Amal Mk2 air jet question

Fast Eddie said:
Are you sure you’re drilling out the right bit Tommy?

Go to around 08.10 in this video…

Click to expand...

Ha! What do you know! I believe the word I´m looking for is ooops! Guess I have to plug that hole right back, there was no air jet in this carb after all. The one I drilled out was to the right of the middle hole, and my carb is a leftie. Thanks for pointing this out.
 
fiatfan said:
Since I´m having an inconceivable (at least to me) problem with my new single Mikuni 34mm on my -73 850, I thought that I´d give an old Amal Mk2 34mm, made in Spain!, a go. It´s my only alternative at the moment. After a lot of reading I was going to remove the air jet, but of course it wouldn´t let go. Tried to use a screw to pull it out but no luck. So I tried to carefully drill it out, but after I got about 2-2.5mm in it is just solid aluminium, no hole. Should I drill deeper? The jet looks pretty long on pictures. The hole in the jet was 2mm diameter, unfortunatly I didn´t check how deep the hole was but it should go all the way through the jet?
I also have to replace several parts since it have probably been used on a 2-stroke.
\Tommy
Click to expand...
I had a stuck jet on a dellorto phf 30mm it is about 25mm long with holes drilled cross ways to weaken it , of course after carefully trying to remove it and with heat and penatrating oil it still broke off , but luckily I had another phf 30 , and it's jet came out easy , so the tip for the story is if you have a sample jet in your hand you'll then know what diameter drill and how deep to drill . Cheers
 
Last edited:
After a couple of test rides yesterday and today, my conclusion is that the problem I have only occurs when the throttle slide is in the bottom position. When I drive it runs nice and smooth even on very little throttle lift, no problems. But as soon that I let off the gas it starts acting like a 2-stroke, igniting even though the throttle is all the way down, and has practically no engine braking. I can not get it to idle properly, it can idle ok for a bit, then it just stops. I´ll try and find a new choke unit, as "marineatlas" tried that and it solved his problem. Even though mine is new.
 
fiatfan said:
igniting even though the throttle is all the way down
Click to expand...
This is lost in translation, igniting means its producing power but the rest of your description suggests the opposite.

If you want to find out if you are rich or lean at idle then get a colortune, note you only use it when the bike is stationary and not under load. You get a window into the combustion chamber and can see the colour of the flame, yellow is rich, pale blue is lean and bunsen burner bright blue is perfect.

 
acotrel said:
Why should a two-stroke carb be different from a four-stroke carb when they both do the same thing ? A two-stroke carb is usually jetted leaner than a four-stroke carb - but the tuning sequence is the same - start rich -then lean-off. When the motor is warm, it should idle when the throttle is closed. wind the petrol control screw in until the engine misses then richen slightly. - Same when setting the needle and needle jet - lower the needle until the motor misses, then raise it one notch. Main jets should always be slightly too rich, so fit the bigger recommended size. If you use this sequence and an air or pilot jet needs changing, you might find the need more easily.
Click to expand...
If you genuinely don't understand why a two stroke carb is setup differently from a four-stroke you really shouldn't be posting here
 
kommando said:
This is lost in translation, igniting means its producing power but the rest of your description suggests the opposite.

If you want to find out if you are rich or lean at idle then get a colortune, note you only use it when the bike is stationary and not under load. You get a window into the combustion chamber and can see the colour of the flame, yellow is rich, pale blue is lean and bunsen burner bright blue is perfect.

Click to expand...

Sorry, not my language, trying the best I can but with 2 different versions of "english" depending on where you people live, it´s no childs play....
I don´t know what other word to use when the spark plug makes the fuel mix go "boom". Please enlighten me.
 
The spark plug is supposed to ignite the mixture.

Where is the boom, a misfire out the carb inlet or one out of the exhaust.
 

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