Can you get fuel mixture screws you can adjust by hand?

[Wes51st]

I love the idea of being able to fine tune my fuel mixture screw by hand rather than needing to take the carbs off the bike to adjust. Does anyone know of some you could get for VM carbs on a 1979 GS550? I think they would make an excellent and hugely useful upgrade!

 

[chuck hahn]

The ones for the KZ 1000s are reputed to be the same needle but with the extended stem as Kawaski had those plastic knobs so you could reach under and tweek the needles

 

[chuck hahn]

Z1 Enterprises has them. Heres a listing from Sirius Consolidated showing them..the stems are longer so the knob can go on them. other than that they should be the same thing. One trick I use on my 650KZ ( I dont have the plastic knobs ) is to slip a short piece of vacuum tubing over the knurled ends and use the tubing to grip and turn the screws. Just leave the tubing there if you want to.

https://www.siriusconinc.com/pro-detail.php?pid=&product_id=6490

 

[Steve]

How often do you plan on tweaking them? They usually don't need to be moved much, if at all, once they are pre-set.

There is a general setting that works quite well, based on the tune of the engine, then you only need to tweak the air screw.

For an engine with stock intake and exhaust, 5/8 to 3/4 turn out usually works well.
For a bike with a header, maybe 3/4 to 7/8 turn out.
For a bike with a header and pods, try 7/8 to 1 full turn out.

For a starting point on the air screws, I usually go just under double the fuel screw.
Simple math tricks get you in the ballpark. Either double the top number or halve the bottom number.
Double 5/8 would be 5/4, so start with 4/4 or one turn out.
Double 3/4 would be 6/4, so start with 5/4 or 1 1/4 turn out.
You get the idea.

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[chuck hahn]

They dont understand that the pilot screw is JUST for the pilot ( idle) circuit and is little to no consequence otherwise. They dont understand that its set and forgotten..that all other adjustments are done with jetting and / or the side mixture screws.

I see these questions a dozen times a week. They want to twitter away then have at it I say. The only reason to even mess with the pilot screws is to initially set them or remove them for a carb cleaning. Replace them if the tips get broke off.

 

[Steve]

Very true.

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[chuck hahn]

Now CV carbs are a different animal as the fuel and air are premixed in the bowls. These you have to tweek the fuel screws to get the highest idle as the manual describes.

 

[hampshirehog]

Whilst you're right Chuck, an awful lot of riding is done on the pilot circuit (unless you're 19 years old or thinking you are - like me sometimes ....). So pilot circuit set up is important, not just for idle. You know that I'm sure but it didn't come across in your post the way I read it.

Having said that, your absolutely right about fit and forget the fuel screws. As long as you get them close enough the final adjustment can be done easily on the airscrews.

 

[chuck hahn]

True..up to around 2,000 RPMs or so but after that youre transitioning to the needles so that why I always tell folks do the 7/8 out. At 7/8 its rich enough to idle and not foul plugs and is still rich enough to add to that sweet spot just as the needles are taking over. Ive tried the 3/4 turn on my 77 750, the Cooley, and the other 3 1000s i have and none of them liked it s far as smoothness getting onto the needles. At 7/8 they seem to transition well without any soft spots.


EDIT....... I should note that all my bikes are stock airbox and exhaust setups.

 

[Steve]

Now CV carbs are a different animal as the fuel and air are premixed in the bowls. These you have to tweek the fuel screws to get the highest idle as the manual describes.

And you don't have to remove the carbs to make that adjustment. :encouragement:

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[Wes51st]

Thanks for the tips.

I know the mixture screw is something you don't need to adjust often, but for my particular problem of idle issues, it would be lovely to be able to adjust without the need to remove the carbs.