Cutting Stock Exhaust

[Paul75]

Hi guys

Please see image, where do I need to cut this to enable me to take off the stock mufflers, I want to keep and reuse the headers. I understand there are inner pipes that I need to keep somehow,

Any advice appreciated

Paul

 

[Growl]

There is an inner pipe which is the header and the length is tuned. If you cut this you lose low end and mid range punch. If you manage to salvage the inner pipe it will be worth it.

 

[Growl]

I downloaded your photo and marked it up. The arrow is where people typically cut through the whole thing, both outer layer (muffler) and inner header pipe. The dashed lines show how the header acually extends into the muffler. Best if you can very carefully remove the outer layer without harming the header... use a grinder perhaps. Then have someone weld a bead to fill between the layers right where the arrow points. I also marked area "A" which where you can clamp on a muffler. It's A-okay for the protruding header to extend into your new muffler... recycled older (pre catalytic converter) harley mufflers work well, but the after market has a lot of choices too.

 

[Paul75]

Brilliant appreciate it! What is the hole in downpipe? I just noticed it in the image!

 

[nj1639]

On Growls pic.......I cut about 3/8's" after the frame mounting tab, where the "A" designation line begins, and then use adapters per PamcoPete's muffler mod. I guess it all depends on what type of silencers you're going to use.
Other opinions may vary.
I'll add that the hole is for dissipation of condensation. There's another one up by the clamp that secures the header to the head.

 

[Paul75]

Eggcellent Cheers guys....grinder at the ready!

 

[Paul75]

Guys I just need a bit more Info please as it was 6 months since I cut the exhaust. Now what I plan on doing is having a pipe made to cover over the 2 holes on the bottom of the headers....but, what are the holes for? Does it matter if I clamp a new pipe over these? I'm keeping the long inner pipe as remember reading cutting it off messes with the running.

I've got myself a pair of stainless scrambler style exhausts to play with which I'm planning on tilting upwards.....see drawing....

 

[Paul Sutton]

PamcoPete modification:

http://www.xs650.com/threads/after-market-exhaust.276/

See Entry 19. Photos and Sketch provided - Thank you PamcoPete.

 

[Paul75]

Cheers Paul.....If the holes are drain holes for condensation (I'm guessing), then why are they at 90 degrees....surely they should be facing downwards?

 

[5twins]

I'm not sure what those holes are for. The vent hole is farther forward, as shown in the pic a couple posts up. If those were vent holes, they shouldn't go through both pipes like they do, only the outer one. I assume they were covered by the stock pipe you removed (cut off)? I think you can just plug or cover them with the new muffler. I would, I wouldn't leave them open. But then, I wouldn't run stock headpipes either. Their diameter is too small and they hinder performance.

 

[Paul75]

Cheers 5T. I'll cover the holes up. Why did Yamaha run an inner pipe in the first place I wonder?

 

[Paul Sutton]

The following link has some nice discussion about cross-over/H exhaust pipes:

http://www.xs650.com/threads/exaust-h-pipe.499/#post-5776

 

[5twins]

The air space between the 2 pipes keeps the outer one cooler so it doesn't turn blue.

 

[Paul Sutton]

There is poor contact between the two pipes as is the case with heat sinks when a thermal paste is not used. Where they do contact each other they make point contacts and between them are very fine air gaps. This means the heat transfer is not as good compared to a solid pipe of the same total thickness. Lower heat transfer means the outside surface does not get as hot and the chrome does not turn blue as mentioned above.

I have seen pipes on bikes turn blue and thought it was very attractive. The one I remember best was a Norton Commando 850 in metallic blue, but I guess there may be a downside to it????

 

[fredintoon]

There is poor contact between the two pipes as is the case with heat sinks when a thermal paste is not used. Where they do contact each other they make point contacts and between them are very fine air gaps. This means the heat transfer is not as good compared to a solid pipe of the same total thickness. Lower heat transfer means the outside surface does not get as hot and the chrome does not turn blue as mentioned above.
I have seen pipes on bikes turn blue and thought it was very attractive. The one I remember best was a Norton Commando 850 in metallic blue, but I guess there may be a downside to it????

Hi Paul,
like they posted, the inner pipe is the actual exhaust pipe and that's the pipe your new mufflers need to connect to.
The outer pipe is there to look pretty because the airgap don't let the outer pipe get hot enough to turn blue.
The holes in the outer pipe are to let out any condensation that might collect between the inner and outer pipes as the engine cools down.
The bluing on single wall chromed exhausts not only looks nice but it can also work as a tuning aid.
Purple just at the head, fading to blue around the first bend fading through dark then light straw colour half way down the first leg
shows perfect carburation.
The downside is you have to polish the pipe clean again at every jet change, Solvol Autosol ain't cheap and chrome plate is very thin.

 

[Paul75]

I'm not a fan of chrome so I sanded it off and it came out really nicely, its now almost a brushed satin, it matches the stainless scrambler pipes I have and I think will look much nicer than using exhaust wrap. I`ll keep an eye on them for any signs of corrosion but at the moment I've just applied a thin coat of WD40 to them.....

 

[Paul75]

Just an update to this thread, the exhaust is now finished. I sanded all the chrome off the original headers then produced a brushed steel effect, I did this with the link pipe too and it all matches the stainless end pipes.....

 

[Paul75]

 

[Paul Sutton]

Wow its come a long way - Looking very Smart. The lettering is very well done on the alternator cover.

Did you notice in the picture that Benson and Hedges is in reverse on the points cover and the NGK is also backwards??? About a year ago someone was looking for plug caps with NGK in reverse. Where did you get them?

 

[Paul75]

The caps came from Wemoto Paul, if the cap was pointing to the right is would not be upside down....