G9 Running poor help for newbie

Information relating to the Matchless G9 or AJS Model 20 500cc twin
Chris B_LAPSED
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Joined: Mon Dec 28, 2020 8:31 am
Location: Nottinghamshire

G9 Running poor help for newbie

Post by Chris B_LAPSED »

Hi all

So just got my 1953 G9 which had a problem with the charging this had now been kind of sorted. Intermittently i have lights then no lights. My main worry was for the 15 mile ride i did today it seems to be running poor. First 3 miles it felt like it was over revving but not pulling. Almost like a clutch slip feel... then after that the bike went into Hesitating when opening the throttle and struggling to get a speed up. Pulled over the side of the road switched off then tried to restart but she wouldn't for sometime.. there was fuel coming out of the carb end and hole on the tickler. Eventually got the bike started and got home to notice fuel coming out the carb in the same areas. Any ideas please.

Thanks all
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clive
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Re: G9 Running poor help for newbie

Post by clive »

sounds like the float is jamming. What carb have you got? It would originally have been fitted with a 76 but may have the later 376 monoblock. oh and welcome to the club
clive
if it ain't broke don't fix
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1608
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Re: G9 Running poor help for newbie

Post by 1608 »

As stated the carb is flooding due to the float sticking or the float needle is worn. Check that the needle hasn't got a wear ridge. A new viton tipped needle is a good modern replacement. I have found that the new plastic floats are prone to sticking sometimes. Somebody recently commented that the small brass spacer on the float spindle was also too long and fouling. Just a couple of things to check.
This all applies to a mono bloc carb though.
A flooding carb will make warm starting difficult.
SPRIDDLER
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Re: G9 Running poor help for newbie

Post by SPRIDDLER »

Welcome, Crispy.
Having just got the bike I doubt that you want to start taking bits apart so before digging deeper...........
Chris B wrote: Intermittently i have lights then no lights.
All the lights or just one of the lights? If just one light it may be a corroded or loose bulb holder.
If all lights are intermittent it may be a loose main feed from the battery to the switch or a poor battery to Earth (frame) connection.
It may also be a dirty switch esp if the bike's been unused for a while so a squirt of switch cleaner or WD40 and repeated operation of the switch might cure it.
First 3 miles it felt like it was over revving but not pulling. Almost like a clutch slip feel...
Check for clutch slip by putting the front wheel against a post or wall and try to drive forward with just a few hundred revs when you should be able to stall the engine.

As already mentioned re the carb but if yours is a Monobloc the pic below may help
Monobloc float chamber flooding.jpg

Good luck.
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Which taken at the flood............'
Chris B_LAPSED
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Joined: Mon Dec 28, 2020 8:31 am
Location: Nottinghamshire

Re: G9 Running poor help for newbie

Post by Chris B_LAPSED »

Thanks for the input all. So I just got the bike today so going over it with very basic knowledge I have.

So a bit more info the carb is a concentric 626
And the fuel has stopped leaking out now even though the fuel is switched on so could that still be a needle sticking issue? I do belive its been stood a while...

Regards the electrics iv just found out that the bike has a electronic dynamo regulator fitted. And when the lights went off its all of them including horn. The guy I purchased from said he had sorted the problem with a broken cable chafing on metal causing discharge. For now its actually working again so intermittent at the moment.

Thanks Chris
Chris B_LAPSED
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Re: G9 Running poor help for newbie

Post by Chris B_LAPSED »

So just noticed the ht lead was slightly loose with the fastner that holds it in place not engaged to hold it in position. Could this be a cause of the symptoms iv described. Many thanks everyons
Mick D
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Re: G9 Running poor help for newbie

Post by Mick D »

Hi

The leaky carb could have been due to the float valve gumming up, as fuel passes through it dissolves the gum so may have 'cured' itself.

Loss of just lights would have pointed to the switch as this is the common point in the dynamo and battery circuits, however loss of the horn too, which is normally wired direct from the battery points to an intermittent fault on the battery earth line.

Dodgy HT wiring will result in misfiring etc. fix it and go for another ride.

Regards Mick
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clive
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Re: G9 Running poor help for newbie

Post by clive »

Chris B wrote:So just noticed the ht lead was slightly loose with the fastner that holds it in place not engaged to hold it in position. Could this be a cause of the symptoms iv described. Many thanks everyons
Chris you have described a raft of symptoms, one single thing is unlikely to be the cause. You have described a symptom "like clutch slip" until you get the bike running properly this may be difficult to solve but it could well be clutch slip. The failure to pull and then starting again could be the result of a loose ht cable or possibly muck in the carb blocking a jet. Leaking fuel from the carb mouth and the tickler hole can only be caused by a float jamming or the float needle not sealing. As it has now stopped its likely to be the float jamming.

Like many "new" bike owners you are going to have to work through the problems and hopefully with the help of the forum you will soon crack them.
clive
if it ain't broke don't fix
Chris B_LAPSED
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Re: G9 Running poor help for newbie

Post by Chris B_LAPSED »

Thanks everyone for your help. Im going to make a start tommorow and try and rule things out one by one. Will keep everyone posted how far iv got. Cheers :)
Chris B_LAPSED
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Location: Nottinghamshire

Re: G9 Running poor help for newbie

Post by Chris B_LAPSED »

Hi all so made a start this morning by stripping the carb. Found a fair bit of crap in it. So cleaning it up now whilst the kettle is on.

Does the hole where the needle sit in it have central as mine is slightly off. Struggling to upload pics as to large
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