About to blow this thing up!

[brianl289]

Started a new thread for a new issue, hope thats alright. The last 60 miles i have been driving the scooter around and its been running great with the exception of a slight bogging from idle-1/4 throttle, then it clears up and runs fine to 45-50mph. Today i decided to mess with the air/fuel screw a little to try and fix it, also because my plug had a slight white/grey to it.

It was at about 1 and 1/4 turns out. So i put it at 1 turn out and it runs slightly better, still a little bog, but heres a new plug after about 5 mins and random WOT runs and 1/2 throttle runs, mostly white and when i turned the screw in more, it ran terrible. I cant seem to find the sweet spot on this thing

http://i396.photobucket.com/albums/pp47/07mkvgli/DSCN0818.jpg
http://i396.photobucket.com/albums/pp47/07mkvgli/DSCN0817.jpg

Set up right now is 85 main jet, air/fuel screw 1 turn out. 70cc kit, technigas pipe and a BR8HS plug

a 90 main ran pretty horrible, but i never touched the air/fuel screw. Wonder if i should put that back in and put the screw in to about 1.5-2 turns out?

Thanks for any help!

[buguy]

Wow! careful...thats really lean. I would put the 90 back in. I have a 79 in my stock de restriced 2T. Sounds like maybe you have a clogged or maybe too small of pilot jet too. The pilot or slow jet controls 0-1/4 throttle or so. Also be sure when your tuning that you put the airbox back on, it changes things way more than you might think. Mine will barely run with it off.

[harry]

yeah too lean!!!!
go up 2 sizes on the idle jet (0-1/4 throttle)
you might think about moving the needle clip down (1/8-3/4 throttle)
both idle jet and clip settings will have a bearing on
your choice of main jet ( 87.5 -90)
good luck

oilyhans

[OveRReV]

ok judging from your first post i'd say bring it back to 1 turn out for the air screw & put the 85 main jet back since you said it ran horrible (too rich), now for the needle, where is the clip located now? there are 5 grooves in the needle, #1 top (leanest) & #50 bottom (richest), again where is the needle clip at right now?

[zeonsredcomet]

You are screaming lean! Do what overrev says since he beat me to the punch on the advice. That plug would be great if it were a FI car

[brianl289]

Sorry guys haven't updated this in a while. at the moment i am running the 85 at about a turn to a turn and a quarter out. Shes been running great and the plug is a light light brown. I think it could be a tad bit better, but its hitting 50 on the flats so i cant complain.

[buguy]

Man I would think you would need a bigger jet than 85! But if the plug is looking good, and its runnin good, you must on the money.

If you want to mess with it, try that 90 jet again, and work the air bleed screw out a bit, maybe pull the snorkle out of the airbox too (but dont know if that really does much). You might get more speed by getting more air to it, but at a cost of drilling holes in your stock box, or taking it off and putting an open filter on it. I dont know if your looking for more than 50mph, but there should def be more there if you are.

[brianl289]

I fully expected the 90 to work, granted it a filed out 90 by my local shop so its possible its bigger, but it just didnt run well, no matter where the air screw was at. My airbox snorkel is pulled as well. I think that if i ran an after market filter i might be ok, but with the 90 my top speed was around 43 and it didnt get there nearly as quickly. With the 85 it seemed to get to 45 faster, and sounded crisper. I will eventually upgrade the carb and start over with the tuning, but for now its fine.

[buguy]

Heck yeah! If its working well.....then just enjoy it!

[OveRReV]

don't pull out the snorkel, don't drill holes in the airbox, if you do you'll be giving yourself a headache trying to tune the carb, leave it at that & just concentrate on the main jet, pilot screw & needle setting. the stock carb's needle profile is designed to be run with an airbox with the snorkel on, even if you run the carb with no main jet it will still run lean bcoz of the taper & this is a quick trip to seize town.

just back away if you don't know how to tune the carb properly & save yourself some grief, i've ran setups with a much higher state of tune with the stock carb & airbox with no problems bcoz i know what to look for & know how to do it.

[buguy]

Im pretty sure the needle isnt adjustable on a stock Vino carb (meaning there isnt a c-clip that you can adjust the needle up or down). I pulled the snorkle from mine, and it really didnt seem to do anything cep make it sound a little throatier. Think im at about a 74 main (64 was stock) and a 46 pilot. That is on a derestricted pipe and pulling the snorkle from the airbox. But that is on mine at my sea level. Yours may vary.

Also im no master tuner! So I would take OveRRev's advice.

Im curious. Could a guy weld in an O2 sensor bung and tune with a wideband if he wanted? Just think you could see where you are at all rpm's with a wideband, but I dont know if they are designed for 2 stroke or not.

[brianl289]

well the snorkel was missing from the airbox when i bought the scooter, so i couldnt put that back if i wanted to. And i am also at sea level, just got done riding and its about 40 degrees outside. I bet that 90 jet would be perfect now, too bad i dont have it with me. Bike still runs great though.

[Gabe502000]

You can probably find an airbox at ebaymotors.(A whole engine even!:D) Or, make a snorkleheaded air intake tube, from a bit of PVC pipe. Using a Parts Manual picture as a guide. ::usa::

[brianl289]

Is the snorkel really that important? The hole in the airbox is pretty hidden anyways.

Little update. Been running with the 85 for a while now. Bike runs fine, but my top speed has dropped from around 46-48 to 40-42. Im assuming either my belt is worn(which is possible considering how much dust was in the case), or time for a variator upgrade. I purchased this scooter with a 70 kit and a pipe, but the variator wasnt upgraded. So i think i will be doing that next, with a new belt. Maybe even a primary gear upgrade. Id really like to be able to cruise at 45 without being at full throttle. Im getting about 50 miles to a tank because of it.

[Gabe502000]

It's suprising how all of the airbox parts work together to make performance.There's a C3 Scooter mod that doubles the diameter of the inlet snorkle, tunes the airbox,+ makes better power....Quietly! Before you start throwing $$$ at it, try a tank of 93 octane gasoline....It may be all it needs!::usa::

[brianl289]

Well turns out I am also really lazy lol. My tires, were at 12psi. No wonder i could only go a sluggish 40. Filled em back up and back to 45 on the flats with ease. What is the c3 airbox mod? Just replace mine with one from that?

Also my friend just got a vento, and i kill him on the hills. Obviously its stock,but its Good to know this BBK is really working, i was starting to think it was slow.