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vintage_bean

New Website User
Non-VOC Member
I've recently fitted new slides to the standard Amals on my Shadow. The bike starts and runs well, but when it's hot the throttle shut-down is not immediate; the engine settles down to tick over- but it takes a few seconds.
This is very irritating and spoils smooth upward gear changes.

Any ideas guys ?

Thanks,

David Smith
 

Tnecniv Edipar

Well Known and Active Website User
Non-VOC Member
The most obvious reason for this would be that the new slides have less clearance in the carb so particularly when warm they could be hanging up slightly on the working surface of the carb body. Another reason could be a cable routing issue that may have happened during the installation of the new slides.
I think I would remove the slides and examine for rubbing marks that would indicate friction in a particular area.
 

Howard

Well Known and Active Website User
VOC Member
Hi

The first thing I'd try is the fit of the slide in the body - dirty? - burrs on edges?. If everything's ok cold, it may be heat distortion, or just expansion. If it's just slow shutting down, maybe the spring is a bit too weak - give it a stretch to start with that may be a quick fix.

After that it gets technical - slide cutaway, needle position etc, but my guess is expansion/weak spring.

Regards

Howard
 

Howard

Well Known and Active Website User
VOC Member
The most obvious reason for this would be that the new slides have less clearance in the carb so particularly when warm they could be hanging up slightly on the working surface of the carb body. Another reason could be a cable routing issue that may have happened during the installation of the new slides.
I think I would remove the slides and examine for rubbing marks that would indicate friction in a particular area.


Looks like we were writing at the same time - cable route's a good one. Sometimes if you can replicate the problem on the stand, if you shut the throttle quickly and watch the carb top, you'll see the cable go slack, if it's a sticking slide - this might help to find which carb is sticking - might not be both.

Oh well, back to work, Vincent problems are much more interseting.
 

Tnecniv Edipar

Well Known and Active Website User
Non-VOC Member
Looks like we were !! I've had this problem many times over the years , in particular with a '69 Bonneville that was a persistent offender !! I have to be careful with my Velo Viper also , as soon as I even think about removing the tank , which is essential to do any carb or top end work , there seems to be a carb issue afterwards !!
 

Howard

Well Known and Active Website User
VOC Member
I had the same problem on my racing Comet, but for a very different reason. The slide in the 1 1/2" GP carb was very worn, and the air flow would tip it and stop it sliding easily - or at least that was the only conclusion I could come to - new slide cured the problem.

The older you get, the more things you find that aren't in the trouble shooting page of the Haynes Manual!
 

Tnecniv Edipar

Well Known and Active Website User
Non-VOC Member
Haynes manuals have become like owners handbooks now , anything much beyond basic servicing is now often covered with that dreaded phrase , 'refer to your dealer' !!!
 

The VOC Spares Company Limited

Well Known and Active Website User
VOC Member
The other thought is the old slide and the carb body had worn "together" and the new slide maybe hitting a small ware step in the body.
It's a bit like putting new piston rings in a worn bore you need to use a stepped ring to avoid any remaining ridge.
Ian
 

A_HRD

Well Known and Active Website User
VOC Member
An Alternative Possibility

I'm sure the previous answers about carb slides are correct. But if you can't find anything wrong in this department, it might be weak or broken springs on your ATD - if you have one....

PeterB
Bristol, UK
 

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