Not firing.,.

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

The outside cylinder isn't firing, it has spark and there's fuel in the carby bowl ..
Thanks Paul . Cc

Posted: Sat May 14, 2016 6:39 am

Compression?

Posted: Sat May 14, 2016 9:19 am

Which outside cylinder, and is the bike running on the other three ok? Was it running on all 4 up until recently? If yes, start the bike up and while it's running, pull the spark plug wire off the plug of the suspect cylinder. Hold it so that it's almost on and move it out a bit, then back close to the plug. If the cylinder starts to fire, your plug is probably fouled. Replace it and keep an eye on it to see if it's starts to foul again.

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

It's been running fine haven't started it for seven months , when looking at the bike it's the left hand side (outside cylinder)I have taken the plug out it has spark, the bowl has fuel, cranking over with the plug out it has compression all the plugs are new..

Posted: Sat May 14, 2016 11:18 pm

Just because there is fuel in the bowl does not mean it is getting to the engine. Quick check would be to turn off the petcock while running and let it run until it runs the bowls dry on the running cylinders. then open the bowl drains and measure how much fuel comes out of each bowl. If you have almost nothing come out of the running cylinders and a lot more come out of the non-running cylinder, then you have a carb problem - maybe blocked jets. If it has not run for 7 months the jets may be blocked with fuel residue or other junk.

Posted: Sun May 15, 2016 1:03 am

Quote:

It's been running fine haven't started it for seven months

There's a clue. It's either been run regularly or it hasn't been run for 7 months, it can't be both. Carbs foul when not used regularly. Did you drain them when you stopped running it 7 months ago? Or provide some other insurance against phase separation of the fuel and evaporation that plugs up the small passages in the carbs?

Sounds to me like your carbs are probably compromised.

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

The carbys were rebuilt with new seals and new jets everything was cleaned it was running great , it has been sitting for seven months without being started , will try turning of fuel and running till dry
Thanks Paul

Posted: Sun May 15, 2016 2:23 am

Was it sitting with fuel in the carbs for that 7 months???? If so, they're dirty again. They don't stay clean with fuel in them, it separates and evaporates and leaves goo that clogs them up.

Posted: Sun May 15, 2016 4:46 am

Gene, we pay a lot more for fuel than you do over there so we don't have to put up with that crap ethanol rubbish, although some outlets do sell the junk. Hopefully Paul didn't put this in his tank by mistake, but whatever way you look at it, it is probably a blocked jet

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

No ethanol it was premium ....

Posted: Sun May 15, 2016 6:14 am

Yes, but do they use any other high evaporative like MTBE, ethanol not the only thing used. Other chemicals can promote super fast evaporation to clog carbs too.

Posted: Tue May 17, 2016 11:04 pm

Premium fuel in it and been sitting 7 months with Aus fuel in it, not the cause of the problem. That is not to say the jet hasn't blocked but the fuel is not the cause.

Posted: Wed May 18, 2016 6:16 pm

So pull the air filter, and with the engine running on the other three cylinders, spray some aerosol carb cleaner into the airstream going to the dead cylinder.

If that cylinder runs on carb spray, it's not getting fuel--so it's time to dig into the carbs again.

If it won't run on carb spray, it's compression or ignition or blocked exhaust.

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

Took carbys off another clean , even changed plugs , still no fire the pipe is warm , schurkry, I'll try what you recommend ..
Many thanks ...

Posted: Fri May 27, 2016 3:51 pm

Where in oz are you?

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

Victoria ..

Posted: Sat May 28, 2016 2:29 am

Paul, squirting a bit of fluid in through the airbox may make it fire for 2 revolutions but you probably wouldn't get time to notice if it was running. Have you put a compression gauge on it?

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

I don't have a compression gauge.

Posted: Sat May 28, 2016 6:38 am

Did you try running it with the petcock turned off til the engine stopped then drain the carb bowls to see if the non-firing one had more fuel left in it? The only tools you need for that are a screwdriver and a jam jar.

Posted: Sat May 28, 2016 7:09 am

Paul where about in Vic are you, I have a compression gauge and plug fitting

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

Yarraglen

Posted: Sat May 28, 2016 11:36 pm

Hi Paul, bit of a bitch to get across there, I'm in Hampton Park, but if you think you need it I will jump on my bike and head over. I would head out through Woori Yallok and Healesville. We do ride out that way occasionally when the weather is better. Let me know what you think.

Posted: Sun May 29, 2016 12:25 am

paultls wrote:

Took carbys off another clean , even changed plugs , still no fire the pipe is warm , schurkry, I'll try what you recommend ..
Many thanks ...

When you say you're cleaning the carbs, exactly what are you doing?

Id verify there's fuel in the bowls (drain plugs to verify) and Id pull the jets out, let them sit in a jar of carb cleaner for a night, then blow them out with compressed air.

Its not unheard of to have a float valve stick in the closed position. If you don't physically free it, clean the seat and the tip of the needle, you're not going to get any love...

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

Norm , many thanks for your offer, still can't get it to fire , took the air box out and squirted airo start into carby still wouldnt fire . Took the plug out there Spark and plenty of air getting pumped out of the cylinder so I think there's plenty of compression .

Posted: Tue Jun 07, 2016 4:45 am

Try swapping the plugs around to see if the problem follows a particular plug

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

Yes changed plugs and jets , still no joy ..

Posted: Tue Jun 07, 2016 11:01 am

Paul, you will have to pull the valve cover, has to be something going on with the cams for #1 cylinder if as you say you have spark, compression, and it would not attempt to fire with starter fluid into number 1

MB-5 Joined: Sep 24, 2013 Posts: 24 Location: australia

Can you spray aero start into the carby while the engine is running ? Is it safe for the engine to do this .

Posted: Thu Jun 09, 2016 5:25 pm

This is taking too long.

Were the coils fiddled with at all? I would make sure the coil wires (and the plug wires) are hooked up as they should on the coils:

Blue fires 1 and 4
Yellow fires 2 and 3

Just one possible way to explain spark but not combustion.

Posted: Thu Jun 09, 2016 5:31 pm

Take a cup with a poorly sealed lid, put 1/2" of fuel in the bottom of it, and let it sit for 7 months and see what you get. For a test, leaving a couple of pipettes sitting vertically in it the whole time might also be revealing.

I wouldn't really advise spraying starting fluid into a running motor either.