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[Scalyback]

[center]




Kevin the meteor minor has an Amal Monobloc carb.


One spark plug was nicely tan, the other sooty, and I adjusted their gaps to .025, Is this about correct? I think they were B6ES or something like that.



On acceleration, the first half twist of the throttle wether to throttle hard, or just slowly increase speed, the engine start to loose power with a slight jerkiness.
anything 3/4 or over and the engine becomes jumpy. even up a hill when you just need to twist a little more to maintain 50 MPH, it starts to loose power, so throttle off a little and recovers, although end up doing 40 MPH up the hill instead.



Never had an Amal, but am guessing that it may not be happy with needle height or jet size??? or something?



Didn't want to seem like a twat so looked up on here, but I do not have another knowledge of Amals yet to understand them.



up to about half twist, bile runs smoothly, it is only after about half twist that the power starts to revese with ever increasing coughing as throttle ti=urned more.



It does make an interesting speed/power limiter though.



What should I be looking to do with the AMAL (IF it is that???)
















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[Scalyback]

[center]




I meant that everything is fine up until half throttle.

[papasmurf]

More information than you can shake a stick at:-

http://www.hitchcocksmotorcycles.com/hi ... s-monobloc

[Scalyback]

Hi Papasmurf, I guess the info is in there somewhere, but I am not quite sure where to start and was more hoping that someone might just be able to say, "Oh it's just...."



Failing that, I will eventually have to follow your advice and look at the notes, but I have the steep learning curve of a whole bike to get familiar with, and 4 days to do it. (Then I am off to France, bike to follow!)

[simon]

I would look to the ignition for this problem. Does it have a distributor or two sets of points?

[Scalyback]

It has a distributor, but looks to be new.



I feel it is more carb related, only because we went down a long hill, and at just under half twist (before the problem starts) we got very quickly up to over 60MPH, for a short while, but with both bike and me 'under test'. as speed increased over 50, there was no sign of the power problem.



I think the owner two previous (600 miles back) really got it sorted, There is a note with oil change, mileage, when the valve clearances were set and for totally warm engine... So a little surprised at the power problem, anyway off to the Cafe for brekkie soon!



Maybe crap in bowl? (Still doesn't explain one tan and one sooty plug though?)

[papasmurf]

(Still doesn't explain one tan and one sooty plug though?)

If it is just one Monobloc, check both plugs are the same grade. Check the coil on the sooty one.
Just thoughts off of the top of my head.

[Beezabryan]

Carb problems are usually electrical, trite but true. Make sure the electrics are 100% before playing with carb is my suggestion, for what it is worth

[Mark M]

I would be looking at the distributor as well as obvious carb checks. These dizzies are quite cheaply made and 55 years of wear will have taken their toll! Areas to check; distributor cap (cracked? Dirty?) advance retard springs (correct ones? Worn out?) Fit of bob weights (loose on pivot, greased properly so they can move easily?) integrity of HT leads, especially where they fit the dis cap and coil, loose wiring on coil/distributor and finally (very important) the rotor arm. It MUST be the right one! For a long time these were unavailable or could only be had as cheap Chinese copies, they are now available from Martin Jay (The Distributor Doctor) in high quality new repro, part number 54422803 and well worth it. You can see them on his site, which will tell you if you have the right one, there are many variations!

REgards, Mark

[Winkie]

Amal's are fairly simple instruments and most problems tend to arise at slower rather than faster running. The problem is probably a weak spark or sticking auto advance, but there are a couple of simple carb checks you can do. Firstly make sure that the little vent hole in the filler cap is clear - a blockage here will cause fuel starvation at faster running. Stop the engine after it starts coughing and then remove the filler cap; if there is a blockage in the vent you will hear a whoosh as the tank pressure releases.
The other simple check is to partially close the choke when the coughing starts. If the coughing improves it points to a weak mixture. Good luck.
And also stick a couple of new spark plugs in. For some reason old British bikes sometime do not always like NGK's. My AJS twin transformed dramatically when I stuck a couple of old stock Champions in. Modern plugs seem to like for power than old electrical systems can produce.