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Post by userix on May 5, 2014 11:55:14 GMT -5
Then check your air intake side of the carb or your intake manifold you have a bad air leak someplace. Alleyoop I checked the carb and intake as well the intake manifold is brand new and there are no leaks there as well. The carb works fine too. If it was a bad air leak, wouldn't I be having problems all the time? My problem happens like once randomly during a ride and continues to run perfectly fine afterwards. Could it still be the valve gap problem? What about a head gasket leak? Could that cause the problem? |
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Post by alleyoop on May 5, 2014 12:56:54 GMT -5
ok, lets be clear about the sound you are hearing when you decelerate. Is it really a BACKFIRE or is it a POPPING sound big difference. Backfiring is LIKE A GUN GOING off "POW" "POW", POPPING IS just that a POP POP sound. Backfiring is a VERY LEAN CONDITION and usually occurs with a bad AIR leak but it can be caused by not enough fuel when the Butterfly is all of a sudden closed. A POP POP is also a lean condition but will not cause damage like a BACKFIRE will. So first when it is nice and hot at what RPMs does the motor IDLE at? A. The pilot jet fuel outlets are right by the BUTTERFLY, There are usually 4 of them. The Idle speed screw turning it clockwise moves the butterfly back EXPOSING more of the fuel outlets. That is why the IDLE GOES UP more fuel and little more air is being sucked in. Turning it Counter Clockwise lets the Butterfly move forward COVERING more of the fuel outlets and air and your IDLE GOES DOWN. So when you let go of the throttle it may be covering to many of the little fuel outlets due to the idle being to low. 1. If the IDLE is to low it can cause it to run lean from a WOT run from a sudden cut off of fuel down to idle and not enough fuel is sucked up to keep it from running lean. 2. If it is idling at 1500-1800 rpms then rich-en up the Fuel Mixture 1/4-1/2 turn counter clockwise and give that a shot. Alleyoop Here I labeled where the fuel outlets are so you get how the butterfly covers the tiny pilot jet fuel outlets or expose them.  |
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Post by userix on May 6, 2014 15:27:03 GMT -5
ok, lets be clear about the sound you are hearing when you decelerate. Is it really a BACKFIRE or is it a POPPING sound big difference. Backfiring is LIKE A GUN GOING off "POW" "POW", POPPING IS just that a POP POP sound. Backfiring is a VERY LEAN CONDITION and usually occurs with a bad AIR leak but it can be caused by not enough fuel when the Butterfly is all of a sudden closed. A POP POP is also a lean condition but will not cause damage like a BACKFIRE will. So first when it is nice and hot at what RPMs does the motor IDLE at? A. The pilot jet fuel outlets are right by the BUTTERFLY, There are usually 4 of them. The Idle speed screw turning it clockwise moves the butterfly back EXPOSING more of the fuel outlets. That is why the IDLE GOES UP more fuel and little more air is being sucked in. Turning it Counter Clockwise lets the Butterfly move forward COVERING more of the fuel outlets and air and your IDLE GOES DOWN. So when you let go of the throttle it may be covering to many of the little fuel outlets due to the idle being to low. 1. If the IDLE is to low it can cause it to run lean from a WOT run from a sudden cut off of fuel down to idle and not enough fuel is sucked up to keep it from running lean. 2. If it is idling at 1500-1800 rpms then rich-en up the Fuel Mixture 1/4-1/2 turn counter clockwise and give that a shot. Alleyoop Here I labeled where the fuel outlets are so you get how the butterfly covers the tiny pilot jet fuel outlets or expose them. Ok. It's more of popping noises. Not bang bang loud. But this problem happens only during wot. It actually starts dying during wot. Like I lose power while wotting, then as soon as I let go of the throttle it throws a few pops and the. The engine dies. But most of the time, I can start the bike right back up almost immediately. I'm just so confused what is wrong. I mean if it was fuel ratio mixtures and all that I should be consistently running into problems. But this issues only appears once is a while. Seeing how I replaced gasket for exhaust and intake manifold and I made sure no leaks are coming from head gasket base gasket and valve cover, I'm not sure what else it could be. The only thing I can think of is maybe fuel starvation? Could it be my pump having issues? But again if it was the pump going out I should be having problems very often. It just doesn't make sense how after this problem occurs, I can continue riding at wot for a good 30 minutes without any problems for the rest of the ride, which is usually an hour or so more. It probably can't be the electrical system either like CDI? And I'm guessing because this is only happening on wot, the air fuel screw has no effect on it My idling right now is roughly 1800-2200 rpm at running temp. Idle is pretty steady too. Thanks so much for taking time to help me out. This problem is driving me nuts. I keep having to push my bike to the side of the road at traffic lights. Lol |
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Post by userix on May 6, 2014 15:38:05 GMT -5
In your previous Post you said in order to richen up the mixture, I should turn it counter clockwise. Isn't it suppose to be clockwise to richen, according to what you said earlier in your post?
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Post by JerryScript on May 6, 2014 18:10:38 GMT -5
It's a screw that is closing off a fuel port, so tightening it up (clockwise) cuts of the port making it leaner, loosening it up (counterclockwise) opens up the port making it richer.
You may have been confusing the idle speed adjustment screw, tightening it up (clockwise) opens the butterfly exposing the fuel ports.
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Post by alleyoop on May 6, 2014 19:26:54 GMT -5
RIGHT ON JERRY  Ok lets clear this up, NOW your saying it is popping during EXCELERATING that is a completely different fix. POPPING at WOT is caused by your MAIN JET being to big. What size main jet have you got in it? Alleyoop |
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Post by userix on May 6, 2014 21:15:18 GMT -5
RIGHT ON JERRY Ok lets clear this up, NOW your saying it is popping during EXCELERATING that is a completely different fix. POPPING at WOT is caused by your MAIN JET being to big. What size main jet have you got in it? Alleyoop Sorry for not being clear in my description. Ok. When I wot, sometimes I lose power randomly, as if I ran out of fuel. As soon as I let go of the throttle, then the popping happens, hence during deceleration. It doesn't pop during the wot, but it does stall out during the wot. The popping sounds only happen once I let go of the throttle. I just don't get why it doesn't happen all the time. It's just once in a while randomly. Is the jet size printed on the jet itself? I'm not sure what size is currently in there. Should be the stock carb |
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Post by alleyoop on May 6, 2014 22:10:44 GMT -5
Ok, popping on decel you need MORE FUEL, POPPING on EXCEL or at HIGH SPEED to MUCH FUEL.
So richen up the fuel ratio mixture give it 1/4 to 1/2 turn COUNTER CLOCKWISE to richen feed it more fuel(this is the FUEL RATIO MIXTURE on the LEFT SIDE of the CARB(not the IDLE SPEED SCREW on the Throttle cable side with the spring under it). Richen it up might also help your loss of power sometimes.
Alleyoop
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Post by userix on May 7, 2014 1:30:13 GMT -5
Ok, popping on decel you need MORE FUEL, POPPING on EXCEL or at HIGH SPEED to MUCH FUEL. So richen up the fuel ratio mixture give it 1/4 to 1/2 turn COUNTER CLOCKWISE to richen feed it more fuel(this is the FUEL RATIO MIXTURE on the LEFT SIDE of the CARB(not the IDLE SPEED SCREW on the Throttle cable side with the spring under it). Richen it up might also help your loss of power sometimes. Alleyoop Thanks. I understand the idle screw and air mixture screws are different. But I thought the air mixture screw only affects idle and low speed. I thought wot was completely dependent on the main jets And before the popping happens, I start to lose power and stall during wot. I checked the main jet. It is a 102 |
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Post by alleyoop on May 7, 2014 14:47:32 GMT -5
The Fuel Ratio Mixture screw feeds fuel throughout the whole throttle range it is a misconception by many that it is only for idle. It of course feeds less fuel but fuel is always being sucked out of it as well, there is no cutoff from the tiny holes by the butterfly to not have fuel come out.
But now that I know what size main jet is in there a 102 that is NOT BIG enough get a 105 main jet and I think that will fix your problem you may even need a 107.
Alleyoop
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Post by craisin on May 8, 2014 20:50:02 GMT -5
cut a coke can up its about .004inch
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Post by userix on May 8, 2014 21:33:51 GMT -5
Another thing I notice, and this has been like this from before I started having the popping/stalling issue on WOT, when I blip the throttle (WOT it for maybe half a second) from a standstill, the RPM dips really low (~700rpm) and almost completely stalls out, and in some cases, the engine does stall. But if it doesn't stall, the RPM will return to normal idling of ~2000rpm within a couple seconds. What causes this to happen? Is it related to the slow/pilot jet or A/F mixture screw? How do I fix this problem?
I also notice when I start popping on decel, I notice lots of bubbles in my fuel line going to the carb from my Mikuni pump. I just rebuilt the pump using genuine mikuni parts and I made sure all vacuum lines and gas lines are tight. As soon as the engine returns to normal, the fuel lines are free of bubbles. I'm not sure why there are bubbles only during the time I get popping on decel and loss of power during WOT.
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Post by JerryScript on May 8, 2014 23:13:00 GMT -5
Popping on decel is usually an indication of being too lean. If you twist the throttle, and it starts to bog, back off the twist by 1/4, if the engine speeds backup, you are too lean. As Alleyoop said, you need to upjet your main jet, and then tune your carb with the a/f mixture screw. Once you get the highest RPMs you can by adjust a/f, then you adjust your idle speed screw to get the desired idle RPM.
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Post by alleyoop on May 8, 2014 23:34:18 GMT -5
Another thing I notice, and this has been like this from before I started having the popping/stalling issue on WOT, when I blip the throttle (WOT it for maybe half a second) from a standstill, the RPM dips really low (~700rpm) and almost completely stalls out, and in some cases, the engine does stall. But if it doesn't stall, the RPM will return to normal idling of ~2000rpm within a couple seconds. What causes this to happen? Is it related to the slow/pilot jet or A/F mixture screw? How do I fix this problem? I also notice when I start popping on decel, I notice lots of bubbles in my fuel line going to the carb from my Mikuni pump. I just rebuilt the pump using genuine mikuni parts and I made sure all vacuum lines and gas lines are tight. As soon as the engine returns to normal, the fuel lines are free of bubbles. I'm not sure why there are bubbles only during the time I get popping on decel and loss of power during WOT. Your running lean that is why when you open the throttle what happens you just let in a lot of air but not enough fuel so it sputters and it bogs then it catchs up and it gets better. FOLLOW THIS PROCEDURE TO TUNE YOUR CARB and take your time 1/2 turn in either direction makes a big difference and on some even 1/4 turn in either direction makes a big difference all motors are different, it depends on the spark the compression etc.. itistheride.boards.net/thread/12/4ts-carb-tuningIf you got bubbles you have an air leak either on the fuel pump you rebuilt or fuel hose. Alleyoop |
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Post by userix on May 9, 2014 3:33:56 GMT -5
Thanks for the reply. Now what about the weird dipping in idle RPM after a quick flip of the throttle? Is that caused by a pilot jet that is too small? Sometimes the RPM dips so low that it kills the engine.
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..BAD TO THE BONE..
