Do I need to go up one size main jet ...?

[hikermikem]

I'm planning to use a drop-in (stock config) K & N air filter in my GS850GLZ. Currently I'm cleaning/rebuilding the carbs and will soon try to fire up the bike. No pods, just putting a K & N filter in the airbox.

I haven't installed the carbs back on the bike yet, as I'm still doing some other work in preparation for the "start-up" event.

All carb parts are stock, except I raised the jet needles .050" (approx. one notch).

The stock mains are 115's. Should I go up to 120's because I'm using the K & N air filter??

Just wondering if any of you guys have any experience with this.

thanks,

mike

[Nessism]

I don't think you need to go up on the main, at least I didn't after dropping in a K&N. Runs great.

[hikermikem]

I don't think you need to go up on the main, at least I didn't after dropping in a K&N. Runs great.

Thanks - I'll keep it stock then...

mike

[tkent02]

See how it runs, then do what it needs.
Pods on my GS1000 needed a big change, K&N in the box only needed a small change, one jet size.
The 4-1 pipe was already on there, and things are weird from the elevation around here anyway.
If your bike was on the verge of being too lean as it was, a bigger main will be right.

[hikermikem]

See how it runs, then do what it needs.
Pods on my GS1000 needed a big change, K&N in the box only needed a small change, one jet size.
The 4-1 pipe was already on there, and things are weird from the elevation around here anyway.
If your bike was on the verge of being too lean as it was, a bigger main will be right.

Thanks mr. tkent,

I have no history on how the bike ran - it's been sitting for 15 yrs. I was just looking for a good place to start... The current plugs (Champions!!) are a mix of 2 black & 2 whilte - hoping that doesn't mean a bad coil.

I visit Lousiville (up the road from you) every now & then - my wife is from there. i really love the Boulder area. But you're right, the elevation is UP there - we like to go to Brainard Lake & look for mushrooms, that's somewhere arounf 10K elevation if I remember correctly. Engines run different at that O2 level for sure.

Regards,

Mike