Unusual, well not that unusual

[racerboy]

After its warmed up fairly well, heading down the road at an even speed, accelerate alittle, roll off the throttle, the bike will do a slight cough that you can either hear or feel thru the air box. Its not to the point where performance is hampered, its there, just wondering what's causing it. My past 2 maxes experienced this before. so, it has a K&N filter, stock pipe, screws turned out to 2-2.5 turns, stock jetting. Vacuum leak? sticking slide? appreciate any feedback. V/R Scott

 

[sdt354]

Coasting enrichment diaphragms could be bad or circuit plugged up. . Not doing anything else makes me think this. Many possibilities.
Steve

 

[racerboy]

yup, the two oblong diaphragms appeared to be dry rotted. Replaced em both, no more cough

 

[PMaxx]

Thanks for actually writing a follow up reponse...it drive me nuts when I find a troubleshooting topic similar to what I'm experiencing and no one replies with what the problem turned out to be!

 

[DMAN999]

Glad to hear you figured it out.

 

[racerboy]

found another issue but solved it. The rubber boots between the carbs and intake? 2 of the boots had a nice split and crack, apparently, the only reason I did not notice anything, the clamps basically kept the boots from leaking and naturally, no leaks. I was taking all the boots off to chk for dry rot etc and found the future problem. When your bike is well over 8 yrs old, this becomes a problem no matter how much you care and feed and store in your garage process. The rubber will break down! Hell, even my race bike rubber from the coolant hoses to the EFI gas lines need attn! Don't even get me started on my SC 500! All new lines!!

 

[dannymax]

found another issue but solved it. The rubber boots between the carbs and intake? 2 of the boots had a nice split and crack, apparently, the only reason I did not notice anything, the clamps basically kept the boots from leaking and naturally, no leaks. I was taking all the boots off to chk for dry rot etc and found the future problem. When your bike is well over 8 yrs old, this becomes a problem no matter how much you care and feed and store in your garage process. The rubber will break down! Hell, even my race bike rubber from the coolant hoses to the EFI gas lines need attn! Don't even get me started on my SC 500! All new lines!!

THAT'S a wake-up!! I still think of an '07 as a new VMax! :blink000:

 

[Fire-medic]

The early 1970's 500 offroad two strokes like the Yamaha SC500, the Maico 501, the Kawasaki 450, the Suzuki 400, those took big balls to ride fast. It was before long-travel suspension, and most riders were faster on a 350/360 than they were on the 500's. They just put out so-much HP and w/an abrupt delivery, that they were difficult to control, especially w/the limited suspension travel.

I recall that using a different capacitor on the ignition coil circuit would ease the SC5000 output and make it more controllable. My hat is off to you if you can ride that bad boy in anger. I think it was one w/an electrical value for a domestic V-8.

Yes we always are interested in what fixed an issue.