Idle Mixture Screw Adjustment

[HotRodYJ]

I had the pleasure of cleaning the carbs on my 83 last weekend and found that someone had already been into them before, removing the blind plugs to expose the idle mixture screws. The mixture screws were all at different settings. I had one a 2 turns out, another at 2 3/4 turns, another at 3 truns, and the last one at 4 turns out. I'm betting someone has been messing with these in the bikes history and at least a couple of these are no longer at the factory setting.

 

Now for my real question. Given that 2 -2.5 turns is suppose to be the magic number on the idle mixture screws, and the fact that these have already been messed with and I cannot return them to their orignal settings. What are your thoughts moving forward? I'm thinking set them all to 2.25 turns and then try to tune each one individually using max vacuum readings like I do on a car. Any other ideas on how to properly tune each carb?

[Yammer Dan]

That should be a good start.

[frankd]

Yes, that would be what I'd do. I would then turn each screw in a little until the idle drops a little bit. That would put each cylinder on the lean side. Don't worry if the screws end up adjusted a little bit different from each other, the only important thing is that you can peak each cylinder.

 

Frank D.

[jasonm.]

that's a good start. But 4 turns out may be pointing to a bad intake manifold o-ring. I found the #3 I could turn 6 turns out and the idle keep going up. That was a sure sign of a vacuum leak. As the more CCW = richer. New O-ring and fixed. But the carbs have to be pulled out to replace the o-ring. Next best thing to my digital tach is a good sensitive vacuum guage. like mercury sticks. But the engine must be fully warmed up. And not all carbs will have the exact same setting. Mine are between 2 & 3 ccw

[k9cottage]

i use a gunson colortune to get mine set i used to own a kawasaki z13 with 6 carbies and it was a nightmare until i got the colortune now i use it on everything no need to count the turns on the screw just have to watch the colour change in the sparkplug . http://hondacg125.awardspace.com/colortune.htm ps i have the adapters for all size plugs

[Condor]

Just turns the screws out 2.5 turns and don't worry about it. They are the idle screws. How long are you going to let it idle???????