43mm (65cc) issues

[Mystic]

okay i have been heat cycling this new build for a few days now a couple times a day i let it idle for 20 or 30 mins then ride to the end of the drive. I believe i have everything tuned right, pump tied open and an oz of oil in the tank, 100 main jet on stock carb, emgo pod filter, kymco zx exhaust, prodigy vari with 7g rollers and stock clutch springs with matching milled head and bp8 spark plug. she starts on the first kick and the smoke is even starting to clear up. i can only get her up to 15mph on 1/4th throttle when i try to go any fast than that it starts sputtering and wont go any faster than that. on a block she seems to rev past the 15 mark but i dont have a tach or temp guage so i dont know for sure but i am pretty certain its faster when i have it on the stand, any suggestions?

[Mystic]

Dont know exactly what size jet came with this china rebuild kit but it just seemed like the engine was flooding at 15mph when the main jet kicked in sooo i switched and what do you know 25-30 mph this baby sounds like a wicked chainsaw hahah the exhaust sounded pretty even but i could feel the power she wanted to go faster but not going to go over 30 for a week or 2 if i can keep myself from it. I need to find out exactly what size jet this is and maybe get an assortment maybe 95 90 and 85 try to use the biggest jet i can without the sputtering because even with the emgo free flow air filter and the big bore 100 is still too much

[Mystic]

took her for her first spin on the blacktop and got her up to 30 or so the muffler sounds perfect I may need to get a slightly larger jet. 0-15 is decent cant expect much with the small pilot. 15 to 20 is slow i imagine this is where the carb transitions to the main jet, once it pics up gas at 20 it takes off like a cats * hahah wish i had a temp gauge but cannot afford it right now and may wish i had scratched up the money later down the road i think the china jet is an 88 because its a kit for the china carbs they sell on ebay for 1988-2001 sa50 and the early models had an 88 i think may order the daytona pack or a 90 and 95 when i order the rings for my spree af05. have been seriously studing the air/fuel/oil science and i sorta understand it but i have never been good with numbers unless they had dollar signs 35 out of 36 on reading comprehension on the ACT but a 13 on math hahahha if i had another carb to fool with i could experiment with the pilot jet, the china kit comes with the pilot but not sure how to get the old one out, thinking i could pop the old one out and lay it aside and drill the holes out on the china one to one size bigger and the little hole in the carb throat next to the main emulsion tube whatever size drill bit corresponds to 40 anyone have any experience doing this?

[Bear45-70]

Raise the needle to help the low end and mid-range, but I will bet the main is too small.

[Mystic]

thanks bear, i think the jet is a tad small too but its the only one i have other than 100. 68 is too small and 100 is certainly too big. I will see what putting the clip in the bottom notch does for her and post the results. drive her around the circle near my house today about 7 or 8 miles and she seems to run good if a little rich. the plastic almost touches the header on the exhaust and it didnt get hot enough to melt so i think i am good on the temps. only time will tell and a few more miles

[niftyman]

Is a 43mm piston a 65cc if so what does a 47mm pison work out as

[niftyman]

My dio carb has removeable slow and main jets maybe you try and get one of these carbs might make it easyer to tune

[Mystic]

yea I have been debating whether i want to get a 21mm oko but you have to buy the intake manifold, air filter, throttle cable, oil pump plug, and throttle cable to really do it right and i cannot afford all that right now plus an assortment of jets. the 47 mm is like 75cc i think. i can get the whole intake kit from autotech on ebay but its like 135 plus 25 shipping tired of buying parts i wanna ride for a little bit

[Mystic]

I switched the clip on the main needle to the bottom and it seems to have made the transition from pilot to main around 15-20 smoother wont know for sure how well it reacts till i get it back on the blacktop so i can speed up and slow down a few times and listen to the engine but to the end of the the drivewy and back it seemed to have improved and it made the mixture richer cause the smoke started faintly again at idle plus i added a little more premix to the tank to be on the safe side before it was like 50 to 1 now it more like 32 to 1

[Mystic]

well the jet that came with the china kit was a 68 i think, used wire gauges to compare the inner diameter and they appeared to be the same. I stuck the 100 main back in and dropped the needle all the way down to lean it out since it practically floods the engine at middle notch before the engine has reached enough rpms to properly ignite the rich mixture got her up to 35 and it seemed to sound smooth but takes longer to accelerate from 0-20. I found a .8mm drill bit and drilled out the china jet then took the wire guages since they have a rough filing section i used that to file out the inside till i got switch to the next bigger gauge. i got it enlarged to around 90-95, matched it up with a 95 that i have, it will fit the wire next to the 95 easy but will barely slip on the end of the wire i used to measure the 95. I am gonna try it with the clip in the middle on the main needle and see what that does for me. luckily i have the stock keihin at 68 and i am gonna go get a set of wire guage drill bits today and start at around 84 and work my way up in approximate sizes till i get it right if this 90 or 95 doesnt improve my rich condition, i think the 100 main is more suitable for at least 70cc with my setup. Other than drilling the pilot, what can i do to increase acceleration at 0-20? heavier weights?

[the0captain]

well the jet that came with the china kit was a 68 i think, used wire gauges to compare the inner diameter and they appeared to be the same. I stuck the 100 main back in and dropped the needle all the way down to lean it out since it practically floods the engine at middle notch before the engine has reached enough rpms to properly ignite the rich mixture got her up to 35 and it seemed to sound smooth but takes longer to accelerate from 0-20. I found a .8mm drill bit and drilled out the china jet then took the wire guages since they have a rough filing section i used that to file out the inside till i got switch to the next bigger gauge. i got it enlarged to around 90-95, matched it up with a 95 that i have, it will fit the wire next to the 95 easy but will barely slip on the end of the wire i used to measure the 95. I am gonna try it with the clip in the middle on the main needle and see what that does for me. luckily i have the stock keihin at 68 and i am gonna go get a set of wire guage drill bits today and start at around 84 and work my way up in approximate sizes till i get it right if this 90 or 95 doesnt improve my rich condition, i think the 100 main is more suitable for at least 70cc with my setup. Other than drilling the pilot, what can i do to increase acceleration at 0-20? heavier weights?

i have 9 gram weights in mine and its pretty quick up to 20. our setups are pretty close to the same. i have a 65cc with the pod filter on stock carb but i have a stock exhaust. i also have a 1k center spring and 1k clutch springs. i think i may need some heavier rollers for that 1k center spring though. it seemed like it would accelerate a little better with the stock one in. but that may change with some more use.

also, i found that the 95 jet seems to be about right. 90 was too small and 100 was a bit too big.

[Mystic]

it takes a few minutes to transition between low and midrange once it peaks past 20 it picks up quick without much throttle, if i am below 20 and i try to give it much gas it seems almost like it is flooding. i have about a 95 in there now and i still had to lower the needle all the way down with the clip on the top to get it to run, middle of bottom clip and around 15 it sounds like it is missing a pop pop pop from the muffler instead of a smooth puffing. it idles fine whatever jet i put in i am gonna try running it with the needle all the way down until i get some drills to experiment with, i think an 85 or 90 will allow me to put the clip in the middle. my plug is usually wet so i know the jet is too big, it gets too much gas at the top of the low range so it floods before it can get enough rpms to transition. i also have a datona carbon fiber reed in there if i cant get the drills or the jet right after i try drilling i guess i will break down and get that daytona jet kit with all them jets but i am trying to gsave some money here. if i can find another carb to experiment with i am going to see if i can drill out the pilot to 40

[the0captain]

it takes a few minutes to transition between low and midrange once it peaks past 20 it picks up quick without much throttle, if i am below 20 and i try to give it much gas it seems almost like it is flooding. i have about a 95 in there now and i still had to lower the needle all the way down with the clip on the top to get it to run, middle of bottom clip and around 15 it sounds like it is missing a pop pop pop from the muffler instead of a smooth puffing. it idles fine whatever jet i put in i am gonna try running it with the needle all the way down until i get some drills to experiment with, i think an 85 or 90 will allow me to put the clip in the middle. my plug is usually wet so i know the jet is too big, it gets too much gas at the top of the low range so it floods before it can get enough rpms to transition. i also have a datona carbon fiber reed in there if i cant get the drills or the jet right after i try drilling i guess i will break down and get that daytona jet kit with all them jets but i am trying to gsave some money here. if i can find another carb to experiment with i am going to see if i can drill out the pilot to 40

mine made that same popping noise with the 90. i thought it was leaning out when mine was doing it though. thats when i switched to the 95 and it went away

[Mystic]

i have the pump wired open and 1 oz of lucas oil to a gallon of 93 octane. did you have your head milled to match the bore or did you stack head gasket?

[the0captain]

i have the pump wired open and 1 oz of lucas oil to a gallon

well that might make a difference, i'm just running straight gas without the pump being wired open. my temps were higher with the pump being wired open so i untied it and the temps are better now and seems to run better. you may need a bigger jet with all of that extra oil