Why don't upgrades work on my Kymco Super 8 scooter?

by Alan McGowan
(Nashville TN)

Scootin Nashville TN

Scootin Nashville TN

I have a Kymco Super 8 150cc and I have the Yoshimura pipe for it which doesn't increase my speed just kills my Mpg's and makes me really noticeable from its thunderous sound.


I have tried changing out to larger jets and an UNI pod but they too just rob me of mileage and seem to do nothing. At jet #120, the engine starts to sputter and die as if choked with gas.

I have not changed my CDI unit yet due to the fact I seem to have two and I don't know which one is the one I need to change. The one in the front cover looks like the ones they sell on the web, but it has a red ground wire coming out of it, and the ones from the web don't have this.

My top end is about 58mph and I would at least like to hit 62-65 as other scooter drivers claim they have peaked at. Is there any help for me?

Comments for Why don't upgrades work on my Kymco Super 8 scooter?

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Nov 02, 2012
 "2 CDI's " NEW
by: "Neil" from NC

Hello everyone. I finally became the proud owner of a Kymco 2012 Super 8 2T. As far as the two boxes go, the one over the headlights is the CDI. the one down behind the battery is the light control module. I might be wrong but if Ive done my homework right, thats correct. Also, on all the super 8's that ive seen, 150's or 50's and not chinese brands, the voltage regulator and CDI are above the headlights. Light controller behind battery. and for what this is worth, this is a few basic things i've learned as far as scooters go. What order they go in i guess is up to you! The faster you can get air INTO, and OUT OF, the engine, better performance. CDI's a big one and Gearing. I kinda think gearing is where most should start. In my opinion variators play a big role. The bigger outside diameter variator you can squeeze on any scooter, the faster top end. Also, your belt has GOT to travel all the way to the outside edge of the variator. Well, it doesn't have to, but you'll lose M.P.H. you can accomplish that a couple different ways. Every scooter is different. As we ride our scooters the belts wear. They get strectched and worn. ESPECIALLY the width. I had to think about this awhile, but as the belt wears, you loose width. Width = belt travel, as far as reaching the outside of the variator! 1mm of belt wear equal to about 4 - 5 mph! I first usually look at the variator and see where the belt has been running on it. My scooter when new, after break - in and all, would run about an average 43 m.p.h. Now it's about 33m.p.h.! It has about 5500 miles or Km on it now! Never had any problem what so ever out of it other than a battery. Ive had it since this past April. Thanks everyone. I'd love to hear more from ya'll especially the guys on these new Super 8's
May 05, 2012
 Variator NEW
by: Anonymous

Alans comments are most accurate as relates to speed and (Power?). My mechanic is an old friend (60) and can tweak anything. But he says "why f**K with a good thing. That said,KYMCO uses proprietary parts (CDIs for instance) but as explained and shown to me when taking apart a variator this is a critical part related to torque response. And also as (ALAN?) mentioned one can only go so rich with the fuel mix). Yoshi pipes are pretty but not necessary for power increase or torque/ acceleration response. Back to my mechanics response: "why mess with a good thing". I'm on 13,000 miles...no problems. WANT POWER AND SPEED AND FUEL ECONOMY???.. GENUINE 220i BLUR. FUEL INJECTED. DUAL DISC. 75 mph. 70 MPG. check out the video. http://www.youtube.com/watch?v=ZaVl2tKiK8s
May 01, 2012
 Your scooter lacks tuning NEW
by: Jay Garcia

Changing exhaust systems means you have to tune the transmission as well. you need lighter roller weights since the yoshimura tends to raise the powerband. Meaning, lesser power on low rpms but increase power at high rpms.

120 main jet is too high. at most what you can do is 115. i am only using 108 as of the moment.

my scoot gives an easy 71.45mph on a 155cc super 8, with stage 1 cams, racing pulley and transsmission tuning.
Mar 30, 2012
 update NEW
by: Alan McGowan

Thank you all for your help posts, I have found out the very important things about the kymco super 8 and the yoshi pipe.

The cdi on the s8 is propriatary and cannot be modded or replaced by an HP version.

The yoshi pipe is just an expensive steel box, its own intalation paperwork states that it doesn't require rejetting, a red flag telling me it has no performance value. I replaced my variator with a koso 115mm one and replaced my yoshi pipe with a (cheaper) mrp pipe and got it up to 70mph indicated 67 varified by GPS. And to author of exhaust, YES WITH ME ON IT!
Jul 27, 2011
 Exhaust
by: Anonymous

Well first of all most exhaust systems on scooters will not give you a big increase in speed nor will the uni pods. Exhaust on scooters are meant for looks and sound. i have never gotten any increase in speed on my scoots. Since you are dealing with such small engines with such little hp (9-10hp)the gain of power in an exhaust will not even be noticeable except in 2 stroke scoots. Second if you are running a 120 main jet and it's bogging then you are too rich and need to bring it down. third if that is you in the picture (and don't take this to offense) but the greatest way to gain top speed and acceleration is to loose some weight. A 170lb rider goes faster than a 240lb rider. Fourth if you want additional speed play with the CVT (variator, slider weights, kevlar belt, and maybe a Dr. pully clutch)
Sep 29, 2010
 Super 8
by: Anonymous

I thought to add the YOSHIMURA pipe but if you don't get more speed it's a bit too much for sound.
I get 65mph on my super and I didn't do any upgrades at all.
Jul 28, 2010
 Here It Is
by: Jim Zeiser

Here's the listing for Craig's List in your area. I see Red Dog Scooters is near by. They're a great outfit. Also there's a Yamaha Majesty listed for under $3000, a great price. Keep checking daily
Jul 27, 2010
 What Can I Say
by: Jim Zeiser

"I have not changed my CDI unit yet due to the fact I seem to have two and I don't know which one is the one I need to change. The one in the front cover looks like the ones they sell on the web, but it has a red ground wire coming out of it, and the ones from the web don't have this."

I would check and see if that unit under the front cover is your voltage regulator, that's where it's usually located. The CDI is usually located on the frame above the engine. I would back off on the jetting and see if the engine pulls better, say a 115. You can over jet these things. If you really want more speed you might want to look into a used 250cc Honda Reflex. On Ebay they sometimes go for around $2500. Also look at Craigslist.org in your area. The Super 8 is a good little scoot but it's only good for so much.

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