Bandit 600, Throttle Lag up to 6K.

[benallenuk]

Hi guys, have recently bought a new bike, Bandit 600 N, it’s a 2000 reg (y).  Its winter in the UK at the moment, if that mkes any difference.

I’ll describe the symptoms and the work ive done so far.

Modifications from standard: Scorpion straights through exhaust.  Recently changed an old/dirty air filter for a fresh new one.  Both standard.  No mods to airbox, carbs engine etc.  

Symptoms:

1. When you blip the throttle you get a slight choking before the engine pick’s up.  Was worse before balancing the carbs.
2.  When you quickly fully open the throttle when riding, there seems to be a hesitation to acceleration, and then all of a sudden at roughly 6k RPM there is a sudden increase in power.  I’m not quite sure if this is a flat spot, or just the same amount of time, each time for the engine to recover from whatever is causing a problem.
3. Basically a bit of a handful for slow riding.

Work done so far to try and solve problem.

1.   Changed Air filter for standard new
2. Removed Carbs and flushed out jets etc with carb-cleaner.  Didn’t remove jets just blew through.  Needles nice and smooth, no wear marks.
3.  New fuel filter
4.   Checked plugs, HT-Leads, Coils, all look as new.

Any suggestions would be greatly received.  I’m thinking a previous post about shimming needles may be a worth while job.

[solman]

I've had bad plugs with no visual problems.  Try a fresh set of plugs.  Another problem may be that it is running too lean.  If you have an aftermarket pipe and no jetting done, that may be a possibility as well.

[pmackie]

Sounds like its running lean...

All the Bandit's seem to be lean from the factory, my 02 600 is lean, and I run it from 1500 to 8000 feet.

In the winter (higher density air) at sea level, with a new air filter and a lower restriction pipe, I would expect it to be even leaner.

So...
1. Drill out the air screws and adjust them (don't always need a richer pilot jet, but some jet kits come with them)
2. Shim the needles
3. Install larger Main jets

or...purchase a jet kit and install it.