What Jetting for Jardine 4-1 Exhaust?

[Anonymous]

Hello,

I just purchased a new Jardine 4-1 exhaust for my '78 GS550.
Will I need to do any jetting after I install it? If so, what?
Can I raise the needle's on my carbs or will I need a carb kit for that?

On a different jetting note:
For fun I removed my air box cover to open up the air box and let it breathe better. After I did this, I noticed the bike starved for fuel when I tried to go past half throttle or when going up a hill. I put the air box cover back on and it ran perfectly again. I see that it doesn't take much to get this bike to run lean. This is why I am wondering if adding an exhaust will require jetting? Normaly I dont think it does.

Thanks,
Jeff

[Detman101]

With these bikes...it does. They are already jetted so lean from the factory that if you got a roach sized hole in your airbox you would be in rejetting hell.

Dm of mD

[Anonymous]

Ok, so it looks like I will have to jet.
Can I get away with just moving the needle up a few positions?
Also, what is the stock main jet for this bike? What would be a good one to go up to?
I know there is an air adjustment screw on the side of each carb. What is the stock setting? and what way will richin and what way will lean it?

Thanks,
Jeff

[Anonymous]

Try raising the needles to the max lift. It may help midrange pickup but if it falls on its face on the top end, then you'll need new mains at least. Go up 3 or 4 sizes on the mains to start(the numbers are stamped on them) and go from there. You're gonna have to screw around with the pilot side as well to keep the low side "lean beast" at bay.