Running on two cylinders

[BAT]

Bike ran ok, but sat for two weeks then only the two left cylinders will fire. It used to intermittently lose a cylinder, maybe two before. Plugs were new, but wires were crap. Carbs were cleaned before.

I just put new wires on it, swapped the coil, cleaned the carbs again. Its got spark on every cylinder, but the far right carb doesn't seem to be pulling fuel and the one next to it backfires sometimes and def pulls fuel. The far right cyl doesn't seem to be sucking as hard either. Next thing I'm going to do is a compression test.

Any ideas?

[reelrazor]

Yeah. does it do this when it is on the sidestand? Have you tried it with the bike vertical?

[shredex]

My yzf600 is doing kinda the same thing...
got all spark...I cleaned the carbs pretty darn good...
but cylinders 3&4 are showing up cold....
fuel must be starved to them or something.

[haro504]

did you guys check the carb boots

[shredex]

thats a positive on boot checking

[haro504]

are the float bowls filling
compression check sounds right to me

[BAT]

The boots are all pretty cracked, but I'm sure this isn't an air/fuel problem now. The fuel problem was because the gas was low, not on reserve, and the fuel pump didn't stay on long enough to fill 3 and 4 with the bike on the kickstand. Hardly any fuel came out of the bowls. It started right up once I figured that out.

It wasn't running too smoothly so I took it out to see what it would do under a load and it would run great from 4-12000 rpms but lose a cylinder under 4000, then it started to cut out around 10,000. Then died. Still has spark but backfires a little when I turn it over.

I also noticed that the red wire going to the ignition key gets pretty warm, and the ignition box too. I'm wondering if the box is faulty. The bike ran fine when I parked it last time.

[BAT]

I took the ignition box apart and haven't found any water, severe corrosion, or burns. I sprayed it with cleaner and the bike fired up and ran for 30 seconds then sputtered and died. Wouldn't restart, not even a backfire, but still has spark and is getting fuel.

[BAT]

Nothin?

[shredex]

hmm....the best thing is when you have a friend that has the same bike and you can put like his cdi box onto your bike and if it runs then its the problem...

[reelrazor]

I took the ignition box apart and haven't found any water, severe corrosion, or burns. I sprayed it with cleaner and the bike fired up and ran for 30 seconds then sputtered and died. Wouldn't restart, not even a backfire, but still has spark and is getting fuel.

Well, unless you mysteriously holed all four pistons by letting it sit for a while....one of the above are NOT true. Since it is the two 'high side' carbs...I am thinking fuel supply....i.e. fuel filter/petcock screen..OR tank vent plugged.

I also noticed that the red wire going to the ignition key gets pretty warm, and the ignition box too. I'm wondering if the box is faulty. The bike ran fine when I parked it last time.

Heat in wires is always a resistance issue. This means bad connections..quite possibly inside the ignition switch.

[BAT]

The high side carbs were just dry because it sat for a while. They now all have fuel.

Just the red wire going to the switch seems to be hot, but doesn't seem to be doing it anymore.

[reelrazor]

The high side carbs were just dry because it sat for a while. They now all have fuel.

Just the red wire going to the switch seems to be hot, but doesn't seem to be doing it anymore.

Do they have fuel WHILE the problem occurs?

[BAT]

They do, but it doesn't seem to be much. It has trouble starting cold with the choke now, but if I choke the carbs by hand it fires right up. When it dies after running a while, it will only fire for a second if I choke by hand also, but won't restart. And its every carb. So I'm back to fuel again I guess. I can hear the pump come on, but even after sitting for 5 minutes and cycling the pump on and off, it still won't start, warm.

So I don't think its getting enough fuel. Its something that affects all cylinders, all carbs.
I get fuel all over my hand when I hand choke it.
Last time it died while riding and it just began to lose power until it quit, like it was running out of fuel.
Bowl vents are clear.