no takers?
rpm's are out of control
So I've been having some trouble with the cb350k2 lately. It will run just fine for a while, and then randomly when I stop, the rpm's will skyrocket up to 5k (in both neutral or in gear). The throttle tube isn't sticking, the cables are not stuck or pinched, and the carbs are not engaged from what I see. Today I started the bike, let it warm for a few minutes, and then took a 20 minute cruise around the neighborhood and it did it again. I got it back into the garage and decide the first step would be to reset the carbs. I adjusted the cables so they are pulling evenly, adjusted the idle screws so it hums just over 1k rpm, and then began to set the air screws so it would rev and come back down properly. During the air screw session, it kept flying up to 5k and eventually could not be remedied, no matter where the air screws were. It will start and idle fine, but the second you give it more the a 1/4 twist, it happens.
I've done a little research, and it seems that carb overhauls are the answer. I gave them a thorough cleaning last summer and they were fine up until my recent problem. Suggestions?! Thanks in advance.
I've done a little research, and it seems that carb overhauls are the answer. I gave them a thorough cleaning last summer and they were fine up until my recent problem. Suggestions?! Thanks in advance.
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My CB175 does this as well. I was also thinking it could be some type of air leak either between the carb/intake or intake/cylinder. I plan on spraying some carb cleaner around those joints and if it revs high I know that the problem is most likely there.
Maybe someone with better knowledge could answer this question. Could this also happen if the intake rods are not opening/closing properly, maybe closing to slowly? I have no idea but I'll update once I do the carb cleaner test.
Maybe someone with better knowledge could answer this question. Could this also happen if the intake rods are not opening/closing properly, maybe closing to slowly? I have no idea but I'll update once I do the carb cleaner test.
I had that problem where the RPMs would climb to the point where I had to shut the engine off. I ended up just cleaning out the carbs and getting them reset. It seemed to work well enough so far.
weak spark advance springs can do this as well, they are unable to pull the weights back in, and this prevents the rpms from dropping back down.
or if the advance unit is sticky, it may stick advanced as well. worth looking at if your carbs aren't providing the answer.
or if the advance unit is sticky, it may stick advanced as well. worth looking at if your carbs aren't providing the answer.
I broke down the carbs today and found that the left side had 2 small slits in the diaphragm. I either missed it when I did the last clean-out, or somehow tore it myself. Or maybe it happened while riding...is that possible? Anyway, I went to my local indoor bike salvage yard (L and L Cycle in Dallas), and miraculously found a complete matching set of Keihin carbs, still tethered together by the throttle cable. Sweet! I broke them down and the metal pieces are enjoying a relaxing overnight soak in carb cleaner.
Now I need to find a set of o-rings and bowl gaskets for them. Does anyone sell them without the jets? The jets and springs are fine. Hopefully this will be the answer. If not, I'll have kick ass carbs on the bike and know they AREN'T the problem.
Now I need to find a set of o-rings and bowl gaskets for them. Does anyone sell them without the jets? The jets and springs are fine. Hopefully this will be the answer. If not, I'll have kick ass carbs on the bike and know they AREN'T the problem.
CB360.com has them, as does SIRIUS...
any orings may be a standard size OD ID and cross section are ways to measure(also measure the hole size and groove minor diameter) you can get metric o-rings in a kit with many different sizes at harbor frightjazwal13 said:I broke down the carbs today and found that the left side had 2 small slits in the diaphragm. I either missed it when I did the last clean-out, or somehow tore it myself. Or maybe it happened while riding...is that possible? Anyway, I went to my local indoor bike salvage yard (L and L Cycle in Dallas), and miraculously found a complete matching set of Keihin carbs, still tethered together by the throttle cable. Sweet! I broke them down and the metal pieces are enjoying a relaxing overnight soak in carb cleaner.
Now I need to find a set of o-rings and bowl gaskets for them. Does anyone sell them without the jets? The jets and springs are fine. Hopefully this will be the answer. If not, I'll have kick ass carbs on the bike and know they AREN'T the problem.
or visit a NAPA store
any orings may be a standard size OD ID and cross section are ways to measure(also measure the hole size and groove minor diameter) you can get metric o-rings in a kit with many different sizes at harbor frightjazwal13 said:I broke down the carbs today and found that the left side had 2 small slits in the diaphragm. I either missed it when I did the last clean-out, or somehow tore it myself. Or maybe it happened while riding...is that possible? Anyway, I went to my local indoor bike salvage yard (L and L Cycle in Dallas), and miraculously found a complete matching set of Keihin carbs, still tethered together by the throttle cable. Sweet! I broke them down and the metal pieces are enjoying a relaxing overnight soak in carb cleaner.
Now I need to find a set of o-rings and bowl gaskets for them. Does anyone sell them without the jets? The jets and springs are fine. Hopefully this will be the answer. If not, I'll have kick ass carbs on the bike and know they AREN'T the problem.
or visit a NAPA store
Update; I have finished building 2 awesome carbs from 4 decent ones (722a) and am currently waiting on new throttle cables and bowl gaskets to arrive in the mail. I decided to order a varitey of new jets to really get the bike tuned well, and need help with sizing. In your opinion, what is a good variety of jet sizes to have on hand for tuning the carbs? Also, what are typical stock sizes for a 350k2 so I have a good starting point? Thanks!
1970 cb350k2
Pods
2-into 1 with a muffler.
1970 cb350k2
Pods
2-into 1 with a muffler.
just my 2 cents. I have the exact bike as yours.
I had the exact same problem. We cleaned the carbs a few times, however
I really feel the the problem was solved when I put in a new throttle cable.
Sliders maybe sticking too
I had the exact same problem. We cleaned the carbs a few times, however
I really feel the the problem was solved when I put in a new throttle cable.
Sliders maybe sticking too
o.k. I see you ordered a throttle cable. Great.
Yeah, I remember every time I would get back from a ride, and coast into the driveway, it would rev up
to 5000. Or when I was slowing down at a stop sign. Real pain. Anyhow, it looks like your prob will be solved. Good luck.
Mike
Yeah, I remember every time I would get back from a ride, and coast into the driveway, it would rev up
to 5000. Or when I was slowing down at a stop sign. Real pain. Anyhow, it looks like your prob will be solved. Good luck.
Mike
1 - 14 of 14 Posts
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