after market exhaust

[pamcopete]

Los D

Perhaps the earlier models do not have a double walled header. I edited my post above to reflect that possibility.

 

[Los D]

It looks like the earlier models were single walled, going to have to find a new solution.

 

[gordonscott]

Well they posted the dyno chart.

Looks like it's actually decreasing HP throughout most of the usable rpm range and giving a 9hp peak increase at 7,700 rpm where the stock peaked at 7,000. Anything below 3k and between 4.2-6.3k you're losing hp with that system. I'd take the stock exhaust over that if that's the only mod you did. I'd be curious to see what it would do with a more free-flowing intake. The little note on the chart explains a lot.

I've always though of it like this: If just an exhaust upgrade over stock will give you 5hp and just an intake upgrade over stock will give you 5hp, doing both will usually give you more than 10. These things all work together and sometimes one component will be your limiting factor. You can't assign hp ratings to each piece because they all have to work together. That's why I don't pay too much attention to manufacturer's claimed HP ratings for aftermarket parts. Plus there are a lot of things that they usually don't tell you when they claim a certain increase. Also a lot of times you might not care about peak HP and that's usually what they rave about. You might want to increase your low or mid-range HP depending on the machine and the type of riding (driving) you do.

So thumbs up to MikesXS for actually posting a chart and giving a little bit of info on what was done. It's better than just having the 10hp claim and nothing to back it up or any other information on what was done.

Hi Travis, I have done a bit of dyno testing and have a lot of dyno tests from flattrack racers back in the day. Just bolting on a pipe and getting 10hp gain is something I've never seen, not calling anyone out on it just saying I've never seen it happen. A stock xs produces 42RWH at stock spec. I have a one owner "77" that is as new as I'll ever get my hands on and it dyno's at 42.3-5 every time with stock pipes. When I dyno test my systems I only do one mod at a time. That way I know what my pipe is doing on it's own and can figure out gains without wondering if it is a jetting or filter change that's giving me more hp. I have made a 2into1 that makes peak HP @ 4,000 or so rpm. This dyno was done with stock jetting and filters; only pipe was changed so I know what the pipe is doing. Again notice where hp and torque gain is. I have since changed this design again based on testing and have made a pipe that give's more of a gain at same rpm. Also notice 2into1 tested was an open pipe with NO muffler! Diameter and length of pipe is all there is in making pipes, just depends on what you want them to do? Also you can notice the "sniffer" in the end of the pipe, it was NOT running super lean, just off about a 1/2 point! 14 vs. 13 1/2 if I recall? Just sharing some facts, as I know them p.s. loose chain making graph wavy. P.P.S. Please don't flame me on this! Just sharing my experience, yours may differ

 

[Sundie]

And, yes...the outer pipes do have drain holes in them, so if you just clamp the muffler to the outer pipe, the exhaust will leak out of the drain holes.

And brazing these up because exhaust is coming out is a bad idea. (everyone of my stock bikes have them brazed up when i got them)

 

[Sundie]

GS: Liking that torque curve. I think i'm going to go have mine dynoed to see where it is. There's been no point before with the headgasket being as screwed up as it was, but now probably.

 

[xstwin]

http://downloads.650performance.com/XS650_750_engine_modiffication_guide_sample.pdf. Here"s some exhaust info for you guys

 

[gordonscott]

http://downloads.650performance.com/XS650_750_engine_modiffication_guide_sample.pdf. Here"s some exhaust info for you guys

that is from the "XS650/750 Engine Modification Guide!" and the complete guide can be bought at http://www.650central.com/ from Michael Morse

 

[xstwin]

u guessed it

 

[benway0007]

any recomendations on after market baffels. im doing the pipes that alot of people do that end a side out shot just after the kickstarter. i have seen 4 and 8 inch. i dont want an outragious loud exhaust but i also dont want it to be only a small amount louder then stock.

 

[Beemerboy]

I,m new to this forum and glad as hell I signed up. In a few weeks I.ve learned more about building a tracker than I thought was possible to know. So, to the question. I have a '78 Special and would like to use Omar's mile pipes. Anyone have experience with this combination? Are there any brackets I should not grind off to use this exhaust? Any other advice will be appreciated as well

 

[rayth]

DLAB, I got that set-up on my '80 G model. They work great. I am also using the taper tip muffler. The only 'problem' I had was that when all bolted up, the pipe's were up really close to the brake pedal. Solution was to 'bend' the pipe downward with a flat bar. Like a carpenter uses, the flat bar did not damage the pipe's like a round one would. Real easy install,too. About 30 minute's. I used a piece of mild steel for the muffler bracket, as the chrome one was way too brittle. Snapped right off after about 50 mile's. The mild steel one has been on for about 3500 mile's now. The first set of pipe's I got were the Ascot style, with the taper tip muff's. I like the 2-1 style much better, no more dragging when cornering.And they sound nice, not too loud, but loud enough for the cage driver's to hear ya. The sound is alot different than with the 2-2 pipe set-up. I'll post up some pic's when the camera is back.
As far as your carb's go, you might have to go down on the needle setting, & maybe 1 size up on the main. The pilot jet should be fine. Of course, every engine is different, but after a little riding, if you get problem's, post them here. You might run into some 'hesitation' or misfire just off idle up to about 2500-3000 rpm. If you do, that's when to start moving the needle setting. The middle of the needle is the stock setting. Moving the e clip down rich-en's the mix off idle. So moving the e clip up leans it. Riding is the only way to determine any problems, of course, but my BS34 carbs are real close to stock. If I remember correctly, 42.5 on the pilot,135 on the main's, & XS John's needles. He is on another site, but his needle's are worth there weight in gold. Not sure if he make's them for your carbs. Anyway, try this stuff first, then if you still got problem's , let us know. Happy Riding!!! Gordo

Hi Thanks Gordon from Ray downunder
Appreciate what you found when fitting the pipes
Have stareted to do today but appears as if the LH pipe will rub on the RH pipe
have not clamped up but are inserted to each side "loosley"
Was wondering if I should compress the new exhaust gaskets first-then try to align the Y peice
Anything from your experience please
Regards

 

[XSLeo]

On the stock headpipes they all were double wall pipes. The early models had a slip on type muffler. The muffler sliped on to the outside of the outer headpipe and used a screw on nut and gasket to seal to the outer pipe. If you pull off the muffler you can see where they put a slight taper down on the outer pipe and a taper up on the indise pipe and welded the two puipes together.
The later headpipes and mufflers were welded together so they were one piece. When you cut the muffler off where most do you are cutting the two pipes of the header apart. As shown in the pic. These you need to adapt your new mufflers to the inner pipe. On the earlier headpipes you can just clamp new mufflers to the headpipe.
Leo

 

[mikehants]

Does anyone know of a Brit or US supplier/ maker of aftermarket downpipes for my 79 SE?
Or good used ones for that matter.

 

[XSLeo]

Good used ones, put an ad in the parts wanted part of this forum, search Ebay, Craig's List.
New ones Mike's aren't bad, Gordon Scott will make them anyway you want. Get a set of bends and build you own.
Mosy of the Custom builders like TC Bro's and such sell them.
Leo

 

[nj1639]

If your stock headers are double walled, the functional pipe is inside the outer pipe, so if you are going to use the stock headers with an after market muffler, you need an adapter that will connect the muffler to the smaller inner pipe. And, yes...the outer pipes do have drain holes in them, so if you just clamp the muffler to the outer pipe, the exhaust will leak out of the drain holes.

Here is a pic of the inner pipe:

The outer pipe may also leak at the head flange as well. The outer pipes were not designed to flow any exhaust, so there is no guarantee that they are gas tight from end to end.


I used this adapter on my '81/H:

This is a 1 1/2 X 1 3/8" adapter available at most auto supply stores, #548520. The small end will fit tightly around the outside of the inner pipe. Clamp the muffler around the large end. There is no way to clamp the small end around the inner pipe, but it fits real tight, so you can either wait for the carbon buildup to seal it or apply some Permatex muffler sealer.

The small end is completely hidden inside the header, the big end is completely hidden inside the muffler.

This is what it looks like when installed.

Pete, just wanted to say thanks for this idea. I just did another changeup on my Special and this worked great!

 

[rayth]

Hi Thanks Gordon from Ray downunder
Appreciate what you found when fitting the pipes
Have stareted to do today but appears as if the LH pipe will rub on the RH pipe
have not clamped up but are inserted to each side "loosley"
Was wondering if I should compress the new exhaust gaskets first-then try to align the Y peice
Anything from your experience please
Regards

Thanks I somehow missed your reply though was trying to watch
Got them fitted up OK - They sound lovely thru a single aftermarket muffler- had to cut/shut MIG the Y piece to make it all line up and will now need to have this re-chromed ; its not running right yet - might need to play with jets - seems to be getting way to much fuel with the VM 34,s
Will post some pics of the finished result once she is o road
Cheers

 

[XSLeo]

This adapter only needs to be done with the later one piece exhaust that you have to cut the mufflers off. On the earlier bikes the mufflers just slip on to the head pipes. These head pipes have the inner and outer pipes of the head pipes tapered together and welded. So on these older head pipes you can use any slip on muffler, no adapter needed.
Leo

 

[estcstm3]

This adapter only needs to be done with the later one piece exhaust that you have to cut the mufflers off. On the earlier bikes the mufflers just slip on to the head pipes. These head pipes have the inner and outer pipes of the head pipes tapered together and welded. So on these older head pipes you can use any slip on muffler, no adapter needed.
Leo

Hi XSLeo

I have an older 75 with the 2 piece system. Do you know what the ID of the slip on exhaust pipe would have to be to work? I would need to know the OD of the end of the header pipe and the ID of the slip on pipe right?

 

[dirtymike]

Where do you find the adapter(#548520) at. I have had no success at the auto parts store.

 

[XSLeo]

estcstm3, On the 75 head pipe I have in my hand, it measures just under 1 9/16 inch at the very end of the pipe. The pipe has a slight taper about 3/16 inch long. The pipe just past this taper is 1 9/16 inches.
I would buy mufflers that the muffler fits right on a 1 3/4 inch pipe. Some come with a set of adapters that are sections of pipe with a slit in one side. They usually have three pieces. These pieces adapt the 1 3/4 muffler to fit 1 5/8, 1 1/2 and 1 3/8 inch pipes.
The set of mufflers I bought these adapters came with them.
Just fit the largest adapter in the muffler. If it's a snug fit over the pipe your ok. If not add the next smaller adapter inside the first one in the muffler. A snug fit?
Use whatever fits snug on the pipe. The clamps should squeeze them enough for a good seal. If not go to the nearest Harley dealer and buy a pair of their clamps. Around $8 each. Built much heavier with a much bigger bolt. These will clamp with no leaks. I'll post a pic.
dirty mike, most parts stores have an exhaust section. full of muffler clamps, hangers. elbows, straight pipe, mufflers. In this section you will find adapters. They make them in many sizes.
The adapter is 1 1/2 inch od on the big end and 1 3/8 od on the other, maybe 1 3/8 id.
The small end goes in between the inner and outer pipe. The large end you hook the muffler to.
Leo