This really has me confused! My scooter sat for too long and I had to replace the carb...easy. Then I decided to change the air filter and rejet but now the scooter is acting crazy.
The scooter starts fine, idles fine but is crappy after mid throttle. Original carb had a main jet of 107. I switched to 120, 125 and 130 and with each jet (including 107) it sounded exactly the same as the video (below). Spark plug is black so I think I'm running rich?? But why?? With the new air filter I thought I needed a larger jet??
Video
Hmmm any information would be awesome!
Thanks guys
2012 Motobravo Phantom 150cc, 8,000 miles
Hmm..first of..just because it sat..why would you need to replace a carb? I have worked on Barn stored motorcycles and other gas powered items that sat for over 20 years and never had to replace a carb. Just soak and clean it is all. In fact in 30+ years of fixing small engines I have only replaced one carb..because it was dropped and cracked. With only 1 moving part in them..they simply and in reality would never wear out. So now..since you replaced the carb and none of the jets work properly with the new filter..have you installed the stock filter back onto the new carb and tried it? Hint when working on any engine..--> The first thing to cause you any problem..is always the last thing ya did. Simple logic is it not?.. It's very true as well. What size is the pilot jet in the new carb..and did you adjust the A/F mixture on the new carb? Ya see many will tell you the pilot jet ONLY affects the engine at idel to 1/8 throttle. HOWEVER..this is simply not true because the pilot jet is always on and open and giving small amounts of fuel to assist the main jet. Why?..because unlike the main jet which has a slide needle to adjust its flow..the pilot jet has nothing. It is just an open hole sucking fuel from the float bowl. What does all this mean? Well 2 things..try the stock airbox with the new carb and if it is the same..you will need to adjust your A/F screw..which needs to be done anyway with the new carb. A 107-110 jet should be fine with that engine btw. If you have an adjustable slide needle(cause some don't) you can try raising and lowering the clip on it 1 notch each way and try it. But the way the vid sounds..it is as if the A?F screw needs to be tweaked a bit. This MUST be done while then is warmed up and running.. Ponder all of that above..give the stuff a try..and keep us informed..
Glenn
02-26-2014, 09:08 PM
It's very true as well. What size is the pilot jet in the new carb..and did you adjust the A/F mixture on the new carb? Ya see many will tell you the pilot jet ONLY affects the engine at idel to 1/8 throttle. HOWEVER..this is simply not true because the pilot jet is always on and open and giving small amounts of fuel to assist the main jet. Why?..because unlike the main jet which has a slide needle to adjust its flow..the pilot jet has nothing. It is just an open hole sucking fuel from the float bowl. What does all this mean? Well 2 things..try the stock airbox with the new carb and if it is the same..you will need to adjust your A/F screw..which needs to be done anyway with the new carb. A 107-110 jet should be fine with that engine btw. If you have an adjustable slide needle(cause some don't) you can try raising and lowering the clip on it 1 notch each way and try it. But the way the vid sounds..it is as if the A?F screw needs to be tweaked a bit. This MUST be done while then is warmed up and running.. Ponder all of that above..give the stuff a try..and keep us informed..
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