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Post by fladg on Sept 12, 2017 16:42:28 GMT -5
Hey Guys -
New to the forum but I have a Znen (TNG) 150CC scooter with just shy of 5,000 miles on it. Bought it new and have been riding it for a few years now. Oil and CVT changed frequently with slight leaks. Had the valves adjusted and carbs cleaned about 300 miles or so.
This has been happening since the beginning but noticing it more these days. Say I am riding somewhere on full throttle for 3-4 miles the engine starts to loose power. Essentially cuts off on me and i have to let go of the throttle and slowly start giving it gas to get it go again. Sometimes it even shuts off on me and I have to do a few tries to get it started. It sounds to me like overheating but no idea where to begin. The local shop told me it could be the coil or CDI but was not positive. Anyone else have any tips on where to start?
fladg
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Post by wheelbender6 on Sept 12, 2017 18:12:00 GMT -5
When my scooter behaved that way, I fixed it by adding Seafoam to the tank. Since you just had the carb cleaned, the Seafoam probably will not help you.
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Post by tortoise on Sept 12, 2017 18:38:34 GMT -5
Floorboard level gas tank with pulse-pump? |
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Post by fladg on Sept 12, 2017 18:39:33 GMT -5
Floorboard level gas tank with pulse-pump? Floorboard gas tank for sure. How do I check the pump? |
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Post by tortoise on Sept 12, 2017 18:49:47 GMT -5
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Post by fladg on Sept 12, 2017 18:52:50 GMT -5
I'll dig into it but very well could be the fuel pump. Anyway to verify and be certain or just replacing at this point? |
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Post by chewbaca on Sept 12, 2017 18:57:06 GMT -5
Instal a temporary gravity feeding fuel tank
just strap something to the rack that can hold gas and has a fuel port
If the problem goes away then it's the pump
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Post by fladg on Sept 12, 2017 20:02:05 GMT -5
Cool thanks. I'll have to google around some ideas of how to best/easiest do this.
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Post by chewbaca on Sept 13, 2017 22:41:31 GMT -5
Go to www.homedepot.com/p/TruFuel-4-Cycle-Ethanol-free-Fuel-6527238/203571144Get that Drill a 1/4 inch hole in the cap insert a long 1/4 inch pop rivet add washer so as not to split the plastic carefully close the rivet tight so the expanded aluminum tube sticks out the top when when the cap is on Remove the steel mandrel The rivet should have expanded big enough for a 3/8 inch fuel line to fit on with a hose clamp add a filter somewhere inline screw the can back under the cap turn upside down pop a little bitty hole in the bottom of the can to break the vacuum Should last long enough to figure out what you need to If you want to refill with pump gas just plug the vacuum port with your finger |
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Post by seamus26 on Sept 14, 2017 6:54:41 GMT -5
I have the same bike with just shy of 6k miles. Great ride.
You say it happens only at WOT? Do you have an inline fuel filter you could swap out?
Also, one of the early things that we did with mine was up-jet the carb. The 150s - from what I hear - are under-jetted. I haven't had any issues and cruise at 50-55 all day.
Keep us posted. I hope it's a simple fix.
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Post by fladg on Sept 17, 2017 12:11:37 GMT -5
Go to www.homedepot.com/p/TruFuel-4-Cycle-Ethanol-free-Fuel-6527238/203571144Get that Drill a 1/4 inch hole in the cap insert a long 1/4 inch pop rivet add washer so as not to split the plastic carefully close the rivet tight so the expanded aluminum tube sticks out the top when when the cap is on Remove the steel mandrel The rivet should have expanded big enough for a 3/8 inch fuel line to fit on with a hose clamp add a filter somewhere inline screw the can back under the cap turn upside down pop a little bitty hole in the bottom of the can to break the vacuum Should last long enough to figure out what you need to If you want to refill with pump gas just plug the vacuum port with your finger Thank you! I'll give it a shot and post my results. |
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Post by fladg on Sept 17, 2017 12:13:28 GMT -5
I have the same bike with just shy of 6k miles. Great ride. You say it happens only at WOT? Do you have an inline fuel filter you could swap out? Also, one of the early things that we did with mine was up-jet the carb. The 150s - from what I hear - are under-jetted. I haven't had any issues and cruise at 50-55 all day. Keep us posted. I hope it's a simple fix. Bikes been great otherwise! It only happens on WOT for extended periods of time. When it does happen and say I stop at my destination the bike has a hard time starting back up afterwards. Takes quite a bit of tries but eventually does. I want to say I have replaced the fuel filter but I'll double check it as well, can't hurt. If it's the original, I'll swap it out. |
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Post by pistonguy on Sept 18, 2017 9:12:30 GMT -5
You mentioned that You had the Valves Adjusted some 300 miles ago or so.
Was this done by a friend, technician or you?
At WFO for extended periods the engine is at its Max Temp, if your Valves were adjusted a Tad tight or Incorrectly 300 miles ago the Lash may be closing up at that WFO extended period.
The Exhaust Valve being the Hotter of the Two is Most likely closing the lash at that Max Temp leaking compression, the engine Will slow down till it quits ,also explain why its so hard to start back up while Hot. ya prolly got squat for compression when Hot.
With the extra cranking it takes to get it started the Fresh Fuel charge cools the assy, to were it will start up and repeat...
I would dbl, and triple check my Valve lash.
Kinda sounds like a classic case of a GY closing its Lash.
Good luck
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Post by fladg on Sept 18, 2017 21:36:04 GMT -5
You mentioned that You had the Valves Adjusted some 300 miles ago or so. Was this done by a friend, technician or you? At WFO for extended periods the engine is at its Max Temp, if your Valves were adjusted a Tad tight or Incorrectly 300 miles ago the Lash may be closing up at that WFO extended period. The Exhaust Valve being the Hotter of the Two is Most likely closing the lash at that Max Temp leaking compression, the engine Will slow down till it quits ,also explain why its so hard to start back up while Hot. ya prolly got squat for compression when Hot. With the extra cranking it takes to get it started the Fresh Fuel charge cools the assy, to were it will start up and repeat... I would dbl, and triple check my Valve lash. Kinda sounds like a classic case of a GY closing its Lash. Good luck Thanks. I had a technician do it but worth a recheck as well. I did have a feeling it was due to overheating but wasn't sure where to start. I'll start with this one and then work my way through. |
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Post by pistonguy on Sept 18, 2017 21:49:13 GMT -5
You mentioned that You had the Valves Adjusted some 300 miles ago or so. Was this done by a friend, technician or you? At WFO for extended periods the engine is at its Max Temp, if your Valves were adjusted a Tad tight or Incorrectly 300 miles ago the Lash may be closing up at that WFO extended period. The Exhaust Valve being the Hotter of the Two is Most likely closing the lash at that Max Temp leaking compression, the engine Will slow down till it quits ,also explain why its so hard to start back up while Hot. ya prolly got squat for compression when Hot. With the extra cranking it takes to get it started the Fresh Fuel charge cools the assy, to were it will start up and repeat... I would dbl, and triple check my Valve lash. Kinda sounds like a classic case of a GY closing its Lash. Good luck Thanks. I had a technician do it but worth a recheck as well. I did have a feeling it was due to overheating but wasn't sure where to start. I'll start with this one and then work my way through. Perfect, I think your headed in the right direction dbbl and triple check the work, any doubt roll her over again end check your work. Good luck |
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