96db Jackpiner

[Scott Summey]

I have a 74 Jackpiner with stock exhaust and Sparky attached and need to get decibel level down to 96 for our new club lease due to close proximity to area homes. I don't want to hack up the stock pipe other than what I've done to attach the Sparky (USFS stamp required). It has been suggested that I could weld in some metal disc's/baffles. Pipe has been cleaned and packed but being a straight through design does not do much. What do you guys think.

Scott Summey
Jacksonville, Florida

[derek martin]

Do a forum search on "Sound Check" for a post from August of 2013 regarding work done to pass the 2013 ISDTRR sound check. The check was for real at the event and I passed it easy.

[JP Morgen]

If you too off the one into two end piece to mount your sparky that will make the bike quite a bit louder.

[wfopete]

Some of your sound challange may come from the air cooled engine noise; not just the exhaust.

Pete Petrick
175 Jackpiner
Slow but Good

[Scott Summey]

Thanks for the response. I don't want to wrap the bike up with rubber bands and stuff the cylinders to reduce the mechanical noise as the bike will be ridden the way it passes the test. I've been wondering if using the Supertrapp diffuser pack on the end of the stock pipe will make a noticeable difference. Any thoughts or experience. Searched the site and came up with quite a few the bikes using the Supertrapp system.

Scott Summey
Jacksonville, Florida

[Richard Colahan]

Re: "stuff the cylinders to reduce the mechanical noise as the bike will be ridden the way it passes"

I'm not sure I understand the concern...
My 1974 Husky 125 has had small (1/2" or so) pieces of rubber fuel line stuffed between the cylinder fins for over 40 years.
Also lined the air box with thin carpet to cut intake noise, and clamped fuel line around the circumference of the pipe to cut down vibration.
All helps to reduce non-tailpipe noise which Pete Petrick refers to.

None of those items impact performance a bit...

Richard Colahan
1969 V1225
Upper Black Eddy PA

[Lew Mayer]

I may have a Supertrapp to fit a Jackpiner. I'll check when I get home.

Lew Mayer

[Scott Summey]

Thanks for the suggestions. Today I had some garage time and pulled off the Sparky (per JP) and re-installed the factory tip with the results being around 101 - 103dbl which is about 5dbl improvement over running the Sparky without the end piece. I may try stuffing the cylinder fins (per Richard/Pete) to see what happens. Still working...Thanks guys.

Scott Summey
Jacksonville, Florida

[Lew Mayer]

No, the Supertrapp that I have fits a SixDay pipe.

Lew Mayer

[Scott Summey]

Lew, thanks for checking. When I get a chance this week I'll try isolating the fins to see if that has any effect. If not I think baffling the pipe is an option.

Scott Summey
Jacksonville, Florida