Secondaries Help Needed
12-21-02, 04:32 PM
#1
Secondaries Help Needed
I have noticed for the last couple of weeks that the secondaries don't seem to be kicking in on 85 GS. It also seems that if I open it up and let the rpms get up pretty high (6k) the the secondaries will kick in. But when I let off the accelerator the throtle seems to be stuck open. The engine continues to rev for period of time and then drops back. This seems like something is causing the secodaries to hang and the at high rpms they open some but do not move freely. I guess dirty carb.
I took a little time today and tried cleaning the carb with spray cleaner. This didn' seem to have much of an effect. But honestly, I am just spraying stuff. I really don't understand how a carb works. If someone can point me to a good write up on the Nikki carb or tell me what to look at/for to get my secondaries opening I would really appreciate it.
Help a brother out.
I took a little time today and tried cleaning the carb with spray cleaner. This didn' seem to have much of an effect. But honestly, I am just spraying stuff. I really don't understand how a carb works. If someone can point me to a good write up on the Nikki carb or tell me what to look at/for to get my secondaries opening I would really appreciate it.
Help a brother out.
12-21-02, 04:38 PM
#2
Rotary Freak
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Sounds like you need to rebuild that good ol' carb of yours. Also, Sterling did a nice tutorial on how to disable the vacuum diaphragm on the secondaries and making them mechanically operated.
12-21-02, 04:42 PM
#3
aheadau
Check the diapham area and linkage. Check by hand the movement. (engine off, fully depress throttle, move secondaries with the linkage out side the carb.) When spraying to clean, concentrate on the "shaft" of the secondaries where it goes thru the sides of the carb. Dirt between the shaft and the housing may cause it to stick.
12-21-02, 06:36 PM
#4
Nikki-Modder Rex-Rodder
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Yeah- That write-up is really for when you've familiarized yourself with the carb. If you don't know carb basics, it could screw you all up.
Chances are that your linkage is all crudded up. Open the primary shaft (or just have someone hold the pedal down- car off) and turn the secondary shaft by hand. With the primaries all the way open, there should be very little resistance. You'll probably hear the crumpling sound of the diaphragm that is in the square box at the bumper side of the carb. That's the diaphragm that pulls on a linkage that opens the shaft. There is a hole that snakes around inside the carb to one of the primary venturis. When the vacuum is enough to pull that diaphragm, it sucks it open and the secondaries open. There is a spring inside the housing that pushes against a metal button in the center of the diaphragm. It offers resistance so that the secondaries don't open too much (MPG reasons is all.)
If you deduce that the secondary linkage is all working smoothly, and the tiny cotter pin is'nt hanging on anything or broken (You'll see what I'm talking about), then it's time to open that "squared" round cover and look at the diapragm and seal gasket. Make sure it's cean. Any dust/oil/dirt in there is an indication that vacuum signal is'nt all going to the diaphragm. This will mean you need more signal to open the secondaries.
If all is well, it's time to try clipping one third of the spring off. Clip it and stretch it just a little bit- not as long as it was, about in between the 2/3rds length and the original. Make certain that the cliped end, which is probably very sharp, does NOT puncture your diaphragm!!!.
Let us know what you find as you check these things out.
Chances are that your linkage is all crudded up. Open the primary shaft (or just have someone hold the pedal down- car off) and turn the secondary shaft by hand. With the primaries all the way open, there should be very little resistance. You'll probably hear the crumpling sound of the diaphragm that is in the square box at the bumper side of the carb. That's the diaphragm that pulls on a linkage that opens the shaft. There is a hole that snakes around inside the carb to one of the primary venturis. When the vacuum is enough to pull that diaphragm, it sucks it open and the secondaries open. There is a spring inside the housing that pushes against a metal button in the center of the diaphragm. It offers resistance so that the secondaries don't open too much (MPG reasons is all.)
If you deduce that the secondary linkage is all working smoothly, and the tiny cotter pin is'nt hanging on anything or broken (You'll see what I'm talking about), then it's time to open that "squared" round cover and look at the diapragm and seal gasket. Make sure it's cean. Any dust/oil/dirt in there is an indication that vacuum signal is'nt all going to the diaphragm. This will mean you need more signal to open the secondaries.
If all is well, it's time to try clipping one third of the spring off. Clip it and stretch it just a little bit- not as long as it was, about in between the 2/3rds length and the original. Make certain that the cliped end, which is probably very sharp, does NOT puncture your diaphragm!!!.
Let us know what you find as you check these things out.
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