Running on 1 cylinder?

[Scott Dixon]

Gen 1, COPs fitted (from Morley’s). Bike has been garaged for 2 years. New battery was fitted and the bike started without any problems. 1 week later (battery still good) struggling to start, eventually starts (just) but is running on 1 cylinder. Any ideas? Bad fuel? Blockage, filter needed? shotgun needed?

I’ll be check for spark later today.

 

[MaxMidnight]

Given that it ran OK to start with then my gut feel is that the idle circuits are blocked but it could be any of the things you mentioned and you will need to work through them to establish what is causing the problem.
Assuming it has spark did you put fresh fuel in if not do so.
I'm surprised it will run on one cylinder but can you get it to fire on all four with some throttle i.e. once it is getting fuel from the main jet?
Does it run differently on or off choke?
Have you drained the float chambers to see if any contaminants come out; also check the fuel tank for corrosion.

Remember the first rule of diagnosis: Don't rely on gut feel rely on facts.

 

[Scott Dixon]

Given that it ran OK to start with then my gut feel is that the idle circuits are blocked but it could be any of the things you mentioned and you will need to work through them to establish what is causing the problem.
Assuming it has spark did you put fresh fuel in if not do so.
I'm surprised it will run on one cylinder but can you get it to fire on all four with some throttle i.e. once it is getting fuel from the main jet?
Does it run differently on or off choke?
Have you drained the float chambers to see if any contaminants come out; also check the fuel tank for corrosion.

Remember the first rule of diagnosis: Don't rely on gut feel rely on facts.

Yeah will eventually run (just) on 1 cylinder only, not running on all four at all, rear right hand side (number 3). Will only start with no choke now, tickled with a little throttle. It did start normally last week. Unfortunately I am in a bit of a rush as we are moving so I didn’t drain out the old fuel. I will now after draining carbs etc. Fuel tank looks fine. Thanks.

 

[Fire-medic]

Some profound fuel blockage? I think I'd use the open drain screws, and turn on the ignition so the fuel pump cycles on, and as the float bowl won't fill because of the open drain screws, see what comes-out or what doesn't come-out. Best would be to have 4 receptacles, or just do one at a time. Check the contents to see what drains-out. Any particulate material? Anything liquid (not gas) forming a 'lens' on the gasoline?

Try removing the fuel filter and blow through it, there should be nearly-no restriction. Drain it first, of course.

 

[Scott Dixon]

Some profound fuel blockage? I think I'd use the open drain screws, and turn on the ignition so the fuel pump cycles on, and as the float bowl won't fill because of the open drain screws, see what comes-out or what doesn't come-out. Best would be to have 4 receptacles, or just do one at a time. Check the contents to see what drains-out. Any particulate material? Anything liquid (not gas) forming a 'lens' on the gasoline?

Try removing the fuel filter and blow through it, there should be nearly-no restriction. Drain it first, of course.

Thanks, I’ll give it a go as soon as I can and report back.

 

[Scott Dixon]

Ok, (just for info I have spark) no fuel coming out of carbs with drain screw loosened other than the cylinder that’s firing? Fuel filter is old (new one on its way). Could it be the fuel pump or pump relay?

 

[CaptainKyle]

Ok, (just for info I have spark) no fuel coming out of carbs with drain screw loosened other than the cylinder that’s firing? Fuel filter is old (new one on its way). Could it be the fuel pump or pump relay?

If you are getting gas to one carb most likely the pump is working. Can you here the pump running ? It almost sounds like the floats are stuck closed .

 

[Scott Dixon]

The fuel relay tests ok and 12v is getting to the pump but now no noise from the pump! I pulled off the fuel filter and replaced it with a clear one and no fuel is being lifted. The pump is coming off.

 

[Fire-medic]

Once the system is pressurized, no sound will come from the pump until the fuel is consumed. As the float bowl fuel level descends, the float valve opens to flow more gas. The sound of the pump is masked by the engine running.

Be careful working with gasoline, as the vapors can travel many feet to a source of ignition, like a gas-fired water heater, or a furnace gas heater. A dry chemical ABC extinguisher may make a big mess, extinguishing an incipient fire, but left to spread, unchecked, the fire can cost you your home.

 

[Scott Dixon]

Once the system is pressurized, no sound will come from the pump until the fuel is consumed. As the float bowl fuel level descends, the float valve opens to flow more gas. The sound of the pump is masked by the engine running.

Be careful working with gasoline, as the vapors can travel many feet to a source of ignition, like a gas-fired water heater, or a furnace gas heater. A dry chemical ABC extinguisher may make a big mess, extinguishing an incipient fire, but left to spread, unchecked, the fire can cost you your home.

Yeah, thanks. Emptied and cleaned the pump. All ok pressurised the system again and still won’t start. No fuel in 1,2,3 fuel bowls.

 

[CaptainKyle]

Yeah, thanks. Emptied and cleaned the pump. All ok pressurised the system again and still won’t start. No fuel in 1,2,3 fuel bowls.

Time to get into the carbs !

 

[Scott Dixon]

Time to get into the carbs !

I think you may be right…

 

[MC Sencha]

Ah! I have a very similar problem. The bike passed biannual maintenance check last month. I went on a 300km ride 4 weeks ago and after 4 weeks it seems that only one cylinder is working or 2. Or the gas is not going through.

How do you know it is running on one cylinder? By checking the exhaust? Thanks.

 

[marsmax85]

infrared gun is a safe way to check
or at first start feel exhaust pipe coming out of each head quickly : )

 

[dannymax]

Remove the 4 carb drain hoses and open drain screws. May find the hoses are plugged and all carbs are getting fuel.
+1 to Kyle's post....time to get in them carbs.