Pilot jet

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Location: Essex

Re: Pilot jet

Postby ChrisTheChippy » Sun Aug 12, 2018 12:58 pm

Hi all
Thank you Duncan and clive for your recent posts . The fuel tank is currently off the bike as it needs cleaning out and I'm running the bike via a dummy fuel tank . The small air hole between the slide and air intake is definitely clear as I had a similar issue with my Enfield when I first got it and that was the problem so I made doubly sure of clearing that . One thing I can't remember doing is to blow through the small hole where the air jet screws in ( the one at the bottom under the cover nut ) . I'm assuming this jet should be screwed all the way in ? One thing I have read is that they get tightened too much and it can damage the seat. Don't think that's the case here though.
I have a new rubber for the carb flange so I will fit that and check for distortion at the same time .
Regards the rebuild issue don't think that applies here as after rebuild bike was ridden round London for a while before being stored when the po moved . I was very careful with reassembly of the carb and the top is definitely not cross threaded also still has choke fitted so no hole there.
I will be taking carb off again and I will go over what I've already done to make 100% sure it's correct before looking anywhere else for the problem .
Might replace the slightly bent needle jet just as a matter of course even though it's not causing a problem atm
So it's out with the carb cleaner and air line again .
Finding time is my biggest challenge at the moment and I hate rushing things so I will update if I have any news .
Thanks for all help and advice certainly given me lots more I can check.
Regards Chris

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Re: Pilot jet

Postby dave16mct » Sun Aug 12, 2018 1:57 pm

If you haven't cleaned the pilot jet hole then that will be the problem. If the needle is only bent at the top at the notches, I would straighten it carefully with a hammer on something smooth and flat. It should have a letter 'D' at the top and 106mm long.
Dave.

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Re: Pilot jet

Postby ChrisTheChippy » Sun Aug 12, 2018 10:25 pm

Thank you Dave
Regards Chris

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Re: Pilot jet

Postby LeYves23 » Fri Aug 31, 2018 9:39 pm

Just a little sidenote, since nobody mentioned it. (Might be trivial for you ) Best way to check for air leaks is to spray brakecleaner on the carb while the engine is running. If it revs up by it self while you are spraying you have a leak. And give it a good spray into every corner and from every angle...


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Re: Pilot jet

Postby bob121 » Sat Sep 01, 2018 8:19 am

Or use a small burner. Turn the gas on low and move it slowly around all possible leak points.if the engine speed is affected, then you've found a possible leak. Some people also attach a length of small hose to enable access to hard to getting corners.

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