carb settings/ jetting

[arran]

what are the standard jet sizes for a 2003 fzs600?
also how many turns out for the mixture screws?


my bike has aftermarket downpipes and is really fluffy/ spluttery below 5000rpm but i'm not sure if this is causing the issue or whether someone has being messing with the jetting already.

[Dead Eye]

First thing to check is the carb balance before fiddling with the jets / mixture. Your symptoms suggest they may out of balance in my opinion

If you like doing your own work, then its worth investing in something like a Morgan Carbtune as it pays for itself after one use if you would otherwise have gone to a garage

[Paul]

Personal experience with Motad header pipes:
If you change your exhaust headers make sure the restrictor point of the new set is similar in overall opening size to the original set.
The original outlet is: 35mm – 43.5mm external at its most restricted point.
I’m not sure what the wall thickness is but I reckon it must be somewhere between 1.0mm and 2.00mm, my original pipes are still in good condition and I was loathe to saw them up to find out.
In any event the Motad replacement header system outlet pipe is has a clear open area of 1364sqm.  Whereas the original outlet is restricted to somewhere between 962sqm and 1075sqm.
When I fitted the Motad headers the power band almost evaporated and a gas analyser showed it be running far too weak, this being supported by the plug colour.
A further test was done by a lazer temp gauge on the exhaust clamp bracket of both original and new pipes and this showed the exhaust gas temp had risen.
To solve the issue the Motad pipe was sleeved down first to 1075sqm which improved things no end, and finally down to 975sqm, which seems to be better.
Plugs were checked and exhaust gas analysed and the results were as good as I could get them.

[arran]

dead eye. going to clean and balance the carbs one evening this week as its on my list of possibles.
paul. where is the restricter point in the pipe? at the collector?
while i have the carbs off i want to check the jet sizes so what are the standard jet sizes? and what is the mixture screw setting?

[Dead Eye]

I believe the standard mixture setting is between 2 and 2.5 turns out

I think the jet sizes are in the stutter bible but that's far too long to wade through - I'm sure someone will be along with the answer

[arran]

sorted.
new plug caps and carb balance did the trick.
still a  bit uneven on tickover but pulls cleanly right through now.

[Dead Eye]

Glad to hear it

Its worth keeping on top of the carb balancing usually about once a year as they do get out of sync over time