Honda CX 500 Forum banner
1 - 20 of 55 Posts

·
Registered
1982 Honda Silverwing GL500
Joined
·
24 Posts
Discussion Starter · #1 ·
I have 82 gl500 that has been sitting for 10 years with the gas in it. I know, I know. Not good. So, I disassembled the carbs, cleaned them up. Upon assembly, it will run on choke only. Do I have the jets backwards? The bigger one is where the big needle goes thru the carb. Do I need to adjust something? I’m not exactly a carb man as I work on diesel trucks. So any help would be appreciated. Thanks.
 

·
Registered
Joined
·
288 Posts
Assuming you have the idle set screw in a reasonable starting point, the most likely answer is that you didn't clean the idle circuit well enough. The passages are very small, difficult to get completely clean, and there are several of them.

Some common questions are:
  • Did you remove the air/fuel mixture screw, fish out the old oring and washer? The washer can be re-used, not the oring.
  • Did you use an ultrasonic cleaner followed by compressed air?
  • With the jets, cutoff valve, and mixture screw out, did you progressively block all possible outlets of the idle circuit to check each passage using compressed air, including the air cutoff valve? There are at least 4: idle jet holder, mixture screw opening, cutoff valve opening, and tiny holes in the carb outlet port near the throttle butterfly valve.
  • Did you check the cut off valve diaphragm to make sure it isn't torn, even just a little? If torn, they can either be replaced or blocked off.
  • Did you replace the oring and washer for the mixture screw?
  • What are the mixture screws set to?
  • Are you using the factory airbox&filter and are all the connections good?
 

·
Super Moderator
Joined
·
5,078 Posts

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,066 Posts
What they said^^^

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 the Previous Owners may or may not have done 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).
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
10,885 Posts
Where are you in MN, Truckmech?
If you're in the Twin Cities area, I can help.
 

·
Registered
1978, Honda CX500
Joined
·
59 Posts
If the float is not set properly, on either of the carbs that cylinder might not run. Check if both cylinders are firing, you can touch the header pipe from cold start to see if they warm up.

Also, did you disconnect both carbs or just cleaned them with them connected to each other?
 

·
Registered
1982 Honda Silverwing GL500
Joined
·
24 Posts
Discussion Starter · #7 ·
Thanks for all the points to look at. I’ll try and answer some of the questions. I separated the cards for the rebuild. The kit I purchased had most of the parts I needed. I reused the jets after I cleaned them in a chem dip carb cleaner for a few minutes. I replaced the acv’s and the accelerator pump, the mixture screws on each and the float needles. I could not get the oring out of the mixture hole. The needles were turned all the way in and backed out 1 and 5/8ths turn per my manual. I added an additional half turn on each. I will be reinstalling the factory air box once I get to that point. I have it running with out for the moment in the shop. I did notice that the left header is cold after a few min of running while the right is too hot to touch. Randal, I am in the St. Cloud area. I hope I answered all the questions. Any further suggestions are appreciated. Thanks everyone. :) oh one thing to add, the connector tube from carb to head on left side has a slight crack that I am hoping some silicone might fix??
 

·
Registered
Joined
·
288 Posts
hmmm, if the left cyl is not firing and also has the crack in the connector tube, it could be that too much air is getting in and messing with the air/fuel mixture/. One simple test is:
  • start bike
  • remove sync port screw from the left cyl
  • drip some fuel into the sync port, I use a child's medicine syringe.

If the left cyl comes to life with the manually injected fuel, then it's either still starved for fuel at idle or there is too much air in the system. One quick fix could be gorilla tape over the crack on the left connector tube. Might not last, but it's easy.
 

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,066 Posts
Shoe Goo works well for sealing cracked intake runners.

If you used mixture screws and float needles that came with an aftermarket carb kit it is also possible that they are out of spec and contributing to the problem (there is usually no good reason for replacing any of the metal parts of the carbs and the ones that come in kits are usually poor quality).

I thought the starting point for these carbs is 2 1/4 turns out. Which manual are you using that says 1 5/8?
 

·
Registered
1982 Honda Silverwing GL500
Joined
·
24 Posts
Discussion Starter · #10 ·
Shoe Goo works well for sealing cracked intake runners.

If you used mixture screws and float needles that came with an aftermarket carb kit it is also possible that they are out of spec and contributing to the problem (there is usually no good reason for replacing any of the metal parts of the carbs and the ones that come in kits are usually poor quality).

I thought the starting point for these carbs is 2 1/4 turns out. Which manual are you using that says 1 5/8?
 

·
Registered
1982 Honda Silverwing GL500
Joined
·
24 Posts
Discussion Starter · #11 ·
I am using the Clymer repair manual. I used all the original metal except the mixture screws because right side screw had a drill bit stuck in it where someone broke off the end of the adjuster and tried to drill it out, so I replaced those. I also used the new float needles.

where are the “sink port screws” located? Is that the air fuel mixture screws? I will try and seal up the connector tube tomorrow after work. I’ll check back for more updates then. Thanks guys. You have all been helpful. :)
 

·
Super Moderator
Joined
·
22,915 Posts
The sink ports {synch ports} are the JIS cross head screw blocking a hole at the front of each intake runner.

Self amalgamating silicon rescue tape is also a good way to repair cracked intake runners.
 

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,066 Posts
I am using the Clymer repair manual.
Stop doing that Clymer manuals are renowned for conrinuing to print the same errors years after they have been informed of them (their GL1000/1100 book even shows the carb jets reversed).
Download the Factory Shop Manual from the CX Wiki (link in my signature) and use it.

I used all the original metal except the mixture screws because right side screw had a drill bit stuck in it where someone broke off the end of the adjuster and tried to drill it out, so I replaced those. I also used the new float needles.
Order the correct screws and needles from your Honda dealer and toss the ones that came in your kit because they are probably so out of spec that they are causing your problems.
And even if they aren't you can look forward to things like this
More Problems with Aftermarket Float Valves | Randakk's Blog
Pic below from Randakk's (link above), courtesy of Mike Nixon. When 2 guys like that tell you something you should probably listen.
Aftermarket Float Valve

where are the “sink port screws” located? Is that the air fuel mixture screws?
No such thing as "sink port screws". You are looking for the synch port screws, where you would connect the vacuum gauges when you synch the carbs.

I just skimmed through this thread again and you mentioned that you are running it without the airbox. That could make it not want to run without choke too.
 

·
Registered
Joined
·
27 Posts
Just wanted to throw in my 10cents (new inflated value of my old 2 cents)

I agree that opening the synch port and dribbling/spritzing/spraying in something that burns (gas/starter fluid/carb cleaner) will immediately tell if it is a fuel issue. You will definitely hear the idle pick up, then go back down once the fuel is removed. Good beginning to tell which direction to go next.

Next, if nothing happens, check spark. Pull that plug (after blowing out plug well) and check for spark. If it is weak or non-existent, start with new plug then go to new plug cap/resistor cap. These old bikes are starting to see plug cap failure, I keep a couple of replacements around for the bikes that come to me needing these odd-ball long caps. You can first verify need for a plug cap by removing the old and holding the wire a few mm away from metal while cranking....you will see spark if it exists

If fuel is the issue, you have to go back and verify your carb work. My guess is the idle circuit is clogged. It will idle nicely without the airbox, but it may bog bad when you open the throttle if no airbox is present. This still means the exhaust will warm up evenly at idle... be careful verifying just how warm.

Lastly, keep in touch here and let us know results of your repairs. Recording what worked for you may help the next gal/guy trying to get grandpa's CX500 back to life. Good luck!
 

·
Registered
1982 Honda Silverwing GL500
Joined
·
24 Posts
Discussion Starter · #15 ·
Hey guys. I appreciate all the help on this one. So, quick update. I dribbled fuel into the left sync port (my spelling was auto corrected in that previous feed. Lol) and the cylinder comes to life. Upon removing the carbs, both bowls had fuel in them. I did split the carbs when I cleaned them but I hooked up the little springs and cross shafts like they were. Pictures sure do wonders. I am going to double check to make sure the sizes are in the right spots for the jets. I sealed the tube with black rtv. It’s been curing for a few days. That’s about it. Gonna take carb apart tonight. Will post updates as they happen. Thanks guys. TM
 

·
Super Moderator
Joined
·
5,078 Posts
When cleaning your carbs did you remove the slow or idle jet? That is the one down in the well which requires a good fitting screwdriver to remove.
 

·
Super Moderator
Joined
·
5,078 Posts

·
Registered
1982 Honda Silverwing GL500
Joined
·
24 Posts
Discussion Starter · #18 ·
Yes, I removed the slow idle jet. I cleaned it and put it back in its place. Is there something I might have missed there? I will read this link you sent. Thanks. TM
 

·
Registered
Joined
·
2,398 Posts
Concerning the low speed jet, its the multiple passages that are also critical and become “cleanable” when this jet is removed. But getting the jet out without damaging it is more than half the battle! Good on you!
 

·
Registered
1982 CX500C
Joined
·
71 Posts
I realize I’m quite a bit late with this response, but a couple years ago I wanted to reseal the rubber boots (carb to head) on my bike because they were drying out and had several surface cracks and I suspected may have been leaking air (no definitive proof just wanted to rule it out for sure).

I ended up buying a 1 foot length of 3” heat shrink off Amazon and cut it down to the lengths I needed. It formed almost perfectly to the valley for the clamp and unless you look closely you’d never know it was there. Before applying it I “painted” a layer of liquid gasket maker on the boots.

Below is a pic of mine (clamp removed for clarity) - if the crack in yours doesn’t extend too closely to the flange this should work for you too.

Just make sure to get the soft wall heat shrink - the thick wall heat shrink will not flex and form to the boot/insulator shape as easily and may even deform it.

Motor vehicle Automotive tire Automotive design Automotive fuel system Rim
 
1 - 20 of 55 Posts
Top