Daytona 125 Carb Issues

This area is for discussion/information on the "modern" AJS motorcycles manufactured in China from 2006 onwards.
Hooli
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Daytona 125 Carb Issues

Post by Hooli »

Hi all,

New member here who's sorting out a 2013 Daytona for a friend's daughter after she threw it down the road last year.

I've got it sorted, running & MOT'd etc. But it's losing power & misfiring badly above about 1/4 throttle, so you can't get over 30 in 3rd for example. Obviously a bit of a pain on a 125!

I know it's a carb issue as I've fitted a replacement engine after she'd smashed the side casings off & left it in bits for over 12 months outside. They'd already sourced another engine so rather than try to sort the rust out & refit the stator etc on the old one it was quicker to swap it. I've put new plugs in & the coils that came with the new engine. The only bit I've resused is the carbs. The bike had this issue before I got it, so it has to be the carbs really & it does feel like a carb issue.

I've stripped & cleaned the carbs the best I can, but obviously not well enough. I was hoping someone would know the carb settings (needle position etc) for these Klien PD26JS carbs as I can't find much on google. So I can at least check it's all set right when I take them apart again this weekend.

Thanks in advance.
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clive
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Re: Daytona 125 Carb Issues

Post by clive »

Hi Hooli, most of us using this website have the older AJS or Matchless machines but we help when we can. Your request for carb settings mat challenge us but there are some members with both old and new bikes. Have you tried contacting the importer for the informations? My immediate thought was is it an air leak between carb and inlet track.
clive
if it ain't broke don't fix
Hooli
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Joined: Thu Oct 22, 2020 10:25 pm
Location: Aberdeenshire UK

Re: Daytona 125 Carb Issues

Post by Hooli »

Hi Chris,

I was surprised to see a section for the new bikes here if I'm honest, I didn't think you lot would accept them as real AJS'.

I hadn't thought to speak to the importer tbh. With it not being my bike I was hoping to find something on google so I could sort it & return it to the owner, it's annoying that all the big work on it was dead easy & now it's one fault that should be simple that I'm stuck on.

I see what you mean about air leak, but I don't think it is. I'll retest spraying something flammable around the manifold & see what happens though. I should be able to solve it as I'm rebuilding a Triumph Bonnie T140v from scratch, so it's annoying me that I can't resolve it yet.
SPRIDDLER
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Re: Daytona 125 Carb Issues

Post by SPRIDDLER »

Hi Hooli.
I've deleted my earlier ramblings as I've just realised that you said the problem existed with the previous engine.
I really don't know much about the modern AJS although I have fettled a bit on my Chinese 250 Herald Classic which has a carb and an EGR valve, necessary to meet emission regs. I don't think one is fitted to the same but later fuel injected engine. The EGR system works by returning a small portion of an engine's exhaust gas to the engine's combustion chambers through the intake manifold, reducing the amount of NOx emitted. Could it be that there's an air leak on the EGR system or at the carb or the inlet manifold? If there is a leak the fuel mixture will be too weak and as well as the engine not producing sufficient power the zorst pipe will turn blue/mauve for the first 25cm after the cylinder head.

I had very similar issues with my carburetted Chinese 250 which I traced to a split in the tin case of the EGR valve.

There are a couple of Chinese 125 owner forums on the web which may be worth a punt although they are mostly populated by teenagers asking how to get 90mph from their 125's. ;)
'There is a tide in the affairs of men
Which taken at the flood............'
SPRIDDLER
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Re: Daytona 125 Carb Issues

Post by SPRIDDLER »

Hooli wrote:......it's losing power & misfiring badly above about 1/4 throttle, ........so it has to be the carbs really & it does feel like a carb issue.
As is well known, 50% of all carb issues are electrical, and vice-versa, and since you mentioned that the problem existed when the previous engine was fitted...... :?

All Chinese bikes have a reputation for poor electricals, in particular switches, connections and waterproofing so it's possible that at certain vibrations the misfiring may be caused by an intermittent fault in the low tension side of the ignition/electrical circuits.
As well as a multi-function key operated main switch my Chinese bike has an ignition cut-out switch for when the side stand is down and also a handlebar 'Kill' switch, although the starter will still operate. Maybe one of the switches is faulty (weak positioning spring, corroded contacts?) and at certain speeds and vibration they cut the ignition intermittently.
'There is a tide in the affairs of men
Which taken at the flood............'
Hooli
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Joined: Thu Oct 22, 2020 10:25 pm
Location: Aberdeenshire UK

Re: Daytona 125 Carb Issues

Post by Hooli »

SPRIDDLER wrote: There are a couple of Chinese 125 owner forums on the web which may be worth a punt although they are mostly populated by teenagers asking how to get 90mph from their 125's. ;)
:lol: :lol: The same kids who then get a 600 that does 180mph...

Anyway it's sorted.

I stripped the carbs again and found the same jet blocked in both of them (it's a twin carb 125cc twin). I'd assumed they were emulsion tubes or similar as the same jets are also blocked in the spare carbs off the other engine. But as an experiment I used a pushbike pump & football adaptor to force some air though one & it cleaned up, so I cleared the others out too. Put the two where the hole looked best back in the bike & tried it. It'll now do 40mph in 2nd, rather than 18mph & then spluttering like mad. I can ride it back to the owner's place when I arrange a lift home now.

Thanks for the ideas & helpful comments to a newbie on your forum.
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clive
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Re: Daytona 125 Carb Issues

Post by clive »

forget the T140V and get a 650 Matchless then you can stay on the forum!
clive
if it ain't broke don't fix
Hooli
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Re: Daytona 125 Carb Issues

Post by Hooli »

clive wrote:forget the T140V and get a 650 Matchless then you can stay on the forum!
:lol: :lol:

Don't be daft!

I do need more old bikes though, when finances allow.
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spookefoote1956
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Re: Daytona 125 Carb Issues

Post by spookefoote1956 »

Hooli wrote:
SPRIDDLER wrote: There are a couple of Chinese 125 owner forums on the web which may be worth a punt although they are mostly populated by teenagers asking how to get 90mph from their 125's. ;)
That would be me! :rofl: :rofl: :rofl: :rofl: :rofl:
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bob121
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Re: Daytona 125 Carb Issues

Post by bob121 »

Collapsed catalyst can cause a loss of power. I don't know about this model but on some of the others they are bolted in separately. Its worth a mention.
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