Ajs350 1948 hunts while cruising

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got2BaSBT
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Location: Staffordshire UK

Ajs350 1948 hunts while cruising

Post by got2BaSBT »

Hi folks,
I'm a newbie to old brit bikes having always ridden japan bikes.
Please can you offer a little advice, I've recently purchased the above bike and whilst it runs ok generally, whilst cruising it hunts slightly.
The valve clearances, points and carb needle clip position are correct....any ideas on where you would look next. I was thinking float level height as I know that the clip recently came off before I bought the bike. I understand though that there is no spec for this?
Cheers
James
Mick D
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Re: Ajs350 1948 hunts while cruising

Post by Mick D »

Hi

Check the float and needle are moving freely, (check the needle is not slightly bent). Check you don't have an air leak at the carb flange.

Regards Mick
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clanger9
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Re: Ajs350 1948 hunts while cruising

Post by clanger9 »

Definitely check the float height. It's often disturbed when people change the washer on the fuel inlet union without realising how important the washer thickness is.
Here's a guide for checking a monobloc: http://www.whfolk.co.uk/REOCHUMBER/Arti ... nobloc.htm
1989 Moto Morini Dart 350
1993 Ducati 750SS
Mick D
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Re: Ajs350 1948 hunts while cruising

Post by Mick D »

Oops

I assumed the carb would be a 276

Regards Mick
alanengineer
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Re: Ajs350 1948 hunts while cruising

Post by alanengineer »

how many grooves have you got on the needle for the clip to fit into. Im assuming you have a carb that has a float chamber next to the main part of the carb.
got2BaSBT
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Location: Staffordshire UK

Re: Ajs350 1948 hunts while cruising

Post by got2BaSBT »

Thanks for the replies and guide folks.
It does have the earlier carb with the screw off cap on the float bowl.
I've been for a chug on it today and I'm convinced it's running rich, I also noticed that it idles faster and smoother when it's leaned over on its side stand.
I don't think there's any "pip" on the float bowl like in the guide.
The previous owner said they had trouble with the float because the clip had come off? I'm not sure how this could happen, but if it did how do you know where on the float shaft to clip it back on?
Mick D
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Re: Ajs350 1948 hunts while cruising

Post by Mick D »

Hi

See here:

http://amalcarb.co.uk/carbspec/carburet ... s/id/6472/

It doesn't look like there is an option of where the clip fits on the float needle, (item 45) - the needle jet needle should be in position #3

Regards Mick
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clive
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Re: Ajs350 1948 hunts while cruising

Post by clive »

The 76 pre monobloc carb which i think you are describing has a float with a needle with a cone at the bottom. When the float rises this lifts the needle so sealing the inflow of fuel. The float needle should have only one grove in it where the clip on the top of float locates. The clip is two pieces of bent metal which can be pulled outwards (if i remember correctly) to retension the clip. Its also possible the clip unit came off the top of the float and has now been soldered back on incorrectly.
clive
if it ain't broke don't fix
Andy51
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Re: Ajs350 1948 hunts while cruising

Post by Andy51 »

Hi James, don't know much about needles and float height, but I concur with Mick re flange straightness. I recently refitted the carb on my '54 18S (been on for years, but never checked) and saw that the flange was very definitely bowed. Easy to check with a straightedge and easy to rectify with a piece of emery paper on a surface plate or bit of plate glass. Hope this helps, Andy
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clanger9
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Re: Ajs350 1948 hunts while cruising

Post by clanger9 »

Oh, my mistake, I hadn't realised these are pre-monobloc.
1989 Moto Morini Dart 350
1993 Ducati 750SS
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