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Hello guys, please help me on this one. I have a P-180 UG3. After my last service there is a problem that has come up. Whenever there is any engine braking, pops are heard from the exhaust. Like it goes rrrrrrrrrrrrrrrrrrphatrrrrrrrrrrrrrrrrrrrrrrrrrrrp hatrrrrrrrrrr. "rrrr" being the normal noise. Its like a RE Bullet's soul entered my bike for a second. Sometimes it comes on simply leaving the throttle. Pops also come occationaly when i race the engine in neutral. No starting trouble, idling is stable, not much difference in handling. I believe this is backfire or afterburn. Not sure exactly. I've heard its caused by a problem with the mixture setting.
The craby was not handled during service. The engine was flushed, oil changed to semi synth from mineral (Activ 4T Xtra to Valvoline 4T Premium), oil strainer and centrifugal filter cleaned, air filter cleaned, spark plugs changed (to normal NGK), tappets readjusted. Silencer was removed for swing arm service. Most (all) cleaning was done with petrol, don't know what flushing oil was used. First i thought it might be some stray petrol burning away. But it is not going away, been 2 weeks.
Also, i have to mention a rattle has also started coming from the engine after the service. Mech said its the timing chain and it is showing now because the flushing oil must have removed the sludge. He said timing chain can be replaced next service. I took it back to the mech, he said probably the manifold (carby insulator, black rubber part between carby and engine) has developed cracks so is letting air in after charge is mixed. So i bought that and he changed it yesterday, but the problem persists.
So today i played with the volume control screw. I think it was set ~3 turns out from fully closed. The service manual says "VC screw setting : 2.5 +/- 2 turns out". So i set 2.5 turns out. Then as i was racing and leaving the throttle there was a pop every time i let go of the throttle from the open position. Now i have put it 3 turns out, 360 (degrees) x 3 anticlockwise. But i am not sure if its right.
Does the VC screw control amount of air or amount of fuel? I am thinking fuel. And anti clockwise increases whatever it controls right? I dont know whether something else has to be adjusted. I want to go on a long ride (~250km) day after, and i don't want a lean and overheating engine. Please, please help me solve this problem.
The craby was not handled during service. The engine was flushed, oil changed to semi synth from mineral (Activ 4T Xtra to Valvoline 4T Premium), oil strainer and centrifugal filter cleaned, air filter cleaned, spark plugs changed (to normal NGK), tappets readjusted. Silencer was removed for swing arm service. Most (all) cleaning was done with petrol, don't know what flushing oil was used. First i thought it might be some stray petrol burning away. But it is not going away, been 2 weeks.
Also, i have to mention a rattle has also started coming from the engine after the service. Mech said its the timing chain and it is showing now because the flushing oil must have removed the sludge. He said timing chain can be replaced next service. I took it back to the mech, he said probably the manifold (carby insulator, black rubber part between carby and engine) has developed cracks so is letting air in after charge is mixed. So i bought that and he changed it yesterday, but the problem persists.
So today i played with the volume control screw. I think it was set ~3 turns out from fully closed. The service manual says "VC screw setting : 2.5 +/- 2 turns out". So i set 2.5 turns out. Then as i was racing and leaving the throttle there was a pop every time i let go of the throttle from the open position. Now i have put it 3 turns out, 360 (degrees) x 3 anticlockwise. But i am not sure if its right.
Does the VC screw control amount of air or amount of fuel? I am thinking fuel. And anti clockwise increases whatever it controls right? I dont know whether something else has to be adjusted. I want to go on a long ride (~250km) day after, and i don't want a lean and overheating engine. Please, please help me solve this problem.
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