Hi,

I'm thinking about cleaning the carbs on my bike to try and rule them out to the problem I have. I've never done it before and was just wondering how hard/easy it is? And if I do take them apart to I need to replace anything i.e. Mounting Rubbers etc.

Thanks

I've recently done this to the carbs on my NC30, having never done it before and it wasn't too bad - the main thing is that they are a pain to get back on; it's fiddley and the screws for the clamps are in near-inaccessible places. First turn your fuel tap off and remove the tank, then the airbox, filter and the plastic plate that it all sits on. Then you have to un-plumb the carbs and loosen off the clamp screws and just lever them off the engine. Then tip them up (outside) to drain any petrol out of them.

Next I took off each float chamber cover and had a look inside for build up of any crap, corrosion, blockages and general gunk that shouldn't be there. I unscrewed the main jets in each carb, sprayed it with WD40 and blasted it with an air line. I also used WD40 and some brake cleaner on the rest of the carbs, spraying it on and blasting it with air to blow out any crap (mine were in pretty good condition). I also tested the floats to make sure they sprung back properly. If you press the floats with your finger they should move down and come back to their original position on their own - if they return slowly or stick then you may need to replace the float springs - i changed two of mine because they were a bit tired. The float springs are diamond-ish shaped and look like they could be part of a ladies necklace (s'what i thought anyway!) and the floats hook into them - I can't find a picture of them though. The floats are held in place with a metal pin that you can push out with the right tool and you get the pin back in the same way. I reckon an air line is a must because after applying petrol / WD40 etc you can blast it off and any crap should come away under the force of the air. It's also worth checking the needles and cleaning them too. Remember to block up the inlet for each cylinder with some scrunched up tissue or similar to stop anything getting in, and stick some tissue in the rubber stacks to block them up while they're off too.

When it came to putting the carbs back on it was a hassle because it's really fiddly. I cocked mine up first time as couldn't get a proper seal on one of the cylinders. I think I tried getting the front two carbs sealed into the subber clamps first then with a bit of force got the rear two to seal and tightened up all the screws. It's useful to have a torch to locate the screws - it took me a while to find one of them purely because I couldn't' see it. Once the carbs are back on then put the airbox / filter etc and tank back on and Robert's your mother's brother etc...

Hope that helps. I'll try and dig out some pictures I took of my carbs off, being cleaned etc and post them on here.

Labelled carb parts...

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As above really.

Make sure your have pleanty of old rag / newspaper to soak up petrol.

The carbs come off as a complete unit if you unscrew the clamps on the rubbers that join them to the engine.

Pay attention to throttle / choke cables as they'll need to be released from the carbs in order to get them off the engine.

Invert the carbs and remove the float bowl(s) and clean the internals by removing the Jets and the Jet holders, blast everythign with carb cleaner and blow compressed air through all passages to clear debris. Do not be tempted to use a pin to clear any blockages as you'll alter fueling if you widen any passageways.

Work only on 1 carb per time to avoid mixing up component, jets and emulsion tubes are different between carbs.

With the carbs the right way up remove the top(s) of the carbs one at a time and check the rubber diagphram has no holes and the slider / needle are in good condition. Again blast and passageways and check everythings clear.

With the carbs re-assembled make sure all the linkages move ok and the springs are greased etc.

Re-fit carbs to engine and make sure choke / throttle cables operate properly.

Check carb synch with vaccumn gauge and adjust accordingly.

Oh yeah - forgot about the throttle and choke cables. Neosophist's just managed a more succinct explanation, rather than my rambling! I'd say pay attention to his reply

Thanks for your help. Not sure when i'll do them though.