Carburettors 101 – Suzuki Intruder VS1400

If your bike has been sat for a while, you may have an issue getting it started, and if it does start, you may have performance issues including popping and backfiring. A lot of the time, this will be because the carburettors are dirty on the inside because they weren’t drained of fuel with the petcock closed and if it’s been unmoved for a long time in this state then gunk will build up on the inside and won’t allow fuel to pass through.

Once you’ve got the carburettors out of the bike, and onto the bench, we can check the cleanliness. Do not soak the whole carb in carburettor cleaner – If it gets into the diaphragm on the top, you’ll destroy your carb.

Firstly, we want to take the float bowl off as this is going to give us a good idea of the condition of the carb, so grab a screwdriver and undo the four screws holding the float bowl on. Once you’ve got the float bowl off, there are a 4 main basic things you need to take notice of:

1. The Gasket – You may want to make sure that you’ve got a spare one on hand before you take the float bowl off, as it may have perished if you haven’t changed it in some time.
2. The Float – This works the same way as your toilet cistern does. When the level of fluid inside drops, it enables the flow of fuel from the tank to enter the float bowl and once it rises to a certain point (because it floats on top of the fuel) it cuts off the supply. If this gets damaged in any way, it may allow fluid to go inside and not float, therefore allow too much fuel in so the bowl continually floods. Also make sure that the float can move freely, otherwise it won’t be doing it’s job.
3. The Main Jet – There’s a little brass nipple with a hole in the middle which can be removed with a flathead screwdriver. This is your main jet. The hole is a certain size which is rated to the carburettor, so if you hear about people “jetting” their carbs, they get a new nipple with a bigger hole which allows more fuel to come through. The important thing to do with your jet, is to check that there is no obstruction on the inside by trying to see through it. If you can’t see through it, clean it! Take a pipe cleaner or some compressed air and remove any dirt or debris blocking the hole. Once it’s clean, make sure you pop it back on, with the washer.
4. The Pilot Jet – This jet is next to your main jet and requires a smaller flathead screwdriver. Undo it, tip it out and make sure it’s clean and that you can see through it.

Make sure you put it all back together correctly afterwards, and take your time. If it does like really dirty inside, consider getting it ultrasonically cleaned. Keep in mind that this is not a comprehensive “how-to” but should give you a good base to get you started and answer the majority of questions for first-timers. Just remember, you need three main things to get a bike to run: fuel, air and spark and if you don’t have one of those three things, your bike isn’t going to run.