Bandit Alley
MODEL SPECIFIC => SUZUKI BANDIT 250 & 400 => Topic started by: PitterB4 on April 19, 2005, 09:46:38 AM
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I know that carb questions from novice wrenches like me get old but...
I've mentioned here several times that, when it's cold out, my B4 has a bad flat-spot in the 4-5k range. It got way worse when I went to my modded airbox (which I have since removed and gone back to the stock one). So, I figure I'm lean on my needles and raise them one notch. The flat-spot is gone but now I seem really rich - lots of tailpipe soot and it seems to bog every once in a while if it's warm and I'm cruising at that same rpm range (<1/4 throttle). So, my thought is that I could drop the two inside needles back down and leave 1 and 4 where they are - thinking that the inside cylinders don't get as much cooling and run hotter and therefor need to be leaner. Does that make ANY sense or am I way out in left field?
Before I do it, I'll pull the plugs and have a look at them but I was just wondering if this was at all reasonable. I'd love to get on a dyno with a tailpipe sensor too but I don't think I'll have an opportunity b/f the rally.
Any and all help is appreciated!!!!!!! :bigok:
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insides run leaner because of less air ne to be richer how about a washer for a half a needle raise.
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Rob have you changed your thermostat to get your engine running at a consistant temp.
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Rob have you changed your thermostat to get your engine running at a consistant temp.
Nope - what would you suggest?
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I've never heard of anyone who has staggered the needle settings (diff clips) before but I suppose that it might work. I can't believe that there would be that big of difference between your carbs. I would add a shim (half a step) to the leaner running cylinders and see what happens. It is common for guys to stagger the jetting (i.e. main jets). The inner cylinders run hotter and therefore can take a slightly larger main to make them run cooler. If your headers show a pretty even color, that would indicate that they are running about all the same temp. If you have a couple blue pipes and a couple gold pipes, I would consider doing what I suggested above.
Dave
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Thanks all... Dave - North American B4s have black coated pipes so, mine are all the same color :lol: .
An update: I rode to work yesterday. Going home (first 80 degree day of the year - 50 mile trip), it was really bad stumbling all over itself. I had to run a gear lower to keep the RPMs up above that range. Assuming the plugs all look about the same, I'm just going back to the middle postion and put-up with the flat spot when it's cool out. When I get back from the rally, I'll play around with the modded airbox, larger mains and different clip positions. Right now, I just want reliability for the rally.
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I just put in 110 mains, with middle clip position... I'll let you know how it goes if my petcock ever arrives.
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I just put in 110 mains, with middle clip position... I'll let you know how it goes if my petcock ever arrives.
What other perf mods do you have - exhaust, airbox, air filter, jet kit...?
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Full Yoshimura exhaust, K&N air filter and jet kit (I think, it was installed when I bought the bike had 97.5 mains in rather then 102.5 that where stock).
I haven't tinkered with the air box.
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On my old gsxr750, there is a flat spot in the 4K rpm, the problem turns out to be the worn emulsion tube, I have to keep dropping the needle to solve the problem, eventually I decided to junk the dynojet kit and put back the stock jets.