another perfectly good motorcycle ruined.......

Thursday, 26 July 2012

boxer racer project




top photo shows the supertrapp's on my sporty, i'm really pleased with them, they give good performance and are reasonably quiet, they were originally developed by the u.s. forestry commision, they had trouble using generator's to power their cutting equipment in the forest's, basically, spark's coming out of the exhaust and causing fires, the supertrapps used a 'closed end' cap to prevent spark's, some genius recognised that you could use the diffuser rings to increase performance on a motor vehicle by adding or subtracting the diffuser rings to tune the exhaust system to the motor and at the same time, cut down the noise emissions, as the exhaust gases pass through the disc's to atmosphere they create a pressure drop that increases the scavenging effect to allow better, ie, more efficient cylinder filling, adding more discs increases the exhaust outlet and reduces the back pressure, moving the power up the rev-range but increasing the noise level, subtracting the discs causes a wider spread of torque across the rev-range and quieten's down the exhaust noise at the expense of top-end power, so, as you can see, it's all a compromise, i have to run the bike at the meeting's at a maximum of 105 db but, i don't want to compromise performance, made up the adaptor rings and fitted them into the end of the original triumph megga's, luck being on my side, they are exactly the same size as the supertrapp diffuser rings and end caps, so, four disc's to pass the noise test, get the sticker and add another five after scrutineering i reckon.......................................

2 comments:

  1. Thanks for the background gumph Lovey, I think you'll find you used up up all your bad luck prior to getting the Buzz Bomb up and running, it'll all be apples from here on in . . . let's have a yarn on the weekend if you've got the time Professor.

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  2. Nice job on the adapter rings. I still have a little black Supertrapp from back 'in the day' when my brother and I built a little Honda for off-road and had to meet the new for then, requirement for a spark arrester. Don't know if they are still manufactured in the nearby city of Davis, Calif. Remember a story from a friend that went to college in that town. He said that after they finished designing prototypes to fit bikes that the manufacturers would send, sometimes the bikes would end up in the dumpsters behind the shop. He scored lots of goodies that way. Seems to me that the original owner of the outfit sold it on, and formed another company to develop a "flying car"...I'll have to go google that...

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