150cc GY6 - #125 jet too much? By macmogul (Read 9,000 times)

[macmogul]

I have a 150cc GY6 with the basic 24mm CVK carb and I upgraded the stock main jet to #125 because I have free flowing exhaust and short-ram intake.

I don't know what the stock jet size was and I have subsequently lost the stock jet... so tiny, goodbye forever...

I did some upgrades/fixes today and now with the #125 jet, the scooter sputters and falls on its face when I try to give it some throttle. I can eventually make it up to about 40mph but any more throttle than that and it sputters. Is #125 too rich? I wouldn't think so.... have I missed a step in the installation? (Seemed pretty straightforward to me...) is there something I should need to adjust?

I've ordered a #115 jet just in case the #125 was too rich, but I'm pretty perplexed- Everything I have researched said that if you had intake and exhaust, you should look at #120-130 main jet size which is why I went with #125. (Though now that I'm thinking about it, that may have been referring to aftermarket 30mm carbs and not the standard 24mm)

The other things I did today were new fuel filter and fuel lines along with a new fuel level sender. As far as I can tell, I hooked everything back up the way it needed to be. Scooter idles like a champ.

Anyone have similar experiences?

[Guitarman]

That's a HUGE amount of gas for a 150. I have a 125 on my 250cc and I still have to dial it back a bit. I'd change to a 110 or somewhere in that area.

[Bashan]

Pull the plug, if it's black or dark it's too rich. 125 is huge, it's probably too big. The stock is 104.

[Alleyoop]

Yes a 125 is WAY to big, I know where you got that information from one of the banners on the top of the page ITS WRONG INFORMATION. RULE OF THUMB, a 24mm carb on a 150cc scoot will come with a MAIN JET anywhere from 103-107. So if you add a free flow filter you up the jet size by 2 so if the carb has a 107 get a 110, now if you add a free flow muffler you add another 2 size to the main jet so now from a 110 you go to a 112 MAX 115. And the pilot on a 150 should be a #35 unless you put a Big Bore Kit 61mm or higher then you can up the pilot jet to a #38.
Alleyoop

[rks]

Think you'll be happier with the 115...Put that size in my carb when I threw the air box away in favor of a K&N cone filter. That was 4000 miles, and over 2 years ago....haven't touched the carb for any reason since then....Bob

[macmogul]

Sorry for the delayed update, but I put in the #115 and everything is as it should be!
I feel dumb for wasting my time on the #125 though... and it wasn't just from a banner that I misunderstood the idea of up-sizing the jet, it was from various forums and information boards...