Author Topic: Throttle stop screw (Concentric carb)  (Read 945 times)

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chaz

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Re: Throttle stop screw (Concentric carb)
« Reply #15 on: 08 November, 2021, 19:43:42 »
plug fouling, would be interesting to try another dry plug to see if it runs straight away.
http://amalcarb.co.uk/downloadfiles/amal/amal_tuning_guide.pdf
http://amalcarb.co.uk/downloadfiles/amal/Mk1_Hints_and_Tips.pdf

obvious question, black plug, is it fuel or oil? over fuelling or rings?

Phil C

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Re: Throttle stop screw (Concentric carb)
« Reply #16 on: 08 November, 2021, 20:51:55 »
Might be obvious to you Chaz! 😁

Before I had the conking out problem which brought all this about, I didn't have a black, wet plug. So I guess it's something to do with the carb. Maybe tomorrow I'll wind up the throttle stop screw a bit (that might help prevent the eventual stalling that's happening) and unscrew the pilot air screw a bit (which might weaken the mix a bit.)

Phil

royblackburn1@btinternet.

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Re: Throttle stop screw (Concentric carb)
« Reply #17 on: 09 November, 2021, 00:41:20 »
I have always been told to take my bike for a run then check the plug condition when the bike has been under load not sat on the drive and just revving it hope this helps

Phil C

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Re: Throttle stop screw (Concentric carb)
« Reply #18 on: 09 November, 2021, 06:32:09 »
I'll do that - thanks Roy.  Phil

Phil C

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Re: Throttle stop screw (Concentric carb)
« Reply #19 on: 09 November, 2021, 15:57:12 »
Okay well I've been doing a bit of tweaking with the two adjusting screws on the carb and it sounds to be - in the garage anyway - running okay. I'll take it for a little run out tomorrow (if it's not raining) and see how it goes and then what the plug is showing.  I confess I've lost track of how far in or out the two screws are. Does that matter if it seems to be running okay?   Phil

AdrianS

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Re: Throttle stop screw (Concentric carb)
« Reply #20 on: 09 November, 2021, 22:00:13 »
You adjust the screws to make the engine run ok. If the engine is running ok, the screws must be adjusted correctly!

When the engine is running and warmed up, screw in the throttle stop screw to give a fast tick over. Then adjust the air screw to get the engine to run as fast and cleanly as you can. Then back off the throttle stop screw and carefully adjust the mixture screw to give the smoothest running of the engine.

The mixture screw only affects tick over and low revs. The mixture at higher revs is changed by needle position, main jet size and slide cut away.