Air Jet in CV carbs

[redmike]

Since I'm new to GS ownership, I was wondering if anyone can tell me what the purpose is for the air jet on CV carbs on a 1981 GS1000GLX? Are they adjustable and how do you know when they are adjusted correctly? Thanks

 

[Jethro]

Ok, we need to establish that you and I are on the same page about an air jet. In my mind, an air jet is not something that is adjustable without replacing it with another jet. You may be talking about the air mixture screws. There are four of them on top of the carbs as you are looking down from the top? Technically, the air jet is located behind the rubber boot to the air box, in the flange for the carb manifold. It's a little brass screw with a hole in it. That is the main air jet.

The mixture screws were never really meant to be messed with, and were delivered on bikes with aluminum plugs pressed in the hole to cover the screw. Many owners have pulled the plugs out so they can adjust them.

So, are we on the same page as to what air jets are? And why do you feel you need to adjust them?

 

[salty_monk]

The main air jet on a CV is not adjustable without drilling or a bush.. (hence the bushes you get in several Dynojet kits).
The pilot air jet is replaceable by different sizes & is the one Jethro talking about in the first instance that can be replaced... Both sit on the carb mouth front face - airbox side.

Dan

 

[redmike]

I am having some issues with my CV carbs with pods (on another thread) and I was on BassCliff's website looking at the carbs and noticed there was an airjet on the carb mouth behind the airbox. I wasnt sure what these jets were for and was hoping that if these were interchangable it would relieve my problem. Doesnt seem like it would though. Thanks Jethro and Dan for your insight. I'll be leaving these jets alone.

 

[Steve]

Generally speaking, the air jet (the one in the carb intake) does not need to be changed for pods. What you do need to change are the main jets (the big ones in the float bowls) and the setting on the idle mixture adjustment screws (the ones under the aluminum plugs that Jethro mentioned). Unfortunately, there seem to be no standard settings for them when you switchh to pods. What seems to work for one bike won't necessarily work for another similar bike. Why did you switch to pods?

.

 

[redmike]

Generally speaking, the air jet (the one in the carb intake) does not need to be changed for pods. What you do need to change are the main jets (the big ones in the float bowls) and the setting on the idle mixture adjustment screws (the ones under the aluminum plugs that Jethro mentioned). Unfortunately, there seem to be no standard settings for them when you switchh to pods. What seems to work for one bike won't necessarily work for another similar bike. Why did you switch to pods?

.

Mostly for performance. I was under the assumption that I could gain a few more HP with pods.

 

[twiggy2cents]

few more horsepower, lots more headaches

 

[salty_monk]

Putting a bush in the main air intake is a valid tuning procedure & seems to be necessary on a number of the models when going to pods. Some that I know of offhand that need an air corrector bush:

GS1000G / GS1000
GS1100G / GS1100 8v
GS750 16v

Sure there are others.....

Out of interest the 1100 16v CV34mm carbs have the same size air corrector bush as standard as the bushes supplied with the 1000G/1000 kit.

Incidentally - the air corrector bush fitted in Canadian carbs is a different size to the US one for the same model year (at least in my case with the 1000G that was the case).

Cheers,

Dan

 

[redmike]

Thanks Dan. Do you know if these bush' come in different sizes and where I can get them. I appreciate your insight on this.

Mike

 

[salty_monk]

They sure do but last I heard Dynojet wouldn't sell them individually. There used to be some guys in Australia on Ebay that sold them along with jets as a kit. Never tried one though.
It would be pretty simple to make your own. They are basically a piece of brass the dia of the air corrector hole with a hole drilled through the centre at the right size. You just tap them in place. Friction fit. You can pull them out again by putting a woodscrew through them and pulling but you generally wreck them.

You haven't given us any bike info... I am fairly up on jetting now but with my latest project I have still bought the DJ kit - it's not worth all the time it takes for the sake of 100 bucks!

 

[redmike]

Sorry about that.... Its an 1981 GS1000GLX with a vance and hines 4 into 1, Accel coils and wires and new pods. Otherwise its stock. I just adjusted the valves, installed the pods/dynojet kit and the bike runs wonderful, except for on the highway when it bogs big time at higher RPM's and speeds (see my other post). I'm going to re-route my carb vent hoses as suggested by BassCliff and take a ride later. I was hoping that changing the air jets would help. Looks like my only options (other then the air jets/carb vent hoses) so far are replacing the stock airbox (which I don't want to do after dropping $250) or creating a shield to block the wind.

 

[salty_monk]

changing the airjet prob won't help.... maybe you need a bigger or smaller main jet, what pods did you use? If you used those cheap $30 emgo's that could be the problem - you're too rich at WOT.
Spend the money for the K&N's or I have some foam filters that are slight better than super cheapies but not as good as K&N's you can try...

 

[redmike]

Thanks for the offer. I installed the K&N's. Gonna try the carb vent cable fix now.