Cleaning & Servicing Bandit Carbs (works for others too)

[Pete.]

With so many of these bikes on the road and quite a few people reporting poor starting/rough running problems I thought I'd stick up a run-through on how I service the carbs on my bike. Mine is a Mk2 600 but the Mk1 isn't that much different.

Firstly, remove the carbs from the bike. My bike is used in all weathers so they are naturally mingin' with road dirt and other crud.

https://peterrimmer.myby.co.uk/images/carbsdirty1.jpg

I always clean carbs with a trigger-gun of wd40 and an airline. Does a nice job of shifting all the crud even from inside the springs.

https://peterrimmer.myby.co.uk/images/carbsdirty2.jpg

I also put a tie-wrap on the quadrant to hold the carbs open and use a cut-down paintbrush to clean the inside of the throttle barrel

https://peterrimmer.myby.co.uk/images/tiewrap.jpg

Now time to strip off the bowls, of course there's always at least one stubborn screw. They are soft and will round off even if you use a JIS screwdriver.

https://peterrimmer.myby.co.uk/images/bowlscrew1.jpg

No matter, just use a small hammer to flatten the top

https://peterrimmer.myby.co.uk/images/bowlscrew2.jpg

Whack in your screwdriver

https://peterrimmer.myby.co.uk/images/bowlscrew3.jpg

and out comes the screw easily

https://peterrimmer.myby.co.uk/images/bowlscrew4.jpg

Now my float bowls are perfectly clean but the bike's been running rough, so on with the service. Strip out all the jets and emulsion tubes

https://peterrimmer.myby.co.uk/images/bowlinnards.jpg

Now to check out all the ports and passages in the carb body. Start with the choke (more properly named 'fuel enrichment circuit). Here is where the choke pulls fuel in from the bowl. It's quite low down so can be prone to getting blocked.

https://peterrimmer.myby.co.uk/images/choke1.jpg

Fuel passes along that tunnel you see in the pic above and up into the back of the plunger cavity

https://peterrimmer.myby.co.uk/images/choke2.jpg

When the plunger is lifted, air is drawn from the carb top across that port and this pulls fuel out of the bowl and directly into the intake. To test the circuit either use a can of carb cleaner with a straw and blast it through the choke intake or do what I do and dribble a little wd40 over the hole

https://peterrimmer.myby.co.uk/images/choke3.jpg

And then blast air into the plunger hole to see if it blows the wd40 off. If it does, the circuit is clear

https://peterrimmer.myby.co.uk/images/choke4.jpg
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Pete.]

Now for the idle circuit. Probably the most problematic of all the carb systems because of the small amount of air and fuel under control. The idle mixture is controlled by the idle air bleed screw (needle jet). This controls the flow of air over the pilot jet, and thus the amount of fuel delivered at idle.

https://peterrimmer.myby.co.uk/images/idle.jpg

Just below that you can see a brass plug which covers three little drillings, which we'll talk about later.
air is drawn into the idle circuit here

https://peterrimmer.myby.co.uk/images/idle1.jpg

And flows this path, over the pilot jet drawing fuel from the bowl

https://peterrimmer.myby.co.uk/images/idle2.jpg

Before passing through the cavity with the brass plug and into the idle air bleed screw.

https://peterrimmer.myby.co.uk/images/idle3.jpg

Opening that screw out draws more air through the system which in turn draws more fuel up from the bowl making the idle richer.
Now to that brass plug. Under that plug there are three little drill-holes. They are there to increase airflow in the idle circuit just as you open the throttle off of idle. If these are blocked, you will get a huge stumble coming off idle onto throttle.

https://peterrimmer.myby.co.uk/images/drillings01.jpg

I ground a jewellers screwdriver to a thin point and bent the end to make a tool for poking out the dirt. That and a blast of carb cleaner is enough to clean them out.

https://peterrimmer.myby.co.uk/images/drillings02.jpg

In the interest of science I sent an old Fazer carb to the butchers and milled a chunk out of it to show the circuit. you can see where the fuel-air mixture comes into the chamber under the brass plug then on to the needle jet.

https://peterrimmer.myby.co.uk/images/drillings03.jpg

https://peterrimmer.myby.co.uk/images/drillings04.jpg
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Omega]

Good timing! I've started taking my ZZR600 apart to have a go at getting it running again. One of the first jobs on the list is cleaning the carbs and I've just been googling for guides.

If you want to continue with your picture guide and do a head gasket replacement and piston/valve check feel free .

Thanks Pete.

[Pete.]

Last thing to do is set the float height. On Bandit 6 the float height is 17mm +/- 1mm.

Make a gauge from card

https://peterrimmer.myby.co.uk/images/floats1.jpg

https://peterrimmer.myby.co.uk/images/floats2.jpg

And use it to set the floatsas shown here. This should be done with the carbs tilet far enough to seat the needles but not to depress the plunger on top of the needle

https://peterrimmer.myby.co.uk/images/floats3.jpg

And that's it! Carbs all re-assembled and ready to fit back on the bike

https://peterrimmer.myby.co.uk/images/assembled.jpg
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[mudcow007]

Fantastic, cheers for this pete....

i know what im doing tonight, tomorrow an the weekend

[gavcarter]

Awesome little guide!

I used to throw mine in the dishwasher with plenty of fairly liquid and temp set as high as it would go -before dis-assembly made a lovely job of cleaning it up - just had to re-grease springs etc.

Funny how kitchen appliances mysteriously stop working when the mrs is out isnt it?

[mudcow007]

Pete, how do you get the brass plug out!?

all i seem to be doing is digging into it.

i have cleaned the rest of the carbs though

cheers ears

[Pete.]