Bandit running on 3 cylinders

**erik** · 12th August 2008, 23:07

the bandit is running on 3 cylinders and smoking a bit. I've checked the exhaust temps with a wet rag, the #4 exhaust (right most) is cooler than the rest, the other three hiss, it just slowly evaporates the water.
I've tried changing the plugs, I've tested the coil's resistance (both similar). I've cleaned the float bowl and jets of the carb for that cylinder, they seemed clean anyway.

I think I last checked valve clearances around 10,000km ago, the manual recommends checking them every 6000km (but last time I checked them at a larger interval, they were ok). So I'm planning on draining the coolant, pulling the rocker cover off and checking the clearances.
I checked the compression, all the cylinders were about where they were last time I checked it (around 110psi which is admittedly low, but I'm not sure how accurate my gauge is).

The only thing I can think to look for is to see if the valve clearances might have gone way off, but then wouldn't that affect the compression test?

Maybe I've missed something in the carbs? I had a look at the diaphragm in the #4 carb today and it looked ok.

I think this might've started at a trackday earlier this year. I remember the engine sound changing at one point and finding a piece of broken exhaust mesh stuck in the end of the muffler, so I thought the difference in engine noise was because of that, but maybe something else has happened inside it?

Any ideas?

**skidMark** · 12th August 2008, 23:29

It's ya carbs buddy, if you can pick me up in a car and take me to your place im happy to help you out...

**El Dopa** · 13th August 2008, 19:47

Originally Posted by erik

Any ideas?

Erik, when exactly this happened to mine, it was the carbs.

**erik** · 13th August 2008, 20:21

Thanks for the offer of help, skidMark, but I'm only after ideas at the moment. I enjoy doing the work myself.

I hope you guys are right and it is just the carbs. I'll have to pull them apart more thoroughly and have another look after I've checked the valve clearances.

**riffer** · 13th August 2008, 20:35

I've had this exact problem.

Turns out I'd broken the jet needle in #1 carb.

The bike only ran on four cylinders on full throttle.

Can you see the jet needle?

**erik** · 13th August 2008, 21:22

Yep, it looked ok when I dropped it on the floor after pulling the carb diaphragm and slide out.

It was lucky I didn't lose the plastic spacer that sits on top of the circlip (there's two plastic spacers on these needles, one above and one below the circlip, the top one is a seat for the spring by the looks of it).

It'd be nice to have a part time job instead of full time so I had more time (and energy) to work on my bikes.

**FJRider** · 13th August 2008, 21:33

Open the drain on the carb and see if fuel comes out, Shit in the line or fuel float stuck...??

**skidMark** · 14th August 2008, 05:07

My offer still stands.

**Squiggles** · 15th October 2008, 21:50

ever fix this?

**erik** · 16th October 2008, 07:08

Yep, I'm now using it for commuting again.

I cleaned the #4 (right most) carb again, this time pulled the emulsion tube for the jet needle and the small air jets from the carb throat out when I cleaned it (in addition to the other jets). Also cleaned the air filter, balanced the carbs and adjusted the idle mixture screws.
I think it must have just been some crap in the carb, but didn't see anything obvious in there apart from a small amount of gunk around the bottom of the emulsion tube, but I think that was sitting in a dead spot not blocking fuel flow. I checked the valve clearances and they were all within spec. (although a couple were getting tight). In the bandit carbs, there's a rubber bung that blocks the bottom of the tube for one of the jets, when I pulled the carb apart, I noticed it wasn't sitting in there properly, but I'm not sure if I'd bumped it pulling it apart or not.
If you want to borrow my compression gauge, let me know.