Just got some scooter mod's

Hey all,

I just got some scooter mod’s done. I only did two things but here they are

  1. I got 9 gram KOSO bearing and rollers originally had the 11 gram stock
  2. 1500 RPM clutch spring

I had the rollers done first to see if there was a noticeable improvement in performance and there was or is.

I just got the clutch spring installed today and I can’t tell yet if there is any difference.

If anyone out there has done the same please let me know how it went and if you liked the result.


Try 6.5 grams and you’ll be happy. My bike calls for 11 grams too but I use 5.5 or 6. It just stays in peak rev when I’m full throttle and it’s quite fast for a hair dryer.


i noticed a slight improvement when i installed a different spring in my clutch… not huge, but there was a LITTLE improvement…

Ok. My Yamaha Cygnus X has the bigger clutch wheel springs in it (to get the supper passing power), but that only give more midRPM power.

My question is? What not to expensive mods can be made to help out of the line? I know carbs are out due to $ and it has TPS.

part 2 is: What is (are) 9 gram KOSO bearing and rollers? and how do I ask for them in limited English/Chinese?

My mechanic was trying to explain that if I put a pipe on I would need to change something else to see some benefit? He was pointing to the left of the engine thing. Any ideas?

what are some mods that I can do to make my 125cc scooter faster? it’s Symco r1z 125

before you consider how to make your bike faster, consider how to make your bike safer, easier to ride - bigger brake calipers/discs/pads, steel brakelines / adjustable, more progressive suspension / keeping your headlights on all the time / better tires that grip instead of slip

change the roller bearings for lighter ones, they will spin quicker, allowing for better acceleration. acceleration comes at the expense of top speed.

  1. Open airbox, new needle & jet kit for the carb, free-er flowing exhuast. totally ditch your air filter…air here is filthy, but honestly, how many years are you gonna use your scooter…2 years, 3 years, maybe 5? With more oxygen flowing through the carb, your bike will run lean(or ‘hot(re4)’ as the local mechanics say) so you want to play with a combination of a higher needle position(you can throw washers underneath or get an adjustable position needle) and larger main jet. too big a main jet or too high needle position results in a soot-inducing rich air-fuel mixture(‘cold(leng2)’ in local mech-speak) which not only pollutes but gives horrible fuel efficiency(burning more fuel per unit of air than needed) air temp, altitude, humidity all play a part in determining the proper settings for your bike.

aftermarket exhaust does almost nothing except make more noise and attract attention from thieves. get your current exhuast cored-out and welded back together. OEM probably gives you the best bottom-end torque at the expense of top speed, an unbaffled straight pipe from the engine has no bottom end torque, no noise control and no place on a street bike[btw - emmissions is adjusted via your carbureted air-fuel mixture, not the exhaust…so if your carbs properly dialed, you’re good to go]…improperly dialed carbs/leaks anywhere from in-to-out/straight pipes are a good combination for backfire, not a good thing.

aftermarket carburetor is the single most effective way to enhance performance. butterfly valved CVs aren’t bad, but for real fun get flat-side carbs…popular CVs are CV24 to CV30 - the # is the size of the opening…smaller the opening, the quicker the gases flow thru - you may find the smaller opening to be a bottleneck at higher/top speed.

local 250cc scooters come with CVK30(CV30 made by Keihin, thats what the K stands for) so theres no need for any 125/150 owner to bolt on anything larger than the CV30…CV + needles/jets + installed by a competant mechanic may run you 4,000 to 7,000 depending on who you go to. if you’re good enough to do it yourself, its probably 3500 to 4500 for the parts. if you’re good enough to do it yourself, you probably stopped reading 5 minutes ago.

Flat side carbs are the absolute quickest way to ‘re-discover’ your scooter…you should look for PWK & FCR from Keihin or TM, TMR, TMR-MJN from Mikuni. WOW. big smiles all around. welcome to your new ride. may cost anywhere from 8000 to 30,000 depending on your need to demolish everything else on the street(within your cc class).

bigger cylinders/different pistons/cams are available for all of the popular 125/150 scooters. ask around. redwagon seems to really know his stuff in this area. adjustments in this area will need carb adjusting(needles, jets) as well.

you can get a quicker turning throttle holder so that just one small handful can let you run the entire range of your throttle - more useful at the middle to top end, hamfisted slamming open the throttle at the stop light isn’t so useful.

transmission gears can be custom machined if needed, however, this is like getting gold caps for your teeth - actual longevity is questionable and is it really worth it? the bike will be quick, but when will it fail/break, stranding you on some remote mountain road. i’d stick with OEM factory here.

kevlar belts are available for most of the popular scooter makes - these are tighter and less prone to stretching - putting more power to the tires instead of stretching the belts.

thats all i can think of now, good luck with your scooter, hope things turn out well and ride safe!

Ok ok.

The weights have no real effect on how fast the rotating mass spools up. The weights’ centrifical force apply pressure to the front pulley making it squeeze together which in turn makes the front pulley’s belt-contact area increase in diameter. So all you are realling controlling is the curve of the gear ratio. Light weights don’t make the front pulley squeeze as much so it leaves you in a lower gera for longer.

The Stiff spring you put behind the clutch (rear) keeps it from engaging until a higher RPM and helps your launch. You can change the gears 450nt but it doesn’t make a big difference.

Pipe pipe pipe. MOST IMPORTANT! Get a fat sucker. The good pipes aren’t barking loud either. The stock ones just aren’t designed to release the evil.

The next thing you can do is GET A CAM SHAFT 450nt. Get the most agressive one they have. Pipe and cam? :smiling_imp: Good times.

Next, get the carb! 1500nt for a big Keihin 2 stroke carb, for a Dio 50… that’s right DIO. The flat plate carbs are only about 2500nt as well. You need to plug the oil intake port with a piece of leftover hose on 2stroke carbs (easy as pie). You’ll also need to buy a 200 throttle cable for that as well.

You can get a bolt in coil/ignition system for 400nt. It helps light all that raw fuel :smiling_imp:

You can get a bigger piston and cylinder kit for 1500nt. You can go up to 59mm (175cc) without modifying the engine block. I’ve gone to a 63.5mm after the blockjob (I hear it’s about 235cc).

If anyone wants me to source anything for them. Let me know.

All this stuff is for a DUKE (Chinese call them “DJ”) or Freeway scooters. They’re like the Honda Civic of scooters.

if u need a good scooter mechanic, try my old scooter mech…

his shop is on the corner of a small street and wu-chuan-sth rd. head from the science museum down wu-chuan-sth and cross jien-cheng rd. he’s just a little further on your right…

he speaks OK english… not the best, but you should be able to get by… his shop also races (tho you won’t think so looking at it - it’s just a small, grubby shop) and he knows quite a bit about doing up scooters… he’s honest and won’t rip you off either…

he has been my good friend since i started riding bikes (i started on a 125 scoot) and taught me a lot of what i know… and yes, he rides a big bike as well as his scooter

tell him ‘neo’ sent you (a cut from my yahoo user name) if he asks how you found his shop… (shop name is ‘shin-yea’)

cool thanks…can you give me the phone number and address