Speedfight 2 project. Bogging Down.

[Aturnernffc]

Hello,

Long term viewer new poster. Probably an absolute nightmare post for most of you to deal with but here goes.

Me and a couple of friends invested a 100 bucks into a 2005 speedfight 2 50cc we were told it used to run fine was in storage for a year and never ran again. We thought at can’t be nothing to bad so we carried out the purchase.

We got it home and dry and found this couldn’t be more from the truth. There was nothing right with this bike the piston rings had gone the spline on the crank was non existent, no spark, kick start gear worn out, starter motor gone, bearings in the engine were shot cables flying around everywhere, throttle needle was bent you name it we got shafted.

We didn’t let this stop us we bought a new piston and rings and a donor engine in which we could switch parts around to try and get the old girl going again. We are now at a stage where it is running idles okay but has a real issue with bogging down under stress. The spark plug is looking a bit on the black side guess it’s running a bit rich. We’ve cleaned the carb and fuel filter it has a brand new standard exhaust with gaskets. We have reset the mixtures on carb back to standard. Replaced fuel. The only thing missing is the genuine air filter at this moment I guess the replies will be it’s that but I wasn’t so sure that would cause it to bog down and go a maximum of 20mph. I am purely looking for pointers and maybe some assistance as we are at the scratching heads points.

Failing this we shall just add it to the scrap pile and cut our losses thanks in advance

[WD Forte]

20mph is probably 2/3rds of what you could reasonably expect from a 50cc scoot

Considering the black plug
Does it have an auto choke?
These richen the mixture at start and should lean out over a relatively
short time.

If the heater element fails they will run lean from the start.
RICH!! NOT LEAN!
If its ok but gummed up/sticky from long term storage, it may not be able to fully move to the lean position so start well but then run too rich
with subsequent loss of power.

Edit:
I just spouted bollox there
They run RICH at start then lean out as the heater expands the wax capsule
SO
if the heater fails there's no expansion, so no leaning out of the mixture

worth checking anyway as its a common fault
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bikers smell of wee

[Aturnernffc]

Thank you for your quick reply it does have an auto choke but even after 5 minutes it does the same.

[WD Forte]

If you dont remove the auto choke and observe it you
cant know if its working or not
____________________
bikers smell of wee

[Aturnernffc]

Okay thank you for that we have tested the heater and it all appears to be functioning fine.

[WD Forte]

That's me out then.
Normally a 50cc 2 stroke would get a
"Burn it! send it to hell!!" from me but as you're new
and nursie just gave me my tablets, I went easy
____________________
bikers smell of wee

[Easy-X]

I resurrected a similar style of scooter and tried a few daft things with it, "Racing CDI" being the most amusing fail

I experimented with pod filters but could never get the fuelling right. Went back to the stock airbox/filter and it ran pretty good.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter