Hello! So I bought a chinese YD100 kit from a german seller. Anyways i installed it onto my frame and tried to start it... I spend about 30 minutes trying to start it. Was checking if it was getting fuel, if the plug was wet all those things. It was backfiring like crazy at first. After about 30 minutes it started but would not idle. After about 15 more minutes of trying i got it to idle but the throttle response was non-existent. Again after about 15 more minutes it started responding to my throttle inputs. Tried to ride it and it bogs down when i get it going. I let it run for 15 minutes and rode it on a flat road for about 30 minutes but when i came to a hill i wanted to die so i had to pedal with it. Is it normal that it has no power at all while in break in. Before putting the engine on the frame i checked all of the bolts and such and i found out that it had no gasket between the cylinder and the case (it has a 1 piece cylinder and head). I made my own out of gasket paper. There are no obvious air leaks. The needle pin is set on the 3rd groove from the bottom. Should i try tweaking with the carb first? Thanks in advance!
Break In Chinese YD100 no power
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Chainlube
Well-Known Member
You need a thinner base gasket then.
GW's Motorized
Well-Known Member
Make one with a coke can and coat it with some rtv
Well i tried everything... different gaskets (from 0.2 all the way to 4mm) and made no difference at all. Tried to make it out of a soda can and rtv still no difference. I will try to make something with the seller to send me a new engine and in the mean time i will split the case to re-seal it and check if it has any cracks.
GW's Motorized
Well-Known Member
That sucks, I don't know what else your problem could be.
Well finally good news!
I re-sealed the case with rtv, cleaned the carb and polished the needle valve (i noticed it was leaking a little bit) and the engine now runs about 80% better and actually moves under its own power. I dont know what the performance of a brand new engine is but it seems good to me (i also got send a very small rear sprocket 36t i belive). One thing i noticed is that under about 60% throttle its not that responsive (i would have to play with the needle pin to fix this?) And for the little time i went full throttle (since it is still new) it didnt rev that high. This would be the jet size right? I have the newer styile BoFeng carb...
I re-sealed the case with rtv, cleaned the carb and polished the needle valve (i noticed it was leaking a little bit) and the engine now runs about 80% better and actually moves under its own power. I dont know what the performance of a brand new engine is but it seems good to me (i also got send a very small rear sprocket 36t i belive). One thing i noticed is that under about 60% throttle its not that responsive (i would have to play with the needle pin to fix this?) And for the little time i went full throttle (since it is still new) it didnt rev that high. This would be the jet size right? I have the newer styile BoFeng carb...
Tell me where exactly you have the C clip right now on the needle valve and your approximate elevation above sea level and maybe I can give ya a position to place the needle valve.
The C clip right now is at the 2nd position from the needle up... my elevation is at about 250-300m
Also what jet size would be best for this 100cc engine?
Was also thinking about sanding down the magnet key so i could adjust timing if that would be a good idea...
Again thanks for all of the help and tips!
GW's Motorized
Well-Known Member
So the needle is in the middle then? And that's about 800 to 1000 feet. I think a base line tune is good, maybe a little richer.
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