Post by jdbrees on Jun 1, 2008 10:59:40 GMT -5
Hi all -
I bought Rodentrancher's 78 SR500.
It's in great shape for a 30 year old bike with 28K.
He'd fitted the tm36-68 Mikuni pumper carb - great carbureter!
As he'd pointed out, the exhaust on the bike was a problem.
The headpipe is not too bad, but the muffler had to go.
The single outlet was about the size of a nickel (12-13mm) and there was no packing at all. the endcap was welded on so there was no way to re-pack. Just like Rodentrancher said - too loud and too restrictive.
I bought a pair of Emgo Dunstall replica mufflers on eBay as this style gives the low rumble sound I like. The seller claimed they fit 1.75" head pipes, but he was WRONG.
The O/D of the muffler is 1.75" and the O/D of the headpipe is also 1.75".
The adapter sleeves that came with the muffler only work to adapt the muffler to a smaller diameter headpipe.
I thought about fitting an internal piece of pipe, but the wall thicknesses of the headpipe and muffle are different. Also, I would have had to slot the end of the headpipe and use two clamps - one each for the muffler and headpipe.
Since I had two mufflers to work with, I hacksawed slots in one muffler so I could expand the end with pliers and, after getting it over the end of the headpipe about 1", used a hammer to "re-shape" the resulting mess to more or less conform to the headpipe.
After tightening the clamp, I was left with exposed slits in the muffler that I covered with a bead of high-temp silicone sealant. Amazingly, the sealant has held up to the high exhaust temperature, but I'm just not happy with this jerry-rigged (no pun intended) "fix".
I am very happy with the sound of this muffler, and it flows much better than the old one - really transformed the bike from 2000 rpm and up.
I'm sure I can squeeze some more power out now with jetting mods.
I plan on purchasing a new headpipe from Thumperstuff some time down the road, but will have the same problem as I've confirmed with Mark that his headpipes have a 1.75" O/D. This size seems to be common with aftermarket headpipes. I don't want to hack up my second muffler when it comes time to use it.
Has anyone had a similar issues with muffler/headpipe fit-up, and what solutions have been found?
Jerry
I bought Rodentrancher's 78 SR500.
It's in great shape for a 30 year old bike with 28K.
He'd fitted the tm36-68 Mikuni pumper carb - great carbureter!
As he'd pointed out, the exhaust on the bike was a problem.
The headpipe is not too bad, but the muffler had to go.
The single outlet was about the size of a nickel (12-13mm) and there was no packing at all. the endcap was welded on so there was no way to re-pack. Just like Rodentrancher said - too loud and too restrictive.
I bought a pair of Emgo Dunstall replica mufflers on eBay as this style gives the low rumble sound I like. The seller claimed they fit 1.75" head pipes, but he was WRONG.
The O/D of the muffler is 1.75" and the O/D of the headpipe is also 1.75".
The adapter sleeves that came with the muffler only work to adapt the muffler to a smaller diameter headpipe.
I thought about fitting an internal piece of pipe, but the wall thicknesses of the headpipe and muffle are different. Also, I would have had to slot the end of the headpipe and use two clamps - one each for the muffler and headpipe.
Since I had two mufflers to work with, I hacksawed slots in one muffler so I could expand the end with pliers and, after getting it over the end of the headpipe about 1", used a hammer to "re-shape" the resulting mess to more or less conform to the headpipe.
After tightening the clamp, I was left with exposed slits in the muffler that I covered with a bead of high-temp silicone sealant. Amazingly, the sealant has held up to the high exhaust temperature, but I'm just not happy with this jerry-rigged (no pun intended) "fix".
I am very happy with the sound of this muffler, and it flows much better than the old one - really transformed the bike from 2000 rpm and up.
I'm sure I can squeeze some more power out now with jetting mods.
I plan on purchasing a new headpipe from Thumperstuff some time down the road, but will have the same problem as I've confirmed with Mark that his headpipes have a 1.75" O/D. This size seems to be common with aftermarket headpipes. I don't want to hack up my second muffler when it comes time to use it.
Has anyone had a similar issues with muffler/headpipe fit-up, and what solutions have been found?
Jerry
