250 2c carb tuning
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Thread: 250 2c carb tuning

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    Junior Member Towerdave's Avatar
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    250 2c carb tuning

    I have a restored 1974 250 2C. Nut and bold rebuild but apart from cleaning out the carbs haven't changed any settings. The bike starts on full choke but refuses to run at all even when warmed up unless the choke lever is fully open. Any ideas. Also the offside silencer is almost completely blocked ( the nearside one is NOS). can they be dismantled and what's the best way to clean them?

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    Hi, You won't get the bike in tune with a blocked silencer. The cross-over tube means the blockage will affect both cylinders. Yes, the silencers can be dismantled. Take off the end caps and then use a slide hammer set up to attach to the end of the muffler assembly inside the pipes. A few knocks and it will come out. Pull the assembly apart and clean it with a wire brush. It's a filthy job. Some people clean the inside of mufflers with caustic solution but I have never tried it. Too hard, too dangerous. With the 2C a stiff wire brush attached to a long wooden dowel will clean everything from inside the silencer tube. Again, a filthy job. Once you've done all that, set the carbs up as per the manual. I drop the needles one notch as I run 30:1. Make sure the floats are correct and carbs are balanced. The 2C always requires choke to start - hot or cold. Cheers, Tony

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    Senior Member DenH's Avatar
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    ive used caustic soda on two strokes,its quite effective.
    when i was young i was very indecisive,now im older im not so sure.

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    Junior Member Towerdave's Avatar
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    Quote Originally Posted by bantam1949 View Post
    Hi, You won't get the bike in tune with a blocked silencer. The cross-over tube means the blockage will affect both cylinders. Yes, the silencers can be dismantled. Take off the end caps and then use a slide hammer set up to attach to the end of the muffler assembly inside the pipes. A few knocks and it will come out. Pull the assembly apart and clean it with a wire brush. It's a filthy job. Some people clean the inside of mufflers with caustic solution but I have never tried it. Too hard, too dangerous. With the 2C a stiff wire brush attached to a long wooden dowel will clean everything from inside the silencer tube. Again, a filthy job. Once you've done all that, set the carbs up as per the manual. I drop the needles one notch as I run 30:1. Make sure the floats are correct and carbs are balanced. The 2C always requires choke to start - hot or cold. Cheers, Tony
    Thanks Tony. Yes it was a dirty job but the silencer came apart relatively easily. Now for the tuning bit!

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