Is my engine too rich or too lean? (pics + vid)

FrizzleFried

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Chances are slim. Yesterday I swapped out my stock Chinese plug (very small) with an NGK and I noticed exactly zero difference.

Your mileage may vary.
 

Kehkou

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I'm told brown is ideal which appears to be the case
That's good; that's what I expected mine to look like, but take a look; this is superlean:
Yesterday I swapped out my stock Chinese plug (very small) with an NGK and I noticed exactly zero difference.
As did I yesterday (sounds like your Chinese plug was functioning properly), but I noticed this:

img_20220722_190209_6-jpg.177986
 

Chainlube

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Took the carb apart. The jet has no identifying numbers on it. It looks like the keihin 99101-124 that was mentioned (I ordered a #68). I would have preferred to buy a kit here for a few bucks more which includes .66 - .70 ( https://www.bikeberry.com/products/...mm-68mm-69mm-70mm?_pos=1&_sid=6efef7e11&_ss=r ) but I have no idea if it will fit and the jets appear different.

Would these bikeberry jets fit or am I better off with the keihin 99101-124 #68? From this video its stated #66 is the best

If you need jets get in contact with @Pablo , he will want to sell you 2000 though.

Unlike that video, never run without an air filter, even if it is a short distance. One tiny piece of grit that bounces off a tire can destroy your engine.
 

FrizzleFried

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To counter:



For Clarity: I do not recommend running without an air filter either... just because it's super cheap and and super easy to run one that does not restrict air flow... plus they look sorta cool too... so why not?!?

That said... this gentleman does make some valid points... and I do believe that we're probably overly-anal about these tiny little motors... but that's not entirely a bad thing.
 

FrizzleFried

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I re-visited my Bofeng carb... I just can't get it to stop 4-stroking out of the box. 1-16mph... fine.... anything over 16mphs and it 4-strokes.

My stock NT/speed carb works much better for my engine. I even get better torque with it at the low end. I'm just terribly unimpressed with the Bofeng carb to be 100% honest.
 

DAMIEN1307

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Does it four stroke only when cruising at those low speeds???...Does it pick up right away when you hit the throttle and stop four stroking when excellerating and under load like going uphill???
 

FrizzleFried

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Nope...once she warms up she runs fine at lower RPMs... and even idles fine. Every time though at about 15.5-16 mphs ... it's right to 4-stroking where it stays. I've tried to "run out" the 4-stroking but even after a good 20-25 seconds of full throttle...I was up to maybe 20-22 mph and it was still 4-stroking...no end in sight...not even a BLIP of proper firing.

What is a little odd (to me anyway...but I admit I am a newb at this) is that it's supposed to be 70 jet in there... but my speed carb is running a 72 and it's not a problem.
 

DAMIEN1307

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it's supposed to be 70 jet in there
The BoFengs come stock with the #70 jet...I am assuming your at a 3000 ft altitude thereabouts and that your needle valve C clip is at the second notch to the TOP of the needle??? If so, Move it up to the very top notch and see what happens.
One thing I have different on my BoFeng than you do is a much better, non restrictive airfilter that is a no fuss direct replacement for those stock ones...Less restriction, more air, is much better to run at altitude.


You can see it on my motor here below, I'm at 4500 ft.

Gasoline makes all the difference in the world too...I use Ethanol-Free gas which burns and powers much better than the regular gas that now has 15% ethanol.

DSCN0229.JPG
 
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