Author Topic: Speaking of restricted exhaust  (Read 2134 times)

Offline Don G

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Speaking of restricted exhaust
« on: March 29, 2018, 08:55:27 AM »
I was interested in Meinolf's post about restricted exhaust, so not to steal his thread, I thought that I would post a picture of the cross over on my 750S, I have never seen one of these before and was wondering if this is normal.




It seems that the cross over is a bit narrow, the head pipes are touching the frame, I  was thinking that the pipes that run from side to side may be in too far?  DonG

Offline RinkRat II

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Re: Speaking of restricted exhaust
« Reply #1 on: March 29, 2018, 01:34:59 PM »

 I believe they were going for the scavenging effect and something went terribly wrong. Pipe intrusion seems excessive and a good holesaw run down the interior of those pipes would be beneficial . My $.02 :popcorn:


     Paul B :boozing:
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Offline Kiwi Dave

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Re: Speaking of restricted exhaust
« Reply #2 on: March 29, 2018, 04:26:20 PM »
I believe they were going for the scavenging effect and something went terribly wrong. Pipe intrusion seems excessive and a good holesaw run down the interior of those pipes would be beneficial . My $.02

I doubt you will experience any difference.  My $0.02ยข too.

Online rodekyll

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Re: Speaking of restricted exhaust
« Reply #3 on: March 29, 2018, 04:43:00 PM »
I have seen those for sale, but none on the street.  Although curiously sloppy construction, I don't think the intrusion of the cross pipe affects flow.  There is probably a lot more pipe than needed already.  I think the only issue would be if the assembly is too narrow to properly align the head pipes.  If there's no way to coax the head pipes away from the frame without stressing the parts as they tighten down, it's too narrow.  Stressing exhaust bits during assembly causes exhaust leaks and cracks.  Other than finding a way to bend the straight legs to fit (doubt it with those welds) I doubt that there is any "fix" for them other than to cut the cross tubes and use flex pipe to spread them.  I've used flex pipe on the cross tube of a traditional H pipe to improve the fit.  It works but it's ugly.

Shimming the contact points to the frame with playing cards or other shim stock while you tighten them down might help.

Offline huub

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Re: Speaking of restricted exhaust
« Reply #4 on: March 30, 2018, 02:40:15 AM »
amazingly , they are all like that, the v7sport has the same cross over.
apparently the idea is to devide the exhaust pulses between the two cilencers
i once ground one smooth on the inside, expecting ato improve engine  breathing,
quite a lot of work, especially because it made no diference at all!

Offline Don G

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Re: Speaking of restricted exhaust
« Reply #5 on: April 02, 2018, 12:35:58 PM »
Thanks for the reply's! I will try and wrestle this cross over into place, I wonder why a lot of the Italian exhaust is so piss poor? Like did Ray Charles have a part time job over there?  :cheesy: DonG

Online rodekyll

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Re: Speaking of restricted exhaust
« Reply #6 on: April 02, 2018, 02:17:21 PM »
Probably not.  Like any other instrument, Ray Charles could tune an exhaust.

Offline Don G

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Re: Speaking of restricted exhaust
« Reply #7 on: April 02, 2018, 02:24:44 PM »
yeah, but he was the Dude welding it together I think!  DonG

Offline TOMB

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Re: Speaking of restricted exhaust
« Reply #8 on: April 02, 2018, 05:23:23 PM »
V7 sport I owned a 1973 had x overs like that which came stock.
Those look like SS .
They are angled to help the flow and do not flow into each other as the are separate
TOMB
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Re: Speaking of restricted exhaust
« Reply #9 on: April 02, 2018, 09:00:55 PM »
They all come like that Sir.

Offline Don G

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Re: Speaking of restricted exhaust
« Reply #10 on: April 03, 2018, 08:40:46 AM »
That is what I was wondering about, thanks Jim.  DonG

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