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sr250 supersound exhaust temp fix

Discussion in 'Technical and Troubleshooting Torque' started by Devery, Dec 15, 2009.

  1. hi all,

    I've been kindly lent a supersound exhaust to keep my yamaha sr250 on the road this summer.


    I have it all mounted and set. I took it for a test run and I think it is running lean. The bike will sometimes feel like it doesn't fire (its not awful but its not good). I'm guessing this is lean, too much air, not enough fuel? My question is, is there anything I can do that is not major modifications to restrict the air flow so I can have this bike on the road until I decide on a muffler and K&N filter and then I'll rejet the carb or pay someone to do it. Maybe packing out the muffler? Or is there some carb adjustment I can perform without having to buy a new needle? (the only reason I dont want to do this is because its a temporary fix).

    Not sure if any of my ideas would work or if there is a better one, but please share some ideas and help if you can.

    Thank you very much


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  2. James, I only just saw this (was wondering how you were getting along with it). I don't know much about these things. A bigger main jet will set you back maybe $7, and you should be able simply to adjust the height of the needle you have, to richen things. Have you done a plug chop to see what it's like? Is the poor firing you mentioned happening at half open throttle,or 3/4 and above, etc?

    Keep asking around - there's no doubt some simple good bodge, using exhaust tape or something....

    I can loan you a K&N to chuck on, to see if that roughly gets things close enough. Mine's an RU1700 (can't remember the ID to go on the carb, but their website will have it). Obviously this is a bike you need to push at 100kph, and you don't want to be running it too lean, esp in the heat. A colder plug might be a good idea. Even better, I might be able to lend you the exhaust off my old SR185 - don't hold your breath, but if I can I'll come back from Christmas with it. What's the outer diameter of your header pipe?
  3. Hey Matt,

    Yeah I think I should have a go at adjusting the carb. I think its the next thing to learn about on this bike. I'm just so slack with trying to find what kind of carb I have on it? Does anyone know what the stock carb is? Then I'll buy the appropriate needle...

    The headerpipe gets to 45mm where the muffler joins.

    Things are slowly going on hold with christmas... all good though.
  4. I took out two plates. It has improved dramatically, I doubt its perfect but I want to know if its ridable.

    It makes a poping sound when slowing down, but not too dramatically and sometimes not at all. It seems too miss a beat in the high revs of second gear but not really anywhere else though I haven't taken it on the highway.

    Just want to know if I'll be able to ride around like this around town until I get a new exhaust, filter and needles?

  5. Plug chop is your friend....