New old exhaust

[highboy_coupe]

Got this random exhaust off the 'Bay, complete with home made bendy pipe. I believe it was fitted to a 500, as the mount is about 5cm off the 350 frame mount. I Spent about 2 hours with a wire brush drill attachment getting all the white (!) spray paint off, and made a crappy alloy adapter for the mouting hole.

It is very loud on full throttle, and quite nice and quiet off. It is straight through and weighs about half of the original silencer. I have lost about 5MPH to speed though

I do have a bigger main jet fitted, but no carb mods apart from the airbox, do 350's need some back pressure?

[appyarry]

You need a dyno

You could try a richer needle and do lots of plug chops. Or you could try the washers under the needle path but I'd be very careful about long high speed journeys without doing the plug chops. If it runs too weak it can melt pistons.

Allways remember speed gains costs money. To get a cheap increase in speed first lose all excess weight from bike and rider

Good Luck,

[highboy_coupe]

Thanks for that,

This wasn't a quest for speed, honest! My original exhaust has rusted through and full of holes and this was cheap

I have a bigger main I can put in, or I could try and repair my old exhaust.

[freddy54]

the exaust system DOES need back pressure , see my posting here http://forum.mtridersclub.co.uk/viewtop ... 87&t=15382" onclick="window.open(this.href);return false; the bike sounded nice but ran very slow , untill I almost restricted it ,

think back , cutting baffles down to "go faster" , when in fact , all you did was make noise!

look at a car , when the rear box rusts away/falls off , the car runs crap ,

untill funds permit , I have welded up my old silencer and refitted it

I do believe "mr shiney" was selling a good 350 system

[highboy_coupe]

Well its going really well now. Better than expected anyway!
I put in a 170 main jet, did the carb mod, turned the mixture screw out 2.5 turns and put in a new air filter as the old one was soaked in oil.
We now have meaningful acceleration, top speed is now the 'D' of Davidson and it makes a nice noise. Plug now suggests richness, but I can live with that for the time being.

[appyarry]

Great stuff, the reason a motor runs worse (generally) with an open exhaust is because the motor is not tuned to work with low pressure. If correctly jetted it will out perform a restricted sytem, it may make your ears bleed though

Sounds like your getting there, if it's running rich it will be slower and will drink petrol.

Good Luck,

[highboy_coupe]

Thanks for the encouragement!

I went from a 165 to 170 jet, so I haven't got anywhere to go to lean it out again. I will do a few tankfuls to check the mpg....