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NORTON 1951 Big 4 tick over

Submitted by christopher_page on Fri, 23/12/2016
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Hi,

I recently purchased the bike, it starts very easily but wont' tick over.

the revs die down and it cuts out.

Any ideas what may be causing it to do this ??

Thanks,

Submitted by christopher_winsby on Sat, 24/12/2016

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Previously christopher_page wrote:

Hi,

I recently purchased the bike, it starts very easily but wont' tick over.

the revs die down and it cuts out.

Any ideas what may be causing it to do this ??

Thanks,

Clean the carb and check it. Then check the ignition. Fresh fuel ? Good compression?

Submitted by george_phillips on Sat, 24/12/2016

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Sounds like fuel starvation. Check fuel filter, fuel lines, carb jets (pilot) nd just for fun the hole in the fuel cap. George

Submitted by robert_tuck on Sat, 24/12/2016

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If you have a pre-monoblock carb (most likely) you can easily get a blocked pilot fuel passage in the brass jet block or carb body. The jet block can be knocked out for cleaning ,the pilot passages are very fine and will not respond to compressed air or ultrasonic cleaning. You will need a new gasket on the jet block.

Submitted by christopher_page on Sat, 24/12/2016

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Hi,

Thanks for your replies.

I replaced the fuel lines and fittings yesterday, i think I'll remove the carb and check it over next.

Have a good christmas

Chris.

Submitted by christopher_page on Sat, 24/12/2016

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Oh, One thing yesterday.

As I said it starts just fine, but when it was running I gave it a few revs and had a few pops and bangs from the exhaust plus a couple of flames !

Submitted by paul_knapp on Sat, 24/12/2016

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Have you tried adjusting the idle speed screw on the carburettor side, the one that points up on an angle? Though, I also think there is probably a blocked idle mixture passage.

Xmas greetings to you also, and to all the Norton gang. 40 Deg.C forecast here tomorrow, that will make the oil run thin. Frown

Submitted by robert_tuck on Sat, 24/12/2016

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With these old beasts its usual to have any number of small issues that add up to an interesting whole!. None of the items are enough to stop the thing running in some form. The greatest pleasure is usually obtained when after some years of struggling with a sulky monster ,suddenly you find its a sweet easy to start pussycat that ticks over like a metronome. Perhaps next year ,or maybe the one after.

Submitted by christopher_page on Sat, 24/12/2016

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Previously robert_tuck wrote:

With these old beasts its usual to have any number of small issues that add up to an interesting whole!. None of the items are enough to stop the thing running in some form. The greatest pleasure is usually obtained when after some years of struggling with a sulky monster ,suddenly you find its a sweet easy to start pussycat that ticks over like a metronome. Perhaps next year ,or maybe the one after.

Submitted by christopher_page on Sat, 24/12/2016

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Well, I'm running out of days for this year, so it will definitely be next year, but very early on !!

I'm guessing the carb is the next thing to look at then.

Need to get out on it in the winter sunshine.

Submitted by george_phillips on Mon, 26/12/2016

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The pops and bangs could be indicative of a leak in the exhaust system (exhaust outlet on cylinder, silencer connection?) as the unburnt exhaust gases are reignited when the get the fresh air being drawn into the leaking exhaust system. They are also indicative of a weak mixture. George

Submitted by mikael_ridderstad on Mon, 26/12/2016

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Bangs and flames might be due to ignition too retarded. Remember my first bike, an old Harley I had before seeing the light and got a Norton. Left twistgrip was ignition and right the throttle. When both turned off, boy what a sound and flames. Cheaper than to buy fireworks for new years eve.

 


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