Honda CX 500 Forum banner
1 - 4 of 4 Posts

·
Registered
1979 CX500C
Joined
·
4 Posts
Discussion Starter · #1 · (Edited)
Backstory: I bought my 79 cx500c last fall from a guy who couldn't ride anymore (health issues) and he says he always stored it with stabil in the gas and ran the carbs dry. When I test drove it, it had all the power and no spits and sputtering or anything. I brought it home and ran multiple tanks of gas through it, probably 5 or 6, and then one day it just bogs when I give it hard throttle in any gear above 3500-4000 rpm. I pulled the carbs and did a quick look at the bowls and jets, jets were basically clear, little sediment in the bowl. When it bogs, pulling the choke does not help, and the bike always starts super easy and idles with no issue. Runs great if I'm light on the throttle, it is still completely rideable, just takes a while to get to speed because of the bog when I punch it. I have done the stator test when it was both cold and warm, plugs look like fairly new ngks. The bike only has 16,000 miles, not sure if that's enough to cause the stator to go bad or not. Just looking for some input on where to go from here.
Property Product Font Automotive tire Engineering
Font Darkness Number Monochrome photography Screenshot
Property Product Font Automotive tire Engineering
 

·
Registered
1979 CX500C
Joined
·
4 Posts
Discussion Starter · #2 ·
UPDATE: checked ignition coils by the tank, both ran about 8k ohms. Then checked the spark plug caps and only was able to get a reading out of one. Opened them up and one looked brand new and the other was very crusty and corroded. I did a temporary fix with some 1/8" welding rod to replace the resistors and The bog under hard throttle was cured. Put on about 20 miles and the issue started to come back. The welding rod was a little thinner than the resistor, and so it didn't exactly fit on the spring in the plug cap, so I think I'm going to buy some thicker brass rod if I can find it and "fix it right".
Should I buy new plug caps?
Are the resistors in the plug caps necessary?
If I don't buy new plug caps, and I keep the old ones with the rods, do I have to buy different plugs?
I've been trying to diagnose this issue for quite some time now and I was on the verge of buying an ignitech lol. This gave me a burst of hope. Thanks for any input.
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
12,075 Posts
After the brass rod mod, use plugs with integrated resistors. NGK DR8EA
 
  • Like
Reactions: Hondanoob226

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
18,408 Posts
Welcome to the forum. Please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).
 
1 - 4 of 4 Posts
Top