Hyosung Prima Racing SF50 ultimate build
- Thread starter RAW
- Start date
hello!
Im also raping Hyosung sf50 scooter,
and I know this requires really big patience 8P
installed:
malossi 70cc group
technigas exhoust pipe
lightweigt roller comp
air intake
malossi reed valves
and with such modification spent riding three seasons. had luck to change piston maybe three times already.
first time was mistake with fuel 95 instead 98 ;/ other times it was like piston ton covers with carbon and oil mixture and this mixture makes rings to stuck on piston and than piston starts to burn ;/ so I started to put less oil in to gas.
this scooter does have mechanical oil pump but this stock pump have been sucking oil for 50cc cylinder, so I added manually 50ml to (5L) gas tank. this time anyway piston rings stuck and broke..
so I bought new one again and decided not to put oil to gas anymore and after bout 1500 km now i opened engine again to see what is the picture. (I had many accidents so I had luck to meet each side of this scooter
)
so after opening I saw this: piston top bit covered with carbon but dry without oil. and cylinder head covered also (not so much as earlier times) but covered with abit oily carbon.. Im using NGK BR8HS
picture here:
would be nice to hear if someone have some suggestions bout what can cause this 'burning'
but no adding oil caused to work some engine parts more loud.. so now Im gonna make oil pump work with bigger amount or disconnect it and use oil gas mixture only.
with this chance I also cut exhaust pipe a half to clean all oily carbon stuff from inside, sand it and paint it. also to change the stuff inside little canister in the end of it (oh terminology
)
planing to put other shock breaker (if the right name, sorry) with manual inflation. just used one from some other motorcycle.
to change tires and regulate to get richer mixture or also to change carburetor to bigger one.
later Ill put some more pictures of what Im doing.
Im also raping Hyosung sf50 scooter,
and I know this requires really big patience 8P
installed:
malossi 70cc group
technigas exhoust pipe
lightweigt roller comp
air intake
malossi reed valves
and with such modification spent riding three seasons. had luck to change piston maybe three times already.
first time was mistake with fuel 95 instead 98 ;/ other times it was like piston ton covers with carbon and oil mixture and this mixture makes rings to stuck on piston and than piston starts to burn ;/ so I started to put less oil in to gas.
this scooter does have mechanical oil pump but this stock pump have been sucking oil for 50cc cylinder, so I added manually 50ml to (5L) gas tank. this time anyway piston rings stuck and broke..
so I bought new one again and decided not to put oil to gas anymore and after bout 1500 km now i opened engine again to see what is the picture. (I had many accidents so I had luck to meet each side of this scooter
)so after opening I saw this: piston top bit covered with carbon but dry without oil. and cylinder head covered also (not so much as earlier times) but covered with abit oily carbon.. Im using NGK BR8HS
picture here:
would be nice to hear if someone have some suggestions bout what can cause this 'burning'
but no adding oil caused to work some engine parts more loud.. so now Im gonna make oil pump work with bigger amount or disconnect it and use oil gas mixture only.
with this chance I also cut exhaust pipe a half to clean all oily carbon stuff from inside, sand it and paint it. also to change the stuff inside little canister in the end of it (oh terminology
)planing to put other shock breaker (if the right name, sorry) with manual inflation. just used one from some other motorcycle.
to change tires and regulate to get richer mixture or also to change carburetor to bigger one.
later Ill put some more pictures of what Im doing.
Last edited:
Question for you!!
Have you changed to a larger custom intake?
If not Stop i can not say it enough. The intakes on our scooters SUCK!!!!!!!!!!
They are so small that going to a larger car and jets require more AIR. And the intake is so small you can only get so much threw a straw does not matter carb you try.
My guess is this is why you are running rich{!
Having built 3 custom intakes and now I am making 8 more at this present time for others in our boat.:'(
Have you changed to a larger custom intake?
If not Stop i can not say it enough. The intakes on our scooters SUCK!!!!!!!!!!
They are so small that going to a larger car and jets require more AIR. And the intake is so small you can only get so much threw a straw does not matter carb you try.
My guess is this is why you are running rich{!
Having built 3 custom intakes and now I am making 8 more at this present time for others in our boat.:'(
original air filter was removed and I placed on like that
http://www.scootershop.com/catalog/images/DSCN4070.JPG
his story begun like that:
the inner diameter of 70cc malossi was 47mm ant it could not fit inside the original hole..
so I had to cut a bit these sides.. than it worked
yes intake and carb unfortunately is pretty small: its 16mm on carb out and intake in. and 21mm on intake out.
this metal plate I threw away at very beginning it was only 9 mm something hole
so I went with this original one all this time and max speed I had was more than 100 km/h but i had to close bout a 1/3 of this cone filter surface with scotch tape to let inside less air, like that scooter was much faster.
so I was thinking if to replace carb and intake pipe also ?
after your comment I watched all around again and saw one more thing.. this hole in yellow, is 19-20 mm on original and on my 70cc cylinder this hole is 24 mm wide... so you had idea about this hole ?
maybe this one enough (in blue) and gas will go ok ?
maybe bigger pipe will go ok and no need to cut 'yellow' hole to do it 4mm wider.. and gas will go inside pretty well other ways (if Im not wrong|( ) ?
some brainstorming here from my side.. 8P please comment
http://www.scootershop.com/catalog/images/DSCN4070.JPG
his story begun like that:
the inner diameter of 70cc malossi was 47mm ant it could not fit inside the original hole..
so I had to cut a bit these sides.. than it worked
yes intake and carb unfortunately is pretty small: its 16mm on carb out and intake in. and 21mm on intake out.
this metal plate I threw away at very beginning it was only 9 mm something hole
so I went with this original one all this time and max speed I had was more than 100 km/h
but i had to close bout a 1/3 of this cone filter surface with scotch tape to let inside less air, like that scooter was much faster.so I was thinking if to replace carb and intake pipe also ?
after your comment I watched all around again and saw one more thing.. this hole in yellow, is 19-20 mm on original and on my 70cc cylinder this hole is 24 mm wide... so you had idea about this hole ?
maybe this one enough (in blue) and gas will go ok ?
maybe bigger pipe will go ok and no need to cut 'yellow' hole to do it 4mm wider.. and gas will go inside pretty well other ways (if Im not wrong|( ) ?
some brainstorming here from my side.. 8P please comment
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it took me something one hour to make 'yellow' hole same wide as on cylinder 24-25mm. covered inside and while brushing metal I kept holding very strong vacuum cleaner to suck all small peaces, not to get them inside.
so now the only option is to change carb and intake pipe ?
so now the only option is to change carb and intake pipe ?
You are on track but the intake is a must as i said.
Just think of how small it is now and restrictive on the 50cc and you are going to demand another 40% more air flow with the 70cc kit. The factory intake will not supply enough air to properly tune the stock 50cc let alone the 70cc.
Just think of how small it is now and restrictive on the 50cc and you are going to demand another 40% more air flow with the 70cc kit. The factory intake will not supply enough air to properly tune the stock 50cc let alone the 70cc.
IkKe00
Well-Known Member
Why don't you (both) make some kind of straight intake, just make a ground plate and drill holes on the right spot, and weld a straight piece of metal tubing to it (with the diameter you want to use).
then just find a minarelli carb (or something like that) and make it slide into the tube.
Your intake will be allot shorter, and i'm sure it will be cheaper then mess around with that strange stock intake.
just my 2 cents
then just find a minarelli carb (or something like that) and make it slide into the tube.
Your intake will be allot shorter, and i'm sure it will be cheaper then mess around with that strange stock intake.
just my 2 cents
thanks IkKe00 !
with having shops we forgot that we have own hands to make things sometimes +ralf+
p.s. some question bout oil...
before some time I used Motorex and later Eurol oil and Eurol was maybe leaving little less mess inside cylinder.
now Im thinking to try liqui-moly and they have two types:
Racing Scooter 2T synth and Racing 2T synth maybe anyone have experience with this kind of oil ? witch is priority ? any suggestions ?
with having shops we forgot that we have own hands to make things sometimes +ralf+
p.s. some question bout oil...
before some time I used Motorex and later Eurol oil and Eurol was maybe leaving little less mess inside cylinder.
now Im thinking to try liqui-moly and they have two types:
Racing Scooter 2T synth and Racing 2T synth maybe anyone have experience with this kind of oil ? witch is priority ? any suggestions ?
Well I quess i have not made it clear.I have made custom intakes for my Prima as there is not a single intake in the WORLD made for our scooters by a aftermarket company at all.
With this I did several at one time as getting them cut up on a waterjet is better to do several than one only.
If you want one contact me .
Here is some info on them.
http://korider.com/index.php?topic=9433.0
With this I did several at one time as getting them cut up on a waterjet is better to do several than one only.
If you want one contact me .
Here is some info on them.
http://korider.com/index.php?topic=9433.0
I wonder where goes this blue pipe, from intake pipe. factory default it have been connected to oil pump and now you're not using factory oil pump anymore ?
The blue line off the intake was for a 70cc boost bottle which i tried it !!
was in hospital for some time.. now time to continue
for intake its big price for me personally... its like quarter of all scooter price. I would sell my scooter for 600-700 $ plus I would give additional scooter (same model) after crash (good fot spare parts) and additional cylinder.. so you see its like..
Ill try my chances to find used carb and intake.. 8P
for intake its big price for me personally... its like quarter of all scooter price. I would sell my scooter for 600-700 $ plus I would give additional scooter (same model) after crash (good fot spare parts) and additional cylinder.. so you see its like..
Ill try my chances to find used carb and intake.. 8P
Crank
Hey RAW, just had an '06 Rally given to me with a bent crank,
i have been looking over your rebuild and thinking my life is too simple,
so i must complicate it with getting into changing the engine to a 70cc kit
so i may be after an intake,
but have you any idea as to where i could get a complete crank?
Hey RAW, just had an '06 Rally given to me with a bent crank,
i have been looking over your rebuild and thinking my life is too simple,
so i must complicate it with getting into changing the engine to a 70cc kit
so i may be after an intake,
but have you any idea as to where i could get a complete crank?
