Sting 50 Build

[19krevs]

hi all

I received a Kymco Sting 50 for free from a mate of mine (he didn't like how it looked.. vespa style) and I've been looking to get more performance out of it, I just like working on stuff so my mindset is what I'm paying for these performance parts would be equal to how much buying the scoot would be in the first place anyway. For those who don't know it has many of the same parts as the S9 hence why I'm posting here.

so far I've ordered:
-TECNIGAS Next R Exhaust
-A bunch of lighter rollers
-75-90 Jetting Kit

I'm thinking about buying a Naraku 70cc kit (http://www.ebay.com.au/itm/400629043846) and 19mm Naraku Carb (http://www.ebay.com.au/itm/271327985859)
-Install the pipe and tune the rollers first (ofc upjetting aswell) and then install the 70kit and Carb.

does anyone have any advice on:
if I should get a 21mm instead of the 19mm
what jets I should start on after I install the 70 and carb
general carb installation

I was planning on just getting a 70kit not knowing a bigger carb is necessary (thank the lord I didn't) and thinking about how a lot of guys I know have had their engines blow up and run badly with 70 kits and stock carbs, it made a whole lot of sense.

I also wanted to post this after I had installed the pipe etc but shipping from europe to australia is such a pain 

[19krevs]

Update:
After researching the Naraku 70cc kit I've decided to go with the Airsal 70cc kit instead because of lack of reviews and apparent bad build quality.. sigh. I'll be getting the Dellorto 21mm carb aswell. I think removing the oil injection system and running premix fuel would be the safest too, if any of you guys have advice on that I'm all ears
I'll keep this build thread updated, hopefully I receive my exhaust and other parts soon!

[245luigi]

I have the Malossi 70cc kit and a dellorto 19mm carb on a very slightly modified stock airbox. My idle jet is 42 and I have a rich main at 102.

[joebro]

I like 245luigi's setup. I would advice Malossi or Airsol, been hearing not so good things bout Naruku (maybe true maybe not everyone has a opinion ).

[19krevs]

It has been a long day, finally finished.

I took your advice joebro and went Malossi haha, figured that if I'm spending the money it might as well be on good well known parts. These arrived yesterday: (20mm Intake, 21mm Arreche Carb, Malossi 70 Kit, fuel line)


Chucked the carb and bigger intake on first so I could make sure it was running all good before putting the 70 in, grinding the top of the carb cable (where it connects on the stock carb) was the biggest pain, got the carb on and then it wouldn't start. Clear fuel lines are real nice fyi, no taking the float bowl off to see if there is fuel flow or not, figured out the cable was too short and it wasn't blocking off the intake. Got her running (although rich on a #90) so I moved to the 70 kit, my old head & cylinder looked down right disgusting! this ped only has 4000km's on it.... (guess it might've been left somewhere under weather..?).


Put the 70 together and made sure I lubed it heaps, fired up first try, so stoked with it.


I'm running 100# main jet with a little bit of premix and oil-injection for now, will definitely be changing to pre-mix when I get the time since both is just a hassle. Runs good!

Next up is to:
-change to the lighter rollers.... which was a complete failure when I tried today, I ordered a variator holder/bracket (?) for the yup and it doesn't fit, so there goes that, but keeping the rpm's down during the run-in period with the heavier rollers works out well.
-bigger idle jet
-reeds (the ones which came with the 70kit don't fit)

Thanks luigi for the specs, gave me a good area to start for the jet size

Some pics:



Just realized this ^ photo is before I put the carb on.. whoops

[245luigi]

We are running very similar setups now! Nice pics.

No problem with those carb specs, I WISHED someone ballparked me when I did it. You can see my panic in my BBK post under technical info. Took me 4 damn days to figure out!

Only difference is that I dont run premix, I have zip tied the oil pump 100% open. I imagine premix is better as you have far more control of the oil getting to the cylinder. 

Let me know what kind of speed your getting. Enjoying the new take off too I imagine!!

[19krevs]

cheers c:

haha yeah I read those, you definitely did your research, I spent a lot of my time using the search function on these forums
I've got mine set to about 1/4 open all the time, which is the best I can do from the stock adjuster since I have no zip ties left. Do you run pre-mix aswell or?

Take off is definitely a lot better, but I still feel like the bike isn't solid, a higher idle jet running in it right now would do me a little confidence.
I'm getting max 80km/h right now ; _ ; if that, I know it wants to go faster because it'll sit at 70km's without a problem while I'm 1/2 throttle, my 50cc got as high as 90km's once on flat (no idea why).
I got scared today/yesterday because of how much vibration it was having sitting at certain RPM's, at first I thought the worst case scenario that I might've been running lean and it was ruining the rings or something.... (doesn't make sense because I did a few plug chops and it was a nice light brown colour) anyhow after putting the needle back to mid (from high) and changing to a 105# instead of the 100# my plug fouled...
I noticed it would bog down when I had the 50 in it sitting at rpm's too, and cause vibration at higher rpm's aswell (around 80-90km) so I think the rollers have bad flat spots and it's putting off the balance... either that or something in the variator. Pretty frustrating having new sets of rollers just sitting here and not being able to get the variator nut off.. don't think it would be the clutch either since the only time it doesn't seem to vibrate is when I'm accelerating.

Anyone have any other ideas as to what it might be?

[19krevs]

Okay out of luck I managed to get the variator nut off with the help of another bracket to hold the variator lock in position, and I've put 6,3 polini rollers in it (have to switch those out with some heavier ones). The vibration is still there sigh... I'll see if I can try that 'rear brake acceleration' on my clutch tomorrow morning and figure out if it is my clutch, saw some posts about engine mounts and center stands causing vibration, if not, guess it's back to square one and I'll check the head/cylinder :\

[245luigi]

Make sure all bolts important bolts are torqued to spec such as cylinder head bolts, engine hangar bolts, variator, clutch and shock mount.

I put heavier weights in my variator; I went from 8gm to 10gm rollers. Reason being I am waiting on my upgear kit. When I compared x rpm vs x speed before and after the BBK, I found the RPMS higher (uncomfortably higher) in the current setup. Heavier rollers drop the rpm at any given speed. That may be the source of your vibration.

Also 2 strokes are know to "resonate" in the intake manifold. That can also appear as a vibration http://www.kymcoforum.com/index.php?topic=9791.15

[19krevs]

Re-torqued just about every bolt I could from in the manual, swapped my rollers out for new ones (same gram) she's running fine now on 35:1 pre-mix without the vibrations (phew)
I've tested top speed once on flat and the needle went way past the 80 mark (would be around 110?) but I would say no faster than 95km/h? //Also used a crap load of my fuel.
I'll try GPS it when I have time, ordered some heavier rollers and other bits n bobs aswell.

[zombie]

I can envision Mel Gibson riding that to his ex's house a sawed off strapped to the front cowl.
Nice looking build!

[19krevs]

Still eagerly awaiting parts 

Thanks zombie haha, and I dig that theme too, It was decided when I first got it I would be going for a 'why would anyone want to steal this?' vibe not a 'flash' build were it's all clean-glossy paint, matte black was a must, although I do get envious sometimes of all those guys in europe with their ridiculously good looking aerox's aha.

Luigi be sure to make a post about what speeds you're getting when you do install your gear-up kit, since we're similar builds it interests me greatly not that I am looking at getting one, since the word overkill comes to mind haha.... Scoots are banned from freeways here in AUS so doing over 100 anywhere else could lose me my license and ped Although getting reactions from people seeing a 50 on the freeway would be great!

Another pic- love the back view.


I'm gonna try my hand at a homemade boost bottle soon, see if they really do help with low end/mid. Might even make a before/after video since I couldn't find one myself (I think stock/after mod videos should be more of a thing).

[DMblues01]

I like that!
I have a soft spot for evil looking blacked out scoots.
I may have to find me a cheap used scoot as a project for the summer!
Keep the pics coming! It looks awesome!

[19krevs]

thanks DM

wellllll I ran into some bad news today, on the way home I had trouble starting and idling at first but I got it running up until I stopped at some traffic lights and she died on me. So after checking the carb in a parking lot and changing out my spark plug, damn thing still wouldn't idle right. In a desperate attempt to get it home before dark I just managed to keep the revs up with the throttle and it was fine; anyway- would I be right in saying that the reed valve is the problem?

I'll be checking them tomorrow when its light out, but if anyone has any ideas (if possible) on getting those undersized malossi reeds to fit onto my reed block (a couple mm too skinny) it would help greatly.

[zombie]

Sounds like a vacuum leak to me. Do you have a Leak down tester?

Forget the Malossi reeds. They are the wrong ones. They fit Dio intakes