GY6 Proplems - Looking for help

[kittletstv]

Sorry for the long letter but sometimes it takes details to help find the problem /s. Would anyone out there have any suggestions for this GY6 150 that I've been stuggling with? It was already giving me some trouble of not running smoothly, but it was speratic. Then I recently added a new Uni air filter & velocity stack to give it a little pep or so I thought. The original main jet was a 107. They sent me a 125 & a 130 with the new combo. Since we were going from an elevation 0f approx 1,700 ft to a little over 6,200 ft above sea level I started with the stock main jet. It ran fine here in the desert for about 10 -15 mins then it sputtered a few times, then quit. I could barely get it started and up onto the trailer before ti died again and never did restart. Once in the mountains it would not run worth beans so I changed the 107 main jet out to the 125. I had to crank and crank it over to barely start and then it didn't run any better or worse than before. Still sputtering & not coming up to speed, stalling every time I let off the gas. I then changed over to the 130 main jet. The same issues with no changes. I pulled the carb off & tore it down bare, cleaned it out again (even though it was bone clean with no obstructions in any of the passages), and reassembled with the original K34 pilot jet & the new 130 main jet. Had to crank it a while but once it started it ran fine for about 20 -30 mins other than loading up just a little 1 time. I floored it and let it clear itself out and it was fine for another 30 -40 mins. We shut it down for about 10 mins, then it would never start & run right again. After numerous attempts to start it, if it did start even with it floored it would only sputter & bobble along. If I tried to feather it out to find a smooth spot, it would die every time. Then finally it just wouldn't start at all irregardless of what main jet I used, or mixture adjustment was made. Any suggestions or is this what is to be expected from these engines? Also where can I find a carb kit for these things? Everyone I 've talked to tells me that there isn't any such part/s avaliable. HELP!

[baker3]

Why not just buy a brand new carb? They are on ebay for 30-70 dollars for a complete carb.

[Miamieddie]

if anything you need to go smaller on ur jet size. There's less oxygen at that elevation. Get a new sparkplug put the stock 107 jet back on adjust ur air/fuel screw and do a wot test. Look at ur plug and we'll move from there.. always let ur motor cool before removing ur sparkplug. Or you'll mess ur threads up. Also take a look at the sparkplug you have on there now. Its probably rich (black).p.s. you may have to go smaller on ur jet, smaller than 107. But first do what I mentioned first.

[Miamieddie]

Oh one more thing check for air leaks around the carb with carb cleaner while idling. If it changes tone you have a leak. That will also contribute the spuratic behavior.

[kittletstv]

baker3 - It is a new carb. The strangest part of all of this is that I had trouble with the original carb so I bought a new one for it. Inially it worked good. I started it every few days or so checing it out since we had just recently bought it used. Then it started acting up by being hard to start, if it did start it would sputter, run rough and die time after time. This was way before the filter / stack & main jet change/s.

[kittletstv]

Miamieddie - Thank you again for your imput. What exactly is the purpose of the pilot jet? I noticed that the original carb has a 103 main jet, and both the original carb & the new carb both have K34 pilot jets. On your buggy are you using a fuel petcock with a vacuum port or is it strickly a gravity feed petcock? A local shop told me that it would never run right with a gravity feed petcock, however I see them listed online as a possible replacement to the original models with the vacuum port.

[Miamieddie]

Pilot jet controls ur fuel frim idle to 1/4 throttle. I have gravity fed carb and pet cock. To me its the only way I'll ever go, I see to many people having problems with vacumm type carb. If that's what you have then your problem ur having may be that if this is your existing problem (vacuum lines) and you tried what I mentioned above with no improvement will let soneone chime in to help you with the vacuum lines that's out of my league. You may have trapped air or lines connected wrong idk.

[kittletstv]

Finally found the problem. I wanted to update those that helped with different things to check, and to possibly help someone else if they too have a problem similar to mine. After several tests of the electrical system components I found that the problem was the CDI itself. After I got it running, I put the old coil back on as a secondary test just to see if it was still good after all and it was. I did also readjust the valves as suggested, which as it turned out the intake valve was way too tight. It now starts right up cold or hot without touching the throttle. I really appreciate all of the imput. This site and the people that reach out to others to help is a great tool to have. Thank you. Now on to tweaking the carb, exhaust, clutch springs and gearing for running the trails in the AZ White Mountains. Oh What Fun It Is!

[bear]

Awesome job "k"man like I always say, its way better if you can fix it yourself, mind body, & soul! good deal!

[Miamieddie]

Good news there kittles.