Okay experts, I have looked at diagrams of throttle position vs what to adjust ect ect ect This site http://www.carbparts.com/keihin/needles_tuning/keihin_tuning.htm has pretty handy info also. 2 questions 1. How would one know if they were lean or rich in a certain part of the throttle??? 2. Why does it seem like the rev range has more to do with it then the throttle position e.g. runs good at certain rmp no matter what throttle position??? (or is that more to do with balancing? Or do u actually need really fancy equipment to do this?
Constant velocity carburettors do not have a direct correlation between throttle position and rpm. Please read this article http://www.litetek.co/docs/InSearchOfFreeLunch.pdf There is also another good article on my links page about tuning carbs http://vma.cape.com/~patrick/brm/carbkei.htm As for knowing what is rich or lean. Some people who have a lot of experience and/or product knowledge and can feel the difference. Those people usually don't bother writing about it. Some rely on exhaust gas analysers and they can be used with a dyno (very important with a two-stroke, see Fox's 60hp thread) or whilst riding, like the NGK AFX unit. Then there is also a plug chop but that is a black art and almost everything I have seen on the internet is incorrect. 2c worth: In any case, if I were preparing a track bike the last thing I would worry about is jetting (unless it is a 2 stroke). I would be spending all of my time and money on suspension and brakes. Watch some of Simon's videos. It is all about lap times and they come from corner speed. You can take 10 seconds off by riding better. If you have the perfect jetting you might gain 0.1 of a second. Choose one.
Why the questions mate, are you trying to do something or just interested in learning? For me, carbies are one of the most annoying and fiddly parts of a bike mate - they're extremely sensitive and precision engineered. In my mind it's always a toss up between throwing a couple of green bills at a professional to save the hassle or undergo the time and stress of messing with it myself. I think rebuilding carbies is a different skill from being able to tune carbies...
Think we have become more proficient with carbs by which...cleaning.....settings as per manual....access to part and so on, the tuning parts still remains an enigma. And people wonder why I like fuel injection??
Fuel injection is a fantastic invention. Now only if they made bikes that ran on EFI like they used to run on carbies...
A 19k revving inline 4 250cc with EFI would be sweeeet The newer Honda CB400s are EFI, though not 250cc
I haven't been on for a while, busy ect. Well Maelstroms comment was very true and interesting, I thought that I had done something wrong by the carbs until I put a full tank of gas into the bike and it started hauling. Maybe I need to check the fuel lines, fuel filter, tank ect to figure out why the rev's were messing up after putting everything back together. Seems the temperature (cold days/engine not warmed up ect) its not pulling the fuel it needs. @Stu learning and practical really. I knew the bike was running good before but I think all of us crazies cant help but mess with the carbs. Currently I am going off a few factors e.g. sound, feeling, how it was before ect. ATM with a full tank when she is warmed up it seems like the 2 full winds on the pilot jets is too much. But when its getting the fuel it needs the 15, 12, 12, 15 jets work wonders on full throttle with the uni filter and exhaust. Id still like to add that extra washer to the needles. But I will probably just end up putting the pilot screws back to stock, balancing the carbs and throwing some uni filter foam into the "sub air filter" and trying that. Its not really a battle for more hp, its just for the sake of it. Every aspect: power, breaks, suspension, gearing, ect ect ect ect feels like its own separate journey. I just want the power one out of the way next. I have already done a decent bit to the bike. Only a few things left really.
Honestly if I could go back in time and not buy the 60$ air filter I would have left it. But sometimes when you make one mistake you just have to see things through to the end. Its kind of like how you start off with one harmless lie for the sake of it, then it turns into this big deal but you just have to stand your ground and say the BIGGEST lies to see it through (I don't do that but you get what I mean =p)
