A few weeks ago I was in a dilemma. I needed a new exhaust for my ’77 GL1000. New one’s are no longer available from Honda, and aftermarket is still pretty expensive. Expensive to me because I’m a full-time student and money is certainly not a thing I have in abundance.
In abundance, however, is my ability (willingness) to turn a wrench. I was an Air Force aircraft mechanic for 21 years.
There sure are a lot of very noisy Harley Davidson motorcycles on the road these days. Most of them didn’t come from the factory that way – the owners took the stock mufflers off and replaced them with aftermarket pipes to make them belch even louder. They call them “slip-ons.”
The Harley model that is probably most common, is the Sportster. Sportster stock mufflers, with a little tweaking, will fit pretty well on a GL1000 (maybe others too). Since the owners of these Sportsters no longer have a use for their OEM stock mufflers, the mufflers end up on ebay.
I got a pair from a 2001 Sportster with 350 miles on them for $26 + shipping. When buying them, make sure that the original baffles are still installed – some Harley guys punch them out for more decibels. Also make sure they have mounting tabs welded on the sides… I think some don’t.
Here’s what I did.
The stock GL1000 header pipes are not an exact fit for the Sportster mufflers. I took stainless steel sheet metal .010” thick and made shims to fit between the mating surface of the muffler and the mating surface of the header. I used three .010” shims per side. If I were to do it again I would use one shim of .028”. Make sure the entire mating surface is covered (for a good air seal and clamping strength). The sheet metal can be found at art supply and hardware stores.
For clamps I used standard Harley parts. I got a pair for $5 from a Harley mechanic who had them sitting in his toolbox from all those “slip-ons” he installed. New they are $8.50 apiece.
To support the weight of the muffler, I used some galvanized steel ¾ inch wide and about 3/16 inch thick and cut and drilled to size.
Re-jetting… maybe. I re-jetted a little richer to compensate, but mostly to eliminate the off-idle glitch common with the early wings.
You could possibly adapt these mufflers to work on a 1200, but, since the 1200 pipes sweep up(1000's go straight back)you would have to fabricate an angled adaptor or cut off and reweld the back part of the head pipe.
After riding the bike for awhile, I noticed that I was dragging the center stand on the pavement while cornering more than it should. The Sportster mufflers were keeping the centerstand from retracting completely into its stowed position.
My solution was to add an s-shaped exhaust extention between the header pipes and mufflers. Any good automotive muffler shop can do this... I just took one of the header pipes and mufflers to them and told them to make the extention with about a 2-inch offset.Twenty dollars and 30 minutes later I had my extentions.
When mounting them, I rotated the mufflers and extentions to the point where the top of the mufflers were about where the top of the OEM mufflers would sit. Now the centerstand rotates fully up and out of the way, and no more problems with dragging.
Also, with the extentions in place there is no longer a need for the shims that I described in the first post.
The mufflers now look much better and are further back where they should be.
They're certainly louder than stock, but sound much better thanmost of the aftermarket exhaust systems I've heard. The mufflers are high quality and made with heavy materials which, I think, contributes to this.
It's very cost-effective because the Sportstermufflers can be found on ebay for $10-$50.