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Discussion Starter · #1 ·
I have fitted a aftermarket Gen 3 exhaust on my gen one but have started to wonder if the Pipe after the collector might be too small.
It is a lot smaller the a standard gen1.
Has anyone experimented with a larger secondary pipe for power.
58415
 

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Larger pipes usually improve power at the highest RPM, conversely smaller is better for low to mid RPM power. Based on the color of your front pipe near the cylinder is it possible that it's running lean? The closer to purple the pipe gets the hotter it is and hotter it is is generally a sign of lean conditions. Possible to be very rich with the final burn of fuel coming in the exhaust.
 

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Discussion Starter · #3 ·
Larger pipes usually improve power at the highest RPM, conversely smaller is better for low to mid RPM power. Based on the color of your front pipe near the cylinder is it possible that it's running lean? The closer to purple the pipe gets the hotter it is and hotter it is is generally a sign of lean conditions. Possible to be very rich with the final burn of fuel coming in the exhaust.
At the time the picture was taken it was filthy rich. good eye.
Just wondering if slightly larger than stock might be be better, the system I have uses .9mm think pipes, OD is stock and steps down a fraction so the stock gen3 link/muffler slips straight on.
I am thinking of cutting off the step down, because I think it is must be hurting flow.
 

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A larger pipe may help top end power at the expense of low-mid range power. Twins & singles often benefit with a power chamber, lots of FMF Power bombs out there, the purpose is to help scavenge exhaust gases from the cylinder, with a multi the firing of additional cylinders does the job. S&S is making a pipe for the Royal Enfields with a power chamber for each cylinder. That looks like a Black Widow pipe, didn't realize there was a reduction in pipe size, thought it was the same from the cylinder. I'm no expert on exhaust design but looking for top end power generally has large diameter pipes. Try it, if it doesn't work change it back.
 

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Discussion Starter · #5 ·
A larger pipe may help top end power at the expense of low-mid range power. Twins & singles often benefit with a power chamber, lots of FMF Power bombs out there, the purpose is to help scavenge exhaust gases from the cylinder, with a multi the firing of additional cylinders does the job. S&S is making a pipe for the Royal Enfields with a power chamber for each cylinder. That looks like a Black Widow pipe, didn't realize there was a reduction in pipe size, thought it was the same from the cylinder. I'm no expert on exhaust design but looking for top end power generally has large diameter pipes. Try it, if it doesn't work change it back.
Yes its a Black Widow.
I suspect the OD is stock and ID is a touch larger because it's only thin pipe but to joint to the stock gen3 muffler it steps in just a bit to allow for the thicker oem pipe.
I think I will cut off the step down and slip over the pipe.
I am sure it won't hurt, it may not help but I will feel better.
 

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Or you could do a dyno run on the bike and make an informed decision..
 

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Hey OP, what brand Decat did you get and how was the fitment process?

I reached out to Dominator (Poland) about their Gen 3 Decat and they said it won't fit the Gladius, no explanation provided.
 

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Discussion Starter · #9 ·
Hey OP, what brand Decat did you get and how was the fitment process?

I reached out to Dominator (Poland) about their Gen 3 Decat and they said it won't fit the Gladius, no explanation provided.
It is a Back Widow system blackwidowexhausts.co.uk I got mine through Ebay

It did take a little sorting to get on the gen1
I used the gen 1 exhaust stub on the rear cylinder. I would have liked to try the gen3 stub but I didn't won't to spend the money for some thing that may not work and things could work with what I already had.
It may bold on better or worst with the gen 3 stub?

I cut off the mounting bracket on the new system, I wanted to use gen1 frame mounting points.
So with the gen 1 stud, pushed it on as far as I could stopping about 5-6mm 1/4inch before the pipe stop.
The front pipe and the collector fitted and mated well with the head and each other, but the rear pipe needed trimming to fit about 15mm 9/16 inch on mine after the u bend, also requiring a short spring.
Once fitted it was too close to the kick stand so i fitted a couple of spacer washers on the stand. and it was just OK as it passed under the rear suspension.

I made some stainless brackets to weld on the new system sat them in place and with a perm marker marked the pipes and brackets for placement.
Removed the system.
Then paid a local welder to weld them on the very thin stainless The exhaust shop wouldn't do it.
And all good
if I were you I would look closely at the angle of the rear pipe and try imagine it on your bike with its clearance issues.
Rear shock, frame, swing arm (maybe you will need a different stub pipe) etc. that's want I did and then I decided I would I would make it fit.
And in my case I didn't have to do much, but it just depends how much you are willing to do.

Hope that Helps
 

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My dyno tuner said that the M4's make the best power so I got one of those for my Gen 3 and yes the diameter of the piping before it joins to the muffler is larger than the stock system.
 

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Discussion Starter · #11 ·
My dyno tuner said that the M4's make the best power so I got one of those for my Gen 3 and yes the diameter of the piping before it joins to the muffler is larger than the stock system.
Could you measure the OD for me please about 4 inches from the collector, That would be a good reference for me.
No rush and if it's inconvenient don't stress.
Thanks
 

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Could you measure the OD for me please about 4 inches from the collector, That would be a good reference for me.
No rush and if it's inconvenient don't stress.
Thanks
No worries, I'll do it at lunch time.
 

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There's no collector box on the M4 system but the OD of the pipe just before the flange where the muffler slots in is 55mm. The header pipes are 44-45mm OD.
 
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