Dinger1967 Posted July 2 Share Posted July 2 Hi guys, cleaning the carbs,and looked at jet sizes. I noticed the mains are 85,and pilots are 35. Mk1 600 bandits use same 32mm cvk carbs but with much bigger mains at 98/100s. Info is very rare on these models but I found some obscure jap site that had diagrams,original part numbers,and indeed it was an 85 mains. I see from a previous thread that the Inazuma runs 105's (?)...same engine,but not 100% sure same carbs....probably different airbox,he said they were 32 cvk,but often I see them quoted 34mm on spec sites. It seems strange the jets smaller than 600 when it shares same carbs,airbox etc....any thoughts would be appreciated Quote Link to comment
DAZ Posted July 2 Share Posted July 2 (edited) The jets could indeed be smaller as the higher airflow speed through the carb (as the 750 is 25% larger than the 600) would presumably create a larger pressure drop across the jet and cause more fuel to flow through at a higher rate I hope that makes sense , it does in my head but maybe I've not explained it clearly .... If not hopefully someone will come along and do a better job The jets could also be different to the 750 Inazoooma if you're came from a market that has different restrictions e.g. Japanese domestic market , Switzerland,France Edited July 2 by DAZ Quote Link to comment
DAZ Posted July 2 Share Posted July 2 The jets could indeed be smaller as the higher airflow speed through the carb (as the 750 is 25% larger than the 600) would presumably create a larger pressure drop across the jet and cause more fuel to flow through at a higher rate I hope that makes sense , it does in my head but maybe I've not explained it clearly .... If not hopefully someone will come along and do a better job The jets could also be different to the 750 Inazoooma if you're came from a market that has different restrictions e.g. Japanese domestic market , Switzerland,France you could always try the bigger jets and see if it releases a bit more hp if not then you can always put it back to std Quote Link to comment
Dinger1967 Posted July 2 Author Share Posted July 2 Hi Daz...thanks for reply. Gsf750 is a JDM bike,so is restricted to77hp/ 180kmh...but as some other guys helped out,it appears to need a 1.5k ohm soldered into pink wire going into ecu... ....but I've also checked slides do indeed go all way up. Needle has different number compared to 600...N2NQ on 750,I think 600 has N1NQ ....but I have no idea what difference this makes ? Quote Link to comment
TonyGee Posted July 2 Share Posted July 2 the inazuma 750 and 1200 both use 32mm carbs as used on the B600, i used a set of B600 carbs on a 1200 bandit engine and used an airbox, the carbs where bog standard B6 with no jet changes and it ran perfect. was expecting to change jets but no need, go figure 1 Quote Link to comment
DAZ Posted July 2 Share Posted July 2 (edited) The carbs work in different sections doing different jobs , so to speak this is a rough guide as to how I understand it ..... The pilot jet controls low speed running say up to 3.5- 4000rpm The needle which slides in and out of the main jet and emulsion tube controls mid range say 3.5 - 9000 rpm the needles vary in profile as a way of tuning the amount of fuel they let through the jet e.g. The fatter the needle the leaner the mixture so different models have different needles to suit their individual requirements The main jet controls high speed running say 9-12000 rpm , because by this point the needle has lifted high enough that it no longer effects the mixture This is a very basic explanation of how the carb works and proper carburettor tuning is almost a black art ... One I wish I possessed ... Edited July 2 by DAZ Quote Link to comment
Dinger1967 Posted July 2 Author Share Posted July 2 Cheers guys...a few pointers...looks like a bit of experimentation in order ... Quote Link to comment
TonyGee Posted July 2 Share Posted July 2 36 minutes ago, DAZ said: The carbs work in different sections doing different jobs , so to speak this is a rough guide as to how I understand it ..... The pilot jet controls low speed running say up to 3.5- 4000rpm The needle which slides in and out of the main jet and emulsion tube controls mid range say 3.5 - 9000 rpm the needles vary in profile as a way of tuning the amount of fuel they let through the jet e.g. The fatter the needle the leaner the mixture so different models have different needles to suit their individual requirements The main jet controls high speed running say 9-12000 rpm , because by this point the needle has lifted high enough that it no longer effects the mixture This is a very basic explanation of how the carb works and proper carburettor tuning is almost a black art ... One I wish I possessed ... and all them stages overlap each other for smooth throttle response 2 Quote Link to comment
DAZ Posted July 2 Share Posted July 2 27 minutes ago, TonyGee said: and all them stages overlap each other for smooth throttle response Exactly Tony, as I say it's a rough,basic guide as to how motorcycle carbs work ,no mention of air bleeds and power valves accelerator pumps and stuff some have going on it really is a mystical art and those that can do it properly have my utmost respect 1 Quote Link to comment
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