No 3 and 4 carbs leaking from overflow pipes HELP

I've recently bought a 1986 XJ900 which has been sitting outside for sevaral years. I can get it to run on two cylinders but nos 3 and 4 are non starters (cold to touch) - spark is good to these cylinders.

When running, fuel leaks from the overflow pipes of the carbs connected to the non running cylinders. I noticed that the diaphragms on both carbs had small pinholes so I plugged them with a dab of silicone as a temporary fix - they both still leaked. Tried swapping slides/diaphragm from good cylinder - still leaked. I noticed the needles look rather blunt so pehaps that is the problem. Tried tapping bottoms of carbs to free a possible sticking float. Didn't help! Can you get the float bowls off without pulling the whole rack? Looks difficult with limiited screwdriver access! Any help appreciated!

 

Sounds like the carbs should be pulled and cleaned, and at least a few parts replaced too.

Based on your description, it sounds like #3 & #4 are flooding their cylinders. Most likely a float adjustment to fix that, but I'd replace the diaphragms as well. Chacal has all the parts you'll need - he hooked me up with everything I needed to get my '82 550 going again!

Good luck!

 

your float needles are more than likely stuck, and or your float level is incorrect. You can clean your float needles by placing the portion attached to the float itself in carb cleaner, but DO NOT place the end with the rubber tip in it as it will degrade the rubber. I place the float needles standing up (rubber side up) in a carb top with a little bit of carb cleaner and work the needle with a small screw driver until all play is restored.

 

Thanks, is it possible to get the bowls of the bottom of the carbs off without pulling the whole rack off?

 

adrian,
I doubt if you hav room to take bowl without carb off the bike, you may bugger the heads as they would be pretty tight. Its not that hard to get the carbs off and do a clean job..i just finished my Maxim X mikuni carbs and ready to mount tommorw as i painted the engine block same time..check the below link with pictures of a fellow xj`er..it will help you.Goodluck
http://www.xjbikes.com/Forums/viewtopic/t=3690.html

 

What are overflow pipes?

 

Here are some pics of #4 carb Mikuni BS36. In the middle of the carb, the white plastic pipe with the black hose attached is the overflow pipe. The metal pipe just below and to the right of it is the fuel supply pipe.