Bandit GSF250VS carb service

[scary]

My Bandit's got a flat spot in the throttle and has lost a lot of power as well as top end. From reading posts here, I guess it needs new emulsion tubes and needles. I'm confident I can do this (with a liberal dose of KB wisdom) but I don't know where to order the bits from and what other bits I will need, or would be wise to, replace at the same time. Can anyone advise? From comments on this thread I will need some O-rings as well.

The second issue I have is what type of carb I have on my Bandit. There's some pics of the patient on my blog that I can't post here for some reason: http://drchrispook.com/2016/01/02/ra...s-carburettor/

My bike is the G77A ('95 onwards) and I can't find any information on the carbs. I've got the workshop manual for the G74A Bandit ('89-'94) and this says they have Mikuni BSW27 carbs, although one forum post says it might have BDST30 carbs. Can anyone advise me of the carb model for my bike and a source of reasonably priced parts?

[F5 Dave]

Well the first thing to do is strip them down, clean and examine. It may be as simple as blocked jets (common in Suzuki's as the tanks rust silt ) or torn diaphragms. Whilst emulsion tubes are out check them for ovality.

Bright torch, don't poke wire through the jets.

Dead giveaway is one or more sparkplugs will be black.

[scary]

Thanks for the reply, Dave. If I strip the carbs down won't I need to replace gaskets when I reassemble it? I want to do this in one go so I wanted to buy all the bits and kits before I start taking it apart. Or am I being overly cautious? Never done this before.

[F5 Dave]

Never had to replace gaskets before. Go carefully and ask yourself if something doesn't budge, why not? You only learn by doing. Diaphragms you can often check by just blowing into the large hole at the top of the bell mouth. The slide will move up then lower.

Its the lower part the petrol goes into and hence the rust silt etc clogs the tiny jet holes.

[scary]

I've found some amazing pages out there with loads of detail:
http://www.dansmc.com/carbs.htm
http://gstwin.com/carb_work.htm

I'm going to have a go at pulling the carbs off in one piece and looking under the diaphragms. According to this - file:///media/chris/data/Chris's%20stuff/~%20interesting%20stuff/Bandit%20GSF250VS/exploded%20carb,%20part%20numbers%20and%20pricing. html - I should be able to get the needle jets and jet needles (names! ) out and have a look at them without going any further in. These are the emulsion tubes, right? I am so confused.

[F5 Dave]

Yeah the brass tube the needle slides in is the needle jet, or emulsion tube due to the holes in it's side.

To get the carbs out will be a bit of faffing with cables etc but you'll get the hang of it. Often it is easier to spend the time removing for instance the airbox screws to wiggle it back a cm to get some more space. Take your time and walk away if you feel the need for a whopping big hammer. Zen a bit and return and look again.

Next time it'll be dead easy. Some bikes are real easy anyway.

[Swivel]

How did you get on