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xs650 > > High Performance Modifications > > Top End Work > > Headwork with stock exhaust?


Headwork with stock exhaust?
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scotts
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Joined: Apr 03, 2007
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Location: Rock Hill, SC

PostPosted: December 22, 2009, 10:22 am    Post subject: Headwork with stock exhaust?

I have a good running '78 engine with broken fins on the head. I plan on using it in my '75 stock rebuild.
I picked up a nice '76 head with good fins. I have access to a local shop that will hot tank/soda blast the head, lap the valves (or do a valve job) and perform a mild P&P on the exhaust (not sure if they do the intake or not).
I plan on running the stock '75 head pipes and mufflers. Is it worth it to do a mild clean up on the head if I don't plan on running larger exhaust?
I know the exhaust/exhaust port is the bottle neck on these bikes.
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Srinath
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Joined: Sep 10, 2009
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Location: Charlotte NC

PostPosted: December 22, 2009, 11:22 am    Post subject: Re: Headwork with stock exhaust?

The restriction is all in the muffler. Its that last 6-9 inches that does it in.
The headers can flow a good bit, the muffler, well needs to be cored to flow ...

The muffler is the classic 3 chamber design crammed in the last 9 inches before the end.

There are 2 plates welded 3 inches apart ~6 inches from the end.

That effectively gives 3 chambers ... the first is from the head to that first plate, the second is from the plate to the other plate and the third is from that plate to the end.

Now a dime sized pipe connects 1 to 3. Then a dime sized hole connects 3 to 2. Then the outlet pipe you see connects 2 to the outside.

ore flow can be acheived by, and ... My SV has this mod -
Knocking out the pipe you see and replacing it with a perforated tube of larger diameter.
If you want to take it further, knock that tube out, and follow it with a long and large drill and drill into the first plate. Then stick a long baffle or perforated tube through that whole set. Of course you can do 1, then the other and get it to where you like it.

On the xs this is what I would do.
Take a hole saw that is just larger than that outlet and cut that plate off.
Then stick a rod in it and weld the pipe to that rod. Then give it a few sharp hits inward. That would break the welds inside that plate.
The pipe should come out then. Take your prefered baffle (I prefer the perforated stainless cylinders that I have) and put it in there and weld it to the end plate.

Cool.
Srinath.
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scotts
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PostPosted: December 22, 2009, 1:58 pm    Post subject: Re: Headwork with stock exhaust?

So you're saying that I won't benefit from mild headwork if I run the stock exhaust?
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Srinath
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Location: Charlotte NC

PostPosted: December 22, 2009, 2:44 pm    Post subject: Re: Headwork with stock exhaust?

Probably not, but exhaust mods even wiht the stock bell mouths will greatly help.
Why you dont like louder pipes ? I dunno how to make it quiet as well, but some elaborate system of packing the thing wiht fiberglass etc etc can be deviced. Like punch out the center baffle as well as cut away the end cap and punch though the next plate in large holes.
Then make a baffle which goes through the 2 and sticks into the first chamber. Maybe have an hour glass type constriction in its middle. then stuff fiberglass in the 2 chambers. #2 and #3. Then have an end cap that bolts to the pieces of the end cap you ahve left and that end cap would carry the baffle. I did a similar job on my SV, except there is no packing ... I welded the baffle to the end snout and that snout fits back in the cored can as orignal. It looks so stock. very deceptive.
Cool.
Srinath.
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Srinath
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PostPosted: December 22, 2009, 2:49 pm    Post subject: Re: Headwork with stock exhaust?

OK yea, cut one hole right @ the size of the inner pipe, and another larger one ~2 inch larger diameter. Then remove the inner pipe like I said before and then get some sorta big drill and drill into the left over parts of that plate as well. Or not needed. Punch into the next plate and stuff the 2 chambers with fiberglass. Then the baffle is located, and a new plate will cover the end cap hole you cut, and bolt to it and weld to the baffle.
Cant explain it too well ... easier to do it actually.
Cool.
Srinath.
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scotts
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PostPosted: December 22, 2009, 3:12 pm    Post subject: Re: Headwork with stock exhaust?

Do you have any idea how rare a nice set of XS650B exhaust are? I'm sure gonna use them and not gonna modify them.

Maybe I should just have the head cleaned and valves lapped?
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Srinath
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Location: Charlotte NC

PostPosted: December 22, 2009, 3:41 pm    Post subject: Re: Headwork with stock exhaust?

Do the mufflers come off ? cos if they do, you remove them and goober on somehting more common like some harley crap and modify it.

Anyway I believe I have 2 headers for this bike, whoo hooo you say they're worth big $$$ whoo hooo ...

Cool.
Srinath.
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royfisk
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Location: winchester, new hampshire usa

PostPosted: December 22, 2009, 6:46 pm    Post subject: Re: Headwork with stock exhaust?

BS. of course youll benefit by porting the head. And the description of the exhaust above sorta sounds like later special mufflers to me. Although I must admit a free flowing exhaust will take more advantage of that ported head.
_________________
build them , ride them, tear them down, rebuild them, ride them, etc. etc. etc.. They only get better and better
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Srinath
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PostPosted: December 22, 2009, 10:12 pm    Post subject: Re: Headwork with stock exhaust?

Yea mine is a 82 special and that is all I know about. Sorry should have mentioned that ...
Cool.
Srinath.
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dpmphoto
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Joined: Apr 18, 2007
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Location: syracuse NY

PostPosted: December 23, 2009, 12:08 am    Post subject: Re: Headwork with stock exhaust?

I totally agree with roy;furthermore The restriction isn't all in the mufflers nor does it start there. Restrictions starts in the poor casting and valve guide boss shape and position, not to mention the large port volume in relation to the valve opening. Even a mild port by someone who has the slightest clue what their doing will help. Also larger(diameter) headers and mufflers do not make your bike faster,they need to be the optimal size for the specific engine in this case the xs 650.An 1 3/4 header may make your bike perform better in the high end while an 1 5/8 header may give you better overall performance throughout the power band. Scotts Definitely have it ported and polished it should make a noticeable difference and if those pipes off the 75 are real nice maybe you should save them for a special project, sell them or store them away but don't start drilling holes in them.Just my two cents
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danno
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PostPosted: December 23, 2009, 12:56 am    Post subject: Re: Headwork with stock exhaust?

I think scotts' special project IS his 75B,and that is why he is not going to alter the exhaust. A very sweet bike,as all of his are. But if I remember correctly,he is going to restore this one. No need for a definition of "restoration" needed here,been there,heard that.
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650skull
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Joined: Jul 19, 2007
Posts: 1186

PostPosted: December 23, 2009, 1:10 am    Post subject: Re: Headwork with stock exhaust?

The TXA and XSB mufflers are worth a gold mine, i was looking at a single NOS right hand muffler on fleabay and it finally sold for $435US. No headers and not both mufflers but 1
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danno
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PostPosted: December 23, 2009, 1:58 am    Post subject: Re: Headwork with stock exhaust?

Skull,pm me about TXA muffs. I am looking to get a set of new Dunstall replicas,and if I could net enough to get them to my door (about $125 US,and you pay for shipping to your locale),I would definitely part with them. Our first pm exchange was less than friendly,but I am confident you would not be disappointed for the price. I have pics I can send you,so you can judge the condition for yourself. Thread hijack complete...
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gentlemanjim
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Joined: Dec 29, 2007
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Location: South Florida

PostPosted: December 23, 2009, 4:16 am    Post subject: Re: Headwork with stock exhaust?

If you want freer flowing, SS reliability and good looks get a pair of Supertrapps. They are infinitely tuneable, quite affordable about $160.00 at Summit Racing. I have a pair on my Guzzi Cafe and they look and sound awesome. I'm getting my '83 Heritage tomorroow and that's the exhaust I'm gong to use.

www.summitracing.com/p...toview=sku
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scotts
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Location: Rock Hill, SC

PostPosted: December 23, 2009, 8:31 am    Post subject: Re: Headwork with stock exhaust?

My mind's made up on the mufflers. I picked up a very nice XSB exhaust (headpipes and mufflers) in better than average shape for a GREAT price....less than that single muffler sold for on ebay. I AM going to use the stock exhaust.
I was just wondering about the head work. That local shop I mentioned does all the work I talked about for ~$60. Sounds like it's worth it to me.
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dpmphoto
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Joined: Apr 18, 2007
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Location: syracuse NY

PostPosted: December 24, 2009, 4:57 pm    Post subject: Re: Headwork with stock exhaust?

$60 bucks I dunno man that sounds real cheap to me,even for a very mild port(just removing casting flaws and polishing to a mirror finish) it takes me at least 2 or 3 hours add a bead blast and valve lapping thats another hour at least.Are these guys very familiar with the xs? Dano mentioned all your bikes are very nice so I assume your a perfectionist. It just doesnt add up to me maybe these guys know the xs like the back of their hand and are super fast and accurate,or they have child slave labor out back in a mud hut but if it was me i would find someone else who had work done there or shop around for some more prices. I would charge $150 to do that work but it would be perfect I have seen prices from around a $100 up to $250.
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Srinath
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Joined: Sep 10, 2009
Posts: 343
Location: Charlotte NC

PostPosted: December 24, 2009, 6:15 pm    Post subject: Re: Headwork with stock exhaust?

What can I say ... I live in the same area as Scott and all I can say is ... there are a lot of engine guys in this area ... and Nascar recently pitched several 1000 techs. There is a lot of unemployed speed experts around here ...
Cool.
Srinath.
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