Quote:
Originally Posted by NzBrakelathes
This is something almost no one (in my limited experience and my self included) knows anything about.
This comes up over and over and over again when I sell my kits and also others who public;y show stuff.
I understand it in a basic form but I couldn't tell you or even be sure what I have is 100% correct.
Most Hawk folk and other prob make the bike 'run ok" and that is it - hence I have several jets in my kit as that seems to cover most peoples expectations.
Reality the day and temperature/weather conditions of the day will technically want a slight rejet and that is what road racers on old bikes do - they have a whole chart with known settings jets and worked out pretty much the scale when the air temp or conditions of a day change to jet it the best they can for THAT condition on THAT race at THAT specific temp/conditions.
Jets typically increase by 0.01mm on jets or there abouts
New Hawk/TBR7 or any Chinese bike I suggest something like stock pilot to 40/42 and main jet 105 and needle 1 lower then center as a starting point (screw out 1.5 to 2 turns) and THAT is a starting area only not the true final end.
Can take several hours to get it right and that's assuming you know what your'e doingish. if you don't then its a long learning curve.
My bike I have slightly wrong as main is 105, pilot drilled 45 clip, 1 lower ) then center, screw 1.75 turns (best idle), but I never ride that bike so I can't be bothered as I have other things I wanna do (it stumbles at 7500 RPM and suspect a little rich)
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You will not be far wrong if you accept that the factory needle jet and needle is correct. This may change in the future if or when emission regs get tougher, but for now they took the easy way out, i.e. leaned out the idle and the main jet in order to pass....ARH
