Author Topic: Concentric carb experience  (Read 367 times)

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Phil C

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Concentric carb experience
« on: 10 November, 2021, 16:54:00 »
Following my recent adventures learning about cleaning and setting my carburettor, I was going to take the bike for a spin today to see how it went and what the plug might tell me about the mixture, but in the end I didn't, as it was a bit of a wet, miserable day and thought I'd wait til tomorrow. I must say I've enjoyed taking it to bits and putting it back together and as always learning do much from this forum. And of course I'm delighted that the bike is now running rather than conking out about one second after starting! I found the trickiest bit about assembling the carburettor was holding the spring to one side and getting the needle in place. Is there a trick to it? (I was doing it with the cable attached to the throttle and didn't slacken it off - maybe I should have.)
Phil

cdsdorset

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Re: Concentric carb experience
« Reply #1 on: 10 November, 2021, 20:25:42 »
Pull the spring up and flip it over the edge of the slide.

Mike40M

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Re: Concentric carb experience
« Reply #2 on: 10 November, 2021, 23:11:06 »
Clamp forceps. Not perfect but works quite well

Phil C

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Re: Concentric carb experience
« Reply #3 on: 11 November, 2021, 07:59:32 »
Do the forceps compress the spring and hold it tight to the carburettor top?

JulianS

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Re: Concentric carb experience
« Reply #4 on: 11 November, 2021, 08:37:46 »
Slide out the split ferrule at the twist grip end of the cable, this will give you slack in the cable tom make the job easier.

Mike40M

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Re: Concentric carb experience
« Reply #5 on: 11 November, 2021, 09:02:21 »
Do the forceps compress the spring and hold it tight to the carburettor top?
Yes, the forceps grips the wire keeping the spring compressed up to the top. Makes it easier to fit wire and needle into the slide.

Phil C

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Re: Concentric carb experience
« Reply #6 on: 11 November, 2021, 11:02:24 »
Thanks all for the very helpful advice everyone, which will make things easier next time. We learn as we go along!
Took the bike for a quick spin just now (say about three miles), having given the plug electrode a quick rub with fine emery paper). It ran very nicely. Checked the plug colour when I got back. Remember after running in the garage it was black and wet.  It seems (see photo) about right? Actually looks quite like before I set off, after I'd cleaned it with emery. The end of the thread, ie the bit surrounding the electrode, you can see is black and sooty. Any comments please?  Phil

AdrianS

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Re: Concentric carb experience
« Reply #7 on: 11 November, 2021, 16:29:03 »
A three mile run isnít going to give you a fair representation of the mixture by just looking at the plug.
The bike needs a really good run and needs to get really hot for some time before you look at the plug.
If you want to see if the main jet is giving the correct mixture you need to do a plug chop. The bike needs warming up and then running flat out for a fair way and then you need to kill the ignition and then check the plug.
Donít get too obsessed over the plug condition  if the bike is running well and the plug is not oiling up enough to make the bike run rough and difficult to start.

Phil C

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Re: Concentric carb experience
« Reply #8 on: 11 November, 2021, 16:48:54 »
Okay, thanks Adrian.   Phil