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Discussion Starter · #1 ·
so, in contrary to everyone looking for more brute power, i'm looking to get a smoother engine but not a racy character.
stock there's a 107cc engine and fitted in a chinese clone honda super cub. runs nicely but lacks grunt.
not really looking for a faster ride because of the limitations with the drum brakes. max out now at 85kph chin to the handlebar :p
i was thinking about a 140-160cc engine with lower compresssion and the big flywheel and adjust the timing to smooth everything.
just curious what you guys are suggesting.

thanks in advance :)
greets from belgium.

 

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Discussion Starter · #3 · (Edited)
apparently i could just fit a barrel and head and make it a 140cc on the original bottom end?
someone pounted this out to me. but aer some research i saw the BBK of 54mm bore seems at its max,getting close to the studs.
would anyone be able to know wich one i can fit? it's got a 52.4mm bore and 49.5mm stroke ,152FMH engine, if i'm not mistaken.
 

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I think that the max size you can do with that engine is a 125-ish. I would just get a 140yx and then change the timing a bit to smooth it out some, and make sure to get one of the easy start CDIs so you don't have troubles with kickback. You might be able to get a flywheel weight to smooth it out even more. What sort of speed are you hoping for? Are you wanting to keep the semi-automatic clutch?

Also, who makes the scooter, and how much does it retail for, that might be an interesting acquisition for a friend of mine.

Bienvenue !!
 

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Discussion Starter · #5 ·
I think that the max size you can do with that engine is a 125-ish. I would just get a 140yx and then change the timing a bit to smooth it out some, and make sure to get one of the easy start CDIs so you don't have troubles with kickback. You might be able to get a flywheel weight to smooth it out even more. What sort of speed are you hoping for? Are you wanting to keep the semi-automatic clutch?

Also, who makes the scooter, and how much does it retail for, that might be an interesting acquisition for a friend of mine.

Bienvenue !!
yes i foud out there's a BB kit of 54mm instead of 52.4mm but turns out this only gives about 114cc so not worth the trouble.
i would like to keep semi auto clutch, i kinda like it :)
changing the complete engine (to a yx140) is if all else fails.
speed is of no impartance, max 90kph is fine.
the brand of the scooter is super motor company, but this was sold in holland and belgium, they are out of business now tough.
don't know what other brands sell similar model.
 

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You can put a yx160 in but that is more of a performance motor compared to the yx140 which has lower compression but has the same bottom end and gearing as a yx160. Bore up kits are nice and cheap compared to a new motor but if you want a semi auto your going to end up seeing a lot of 125cc semi autos for sale. Yx125 would be my recommendation if you dont get the yx140
 

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Discussion Starter · #7 ·
You can put a yx160 in but that is more of a performance motor compared to the yx140 which has lower compression but has the same bottom end and gearing as a yx160. Bore up kits are nice and cheap compared to a new motor but if you want a semi auto your going to end up seeing a lot of 125cc semi autos for sale. Yx125 would be my recommendation if you dont get the yx140
so i thought too about the yx160 being more performance then the yx140, thanks for the confirmation 👌
as of now i just fitted a slightly bigger carb with good results.
the stock carb measurments in the throat (oval bore) horizontal 14-15mm and vertically about 18mm, the throttle side was +-15mm diameter. (how do you determine exactly the carb size if it's not clearly stamped on the actual carb?)
the new carb is a round bore with 18mm throat ,throttle slide is 20mm.
i still need to fine tune this carb and fit a proper airfilter, will fit some sort of an airbox too to dampen the inlet sound.

so for now another engine is put on hold, and if i should fit another one it'll rather be a 140 then a 125.

thanks already everybody ✋✊
 

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For the carb there are problems with the china carburetor. My knockoff mikuni carb my motor came with had a 22mm horizontal diameter by 28mm vertical diameter. Carb said it was a 22mm but also seen them displayed as a 26mm
 

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Discussion Starter · #9 ·
For the carb there are problems with the china carburetor. My knockoff mikuni carb my motor came with had a 22mm horizontal diameter by 28mm vertical diameter. Carb said it was a 22mm but also seen them displayed as a 26mm
well that kinda makes sense, 26mm is somewhere in between the 22 and 28mm you measured. so average diameter could be 26mm.
but mine says PE17-15 so in my case with the measurements i made i'd rather say it's about 19-20 mm carb.
also the priginal measures 14 to 19 mm ova so that would make about 16-17mm, but the specs speak of a stock 19mm carb...
 

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Mine was considered a 22mm from factory, at least that is what it was called but these cheapo carbs tend to get replaced as many people get irritated with them not performing well enough, best upgrade i did was a nibbi pwk carb(flatslide). For most people the carb upgrade will get rid of there problems or at least most this way but requires a jetting test and tune as most come with a few jets and needles(mine came with 2 needles,3 pilot jet,3main jets
 
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