I've just bought a Yamaha FZR250 to restore over the winter/to help me learn more about bikes. I got it started on three cylinders when I first got it but it needs a new battery, airbox and ignition coils, so whilst waiting for them I decided to clean the carbs. The cleaning side of things was fine but when I went to take the carbs out I noticed several tubes that weren't connected to anything and I was wondering what they are?
I understand pretty much how carbs work and I think the two tubes closest to the camera are overflow? But those other two which look like they should be connected to something I'm not so sure about?? Any help would be great.
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The 3 main connections would usually be: Fuel in, overflow fuel out, and vacuum (from inlet manifold). The two outside tubes may be the vacuum connections, as I think the drain offs are from the little nipples on the bottom (casting).
I did see several articles on Mikuni carbs, so worth a Google.
Ok thanks guys, when I bought the bike none of them were connected to anything? Should the vacuum or drain off's be connected to anything? I'd guess that the drain offs should have a tube running to underneath the bike, so nothing drips directly onto the engine.
Sounds right 'WackoJacko'. The vacuum in the manifold (caused from the piston descending, will lift the fuel needle via the diaphragm in the carb, pulling more fuel into the fuel/air mixture. Result=SPEED!! lol The drain off's need small bore tube to run the petrol away safely under the bike.
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