floor when installed. That should act as a slight spring washer on exhaust nuts which should help to keep them in place.
I have these running on BSA twins, Nortons, BSA singles, and soon Triumphs. If your exhaust nuts are walking out, I would probably fix that before trying these.
I line up the floor to be centered on the valve, In theory they would be less efficient at removing exhaust as the tip would lift from the floor.
Additionally say hypothetically your exhaust nuts fell off and they they were to loosen or rotate there is a very limited range which they can rotate due to the port shape.
I have done multiple checks on these to make sure that my exhaust nuts are not loosening, and I have yet to run into an instance where I have found them to be backed off. I was checking once a week or so, and I stopped checking a couple months ago now. A check just now show they are still tight.
That all said the tip should have some slight pressure into the floor when installed. That should act as a slight spring washer on exhaust nuts which should help to keep them in place.
I have these running on BSA twins, Nortons, BSA singles, and soon Triumphs. If your exhaust nuts are walking out, I would probably fix that before trying these.
I line up the floor to be centered on the valve, In theory they would be less efficient at removing exhaust as the tip would lift from the floor.
"That all said the tip should have some slight pressure into the floor when installed. That should act as a slight spring washer on exhaust nuts which should help to keep them in place."
But that is what bothered me, the Port filler insert kept falling out at the top, it seemed like the "pressure" you mention, pushed the top out and the exh. filler moved and didn't keep the slight "angle" I wanted.
But that is what bothered me, the Port filler insert kept falling out at the top, it seemed like the "pressure" you mention, pushed the top out and the exh. filler moved and didn't keep the slight "angle" I wanted.
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I have a 750 head in front of me right now when I push these into place and press them into place they hold tight enough for me to pick the head up and turn it upside down without the exhaust washer falling out and it does not rotate easily. I get the same results with the three 850 heads I have prototyped these with. You might want to try some 3M Super 77 or Hylomar EAP5. Super 77 will burn off in 20 seconds and EAP5 is exhaust assembly paste and may last longer, not sure that matters.
When installing them I push them into place where the bottom of the washer should not be touching the threads and the spring tension of the floor should be pushing the washer part it into the top of the threads.There should be a slight gap on the sealing surface which will then apply additional spring pressure against the exhaust nut, which also helps to hold the nut into place. I hold tension against the exhaust pipe with tightening the nut, when you press against the exhaust pipe while tightening the nut the spring tension should not allow it to rotate.
When installing them I push them into place where the bottom of the washer should not be touching the threads and the spring tension of the floor should be pushing the washer part it into the top of the threads.There should be a slight gap on the sealing surface which will then apply additional spring pressure against the exhaust nut, which also helps to hold the nut into place. I hold tension against the exhaust pipe with tightening the nut, when you press against the exhaust pipe while tightening the nut the spring tension should not allow it to rotate.
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Jim,
I have just had a look at the inserts on your website, and read how you suggest they work. It is not how I would describe it, but I know what you mean. It is easier to think in terms of gas flow than sound waves. I notice you do Pay Pal, so I will be in touch.
With my bike I thought I had developed the motor as far as was sensible - so I have not ridden it for a long time now. Your inserts have renewed my interest. When I started with the 850 motor, I was not a believer. I am surprised it can be so good. What I raced against last time was not slow stuff.
I have just had a look at the inserts on your website, and read how you suggest they work. It is not how I would describe it, but I know what you mean. It is easier to think in terms of gas flow than sound waves. I notice you do Pay Pal, so I will be in touch.
With my bike I thought I had developed the motor as far as was sensible - so I have not ridden it for a long time now. Your inserts have renewed my interest. When I started with the 850 motor, I was not a believer. I am surprised it can be so good. What I raced against last time was not slow stuff.
Raised exhaust D port floor shoes (2) for increasing flow and performance for all 650s, 750s & 850s
This shape is taken from the world famous Harley XR 750 flat tracker. The exhaust port floor is raised for increased velocity and flow in exacuating spent gasses and allowing for a fuller intake…
jsmotorsport.com
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Out driving today in lovely 12 C. later November sun , small pops on the right side . Pulling in home , the entire pipe cracked off in the Exh. port , at the flare . Took it all off to see the J.S. floor shoe was still in perfect position . More money but end of season anyways .
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I have thought about this stuff a bit. I doubt the inserts would rotate out of the gas stream. It is probably worth the risk. There is probably a way to pin the inserts, so they cannot rotate. however they are such a good idea, that I need to try them. I had pretty much lost interest in developing the Seeley 850 further. I thought it was as good as it could ever be. A thing such as the inserts might give it a substantial boost. With me, road-racing was only really ever about developing the bike. When I started, I believed I was really behind the 8-ball with that motor. I tried to get the bike when it had the Laverda 750SF motor - it appeared to have a lot of potential. The 850 Commando motor did not thrill me much, but it has turned out to be excellent without much modification.
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As I said in an earlier post, the inlet and exhaust tract resonate across the top of the piston at TDC, at a frequency which depends on the revs which the motor is doing. Organs don't push air into pipes which don't have a taper at their beginning. It might have something to with the strength of the note produced - its sharpness and pressure.
Does the motor sound different with the devices fitted - sharper ? If you are looking for a difference, you might not notice it if it appears,
I think these things are a brilliant idea.
Does the motor sound different with the devices fitted - sharper ? If you are looking for a difference, you might not notice it if it appears,
I think these things are a brilliant idea.
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Drove mine today . Did not seem to be a sharper exhaust note ( 750 pipes into 750 mufflers ) , but seemed a bit stronger . No way to tell . Good solid idle .
