Advice re mixture & throttle screws
Advice re mixture & throttle screws
Evening! Took the plugs out of my 1980 Strada and it’s clear it’s running rich. I’ve established the stock setting for the mixture screws are screwed in then 1 1/2 turns out. I’m going to miss the Queen’s party to attend to this, my question is do I have the engine running and/or warm when I undertake it? Also, having adjusted the mixture screws do I need to do anything with the throttle stop screws? If this topic has been explained in an earlier post I’ll search it and whilst I’m aware the carbs probably need proper balancing and timing checking (which I’m organising) I just want to get the basic settings right before I put my new shiny BP7EV plugs in! Thanks in advance 
Re: Advice re mixture & throttle screws
Things to know....
Does each cylinder respond by slowing down as you turn the mixture screw in on each carb or is one unresponsive?
Do the chokes really close off when the levers are down, i.e.the sealing tips are not perished?
Is there a little bit of slack in the cables i.e, slides not hanging on the cables?
The air filters are clean and standard?
The carb jetting is very similar to the data below. The exception might be smaller pilot jets, say 43/45/48 area.
https://www.motomoriniclub.nl/carb.html
You usually need to adjust both mixture and throttle stops to get both slides lifting in unison and a correct mixture.
Have a look at Paul Compton’s Morini carb balancing on youtube.
At least you can get to these carbs easily. My other Morini hides them under a big petrol tank.
Hope this helps.
John
Does each cylinder respond by slowing down as you turn the mixture screw in on each carb or is one unresponsive?
Do the chokes really close off when the levers are down, i.e.the sealing tips are not perished?
Is there a little bit of slack in the cables i.e, slides not hanging on the cables?
The air filters are clean and standard?
The carb jetting is very similar to the data below. The exception might be smaller pilot jets, say 43/45/48 area.
https://www.motomoriniclub.nl/carb.html
You usually need to adjust both mixture and throttle stops to get both slides lifting in unison and a correct mixture.
Have a look at Paul Compton’s Morini carb balancing on youtube.
At least you can get to these carbs easily. My other Morini hides them under a big petrol tank.
Hope this helps.
John
Re: Advice re mixture & throttle screws
Thanks John I’ll check these, the chokes certainly do each close off, I know the previous owner totally rebuilt the carbs, I’ve got the bills! He also fitted the Venhill cables and whilst the action really is silky smooth I guess that doesn’t mean they don’t need checking! I’ll have a go over the weekend but any help is appreciated as I’m no mechanic 
-
- Posts: 2578
- Joined: 22 Nov 2008 17:41
- Location: Even further oop North
Re: Advice re mixture & throttle screws
Before adjusting carbs ensure timing and valve clearances are correct. The screes only alter mixture at smaller throttle openings. You may be running rich at larger throttle openings. This could be needle height, main jet size. Lots to think about.
Re: Advice re mixture & throttle screws
Thanks Mickey, noted!
Re: Advice re mixture & throttle screws
This should be your answer Anne
https://www.youtube.com/watch?v=TEdK7DNuNfM
https://www.youtube.com/watch?v=TEdK7DNuNfM
Re: Advice re mixture & throttle screws
thanks,Al Limite wrote: ↑02 Jun 2022 13:38 This should be your answer Anne
https://www.youtube.com/watch?v=TEdK7DNuNfM
Re: Advice re mixture & throttle screws
Just an update I performed adjustments to the mixture and throttle screws and I must say it’s running much cleaner and ticking over very evenly when warm. My (professional) mechanic mate is going to do the timing and balancing of carbs but for now I’m riding a nicer Strada, thanks all!