Help with fine tunning needed.

F

FelipeCobu

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Local time
11:41 PM
Joined
Jun 29, 2011
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88
Location
Curitiba - Brazil
Hello,

I'm finishing the tunning of my motorized bicycle after converting it to reed valve.

Follows the specs:

Happy Time engine 66cc.
Converted to reed valve using AV-10 (Motobekane) two petal reed valva.
I'm using the normal NT Carburetor.
Main Jet .75 (.75mm)
Using Castrol Mineral Oil.
Using 30:1 Gas/Oil Ratio.
I live at 3000 Ft. Altitude.
Already set the carb float properly.

The Simptons the bike is presenting is some sort of sputtering on WOT.

Follows a pic of converstion and some plugs after running a few minutes:

2013-10-07 21.00.05.jpg2013-10-13 21.41.20.jpg

Thansk a lot!

Felipe Cobu
 
that intake looks really long - you might be shaking the carb enough to cause the fuel to foam in the bowl
 
sublunacy said:
will a 66cc reed motor could run well in varying loads w a stock muff / cdi at wide open throttle?
your engine cant breath is my guess. i think thats 3/4 of the problem.
123 just trying to help/ 4 would be jetting
Click to expand...


Pics don't show but I'm not using the stock muff, and by my guess CDI has not much to see with engine being able to breath...
 
sublunacy said:
why could you file/mould jbweld but backout of doing the same w aluminum? whats up w that?
Click to expand...

No no, since I'm not a native speaker/write of english it may be hard to understand (things I write).

I firstly made a piece of resign then I send this piece to be sand casted on aluminum, this last part is what you see bolted to the cylinder in the engine.
 
FelipeCobu said:
Will increase the jet size on the carb see it stop sputtering and then yeah floor it!

By floor do you mean run it hard is that?
Click to expand...

Hi! You have to keepthat carbuerator level! If it will be leaning to one side or the other it could become very lean. I had the same problem.

Also, I had a problem with my stock NT carb. The fuel flow was restricted by a very small hole just before the float close off valve. After driving at WOT for a while, the gas in the carb would run out quickly, it would begin to sputter and die. I had to drill out the opening to a 1.5 mm size. Then I aslo had to refinish the mating surface where the float bowl valve closes that opening. I recommend that you first make that carbuerator always stand level. No crooked carbs. If it has a float bowl, then it can begin to open badly and you will not have enough gas to run at WOT correctly and it will be running to lean at high rpm - danger!
 
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