View Full Version : TZR carb jets and needles

Nick Long - n/a
3-Apr-06, 10:30 PM
Trying to set up some spare carbs.

AFAIUI, Mixture can be adjusted by 3 means

Different profile needle

Changing jet size

Moving position of needle in the throttle slide

Does anyone know what is the actual effect of different jet sizes or needle positions? Ie, what %age change in fuel delivered do you get for a particular jet size, or for one step in the needle position. Ideally there might be a website somewhere with all this on it.



tonybroad - n/a
4-Apr-06, 07:56 AM
You're fast enough Nick

you don't need to worry your head about needles and jets and things, just run a nice big 280's jet with the needle raised to the highest and you'll have a nice reliable, well oiled engine http://hovercraft.org.uk/images/icons/smiley_icons/icon_razz.gif

p.s. over pitch the blades slightly, keep the revs and the noise well below the red line and give yourself tons of lift, you can never have enough of that can you


Nick Long - n/a
4-Apr-06, 08:43 AM
Thanks Tony,

But can we step back a bit, and you can put your lecturer hat on..

What's the standard jet?

What does 280 mean?

What effect does the change have?

What jets are available, and where?


tonybroad - n/a
4-Apr-06, 09:41 AM

not sure what the numbers actually means 230's are standard - i have a chart of size/cc/min which might help - TZR's use the hexmain jet shown on the chart


at the end of the day keep an eye on the plug colour

i've always understood that the needle position affects the delivery mid range - flat out the jet performs the same

Joe Milligan - n/a
4-Apr-06, 09:54 AM

Is it a VM carb? If so http://www.mikuni.com/pdf/vmmanual.pdf should help.


Nick Long - n/a
4-Apr-06, 10:42 AM
Tony, Joe,

Thanks very much; that is just the sort of thing I need.

(I don't think they are VM's but its close enough.)