I'd had no real issues with the stock muffler but recent rides convinced me perhaps I was "stifling" Scarlett in terms of her ability to push exhaust gases out of the engine.
Scarlett's recent trip to the vicinity of Provo, Utah and back had revealed a rather severe lack of top end power when negotiating hilly portions of highway. Her MPG ratings had plummeted as well since I'd had get gearbox rebuilt by URAL but I'd blamed that on the use of the OR1.02 EFI mapping which was known to be "rich".
So, I ordered some exhaust pipe reducers and they all finished arriving today. Took me a while to remove the remaining stock muffler from Scarlett but with just minimal cursing, it came off.
I had, originally, cut a portion of the header pipe that came from Raceway to accommodate the length of the stock muffler. Using the new adapters, I added back the length and it worked out just perfect to line up the Harley-Davidson Sportster muffler that fellow Uralista Darrell had given me prior to all this.
The installed adapters/reducers. Took three of them to get the right
fit for the muffler and the header pipe extension. I'll be adding one more
clamp I think, forward of the one you see above.
If you look closely, you can see I was able to reuse the bracket that was
used by the stock muffler's circular holder. Lucky.
Took Scarlett out for a test drive, she sounds a bit louder than normal of course with the HD muffler but not annoyingly or obnoxiously so. I drove her to the local toll road and warmed her up. The first run through was a bit dismal, no power going uphill and thereby no real acceleration. This first run, I used the stock speedometer to gauge speed and it was not giving me the readings I wanted.
Decided to mount the Garmin Nuvi GPS that I'd received from SonjaM back in 2013.
Did another run of the same test course and this time, she ran much stronger. It's like the EFI computer adjusted for the newer freer-flowing conditions provided by the Sportster muffler and rendered better performance? Not sure.
Using the GPS, I was certain this time (as opposed to the highly inaccurate speedo from Ural) that I was holding steady speeds of 60 MPH. This second run, she did both uphill portions just fine, holding 55-50 MPH, in fourth gear, with no struggling though I was at WOT. (Wide Open Throttle).
So, satisfied with the initial test run, I filled up her tank (25.5 MPG) and we'll see how the new muffler affects the next tankful's MPG results.
On a further positive note, no backfiring from exhaust leaks when decelerating using engine braking.
More to follow. Perhaps I've become spoiled with Fiona's more powerful engine, but if Scarlett can once again hold 55 MPH while going up hills on the highway, I'll be happy. After all, I've learned to not exceed 55 MPH on the slabs if I want any kind of decent MPG.
If future tankfuls of gas render same dismal MPG ratings, then I'll have to again explore going back to the OR1.01 EFI Mapping or failing that, putting Scarlett back to using the stock mufflers.