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Colour Tune

Discussion in 'Supersport (1974-2007)' started by Lumbux, Dec 26, 2020.

  1. So I'm hoping by the stroke on midnight, that the 900 will no longer be spread over a wide area. So next thing will be firing the old girl back up. I spent many hours titivating the 750 I had, but just wondered if anyone had used the colour tune thingy that I have seen on the net, and if its worth spending out on. Both cards have been rebuilt, with new internals, sparks plugs, so I'm hoping the running gear is in the best it can be, and a little help tuning up will welcome.
     
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  2. Put it on a dyno.
     
  3. I would but the local one is very wired, last time I asked they would tell me whdn they could do it, price or even an hourly rate, was like they didn't want the work
     
  4. He seems to think they’re ok, I’m sure my dad used to use a contraption like this back in the day.


     
  5. Yes, you will need a more old school set-up. Is there anyone who tunes classic race bikes near to you?
     
  6. Paul, I doubt I would bother with a Gunson Colortune on a bike with the stock Mikuni carbs, because of the way the carbs work......everytime you blip the throttle to above 2500 rpm you go from pilot circuit to main jet fuelling.

    With your SS I trust you know if you have a Dynojet kit fitted or not....that's the first thing I would establish.

    However, whether with a Dynojet kit or stock jets and springs etc, I would work with the recommended settings and correct jets; and pilot screw settings.

    Same applies to the float measurement too......thereafter you can tweak it a bit if necessary.

    Gunson Colortune won't really help you balance the carbs, either.....unless you have two Gunsons.....and then you need to be able to judge the colour you see between each side......and that maybe wouldn't be right either.

    Gunsons worked well on my Guzzi Lemans because of the Dellorto carbs, but balancing was done by ear and a mirror mounted where the seat should have been so I could stand at the front and look at the slides in the mirror while I adjusted the carbs.

    AL
     
  7. Hi - pity your local dyno shop couldn't/wouldn't look at your bike. As a matter of interest, who was it - i'm thinking of having my 1198S done [PM me if you prefer].
     
  8. Thanks Al,
    No DJ in these carbs, totally standard, rebuilt with all new internals. Float heights are set to 14mm, haven't set the mixture screws yet, but both are free and have also been replaced. I have 2.5 turns out in my head, nit sure if thats correct or if thats from the 750? I have carb balancing gauges for the balancing, when I get that far. I'm basically trying to get the bike back to one piece ready to move house, then I hope to get her running and ready for the summer, cant see next year being alot better for me so will be putting plenty of miles on her, if I can.
     
  9. 2.5 turns out would be a good starting point but don't expect them to be exactly the same amount.

    Also, I have noticed in my files that for the 900 stock settings, the main needle clip position can be either 4 from the top or 3 from the top, depending on which size idle jets and carb type you have.

    If you have B67 carbs the idle jet should be 42.5, so the clip is 4 from the top.

    But if B97 carbs the idle jet should be 37.5, so clip is 3 from the top.
     
  10. Its set to 4 Al, no idea on the idle jet size so will have to play it by ear. I've decided to leave it dry now until I've moved house, and with all the work to do on the house will hope I can fit it in. The most annoying thing is I've just realised that the two jubilee clips from the air box to the carbs are missing. I can't remember taking it to bits as that was the week the wife left, so my head was a mess, but I've got every other part so can only assume they were missing on disassembly. I believe that they are avaliable on ebay so will have a look.
     
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