Post by scootbydoo on Sept 4, 2023 18:12:35 GMT -5
Hi everyone,
I am a new member, but been an avid reader in the last month to "transform" my old BWS 2002.
So the story goes, after moving from the city to the country side, where a untuned stock 50 cc is not really safe nor fun (way too slow), I've put the scooter in storage and bought myself a KTM XCW 200.
Meanwhile, I had a son and decided to keep it until he would reach legal age of driving it and pass it to him. I also foresaw the extinction of two-stroke scooters (after road bikes and dual purpose bikes, it was just a matter of time before they ban the little smokers...) and thought this thing would be a gem later for my teen.
So, thank you for all those precious info in the forum; it really helped me. I did screw up a couple of things (like breaking a fin trying to lock the variator with a screwdriver to tighten the nut...), but this is how I am (still) learning that buying the appropriate tool is (often) cheaper than replacing the broken part and waisted time.
The build.
BW'S/ZUMA 2002
70cc Malossi Sport + Yasuni Z
Malossi Multivar (5.6g rollers)
Polini sport clutch (green springs + white Malossi contra)
Stock carb (#86 main, #3 needle, stock 44 pilot, 2,75 turn air screw)
Stock airbox (athena filter), stock gears, stock crank
Max speed is 81 km/h (50ish mph) on flat and got to 90 km/h (55ish mph) down a hill.
Max RPM is 9600-9800 on flat and I do not go higher than 10500 down a hill
Clutch seems to catch around 5500-6000 rpms which seems to match the malossi white contra and the 5,6g rollers.
It pulls well, but nothing too crazy, no wheelie machine here. I do have two questions:
I would like it to cruise at 90 km/h on flat (3/4 throotle, not WOT if possible) to avoid aggressive overpass by impatient drivers. Is 14/42 or other ratio gear would work ? If so, will I have to readjustment CVT (variator weights? Contra spring ?).
In the process of jetting, I started at #94 (Polini jets) to be on the safe side. It ran well at WOT, but hesitate/seems it needed air at 0-1/4 (even with air screw turned out 4 turns). Got down in main jets until #88 where the response at 0-1/4 was much crisper. Went down again #86 and it still runs great, 2,75 turns air screw. I feel I could even go lower (RPM and top speed raised a little from 88 to 86). So, my question is, it is said to go 10% higher for the main when you install BBK+exhaust, but, is the stock #80 main is the equivalent of the Polini #80 main for that 10% calculation ? Because I am getting quite close to the #80 stock jet, 2,75 out on air screw. I do not want to go too crazy on the lean side of the force.
Thank you in advance !
I am a new member, but been an avid reader in the last month to "transform" my old BWS 2002.
So the story goes, after moving from the city to the country side, where a untuned stock 50 cc is not really safe nor fun (way too slow), I've put the scooter in storage and bought myself a KTM XCW 200.
Meanwhile, I had a son and decided to keep it until he would reach legal age of driving it and pass it to him. I also foresaw the extinction of two-stroke scooters (after road bikes and dual purpose bikes, it was just a matter of time before they ban the little smokers...) and thought this thing would be a gem later for my teen.
So, thank you for all those precious info in the forum; it really helped me. I did screw up a couple of things (like breaking a fin trying to lock the variator with a screwdriver to tighten the nut...), but this is how I am (still) learning that buying the appropriate tool is (often) cheaper than replacing the broken part and waisted time.
The build.
BW'S/ZUMA 2002
70cc Malossi Sport + Yasuni Z
Malossi Multivar (5.6g rollers)
Polini sport clutch (green springs + white Malossi contra)
Stock carb (#86 main, #3 needle, stock 44 pilot, 2,75 turn air screw)
Stock airbox (athena filter), stock gears, stock crank
Max speed is 81 km/h (50ish mph) on flat and got to 90 km/h (55ish mph) down a hill.
Max RPM is 9600-9800 on flat and I do not go higher than 10500 down a hill
Clutch seems to catch around 5500-6000 rpms which seems to match the malossi white contra and the 5,6g rollers.
It pulls well, but nothing too crazy, no wheelie machine here. I do have two questions:
I would like it to cruise at 90 km/h on flat (3/4 throotle, not WOT if possible) to avoid aggressive overpass by impatient drivers. Is 14/42 or other ratio gear would work ? If so, will I have to readjustment CVT (variator weights? Contra spring ?).
In the process of jetting, I started at #94 (Polini jets) to be on the safe side. It ran well at WOT, but hesitate/seems it needed air at 0-1/4 (even with air screw turned out 4 turns). Got down in main jets until #88 where the response at 0-1/4 was much crisper. Went down again #86 and it still runs great, 2,75 turns air screw. I feel I could even go lower (RPM and top speed raised a little from 88 to 86). So, my question is, it is said to go 10% higher for the main when you install BBK+exhaust, but, is the stock #80 main is the equivalent of the Polini #80 main for that 10% calculation ? Because I am getting quite close to the #80 stock jet, 2,75 out on air screw. I do not want to go too crazy on the lean side of the force.
Thank you in advance !
Not all jets are labeled correctly and that can drive you mad when tuning.
