2007 Vento Triton Li issue

[Geeves]

Hey Gods of tuning, I have a question for you all. I modified my scoots. Polini
Corsa cyl, Technigas RS pipe, 24mm OKO carb, stage 6 reeds, Polini variator,
2 G clutch, Kevlar belt. Carb needle in middle position, air/mixture screw out
1 1/8 turns. I live in Albuq, NM, 5280 Ft. Altitude. My scoot starts right up w/
choke on, then choke off - fine. Ride it around for about 4-5 minutes and as she starts to get real good and warm, it just dies out. I am currently using 91
Super Unleaded. There are no air leaks as of yet. Strong spark on the plug. I
am wondering if maybe I should be running Trick fuel 101 for this motor. I am
thinking vapor lock from the 91 octane pump fuel maybe or I am just having
the motor load up on fuel from the 24mm carb. Any suggestions anyone!!!!

[Axton]

Post a pick of your sparkplug; the jetting is most likely off.

[Geeves]

Plug color is a light brown to slightly dark tan.

[burnt_toast]

What main jet are you using? Does it just die out completely, or sorta slowly dwindle down and shut off after you've been riding?

[Geeves]

Hey burnt, the main jet that came with that OKO carb, I'm dont exactly remember from
when I looked at it before I put it in the scoots. The scoots acts as if I shut off the handlebar switch and slowly dies out a short death. I raced motocross for 12 years & I
always tuned my own bikes, those carbs didn't have a air/mixture screw, pilot jet, needle, and main jet. All of these worked a seperate function in the carb body. I guess on a scooter, the air/mixture screw and main jet work partially together as to add to the carb flow of fuel in total. I never thought of that, so that is why I haven't
thought of adjusting the main jet yet, but now I will. Thanks

[Geeves]

Burnt, I have a 107 main jet, needle in the middle, 42 pilot jet. Air/mixture screw is at 1 1/4 - 1 1/2 turns out. Started out changing the main jet to a 110, bike ran rich and had a real dead spot in the center of the throttle. Still,
when the bike warmed up she died out. Put a 115 main jet in, little richer and the same thing when it got warm. Now, I'm going to put back in the 110 main
and put the needle clip in the top spot (leanest) position. This OKO is a bear
to tune.

[Axton]

This OKO is a bear
to tune.

Get a 21mm Del l'orto like I have; it is really easy to tune.

[burnt_toast]

Burnt, I have a 107 main jet, needle in the middle, 42 pilot jet. Air/mixture screw is at 1 1/4 - 1 1/2 turns out. Started out changing the main jet to a 110, bike ran rich and had a real dead spot in the center of the throttle. Still,
when the bike warmed up she died out. Put a 115 main jet in, little richer and the same thing when it got warm. Now, I'm going to put back in the 110 main
and put the needle clip in the top spot (leanest) position. This OKO is a bear
to tune.

Yeah seriously it is. If you'd be interested, I have a spare 21mm OKO, same as yours but just smaller inlet diameter pretty much.

I have a project scooter that could use a bigger OKO carb, so if you'd be interested in a trade let me know.

[Geeves]

Axton, yea this OKO is running me crazy. When I raced supercross & motocross for 9 years I always had Mikunis on my bikes, easy to tune. This one is made by Mikuni and so I figured no problem. WOW!!! I'm not exactly sure if it is an exact tuning issue. I have went up and down the line with the
pilot jets, needle, and main jet to no avail. This is leading me to be a little baffled, you would think that somewhere I would have found a sweet spot. So
now I am going back to where I started. Air/mixture screw @ 1 1/8 turns out,
needle in the middle, but here is where I will make a change, I will go down to
a 100 main jet - I noticed that the plug color was a bit on the dark brown side
which indites it to be a bit rich, 107 main jet gave me that color. I will adjust the air/mixture screw as needed. I thought that the reason why the engine gets hot is due to the increased compression, so originally I was thinking that
I needed to run some trick 101 octane fuel. If I don't get any change in the jetting tomorrow, I think I'm draining the 91 octane pump fuel out & changing it to Trick 101. The higher octane rating will keep the engine cooler. Thanks for the advice and welcome any other ideas.

[Geeves]

Yeah seriously it is. If you'd be interested, I have a spare 21mm OKO, same as yours but just smaller inlet diameter pretty much.

I have a project scooter that could use a bigger OKO carb, so if you'd be interested in a trade let me know.

Burnt, I'm going to see what I can get out of this OKO tomorrow. With all of the jetting changes I have done, you think I would of found a sweet spot by
now. For the short amount of time I had the scoots running today, I did a plug reading and it was dark brown - not wet, with a 110 main jet. Now I'm going to drop the main to a 100 main and adjust air/mixture screw accord-
ingly. It has been consistent all day, as soon as it warms up good, it just acts as if it is too rich and starts bogging down and then dies out. When the engine is cold, it idles and runs great, but then when it heats up, the problems begin. I was also thinking I might need to run a higher octane fuel like Trick 101 to keep the engine cooler. I'll take all suggestions. Thanks

[burnt_toast]

Just personally, 100 main seems really small for a 24mm carb with a corsa. I mean when I had my 19mm carb on my Triton I used a 100main and it ran real good, 95 worked but it ran a lil hotter.

When I briefly had the 21mm OKO on the Zip I believe I was using a 110main with the needle lowered to leanest position. This setup worked, but using a custom intake it was never smooth and the carb was mounted at a funky angle so I went back to a 19mm arreche with ported polini reedcage and shorter custom fit manifold and I haven't looked back.

You're issue may be that you're overcarbed, since minarelli's seem to perform best with smaller carbs, compared to say dio's which use 28-30mm carbs on same displacement.

But I would go back to 100main and re-try all the needle positions.

[burnt_toast]

Just noticed you alrady had 110 and leanest clip.. hmm

[Geeves]

Burnt, Well Well Well, I finally figured out my problem. Today I stuck in a # 120 main jet in the scoots and behold. IT IDLES, but still a bit lean. I went to my Kawasaki Dealer and picked up a # 135 main and stuck her in. She purrs!!!
Went for a quick spin and DAMN, opened her up a little and the front wheel
didn't want to stay on the pavement. I guess I did a little bit more intake and
transfer work than I originally thought. She deffinately will be doing a lot of
drinking. It's real close now, I think one notch leaner on the needle and it will
be nailed!!!!! o_o

[burnt_toast]

Burnt, Well Well Well, I finally figured out my problem. Today I stuck in a # 120 main jet in the scoots and behold. IT IDLES, but still a bit lean. I went to my Kawasaki Dealer and picked up a # 135 main and stuck her in. She purrs!!!
Went for a quick spin and DAMN, opened her up a little and the front wheel
didn't want to stay on the pavement. I guess I did a little bit more intake and
transfer work than I originally thought. She deffinately will be doing a lot of
drinking. It's real close now, I think one notch leaner on the needle and it will
be nailed!!!!! o_o

Awesome, now that sounds about right. 135main on a 24mm OKO is good.

[Geeves]

Burnt, well today went pretty good. Did more jetting and now I have it at a
# 135 main, needle in the second position from leanest point, air/mixture is
at 1 5/8 turns out (a little more that 1 1/2 turns), pilot jet is what it came
with # 42. Not too bad right now, rode a bit and when I got back it slowly
died as I pulled into the driveway. I think it is still a hair on the lean side. I
could keep going up on the main jet until it just falls flat on it's face and then just lean it up one main jet size and tweak the needle. Other than that, I think it is almost there. Happy Thanksgiving!!!!!

[Geeves]

Axton, Well like I told burnt, it is almost there. # 135 main, needle in the
second position, air/mixture screw just past the 1 1/2 turns out mark, pilot
jet is a # 42. I think it needs to go a little bit richer and then back leaner 1
notch setting, then we will probably have it. I'm going to try the NGK BR8HIX
plug tomorrow to see if it helps with the consistency of the motor. I'll gap it
at .032. Hey, Happy Thanksgiving!!!!!