Total Motorcycle Community Forums

80 CX 500 C is the bike. Problem is it is gutless till you get to 5000 rpms. The right cylinder is not firing. I rebuilt the carbs twice just to make sure I did not miss any passages the first time. I have plenty of compression and there is spark. Brand new plugs and have changed the cap three times. The pulsors test at 220. The weird thing is it idles great just no power till 5k then it takes off like a rocket. I know the right cylinder is not firing cause the pipe stays cold, but after I ride it keeping it about 5k-5500 it gets hot. I do not have another CDI to try. I put kits into the carbs too and there is no air leak anywhere. Help please before I throw it off a cliff.

If I remember correctly they are kinda gutless till you get "on the pipe". Have you tried swapping the coils to see if the problem follows the coil? Do CX's even have separate coils? Have you ,using a multi-meter, taken voltage readings at the coils? Are you reading 12 volts or more?

One cylinder not firing until 5k could be either an ignition problem or fuel problem.

New plugs are no guarantee that they work correctly. I'd try John's suggestion of switching coils, but try swapping the leads as well and see if the problem moves to the other cylinder.

I almost lean to a fuel problem though. The low speed jetting circuit being clogged will cause the problem you have. I know you cleaned them, but I wish I had a buck for every thread that started "I cleaned the carbs" and ended with "after the fourth time I cleaned the carbs (properly), it works fine".

Not saying that is the problem for sure and not an indictment about your work, just stating a very, very common occurrence. Chemically sprayed cleaning often don't get it done right, manual manipulation is sometimes the only way.

I know for sure the carbs are good and I tried another set of coils with no good results. I just tried another cdi and no change. I agree with you buzzz on the fact that people do not check all of the passages on carbs when they "clean them", but I have been working on bikes for 19 years and have done more sets of carbs than I can recall. I did have problems with that when I first started, but over the years I learned to do it right the first time cause I got tired of pulling the carbs twice. I still checked them twice and I know it is an spark problem. The header stays cold till 5k. Now I know that the stator has a low speed right pulsor, high speed right pulsor, and same for the left cylinder. They all test out fine with a multimeter. I am just looking to see if anyone has had this problem and if it was some small dumb relay or something.

this site
http://choppercharles.com/cs/
is dedicated to these bikes. drop over there and take a look around and ask questions. the search function is turned off so don't try and search anything else it's through google. i know there are knowledgeable people here.... but over there they live and breathe these bikes and generally know there stuff. when you figure out what the problem is, post it here so others can have the answer in the future. good luck.

I'd vote that it seems your low speed pulser is not working right. If it doesn't fire til 5K then obviously the low speed one isn't even working at all. If you replace that one then I'm pretty sure it oughta work with no problems.
Granted you've been working on bikes for almost as long as I've been alive... but still! lol

I figured it out the low speed pulsor was the problem. It did test good, but when I pulled it from the motor I found the reason. Something got in there and hit the pulsor pushing it into the plastic part creating too large of a gap to cause a fire. Now tell me what are the chances lol. Thanks for all your input.

Johnj wrote:If I remember correctly they are kinda gutless till you get "on the pipe". Have you tried swapping the coils to see if the problem follows the coil? Do CX's even have separate coils? Have you ,using a multi-meter, taken voltage readings at the coils? Are you reading 12 volts or more?

CX500 should not be gutless on the bottom end. Its powerband resembles a v-twin sportbike, decent low end torque and a bit of a spike (but not a huge one) over 5k.

swap the coils over and see if it carries over, sounds like a spark issue.

you made sure the main jets and air jets are clear on the carb im guessing already? Clogged main jet could cause it to not get enough fuel below 5k (with the air jet kicking in at 5k to get it going)

well at least you figured out what was causing it

Lol well that'd explain it! Congrats and glad you figured it out!