Cygnus Modifications

Hi all,

Well I bough the Cygnus SR and am very happy with it. However, I am still left behind at the traffic lights by all sorts of scooters. :s

The other day a PGA G-max made me eat his dust, and those little JR’s are also realy zippy, then there are the Dukes,the X-PROs and the list goes on.

In fact I am even having trouble keeping up with the X-PRO on the ‘open road’

So, I need some mods! I am not ready to bore the engine out but would like to start out with some of the simple stuff like gears, transmission etc.

I have searched the forum, and read a lot of the stuff about scooter modifications. One post by ‘Turkey Dinner’ was especially usefull but seems to be about the Dukes.

[ … ods#221848](Scooter Mods

Could anyone please outline in brief what I can do to my Cygnus. Or can I use ‘Turkey Dinner’s’ post as a guide?


Mods relating to gears, rollers, cams, ignition systems, valve springs and porting relate to all scooters.

If your Cygnus has fuel injection, carby mods do not apply. I don’t know if it’s worth porting the head either for that matter.

I highly recommend overboring. If your motor is only 125cc, going up to a 150cc bore is 20 per cent more, innit? You could get a lighter piston while you’re at it. Get the lightened rollers for sure too.



Don’t forget that Wolf’s paint mod applies to all scooters too.

If yours is the SR version then it means it is a carb model. If you want all other 125s to eat your dust than get a Yosh carburetor. Yoshimura makes special carbs just for the Cygnus. … rb3&d=1487

It says for the Majesty 125, but can also be used with the Cygnus. With a Yoshimura pipe on, you’ll be uncatchable. … l3&d=1629#

Cheaper option would new variator and rollers or springs.


Armed with these links (and pics!!) I will now try to find a mod shop in Kaohsiung and go shopping.

I highly recommend getting a new CDI. I put in a bigger piston on mine…it lasted a year and then burned its-self out. Luckily I still had the original engine lying around so they threw that back in at almost no charge.

Your stock CDI has a fairly low “cut off” which prevents the bike from going faster than a set top speed. They sell aftermarket ones for about 2-4k.

It’s true an addition of an aftermarket CDI will help out with overall smoothness of acceleration. There won’t be that initial lag from stand still to off the line as you have with the factory CDI installed.

[quote=“KawasakiRider”]If yours is the SR version then it means it is a carb model. If you want all other 125s to eat your dust than get a Yosh carburetor. Yoshimura makes special carbs just for the Cygnus. … rb3&d=1487

It says for the Majesty 125, but can also be used with the Cygnus. With a Yoshimura pipe on, you’ll be uncatchable.

Cheaper option would new variator and rollers or springs.[/quote]

im running a tmr-mjn28 as my 250cc scooter. its quite a piece of work, fully adjustable and very very well built(its made to be stripped apart trackside and rebuilt on the spot). may require a bit of modification to fit your exact application, but when well tuned, this carb may be all you need for your speedfix. Its not cheap, especially if you pruchase it through the taiwan distributor - 28-35 thousand NT dollars depending on the number of accompanying jets you wish to have on hand. i would suggest a faster turning throttle holder and smoother cable set to compliment this extremely fast responding carb.

cygnii can be bored out to around 200cc(197 or so). you can add liquid cooling, a flat-side carb(doesn’t have to be a mikuni tmr-mjn. there are mikuni tm/rs/vm and keihin fcr’s available as well), new bearings and plates/transmission belt

as mentioned before, try to perform safety modifications first before you make your ride uncontrollably fast: stickier rubber, better suspension, bigger brakes/discs/lines, perhaps a fork brace to increase stiffness.

goodluck with your new toy!


Thanks for all the feedback so far.

I emailed Yoshimura in Japan and got this reply:

[quote]Dear Sir,

Thank you for your inquiry.
Your E-mail has been forwarded to our distributor in Taipei, so you will hear from them shortly.

Regarding the Cygnus X, we only have exhaust system and we have never set up the carburetor. It seems our Taiwan distributor has been using Majesty carburetor with some modification but we do not have the information.

Anyhow, please talk to our distributor.
Thank you for your time and understanding.

Best regards,
Yoshimura Japan Co., Ltd.[/quote]

I will have to double check what carb model my mechanic is trying to sell me. They quoted me nt$10 000 for the carb and nt$25 000 for the exhaust.

The mechanic is also finding out if the carb will work on my Cygnus x SR TPS. They are not sure if the TPS is a problem.

Well, the word from the mechanic and Yamaha Taiwan is that there are not many ‘minor’ modifications I can have done to my 3rd generation Cygnus 125SR TPS.

Even though it has a carburator the TPS makes things difficult.

I can’t upgrade the CDI Box and/or carburator unless I have the TPS removed and the whole scooter rewired.

If I have the TPS removed then the scooter won’t perform well, even though it might be faster ( I don’t quite understand that one).

So, I will have the variator upgraded and have an improved exhaust put on, and that will be it:-(

I was told that the best Cynus to buy, if you want to modify, is the model with neither TPS or EFI.

It’s ok, I am still happy with my baby and I suppose it might keep me out of the hospital!

The variator is replaced with a NT$5 500 Malossi variator

There is also a NT$3 000 exhaust on it, about the same size as the original but at a very obvious upwards angle.

My acceleration from 0 to 20km shows a little improvement.

However there is a definite improvement in the mid-range (40 - 80km).

I have discovered that an unmodified X-pro can kick my unmodified Cygnus’s butt.

Tomorrow morning I will see if these minor mods make a difference.

You can have your front forks re-worked and filled with heavier fork oil…it did wonders for my front end handling since I weigh a tad more than the average Taiwanese.(88kg)…it gives less dip when braking and a smoother ride over bumps.

With you power gains, you should also think about stopping properly. The front brake on the Cygnus sucks, so I slapped in some EBC HH pads(1300$NT) and a braided steel brake line(500$nt with bleed job). Once you’ve scrubbed in those EBC pads, your scooter will stop on a dime!

My next little change will be those god awful hand grips that slip all over the place when it rains and a nice High/low horn!


If you can swing down to Chung-Li sometime let me know. There is an aftermarket shop down here that deals almost exclusively in Cygnuses.
Saw one guy do a rolling burnout on his.

Well, the sad news is that in my morning ‘race’ with this x-pro I was still left behind.

However, the rider ( a complete stanger who seems to go to work at the same time as I) did smile, point at my exhaust and give me a ‘thumbs-up’:slight_smile:

What is even worse is that my friend’s Suzuki Swift ALSO kicks my butt, except at high speeds.

This means I now have to get more info on what will happen if I have the TPS removed and the scooter rewired. If that is possible then I can get a new carburator and CDI Box.

Mordeth, thanks for the offer. Do you have a phone number for this aftermarket shop. I will get my friend to give them a call and see what I can do with a TPS model.

I will also contact Autobike again and see what they have to say.

Aaaggh, i wish I had bough the 2nd generation Cygnus! :blush:

Their number is 03-433-3232. The place is called…erm…Autobike. Guess it’s a popular name. I’ve met guys their that ride down all the way from Taipei…and said that they don’t have any shops as good as it in Taipei. I find that hard to believe…but maybe it’s due to rent being so expensive there. If you have some spare cash on hand I suggest you make the trip down sometime. They are open on Sunday…but their mechanics aren’t in then. But they are on Saturday.

Also to improve your acceleration just try switching your rollers and spring in your clutch. Only costs a few hundred to do so.

Today was a Happy Day! I have found a mod shop in Kaohsiung (Chung wa 1st Road). The staff there were extremely friendly and helpful.

The first thing they told me is that I need to wait until I have done 3000km before performance will improve.

The second thing is that they taught me how to break the scooter in.

0-1000km = No faster than 100km/h and change the speed constantly (hit 100km/h then let it drop back to 80km/h)

At 1000km try to get it past 100km/h.

Then keep doing the 100km/h down to 80km/h for another 2000km.

They said that the unmodified Yamaha is well know for poor acceleration from 0. But I can make up for it in the mid-range.

The variator and exhaust mods are the best thing I have done. If I still want more power I need to get the bigger cylinders (150cc) and change the carburator/CDI box. When I change the carburator the TPS will also be removed (because it is attached to the stock carburator).

They Malossi cluth springs will give me a slight improved acceleration.
The Malossi clutch and torgue driver are for modified engines and they will only improve the mid to high range speed.

They advised me NOT to get a new cam as the performance gain is minor and it will only keep on buring out.

The only other thing I can do for acceleration from 0 is to get some GOOD tyres.

Happy day

I’ve been keeping an eye on this thread because I’m considering buying a Cygnus myself. Since I’m not familiar with scooter parts can you guys explain what a “TPS” and a “variator” are? I haven’t come across those terms in regular motorcycles. Thanks.

[url= (Cygnus Thread)[/url]

TPS (Chinese with pictures)

Variator (Automatic Scooter Engine, Explained)

I went to check ou cygnus today it looks kinda odd…symco r1 z 125 looks pretty good but other then those 2 bikes what are some of the faster 125 scooter out there? looking to buy one…and mod it possibly…thanks!

The easiest to modify scooter…and therefore possibly the fastest is the SYM Duke. It can be cheaply modified to reach speeds over 130.

hmm Duke or Cygnus…I might get one of those…howmuch for a brand new Duke?

also for scooters do they usually include insurance and tax?