Problem with Amals

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MrNorton

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Dec 26, 2007
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Hi again,i have a next kind of problem in my MK3,engine stopping very easy when the engine is hot,plugs are really black/soot and carburettors bodies are really hot.
Are those insulate gaskets enough thick(i feel they shuold be much thicker..)
I have checked many times after normal higway speed plugs and they are really nice/light brown,but after a few minutes idle speed engine stopping and plugs are really soot.
 
MrNorton said:
Hi again,i have a next kind of problem in my MK3,engine stopping very easy when the engine is hot,plugs are really black/soot and carburettors bodies are really hot.
Are those insulate gaskets enough thick(i feel they shuold be much thicker..)
I have checked many times after normal higway speed plugs and they are really nice/light brown,but after a few minutes idle speed engine stopping and plugs are really soot.
Click to expand...

Timing????
 
timing

Should be correct-28° tdc,Boyer ignition,starting very(first kick)and when the engine is cold running idle speed well-until...
 
Boyer timing should be 31 BTDC at 5000 rpm. Could be a little rich, try screwing the air screws out quater of a turn.

Cash
 
Hi

It may well be worth checking the pilot jets i.e to large or are they not screwed home and bleeding fuel through at low speed, not had Amals on my interstate but had a similar problem on the Velocette and the pilot jet had come loose.
 
not-ron said:
It may well be worth checking the pilot jets i.e to large or are they not screwed home and bleeding fuel through at low speed,
Click to expand...

The majority of Mk1 Amals, including the ones originally fitted to the 850 MkIII would have had fixed pilot bushes though, not screw-in jets.
 
Thank´s fellows

For good tips,stil i wondering those carburettors bodies-when running idle speed they are really hot.My theory is that:eek:n idle speed coming lot of heat from engine and it goes in to bodies and fuel in the bodies generatting suddenly too rich.
Because plugs are always soot,i have seen in some pics very thick gascets between cylinder head and throtle,so maybe one reason that could be...
 
Yes, try thicker insulators (they are made of Tufnol) if you think they would help?
Have you tried adjusting the pilot screws? As the mixture at "highway speed" will be governed by the throttle slide cutaways (approx. 1/4-1/2 throttle) and the needle jets and needles (approx. 1/2 - 3/4 throttle) and do not control the mixture at idle. http://www.hitchcocksmotorcycles.com/am ... _ht_7.html

You may be able to get thicker spacers from RGM Motors or Norvil? Or make them yourself from Tufnol sheet?: http://www.directplasticsonline.co.uk/h ... QgodlhpxYw
 
Sounds like an idle jet adjust is incorrect, but he mentions more than once that the gasket/insulators appear to be too thin....could be the past owner just put in a paper gasket or some such other incorrect thickness...send us a picture/closeup of the carbs and the gasket just to get that question settled... :wink:
 
Or maybe MrNorton could say how thick they are? As the ones on my MkIII are approximately 2mm thick.
 
The float level should be checked as well, in fact this is the starting point for all carb settings/tuning.

The fuel level in the bowls should be between .170 and .240 below the top of bowl.
 
Missing insulators usually cause the fuel to boil and the will motor cut dead at any speed. It will not restart for two or three minites. Never noticed sooty plugs with this problem.

Before you start pulling the carbs to bits do the simple quick things first;

Visually check you do have inslators fitted, 1mm thick will do. Screw the air screws out a little. Set the ingnition to 30 to 31 at 5000 rpm.


Tickover cold = richness in the primary, to weaken screw the air screw out.

Cash
 
No one seems to have mentioned yet the most prone to wear and bad manufacturing defects the nettle jet.
I just bought a set of 106's one was OK the other way off. I check them with a drill bit shank that mics .1055 Anything more that perceptible movement would be trouble. The way off one was already worn out brand new.
 
Has anyone tried swapping amals with the PWK 30 mm 30Js listed by Steadfast Cycles on Ebay.

After having my float bowl vibrate off today while heading up the highway, I am getting tired of rebuilding/cleaning these carbs!! On the upshot, I did manage to find one bowl screw still hanging off and was able to tighten one in and use my left hand to hold it up for the last 10km
 
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