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Scooters - 125 to 300 => Super 8 150 => Topic started by: misfit77 on March 29, 2012, 04:38:19 AM

Title: Not impressed with jetting or Kymco.
Post by: misfit77 on March 29, 2012, 04:38:19 AM
I got a kit from a place called 6 Sigma. http://www.ebay.com/itm/Kymco-Super-8-150-cc-Scooter-6-Sigma-Custom-Carburetor-Carb-Stage-1-3-Jet-Kit-/330695158383?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item4cfef7aa6f (http://www.ebay.com/itm/Kymco-Super-8-150-cc-Scooter-6-Sigma-Custom-Carburetor-Carb-Stage-1-3-Jet-Kit-/330695158383?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item4cfef7aa6f)
(https://lh4.googleusercontent.com/-N4FmuAlArXk/T3PhmtNysHI/AAAAAAAAANE/uR-j2PEPaMw/s640/%255BUNSET%255D.jpg)
I paid a little extra because this kit was supposed to be custom to my needs. Since this was my first time, a step by step would have been real nice. Well the kit was a basic kit nothing fancy and instructions were generic and even forgot to mention the pilot jet.

It came with shims for the needle, 38 pilot and 110 and 115 main. Various bits for drilling here and there. Stock is 35 and 102.
Overall I am satisfied, but not impressed.


Anyway. I used 2 shims, the .38 and the 110. My plug chops were not really showing lean to begin with. Well, not impressed. Not sure if anything was improved. As a matter of fact I think hitting 60mph is bit of a struggle now.

I will be doing an airbox mod, maybe that will fix it a bit.

Title: Re: Not impressed with jetting.
Post by: zombie on March 29, 2012, 05:02:21 AM
Try putting the needle back to OEM first.
Title: Re: Not impressed with jetting.
Post by: misfit77 on March 29, 2012, 02:22:05 PM
that is actually pretty easy to do.

I will check my plugs tonight and tomorrow on my day off will remove the shims from the needle and give it a shot. thanks.
Title: Re: Not impressed with jetting.
Post by: misfit77 on March 29, 2012, 02:45:20 PM
holy crap......this thing rode like an old mule.

Could not get to 60mph....stayed steady at about 57.

Also last 1/4 throttle did no better than mid throttle.
Title: Re: Not impressed with jetting.
Post by: zombie on March 30, 2012, 12:13:51 AM
Was it better or worse w/out the shims?
Title: Re: Not impressed with jetting.
Post by: misfit77 on March 30, 2012, 01:15:02 AM
sorry....shims are still there. Will try taking them out tonight.

Stay tuned.
Title: Re: Not impressed with jetting.
Post by: misfit77 on March 30, 2012, 05:01:41 AM
Too lazy and tired to try the needle shims.

Took off the air box lid. Got to 64mph...yee ha.
Took off air filter got to 64 a bit quicker....yee ha.

I will check my plug tomorrow morning.


BTW, anyone transplant K&N gauze to factory filter? I might give it a shot, just need a oil filter donor.
Title: Re: Not impressed with jetting.
Post by: zombie on March 30, 2012, 05:14:36 AM
That was showing the carb was rich till you opened the box. It will help to do the transplant. You may need to go to a cone filter in the end but good to see your improvement...
You might be able to pull the shims, and go w/ the stock air box too.
Title: Re: Not impressed with jetting.
Post by: misfit77 on March 30, 2012, 05:42:43 AM
Thinking of removing shims and adding these to the air box....I have to be different.

(http://www.economycycle.com/media/3/a2079161290a4d9510d0d3_m.JPG)

Title: Re: Not impressed with jetting.
Post by: zombie on March 30, 2012, 07:10:26 AM
Keep it one step at a time with jetting. A bad 100 yard run could end it.
Title: Re: Not impressed with jetting.
Post by: misfit77 on March 30, 2012, 04:47:48 PM
oh yeah....remove shims and stock air box first.

Installing torque spring and dr pulley sliders.....if scoot wont do 65mph(GPS) thinking of selling it while I can get my money back.

Title: Re: Not impressed with jetting.
Post by: misfit77 on March 30, 2012, 10:18:58 PM
Well Sheet!

Removed shims. Install 13g sliders and yellow spring (stock was colored yellow). Cleaned the clutch bell and pads, larger& lighter baffled muffler.

This scooter is slow. All this labor and money and speedo won't go past 64. About 55mph actual. Take off is no better.

Waiting to to cool to check plug for mix ratio.

Am I missing something? I be dammed that the valves need adjusting on a nearly new bike.

My old Tank 150 would go in the 70s actual with a 2 stroke silencer, stock pipe, sliders and a Uni filter, no jetting, performance cdi and coil.

I think its time to sell.
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on March 30, 2012, 11:49:59 PM
Come on Munks... Give it up. We all want to know what you know.
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on March 31, 2012, 12:26:26 AM
And focus on one mod at a time

Best advice on the forum!
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 01, 2012, 01:00:09 AM
weights and main clutch have no impact on carburetor settings.
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 01, 2012, 01:06:58 AM
Wanna Bet?
Tire pressure effects jetting...
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 01, 2012, 01:25:41 AM
well the weights, spring and muffler are no longer variables.

While tire pressure has effect I say its neglible. If jetting was that sensitive......I would have to jet twice a day one in the morning for cool temps and again in the evening for warmer temps.

Here is a pic of 38/115 jets, no shims. weights, spring, stock air box and homemade muffler. The plug looks fine, its the dam top speed that is bugging me.

(https://lh5.googleusercontent.com/-8dIm9VSKjQA/T3ZpNxDPPjI/AAAAAAAAANg/Lzj6QMYiHM0/s576/%255BUNSET%255D.jpg)

This is same setup with 110 jet.
(https://lh5.googleusercontent.com/-Dim5H8U08Hg/T3Zo6wsHJ4I/AAAAAAAAANM/yoajfBt5PWA/s576/%255BUNSET%255D.jpg)


This is stock everything except muffler.
(https://lh4.googleusercontent.com/-Pu4flb1G4SA/T3Kfow7aqDI/AAAAAAAAAMU/noJHmj6d8us/s640/%255BUNSET%255D.jpg)
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 01, 2012, 01:30:14 AM
Something is WAY weird. The plug case is black, and the insulator is white.
Have you done a compression test? Adjusted the valves?
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 01, 2012, 01:31:43 AM
Also a running vacuum test! If there is a vacuum leak in the intake system you will read weird fluctuations in the gauge
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 01, 2012, 03:45:42 AM
well I put a new plug in. That's why one looks new, but I was thinking the same thing. the original jets look like I was running rich while new jets look a little lean.

I double checked hoses and connections. Remember this scooter has 1800 or so miles...possibly Km. Things are new and untouched except by me.
Title: Re: Not impressed with jetting or Kymco.
Post by: wordslinger on April 01, 2012, 03:50:35 AM
Wanna Bet?
Tire pressure effects jetting...


..you best believe it CAN!!
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 02, 2012, 02:42:05 AM
"Here is a pic of 38/115 jets, no shims. weights, spring, stock air box and homemade muffler."

So what is the difference between your stock setup and your current setup.

What has been done to the intake that would need a 115 main jet.  And why does it look lean if your going up 13 on the main jet and your using the stock airbox.

Something is not right and your just gonna be frustrated with it.

Just put it back to stock if it runs better at stock.  ;)


Stock with ghetto muffler 60mph. Changed jets (38/110) and shimmed the needle...scoot got slower, about 58 on speedo. Removed air box lid  and scoot would go maybe 62mph. Removed shims, reinstalled lid. Added dr pulley and yellow spring... 62 mph. Tried 115 jet, 62mph.

Just seems like something holding me back. Does the CDI have a limiter?
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 02, 2012, 03:55:47 AM
Your bottle neck may be in the rear gears. What is the tire size, and final drive ratio? What rpm's are you at (wot).
You've said "homemade muffler" Pipes are KEY to power. They are designed to make power at certain rpm's/temp. Maybe your Ghetto pipe is at fault.
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 02, 2012, 07:13:59 PM
these are definelty WOT values....the last 1/4 turn or so do not seem to do much.

My muffler uses a small diameter pipe and a baffled kawasaki muffler. It might to restrictive.

Gearing?....you got me.
Title: Re: Not impressed with jetting or Kymco.
Post by: old mod on April 02, 2012, 09:12:21 PM
Kymco 125/150 is geared to do about 60-65 wot. i did a 170 big bore it was fast but only got to 68 indicated before it destroyed itself! and at that speed the belt was climbing over the cvt. If anyone knows how to change the final drive gearing i'm interested
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 02, 2012, 11:45:48 PM
speaking of...I calipered the amount of untraveled variator...I have about .25 left"

Too soon to see if the dr pulley did anything.


Also, I am just disappointed becuase my old cheapo Tank 150 hauled ass with less time an money invested.
I never jetted the carb and I know that it lasted 2 more owners before I lost track.
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 03, 2012, 02:23:53 AM
Kymco 125/150 is geared to do about 60-65 wot. i did a 170 big bore it was fast but only got to 68 indicated before it destroyed itself! and at that speed the belt was climbing over the cvt. If anyone knows how to change the final drive gearing i'm interested
Try Louie at http://www.spi-parts.com/ (http://www.spi-parts.com/) Mention the forum for 10% off your order. I worked real hard to get us the discount
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 03, 2012, 02:28:58 AM
speaking of...I calipered the amount of untraveled variator...I have about .25 left"

Too soon to see if the dr pulley did anything.


Also, I am just disappointed becuase my old cheapo Tank 150 hauled ass with less time an money invested.
I never jetted the carb and I know that it lasted 2 more owners before I lost track.
.25" is not bad but you should find out why you have extra room. I would remove the contra spring, and re assemble the parts loosely. You can the manually open the torque drive to see if the belt has enough travel. Could be too short. Could also be the Drive boss is too long, or the rollers are worn too far/too light. Check the torque drive first to verify it works, and the belt is long enough... Don't assume.
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 03, 2012, 02:59:29 PM
hmmmm good idea about the belt.

Taken else apart....I think.


I will check belt p/n later this week. I do know the current one is a kymco part, but that means not much.
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 04, 2012, 08:18:22 AM
 I do know the current one is a kymco part, but that means not much.

Now you got it!
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 09, 2012, 04:56:10 AM
did not check the belt. Calculated MPG and I was getting 45mpg

Changed jets again... Pilot=stock 35 and went from 115 back to 110.

I can still only run 62. Went downhill and I hit 66. This is the fastest I have seen it.
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 10, 2012, 03:37:08 AM
So I'm guessing 70 is a good goal? for now...
Title: Re: Not impressed with jetting or Kymco.
Post by: misfit77 on April 11, 2012, 09:24:51 PM
70 is a good goal, but I think not acheivable with out a gearing change......either variator, bigger tire, or actual transmission internals.

I wish the Vespa 300Gt was cheap......only if!
Title: Re: Not impressed with jetting or Kymco.
Post by: zombie on April 11, 2012, 10:52:25 PM
Keep the Vespa idea on the back burner... One will show up at a good price if you wait.
Title: Re: Not impressed with jetting or Kymco.
Post by: sentinex on April 11, 2012, 10:56:20 PM
Keep the Vespa idea on the back burner... One will show up at a good price if you wait.
Well said zombie, also he could be aiming for a Vespa 250, even they no longer in production I only heard good things about it. If he looking for the High Speed it could be a decent choice.