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Post by lain on Nov 13, 2015 14:24:39 GMT -5
When I am running full throttle for longer than like 5 seconds it bogs down kind of jerks and slows down until I lay off the throttle. I've been all through the entire scooter and nothing seems to be wrong besides the fact the main jet is a tad too big. Could this be coming from the jet being too big or maybe I am not getting enough fuel? I am using 1/8 diameter fuel lines. Should I be using 1/4? I have a manual petcock, not vacuum operated. It goes very fast and otherwise has no other issues. I can still cruise easily around 40-45 but if I go faster and use more than about half throttle it jerks and bogs down, also happens when I let the throttle go down from full throttle so it is confusing. I'm not sure if it means I am running lean or rich because the symptoms point to both?
I am running a gy6 139qmb with 50mm cylinder, big head with big valves, 24mm carb, 8g variator weights, stock clutch and variator, bando belt, stock exhaust, uni air filter, ngk plug, orange coil, gold casoli CDI, gaps at 0.004, added crank vent to the dipstick with oil catch can, still within the first 100 miles of break-in of the engine, brand new and rebuilt by me.
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Post by scooter on Nov 13, 2015 15:38:50 GMT -5
When I am running full throttle for longer than like 5 seconds it bogs down kind of jerks and slows down until I lay off the throttle. I've been all through the entire scooter and nothing seems to be wrong besides the fact the main jet is a tad too big. Could this be coming from the jet being too big or maybe I am not getting enough fuel? I am using 1/8 diameter fuel lines. Should I be using 1/4? I have a manual petcock, not vacuum operated. It goes very fast and otherwise has no other issues. I can still cruise easily around 40-45 but if I go faster and use more than about half throttle it jerks and bogs down, also happens when I let the throttle go down from full throttle so it is confusing. I'm not sure if it means I am running lean or rich because the symptoms point to both? I am running a gy6 139qmb with 50mm cylinder, big head with big valves, 24mm carb, 8g variator weights, stock clutch and variator, bando belt, stock exhaust, uni air filter, ngk plug, orange coil, gold casoli CDI, gaps at 0.004, added crank vent to the dipstick with oil catch can, still within the first 100 miles of break-in of the engine, brand new and rebuilt by me. It sounds like lack of fuel. |
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Post by lain on Nov 13, 2015 15:58:54 GMT -5
You think a larger diameter fuel line could be a solution? As far as I can tell the petcock is fine, it is manual and when I open it it lets gas out as it should. Or maybe the position of the fuel outlet ont he petcock might have some effect? It is currently facing towards the front of the bike so I guess when I'm going fast gas might not come out as fast, or am I wrong about that?
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Post by gy6er on Nov 13, 2015 16:36:26 GMT -5
Nope,I had same thing happen and was 2 jets to rich. Pretty sure.
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Post by gy6er on Jan 29, 2016 7:40:40 GMT -5
Did you solve that problem. If you have a perf pipe,drive slow to warm up, then wot a little. Pull over and immediately check if pipe is cooler. Will only work for perf pipe as they cool greatly and you can get an idea of running cold(would be running rich) and no where near burn yourself. I had same jerk and my instance was rich and another way to test with perf pipe is to put baffel in and it should richen up and pipe should be cooler and or bog at wot because of over rich. I suspect it is like 2 jet sized equivalent running baffel in when normally you run without.
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Post by steve on Jan 30, 2016 21:15:49 GMT -5
I had the exact same problem with a main jet that was too large. I would almost guarantee that is it.
I accidentally put a 110 in a 50cc with a 52mm BBK. Acceleration was good, until I got to 15 mph, then it would stutter and jerk.
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