What speed range are you running the new scooter at? It needs to be run-in at below 2/3 of max speed (that's about 30/35 on a 150) for 150 to 200 miles or you can get soft seize issues.
Otherwise it sounds like it could be a defective ignition pickup if its not fuel. People are too quick to start tearing apart carbs on new scoots. Even if you have a spark with a defective pickup it can be at the wrong time and when they get hot they peter out just like you were running out of gas. Usually by the time you open things up to check the spark they have cooled enough to work again making it harder to check them and if you run them with the covers off then until they get really bad the extra airflow prevents them from failing.
Post by powerzombie on Apr 23, 2016 5:36:49 GMT -5
Make sure your gas cap is venting.
Re-check the valves, too tight and it will do what you are describing- as the engine starts to make heat, they exhaust valve loses it's clearance and lifts off the seat slightly causing loss of compression.
Ok.. No super pro,but that,s a nice scoot!! Even I wann see her broke in blazing so.... Just some thoughts New spark plug? Pick up coil loose and when warm-moves out of wack? Maby cdi is dud,especialy after warm up...I may start there and then check pick up. You look like you know about lean/rich conditions,so? Good luck though. Someone help. I would scream into a white jacket. Also, no warranty I take it?
Post by yelloscoot on Apr 23, 2016 21:51:33 GMT -5
I had the same type of issue when I first bought my Roketa 150 back in 2011. I would get a mile or so down the road and it would just sputter to a stop and then die. I found that if I removed the fuel cap it would start right up. So, to solve that, I just drilled a small 1/8" hole in the cap. Problem solved. Never had another issue with it dying out. Just a thought.
(Now that I think about it, the fuel tank vent hose thingamajig, may have been installed backwards.)
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Post by oldchopperguy on Apr 23, 2016 23:29:27 GMT -5
If your gas tank is in the floor, it must have a fuel-pump (which could be acting up). If your tank is up high, with gravity-feed, your vacuum petcock may not be functioning correctly.
I would first try Yelloscoot's trick of running with the gas-cap off, or loose. If that doesn't help, I'd try running a fuel-line directly from the tank to the carb. If that fixes it, replace the vacuum petcock with a manual one.
I had a Chinese 150 for seven years, and fuel-delivery was one of the problems I had. Mine had a gravity-feed, and the vacuum petcock would not stay open. The engine would die at speed. I installed a Briggs & Stratton manual petcock in place of the vacuum unit.
Post by JerryScript on Apr 24, 2016 1:51:51 GMT -5
Had cap venting issues as well on my 150cc. With my setup, i can leave the cap loose, but I recommend drilling a 1/8" hole on the cap, less chance of spillage. I haven't had the issue since I started leaving it loose.