bikesandcars
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I wanted to increase the performance in my Dolmar 5105 by doing a MM. I took a slightly different approach than 2 other muffler mods I saw here.
I Cut the top of the main can apart. When assembling I used the removable heat shield as the new top of the can. I threw the middle part away, and spot-welded the spark arrestor cover on.
I also inserted a steel baffle that helped with the sound. I didn't take a good pic of it, but it's a 2" x 1.5" steel piece welded above the opening and attached to the 2 tubes, it deflects sound forward and to the side so it doesn't have a straight-shot from muffler inlet to exit.
Before welding the spark arrestor on I cut the exit opening wider. With that additional exit space and the screw hole I have some more open area. I welded the screw hole below the chain brake after I installed it, didn't want hot exhaust going right on the plastic brake. The new opening is probably around 75% to 80% of the exhaust port area. Overall it made a big improvement.
I used stainless wire in my Mig welder. I'm not a pro welder by any means and it took me until the final welds to get the machine and me adjusted correctly.
To finish I cleaned everything up in the blast cabinet (glass beads) for that satin look.
Results:
Sound: A little louder but also a better sound, sounds "sporty". Not ear-piercing like a big open hole muffler mod. hearing protection suggested but not absolutely required to avoid a splitting headache.
Performance: Definately an improvement in response, especially acceleration. Bogs less and up to speed very quickly.
Tuning: It seemed to like 1/8 turn richer.
Pulls the 20" bar with 3/8 chain a lot better, doesn't bog as easy as before. I was regretting my 3/8 20" bar upgrade, but now I'm very happy. Tested it in some full-width pine and it cuts very nice.
I Cut the top of the main can apart. When assembling I used the removable heat shield as the new top of the can. I threw the middle part away, and spot-welded the spark arrestor cover on.
I also inserted a steel baffle that helped with the sound. I didn't take a good pic of it, but it's a 2" x 1.5" steel piece welded above the opening and attached to the 2 tubes, it deflects sound forward and to the side so it doesn't have a straight-shot from muffler inlet to exit.
Before welding the spark arrestor on I cut the exit opening wider. With that additional exit space and the screw hole I have some more open area. I welded the screw hole below the chain brake after I installed it, didn't want hot exhaust going right on the plastic brake. The new opening is probably around 75% to 80% of the exhaust port area. Overall it made a big improvement.
I used stainless wire in my Mig welder. I'm not a pro welder by any means and it took me until the final welds to get the machine and me adjusted correctly.
To finish I cleaned everything up in the blast cabinet (glass beads) for that satin look.
Results:
Sound: A little louder but also a better sound, sounds "sporty". Not ear-piercing like a big open hole muffler mod. hearing protection suggested but not absolutely required to avoid a splitting headache.
Performance: Definately an improvement in response, especially acceleration. Bogs less and up to speed very quickly.
Tuning: It seemed to like 1/8 turn richer.
Pulls the 20" bar with 3/8 chain a lot better, doesn't bog as easy as before. I was regretting my 3/8 20" bar upgrade, but now I'm very happy. Tested it in some full-width pine and it cuts very nice.
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