FZS600 3rd cylinder refuses to fire.

[OhHowOriginal]

So she's now on all 4.
I swapped carb 3 and 4s internals, just as a matter of elimination, I figured the worst that can happen is cylinder 4 stops working.
Cylinders 3 and 4 are a bit cooler than 1 and 2, with 3 being about 50C cooler although still at around 100c at the manifold, is this normal while all the built up shit exits? I've not taken her for a run yet either under load and such.
I think the carbs need a sync/balance as well but can't afford to get it done or buy the machine, if anyone's got a Carbtune 4 and would be willing to hire it to me for a couple of days I'd be eternally grateful, big ask though I know!

[stinkwheel]

If you have a long piece of clear plastic tube, you can balance carbs with a manometer. You make a long U-shape in the tube by attaching it to a board. The longer the better but I'd suggest a minimum of a metre long. Fill it with coloured water or ATF so you have the bottom of the U and about halfway up the legs filled.

This is a very sensitive pressure measuring device, the difference between the two columns measures double the pressure difference at each end in mm of water (or ATF).

Now find some way of clamping off one of the legs above the level of the water and attach one end of the tube to the vacuum stub on #1 and the other end to #2. Start the bike and get a steady idle then gradually release the clamp, you won't want to release it all the way or it'll fluctuate wildly with the vacuum pulses.

Adjust #2 until your columns are as near the same height as you can get. Then shut off and repeat with carbs #1 and #3. Then again with #1 and #4.

There is a risk if there's a big imbalance between the carbs that it'll suck the water or ATF into the carb. It's a small amount and is unlikely to do any harm although that pot might cut out until it clears. If you release the clamp slowly enough, you'll see if this is going to happen. If you got the static balance close, it wont happen.

This is effectively how the original (and best) morgan carbtunes work except they use a tube full of mercury instead of water to indicate the vacuum applied which is super heavy and so needs a much shorter column to work. In theory water is more accurate because it is more sensitive.
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