The International CBX Owners Association

I have a 1979 CBX that I am having a hard time with. It takes a long time to get started and it will not start on the choke. It takes about 10 minutes of trying to start off and on. It is getting to the point where I am afraid that I am going to burn out the starter. Once started it runs and idle good. Then it starts right up when it is warm.

Any help that you can give me would be appreciated.

Thank you.

Rob,

This is typical of a lot of X's. 10 minute cranking is more than usual however.

My first guess would be to check plugs and general overall tune of your engine. Beyond that, there could be potential need of choke adjustment.

Some X's will be very hard to start if they haven't been ran in awhile. My '80 will start fairly quickly if it is run once or twice a week. If it sits much longer than that, it takes quick a bit of cranking to get it going. It flies like a missle when its running. :)

It's likely a fuel/air problem as Chris said, my thoughts also would be a malfunctioning choke system/circuit....

PS, You must have a great battery.......

When you say fuel/air problem do you mean that I have the screw turned out to fare or not enough? Here is my setup.

6 into 1 pipe
K&N Air filters
100 main
75 secondary

Fuel/Air screw is at 2 1/2 turns

I just changed the sparkplugs and wires and did a good carb cleaning.

Let me know your thoughts on this.

You may also want to check if your 79CBX has ever been retrofitted with
the vacuum fuel valve on the carbs. If so, take it off and make it a habit to close the petcock whenever you park the bike.
I would also recommend to change to an AGM battery. Ever since I use one in my 81, even this one starts better. A small drop in battery condition will cause the starter to crank slower and will make starting
these 6-cylinders recognizably harder.

How do I check to see if the bike has been retrofitted with
the vacuum fuel valve on the carbs. I do shut off the petcock after every use. I got in this habit along time ago. The start cranks good it does not seem to point to fire at first.

Let me know.

Thank you.

I had a similar experince with an '80.
Carb expert Mike Nixon suggested checking the choke operation/set-up. Sure enough the choke was not working properly. There are two springs at the base of the cable attachment on the back of the carbs. The spring operating the right carb bank was stretched/broken so in fact only 3 of the carbs were being choked. A pain to get at and fix but it solved MOST of my starting problems.
I hope this makes sense, RMBillings. My mechanical skills are as bad as my typing. Even worse, the problem was self inflicted as i had recently changed the choke cable.

RMBillings wrote:How do I check to see if the bike has been retrofitted with
the vacuum fuel valve on the carbs.
Thank you.

The fuel line from the petcock will go into another device sitting on top of the carbs that also has a vacuum line going into it. It is basically a diaphragm that shuts off the fuel and opens through vacuum created by the cranking engine.

I checked my choke last night and all the butterflies are closing when it engaged but it won't even try and start when the chock is on. It just sits there and cranks and cranks.

My fuel line is only about 4 inches long and it goes into a small tube that comes up between the 1 st and 2nd carbs.

Let me know.

Thank you.

Is your acc. pump working??
When I removed the diaphram from my 80 I used to turn on the gas before I put my helmet ,gloves etc on to let the carbs fill as much as possible, then give the throttle 6-7 SLOW cranks to pump gas to the carbs. It would then start fairly easily. If not a couple more cranks would do it if it had been sat for a week or more.

It seems like you have checked most of the common problems.

I would think that next things on the list would be to check timing.

Also, when the bike is running, spray a mist of water on the head pipes. Eventhough the bike is running, it may not be running as well as it should. This is a quick way to check for potential firing problems.

After running a while, you can pull your new plugs and look at them to find potential problems. Your bike may need hotter plugs for example.

Let us know how it goes.

Interesting one this.......

Lets look a this again, something is preventing engine from starting immediately but if the choke is used it never starts... Hmmmmm
With this scenario the plugs may be getting wet due to no burn.....Hmmmmm, I would check the plugs at this stage, after going through this procedure.
OK why no burn ?? Fuel/air in....compression....sparkie...boom, is the normal stage of events but it does eventually start with no choke....
With further thought, could there be a problem with the compression/sparkie parts of the cycle.....Hmmmmm
My next move would be....Does it start straight away with the starting fluid (ether) ???

Terrible when cold and okay when warm? Sounds like leanness to me.

Possible vacuum leak Mike ??

Yeah, I think so. First area to check out. Though everything everyone has said has been very good, including your starting fluid suggestion. Doesn't have to be starting fluid, can be carb cleaner, WD40, brake cleaner. If from a no-start cold condition that works, it exonerates compression, spark and timing, and puts more blame on fuel delivery. :)