The GSXR1100 doesn’t get used much over winter unless we get some sunny days, the smaller GSXR750 takes up the slack during this time. Like most people these days who own classic bikes or classic cars you are probably seeing more and more carburettor issues as a result of higher ethanol in petrol.
Most people notice this when trying to start a car or bike which has been left idle for several months without draining the carburettors.
The entire fuel system from the petrol tap seals through to the float bowl assemble are usually covered in a residue which is left behind by the evaporated petrol. In some cases this may also include rust from the tank because the petrol and ethanol will separate leaving a thin film of water which rusts the inside of the tank.
Some people are lucky enough to escape a carb rebuild by using a fuel stabiliser or fuel system cleaner. I found a neat trick when it comes to cleaning out the float bowls by using a syringe full of fuel and seafoam forced in to the float bowl, which allows you to really extract and compress all the seals to ensure none are leaking and give everything a good clean.
- Drain the float bowls
- Purchase a cheap syringe that holds roughly the equivalent to your float bowl
- Lube the syringe plunger with some lightweight oil (petrol will make it stick in the syringe)
- Fill the syringe with fuel and carburettor cleaner
- Attach the syringe to your drain hose from your float bowl (you can buy some suitable size pipe for cheap on ebay)
- Unscrew the drain screw for the float bowl
- Using the syringe plunger force the fuel/carburettor cleaner in and out of the float bowl.
- When you have forced the fuel in the float bowl, at the point of resistance check for any leaks around the carburettors. On the GSXR1100 the weakness appears to be the float valve seal which leaks back past the main air jet.
- You can either leave the mixture in the float bowl and drain out after a good soak in each float bowl or extract immediately remove – it’s up to you 🙂
You could also try starting the bike or car with the mixture still in the float bowls but you run the risk of moving the debris further in to the fuel system. I have used a product called Seafoam a few times now and experienced good results, but I other cheaper alternatives are around.
Unfortunately I noticed a leak so the carburettors had to come of for a rebuild, so I decided to rebuild all of them as part of the process. It is a fairly simple process if you are careful but just remember not to rush setting your float heights, and also giving everything a good clean 🙂 Just a carburettor balance to do now and everything will be good again!