Read my plugs plz? (1982 GS450TX)

[Guest]

Hey gang,
I'm trying to tune my bike a bit more, but can't tell if I have enough miles on new spark plugs to give me an indication of which way to tune the air/fuel mixture.

Engine behavior = popping on deceleration starts after 10 miles into a 'easy' 15 mile test ride.

Bike = GS450TX

Mods are as follows:
* Carbs re-jetted to: pilot=22.5 / main=130
* Air mixture screws on sides of carbs = out 3 turns.
* Uni foam filters (high airflow, but restricted the exterior side walls so air would only enter from the back of the filter. Trying to smooth out the air travel)
* Emgo Shorty's mufflers (high airflow)

I currently have 72 miles on these plugs.

Any tips?

 

[Steve]

1. I think I know what "plz" means. I'll just say that I detest "texting" shortcuts. I don't use them in texts, either.

2. It does not matter how many miles you ride, what was happening during the 30 seconds before you turned the engine off?

3. To determine jetting by reading the plug color, you need to hold the throttle as steady as possible at 1/8, 1/4, 1/2 and full throttle as long as practical, then hit the kill switch, pull the clutch and coast to a safe place to pull the plugs and read the color.

4. My chart for an '82 450 shows a 45 pilot and 125 main. Why would you put in a pilot that is half the size? And for your intake/exhaust mods, going up two sizes might not be enough on the main.

EDIT: I just looked at another chart, it says that those jetting sizes were for '83 and newer. Your '82 would have 17.5 pilots and 115 mains. Increasing from 115 to 130 might be a bit much, considering you have most of your intake blocked off, but there is no need to go above 17.5 on the pilot jets.

The reason you need to increase jet sizes is because removing the airbox can allow more air to go through the carbs at full throttle, when demand is highest. The small-ish opening of the airbox is your main restriction. At idle speeds and low-throttle openings, your main restriction is your throttle plates, not the size of the airbox opening, so there is no need to increase jetting size.

.

 

[Guest]

steve is, as usual right on. For what it's worth with the info given, popping on decel frequently means lean, and the plugs (again, fwiw given the lack of info re the plug chops) look lean to me

 

[Gorminrider]

yes popping on deccel usually means lean but especially since the throttle plates are closed then, the idle circuit seems to me a prime place to investigate.

as to those white plugs, I need repeat what John Park pointed out to me..Chevron gas will do that! So it's just not the same with modern gasoline as to "lean"