Running too rich?

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srbbnd
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Running too rich?

Post by srbbnd »

I installed a new spark plug today, runs great, but the old spark plug is completely black on top. I am assuming it has been running too rich. My question is that I am assuming I need to adjust the air mixture screw. However, I am uncertain what direction I need go and what increments would be suggested? Lastly, I was wondering if this could be a culprit in lower mpg's?. Maybe I am completely off track or there is another thread I am missing on this topic and could be pointed in the right direction.

Thanks!
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jimmbomb
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Post by jimmbomb »

What possesed you to swap the plug in the first place?
Does it seem to run the same now, as before you did the swap?
Did your mpg go up?
These 4t's are set out to go out from dealers running very very lean.
Maybey your choke isnt pulling completely off..
probally not though... does it run good and idle good when fully warmed up?

Ps.. being the cheap ass that i am, I would wire brush your old plug clean and save it for a spare or swap it back in.
good luck.
let us know what you find out.
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srbbnd
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Post by srbbnd »

Iridium, Irrrrri dddddium, just has a nice sound to it.
I had to change the center stand springs, because the kickstand wasn't pulling up on its own anymore. After failed attempts to get extension springs that would actually fit from local stores and getting the right resistance I ordered some online from a scooter shop, to be eligible for free shipping I got a spark plug and gapper tool. It seemed very logical at the time.
Inititially my Stella would stall constantly all the time so I had the shop take a look at it and they said they adjusted the idle. However, I never really tracked my MPG until after. I was having sub par mpg, but found out my needle pin was sticking and letting too much gas in. After I tinkered with that my mpg shot up to around 75 from around 60. The scooter runs great and really seems to get on it after the shop fixed the idling problem, but I am curious if it is a little too rich. I went throught the Stella Service Manual and it had some nice instructions. I will tinker around when the rain apocolpyse is over in SC and see what happens. In conclusion I was just wondering if running too rich would effect mpg and most importantly the health of the scooter.
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Johnny O
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Post by Johnny O »

How old is that plug? There could be lots of things that play into that. Carb setting seem most obvious, but you could have some oil blow-by into the cylinder causing pre-mature fouling. MPG changes aren't indicative of faulty plugs rather changes in your carbs ability to manage air-fuel ratio. Too much fuel just means you will have too many hydrocarbons (evaporated fuel) leftover. This fuel acts to cool the combustion. This could also be why you are seeing your MPG go to crap. You are running too rich. Not sure what your shop did but lookup basic carb tuning. Get another brandy new plug and some fresh gas and re-tune. If you are seeing any type of smoke in the exhaust and your oil level is diminishing, you may need new rings. Just some ideas.
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srbbnd
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Post by srbbnd »

It is about 4000 miles. I adjusted the idle a bit today, and I think it was too high. It seems like you need a tachometer to really do it right. For the air mixture screw it is protected my an mileage seal protector, whatever that thing is. So I don't think I will break that seal until my two year warranty is up.
Every tutorial I see they always talk about having to use the choke. I have not had to use the choke once since I have owned. Is this normal?
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jimmbomb
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Post by jimmbomb »

Why dont you shoot a youtube video of it idling?
And post it on here.
If itll start without the choke, then it could be partially on, and dirtiyng up that plug.
But if the choke is partially on, it could make it not want to idle at a proper low rpm.. stall out if you get it low enough.
Leta see and hear it idling.
And try pulling the choke out after its warmed up and at idle.
It should kill the motor.
Good luck
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srbbnd
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Post by srbbnd »

I have been driving it around and all is well on a lower idle. It occasionally dies when in neutral or if I am drifting with the clutched pulled in for long periods of time. I am curious to see how this effects my MPG and after a tank or two I will raise it up slightly. What is strange is a while back I bought a carb on Ebay and it does not have a Mileage Protection seal and the air screw is accessible. On mine there is no notch on the screw to turn.
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srbbnd
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Post by srbbnd »

I swapped the carbs, and it works great now, I don't know why. I adjusted the idle and air screw per the Stella 4T manual. I took it out on a spin and for some reason it is much faster and got a top speed of 67 mph with the gps. I have know idea if it is the spark plug or carb swap. The air screw on the original carb was covered in a sticky gum like substance. I will post later on if it has a negative or positive effect on mpg.
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Johnny O
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Post by Johnny O »

you might need to change your title of this post to "Running too Lean?". Check your plug and make sure its not burning up.
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az_slynch
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Post by az_slynch »

srbbnd wrote:I took it out on a spin and for some reason it is much faster and got a top speed of 67 mph with the gps. I have know idea if it is the spark plug or carb swap.
I'm going to guess that it's because the GPS speedometer is set to kilometers per hour, since KPH is illuminated. That'd be more like 41mph. I suspect that a 4T couldn't hit 67mph in freefall. :P
At what point does a hobby become an addiction? I'm uncertain, but after the twelfth scooter, it sorta feels like the latter...

Seriously...I've lost count...

Seven mopeds ...that's still manageable...
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Johnny O
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Post by Johnny O »

az_slynch wrote:
I'm going to guess that it's because the GPS speedometer is set to kilometers per hour, since KPH is illuminated. That'd be more like 41mph. I suspect that a 4T couldn't hit 67mph in freefall. :P
Good eye. Yea, I'd have to invest in that type of plug! It'd be cheaper than a new top end!
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