Can I use Harley sportster mufflers on '81 GS450 without re-jetting?

[sacruickshank]

A common mod on Honda CX500's is to replace the OEM mufflers with Harley Sportster cans. They bolt right on and work with the stock jetting. They are generally cheap whenever a harley owner upgrades their bike, look good, and sound good.

Does anyone know if they can also be used on an '81 Suzi GS450, without re-jetting the carbs? My current project GS has some dents on the exhaust and I have a set of harley cans stashed away. The Suzi pipes are one piece, so I would have to cut off the stock mufflers. The diameters are different, but I can use reducers to fill the gap.

It's running great now, so I'd rather not mess with the jets.

Here's the project for reference. '81 450L with 5570 miles. Wasn't running, but didn't take much to bring her back to life. Now has new tires, battery, plugs, etc and will be 100% roadworthy once the front brake parts come in.

 

[LAB3]

From everything I've read and heard there shouldn't be an issue. My 450 does run a pretty lean overall with stock jets, needle height, airbox and exhaust and I'll be reshimming my needle before heading out for the summer. If I where going to change my airbox or exhaust I'd have probably done that already but like I said, all I've read says you should be OK. Give it a try, if you get any detonation or it seems to be running hotter then a reshim would be your next project.

 

[Guest]

Not sure about a 450, but many a GS has had stock Sportster mufflers installed. I didn't hear of any down side other than people questioning, "your putting a Harley part on a Suzuki?"

 

[Nessism]

Should be no problem. A couple of dents on the stock mufflers may not be justification for the hassle though.

Oh, and before putting your bike into service you might want to check the newbie mistakes thread linked in my signature so you can know what to look out for.

 

[Gorminrider]

They work ok on my GSX 400, which is materially the same as a 450 excepting a different head, but I find I prefer the oem-type...MAIN reason; the Harley types don't have the upsweep and hang lower..and might need some bodgery to clear your axle bolt...(they were awful close- I have to remember that the rear wheel will bounce up and not down-otherwise, the mufflers would interfere..Still, the chrome and quality is excellent! They are also heavier....

by the way, the Harley 'resonance" only came through at idling rpm....at 7000 rpm-well, it's ok but I don't think anyone will mistake you for a Harley or an old triumph ... You need be careful too about which Harley mufflers you use-some have honeycomb fill on ONE muffler that you will want to bash out and that's a real pain...

All in all, They were an excellent fit to my Honda GL500, but I won't put them back on the GSX400 except as interim spares.

 

[Gorminrider]

Here...you can compare.

 

[LAB3]

Good point on clearing the axle nut. The manual says to remove the exhaust to access it so you can remove the back tire, I've been removing the shocks instead and moving the swingarm to get above or below the muffler.

 

[Steve]

MOST of the need for re-jetting happens when the airbox is removed. Unless you go to a very free-flowing exhaust, there isn't much change going from one muffler to another.

.

 

[Grimly]

Be careful what Harley you rob of its silencers. I got a pair from a Dynarod and the baffle plate in each was a different position. Much fiddling and brutality ensued and I finally got a pair of nice free-flowing and very quiet pipes.
The one I've currently got on the GS came from another model - Road Poop or something, and I've partially de-gutted that as it was quite anaemic. More fiddling and brutality led to a nice free-flowing quiet pipe, but it still needs more fiddling (and brutality, natch) to get it the way I want it.

 

[sacruickshank]

Thanks all for the excellent input. I already have the Harley cans ($20) and still debating if I make the mod or not. I'll definitely check axle clearance.

@Nessism - Thanks for the "newbie" link, but not needed. Despite my apprentice level on this forum, the Suzi 450 is definitely not my first resurrection. I've done ~20 of varying levels on bikes from all four J-mfrs and a BMW.

 

[Gorminrider]

as you say ,LAB3, shifting the shocks is the best way to deal with the axle....The originals could be bad trying to get the axle out and I seem to recall the manual had you removing the entire muffler and header to do it! That said, the lower-hanging Harley mufflers I picture were more of a worry in potholes or curbs...though I don't see that I ever scraped them.

I wonder (offhand) if a better look might be a piece of pipe-angle added in ahead of the mufflers, if such a thing can be found.

 

[sacruickshank]

as you say ,LAB3, shifting the shocks is the best way to deal with the axle....The originals could be bad trying to get the axle out and I seem to recall the manual had you removing the entire muffler and header to do it! That said, the lower-hanging Harley mufflers I picture were more of a worry in potholes or curbs...though I don't see that I ever scraped them.

I wonder (offhand) if a better look might be a piece of pipe-angle added in ahead of the mufflers, if such a thing can be found.

Looking more closer at the HD cans, their diameter might grow too fast and hit the frame extension on the '81 GS 450L. There are some tubes that are used to hold the passenger pegs and the muffler holders.

 

[Gorminrider]

...I'm sorry I don't have some photographic detail of my mounting.... I do remember making some straps for the rear and bending them to accomodate. ...loosening the headers and swinging them out a little will help compensate for the extra fatness of the Harleys'. I was able to get a good seal , but I am using adapter-joints rather than the usual split shims that are commonly seen with slip-on mufflers....from my notebook:
" 1+5/8"ID x 1+1/2" OD"
The narrow end suits Suzuki malleted in (1 1/2"OD) while the wide end slips inside most generic mufflers including Harley davidson. (1 5/8" ID)

but you'd best take some calipers to double check if you consider these.
Thinking too much but ...the L with a 16" rear is going to sit a wee bit differently- (1/2"? but still..) than my 17" rear on my GSx400T.

 

[LAB3]

There's nothing wrong with the stock mufflers I have on there but I'm going to keep an eye out for a set of HD's now that I see how well it takes care of the axle clearance issue. Spring isn't too far off down this way which means swap meet season is just about upon us.