Advice re mixture & throttle screws

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funsize
Posts: 72
Joined: 12 Jul 2021 18:11
Location: Rotherham England

Advice re mixture & throttle screws

Post by funsize »

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 😊
3potjohn
Posts: 1243
Joined: 02 Jun 2007 13:58
Location: Devon

Re: Advice re mixture & throttle screws

Post by 3potjohn »

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
funsize
Posts: 72
Joined: 12 Jul 2021 18:11
Location: Rotherham England

Re: Advice re mixture & throttle screws

Post by funsize »

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 🤷🏼‍♂️
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: Advice re mixture & throttle screws

Post by MickeyMoto »

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.
funsize
Posts: 72
Joined: 12 Jul 2021 18:11
Location: Rotherham England

Re: Advice re mixture & throttle screws

Post by funsize »

Thanks Mickey, noted!
lemans
Posts: 63
Joined: 01 Oct 2017 18:52
Location: Heino

Re: Advice re mixture & throttle screws

Post by lemans »

3potjohn wrote: 01 Jun 2022 19:47
Have a look at Paul Compton’s Morini carb balancing on youtube.

John
do you have a link to this video, looked through most of all Paul's video's on youtube but couldn't find it

regards Anne
Al Limite
Posts: 24
Joined: 27 Jan 2020 12:33
Location: Exeter, England

Re: Advice re mixture & throttle screws

Post by Al Limite »

This should be your answer Anne
https://www.youtube.com/watch?v=TEdK7DNuNfM
lemans
Posts: 63
Joined: 01 Oct 2017 18:52
Location: Heino

Re: Advice re mixture & throttle screws

Post by lemans »

Al Limite wrote: 02 Jun 2022 13:38 This should be your answer Anne
https://www.youtube.com/watch?v=TEdK7DNuNfM
thanks,
funsize
Posts: 72
Joined: 12 Jul 2021 18:11
Location: Rotherham England

Re: Advice re mixture & throttle screws

Post by funsize »

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!
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