slight stumble even rpms 3000 to 5000

[skip]

when I run my comp baffle I am getting a slight stumble between 3000 and about 5500 rpm. It goes away as soon as i give it any throttle at all. I have synced the carbs and it got better. I did a plug reading at that rpm range and they looked good. The two inside pipes ar just startin to turn blue but the pipe is 18 years old and the blue barley goes around the the first bend from the head. I checked for intake boots for leaks and found none. (using the sraying method)I havent cleaned my k@n filters in a while and maybe they are not evenly flowing, When I run the more constrictive street baffle I dont notice it hardly if at all. I can more hear it than feel it. The carbs are mikuni RS flatslides 38mm any ideas? I have a few but i thought Id give the gang a shot, some of you guys are really good!

[daveo]

Does this happen only when holding a steady rpm? Could it be described as a slight surging ? (perhaps may indicate a lean condition) too small or partially clogged pilot air jets not pulling up enough gas? Any pop-pop on deceleration with closed throttle? Is this a quiz?

[1100ED]

Does this happen only when holding a steady rpm? Could it be described as a slight surging ? (perhaps may indicate a lean condition) too small or partially clogged pilot air jets not pulling up enough gas? Any pop-pop on deceleration with closed throttle? Is this a quiz?

Dave
I find that t the competition baffle will definitely change the tuning. When i run mine, my bottom end gets smoother. When-it out it is sloppy at lower rpm. I always notice that when I'm cruising at a steady rpm that the engine will have a tendency to slobber a bit at about 3K--it is where the cams start to-work with the added back pressure. I dont think that it can run exactly perfect in both states of exhaust condition.. I theenk 8O

[earlfor]

Re: slight stumble even rpms 3000 to 5000

Well Skip, y'know how 2 stroke tuned pipes work. It works on 4 strokes two, but just not to the same extent. The first thing that comes to my mind is that the different baffle is probably changing the exhaust resonance wave. I would expect that the comp baffle would increase efficiency at higher rpm with a trade off of some loss/stumble at low rpm.

Earl

when I run my comp baffle I am getting a slight stumble between 3000 and about 5500 rpm. It goes away as soon as i give it any throttle at all. I have synced the carbs and it got better. I did a plug reading at that rpm range and they looked good. The two inside pipes ar just startin to turn blue but the pipe is 18 years old and the blue barley goes around the the first bend from the head. I checked for intake boots for leaks and found none. (using the sraying method)I havent cleaned my k@n filters in a while and maybe they are not evenly flowing, When I run the more constrictive street baffle I dont notice it hardly if at all. I can more hear it than feel it. The carbs are mikuni RS flatslides 38mm any ideas? I have a few but i thought Id give the gang a shot, some of you guys are really good!

[1100ED]

I believe we have a situation of one person assuming that that bike has a competition baffle ((me) and another person assuming that you have replaced the stock exhaust systems baffle with a competition one. What exhaust do you have??

[daveo]

[ I find that t the competition baffle will definitely change the tuning. When i run mine, my bottom end gets smoother. When-it out it is sloppy at lower rpm. I always notice that when I'm cruising at a steady rpm that the engine will have a tendency to slobber a bit at about 3K--it is where the cams start to-work with the added back pressure. I dont think that it can run exactly perfect in both states of exhaust condition.. I theenk 8O

sounds right, got to tune for one or the other

[saaz]

Sounds to me like the needles need raising a notch. It could also be a pilot jet/needle combination problem as the motor would be on very little throttle at those revs constant speed mode.

It can also be an exhaust tuning problem. Baffle out is less backpressure and chnaged exhaust tuning.

[skip]

In the past I have been able to change baffles back and forth because I always jet toweards the rich side. the needles are where they are and have been for 10years so i dont think that is a problem. It very well could be exhaust resonince because I recently changed helmets and dont have the same ear cushion I used to. It could also be pilot jets because the float is sticking on one carb due to some gum,so the pilot jet may be a little clogged. any other ideas?

[earlfor]

Well Skip, sounds to me like the the problem is the helmet change and the rider is resonating at a different frequency. :-) :-) :-)

Earl

In the past I have been able to change baffles back and forth because I always jet toweards the rich side. the needles are where they are and have been for 10years so i dont think that is a problem. It very well could be exhaust resonince because I recently changed helmets and dont have the same ear cushion I used to. It could also be pilot jets because the float is sticking on one carb due to some gum,so the pilot jet may be a little clogged. any other ideas?

[skip]

Well Skip, sounds to me like the the problem is the helmet change and the rider is resonating at a different frequency. :-) :-) :-)

In the past I have been able to change baffles back and forth because I always jet toweards the rich side. the needles are where they are and have been for 10years so i dont think that is a problem. It very well could be exhaust resonince because I recently changed helmets and dont have the same ear cushion I used to. It could also be pilot jets because the float is sticking on one carb due to some gum,so the pilot jet may be a little clogged. any other ideas?

makes sense to me and I wont have to get my hands dirty! besides if it starts bothering me all I have to do is twist the throttle and the problem is all gone!