Hello guys, I am having issues with carbon build up fouling spark plugs causing them to foul and misfiring cylinders.

I have fully stripped my carbs and cleaned them, then set the pilot screws on each of the 4 carbs to 2 turns out as factory settings specify.

The bike smells rich when running and starts easily without choke leading me to think the mixture is too rich fouling the plugs.

What would be recommend when it comes to adjusting the pilot screws? should I go to 1 turn out or 1 1/2? etc.

Bare in mind the spark plugs shown in the photos are brand new and the bike hasn't even been properly ran yet as I am waiting to pass my test and recently bought the bike.



Thanks everyone

 

If you can get a bench tach, (the one on the bike isn't accurate enough), I would suggest one at a time, back out your pilot screw until the RPM's no longer increase, then back it off 50 RPMs. Reset your idle adjustment to1,200. Then repeat the carbs. Also, you don't mention the carbs being sync'd. That is highly recommended for overall performance.

 

I am new to working on bikes and have been learning as I go, I was unsure if syncing of the carbs would have a big effect but if you think so then I shall do both .

I will do some research here into Syncing ( if you have any advice it is welcome for that too)

Thanks

 

Syncing is making all four carbs act as one. The engine cylinder valves create the vacuum by which our carbs work. There are variances in valve clearances as well as well as all the carb components not being exactly the same. The goal is to dial all that stuff in so they act as a single single until, not four cylinders and carbs doing their own thing. When a bike is properly sync'd when you roll up the throttle is nice and smooth. There's no hesitation or stutter. It's the sound that makes you all tingling inside.

 

If this was from the bike just idling (not actual riding), then yes, I'd say your pilot screws are too rich.
You definitely should need to use choke to start the bike when it's cold. If you don't, then it's too rich.
Turn them all back to 1.5 turns and try it.

The other option is you still have something wrong:
plugged air filter? if it's a k&n, you've over oiled it like everyone always does.
air bleed orifices at the top of each carb could still be plugged (very small and must be clear).

 

Hey Phil, I will try 1.5 turns and go from there, did a full service on the bike it has a OEM filter in it.

When you say bleed orifices at the top of the carbs where are you referring to ?

I have attached a picture of my carbs which might help to explain where these drain points are for my own reference.

Kind regards,

Daniel

 

Air bleed orifices circled in red.
one of them goes to the pilot circuit in the carbs and supplies air.
The needles controls the fuel.
If the bleed is clogged (which happens), then you get too much fuel (rich) and will foul plugs at idle.

It's not common however to have all 4 plugged, that's why I asked about air filter.
Anyway, they are small orifices. They are also 'Y' shaped internally.
You have to clean them from every opening. Just because you spray in one side and it comes out the other, doesn't mean the entire circuit is clean.
I usually take a single strand of wire from a lamp cord and run it through the openings, then spray with cleaner, and blow out with compressed air.
Repeat for every opening at the top and all the other ends that you can find. Carb like to be really really clean.

 

25 thousandths or .9 millimeters are used to calibrate the spark plug. which is correct

 

Should be 35 thousandths or .9 millimeters.