How big is too big? 130 jet still lean

[Guest]

Ok its a 1978 gs 750 with a mac header and PODS. Needle is raised to it highest spot and im at a 130 main jet Have NOT touched the pilot Jet. It runs fine but plugs tell me a different story. They say its super lean. Ok i was expecting to go up jet sizes but 130 sounds a little too big to be lean since i started at a 100 main. No vacume leaks and it doesn't stumble at all. I just dont want to burn a hole in my piston. do ignore the plugs or keep going up? Do i put shims under the clip or mess with the pilot jet?

[Agemax]

at what point are the plugs telling you its running lean? cruising speed, WOT or where?

have you done plug chops to show you this result?

[stroke]

at what point are the plugs telling you its running lean? cruising speed, WOT or where?

have you done plug chops to show you this result?

Well I took it out on the high way and took her through the gears warmed her up and lugged it a little and ran her through again then cruised home checked the plugs LEAN then did the same cycle again and when i got on my street i WOT i first gear and and hit the kill switch at high rpm to see if i got a different reading it was still lean. What r plug chops?

[Agemax]

Well I took it out on the high way and took her through the gears warmed her up and lugged it a little and ran her through again then cruised home checked the plugs LEAN then did the same cycle again and when i got on my street i WOT i first gear and and hit the kill switch at high rpm to see if i got a different reading it was still lean. What r plug chops?

lol, you have just done one.....

[stroke]

ok looked up plug chops i will pull in the clutch next time i do a test.

[Big Rich]

I can't help with what jets you actually need, but I want to point out: sometimes fueling issues show up as lean conditions. Pinched fuel line, float heights set wrong, clogged fuel filter, clogged gas tank vent, etc, can all be confused with jetting problems.

[stroke]

I can't help with what jets you actually need, but I want to point out: sometimes fueling issues show up as lean conditions. Pinched fuel line, float heights set wrong, clogged fuel filter, clogged gas tank vent, etc, can all be confused with jetting problems.

i suppose but i think it would be more noticeable if it was starving for fuel. but i will change the filter and check float hight when i change the jetting again. hmmm i went from a 120 to 130 and the plug didnt change color at all

[chef1366]

Is the needle on the highest notch away from the tip or lowest?

[stroke]

Is the needle on the highest notch away from the tip or lowest?

yes on highest notch if i want to raise the needle any more i would have to put shims under the clip.

[stroke]

I moved the clip DOWN 2 notches too RAISE the needle

[chef1366]

Lowering the needle is leaning meaning the notch farthest away from the tip that goes in the emulsion will be the leanest setting.

[Steve]

yes on highest notch if i want to raise the needle any more i would have to put shims under the clip.

Add as much as you want under the clip, you will NOT raise it any.

The spring under the clip pushes the clip up against its stop. Adding shims under the clip will just push it harder, it will not change the position. To change the needle position, you need to remove shims from above it or move the clip away from the blunt end and toward the pointy end.

.

[stroke]

there were no shims or springs on my needle just a clip and five notches. i moved the clip DOWN towards the pointy end.

[BassCliff]

Hi,

I found these on some guy's website. I figured they'd be a good reference.

CV Carb Jetting and Cleaning

Plug Chop and
Idle Mixture Adjust Methods
(by Mr. koolaid_kid,Mr. tkent02, Mr. psyguy)

Spark Plugs, How to Read


Thank you for your indulgence,

BassCliff

[stroke]

Thanks Bass Cliff lol

I will dig through it so much info so little time in a day