Starting problem

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Starting problem

Postby AdieB » Sat Aug 31, 2019 8:29 am

My Model 14 has been running sweetly following a rebuild. Recently, the engine will fire on first kick, run for say 10 to 12 firings, then die. If I leave it for about 20 seconds and try again, the same thing happens. I have stripped and cleaned the carburettor as far as I can, but the pilot jet refuses to budge. I can turn the brass screw about one turn before it jams solid. I have now turned off the slot at the end and do not know how to remove the jet. Any ideas would be very welcome. Many thanks.

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Re: Starting problem

Postby Mick D » Sat Aug 31, 2019 8:51 am

Hi

I assume you have an Amal Monobloc carb and it has been removed from the bike and drained of fuel, in which case heat the body in the area of the pilot jet with a fine gas torch, (the type chefs use for crème brulle and merengue)., then apply penetrating fluid whilst hot, taking precautions should it catch fire.
Repeat a couple of times then using a small set of self grip pliers gently agitate the jet, it should free off and be removable with care.

Regards Mick

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Re: Starting problem

Postby AdieB » Sat Aug 31, 2019 9:55 am

Hi Mick. Thanks for your reply. Yes, it is the Amal 375 carburettor and is removed. I will have a go at what you are suggesting. Do you think that the pilot is the cause of the starting issue? many thanks.

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Re: Starting problem

Postby Mick D » Sat Aug 31, 2019 10:31 am

Hi Adrian

Yes a blocked pilot jet could be the cause of your problem. When you have the carb apart check the pilot by pass is clear also, item 8 in the attachment below.

Mono X Section.png


Regards Mick
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Re: Starting problem

Postby Rob Harknett » Sat Aug 31, 2019 1:10 pm

I assume you have checked petrol flows through the pipes OK. Next taken just the bottom nut off the carb, check for muck in the bottom of this nut, turn petrol on. This will check petrol flows through the carb OK, if it not, remove and clean pipe fitting to the carb to ensure petrol is going in the float chamber, check carb jets again also check the float is not sticking. I would always do this first, before taking the carb to bits. You need to start at the tank for petrol flow.. just a dribble will not allow the float chamber to stay at its correct level after first being flooded, for the engine to continue running after starting.

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Re: Starting problem

Postby AdieB » Mon Sep 02, 2019 3:36 pm

Hi Rob. Yes, all that you suggested has been done. I have ordered a new pilot jet and a condenser. Just hope that I can get the old jet out OK!
Thanks for your reply.

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Re: Starting problem

Postby AdieB » Mon Sep 02, 2019 3:37 pm

Mick, thanks for the very useful cutaway diagram of the carb. Really appreciate that.

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