Honda CX 500 Forum banner

1 - 20 of 32 Posts

·
Registered
Joined
·
72 Posts
Discussion Starter #1
Hey guys,

So I used to have a bad high idle problem. My bike idled at around 3k RPM's when it was warm. I recently bought the Randakk's rebuild kit and rebuilt my carbs and cleaned them through and through. Once I got my carbs back together, I went to start the bike, and things have improved but it still idles at around 1600-1800 RPM's. I have investigated vacuum leaks, and noted one at my intake manifold, but sealed it and the leak is no longer present there. I cannot find an air leak anywhere else, and with the pilot screws set to factory (2.5 turns out) I am not really sure where to turn to next. My throttle also lags quite a bit. When I go to accelerate, it bogs down, so I have to crank it hard. But when I do actually accelerate, my RPM's hang up, and then slowly come back down. I just watched a video on howtomotorcyclerepair.com (he seems to mostly work on shadows) where he mentioned getting a different sized pilot jet depending on whether your bike is running rich or lean. Seem like a possible solution? Or anyone have any additional solutions?? Thanks for any help guys
 

·
Registered
Joined
·
2,167 Posts
This has nothing to do with replacing jets and running rich or lean. How did you clean the carbs?? did you buy Larrys book and rebuild them via the book? Take some pictures of the bike, the intakes, the carbs, and whatever else you think would help us help you
 

·
Registered
Joined
·
178 Posts
Somebody will correct me if I remember this wrong.

Turn out the air bleed screws two turns, set the hot idle to 1100-1200 rpm with the idle speed screw, turn in the air bleed screws until the rpm drops 100 rpm, then back them out a quarter (or is it, a half) turn.

If they bottom out before the rpm drops then do it over starting from one turn out.

These carbs do not take as much air bleed as a car carburetor.
 

·
Registered
Joined
·
24 Posts
if its idling high its not because of jetting or anything you choke is slightly stuck open. i had the same problem on my bike. its simple, just get a can of spray grease (i prefer kroil) and lube where the rod enters the carb on both sides. if that doesnt fix it you can set the idle cable holder ( next to the throttle linkage) forward a bit to losten your cable and help it spring back all the way.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #5
This has nothing to do with replacing jets and running rich or lean. How did you clean the carbs?? did you buy Larrys book and rebuild them via the book? Take some pictures of the bike, the intakes, the carbs, and whatever else you think would help us help you
I did rebuild via Larry, and the rebuild helped to an extent. I removed all the jets, carb cleaner, q-tips, etc. I have heard a lot about ultrasonic cleaners, but I am fresh out of college still job searching, so I am on a tight budget. I'll get some pictures up soon of my linkage, intakes, everything.


Graywolf, if you will, could you expand? I am not the most mechanically inclined, and I am new to bikes. Rebuilding the carbs correctly was a feat in itself for me, and from all that I have read online and in the factory manual, I only know about adjusting the idle through the pilot screws and throttle stop. I would love to try your suggestion, but in all honesty, have no idea where the air bleed screw is or what the idle speed screw is haha :confused:


Lilwrench, I'll give your solution a try since it is quick and easy.

Many thanks for the help fellas; as I said, i"m still learning all the in's and out's of motorcycle me-canistry
 

·
Registered
Joined
·
3,999 Posts
My throttle also lags quite a bit. When I go to accelerate, it bogs down, so I have to crank it hard. But when I do actually accelerate, my RPM's hang up, and then slowly come back down.
Along with the high idle, what you describe in the above quoted text is a classic symptom of a lean condition,,most often caused by a vacuum leak.

Check your linkage and make sure the correct jets are installed(the factory sizes are the ones you want unless you have a modified intake or exhaust system), but also keep looking for a vacuum leak, if you have checked around all the joints and the rubbers of the intake manifolds then also check around the carbs themselves, check where the throttle shafts enter the carbs etc.
 

·
Registered
Joined
·
4,033 Posts
Did you split the carbs when you rebuilt them? Did you align them back up?

Is there the correct free play in your throttle cable?

I haven't read Larry's book, but I fairly certain all of this is covered there.
 

·
Registered
Joined
·
7,223 Posts
Get a can of carb cleaner or something similar and with the bike running spray it around the car manifolds to the head, if there is a vacuum leak there the RPMs will momentarily change.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #9 (Edited)
Along with the high idle, what you describe in the above quoted text is a classic symptom of a lean condition,,most often caused by a vacuum leak.

Check your linkage and make sure the correct jets are installed(the factory sizes are the ones you want unless you have a modified intake or exhaust system), but also keep looking for a vacuum leak, if you have checked around all the joints and the rubbers of the intake manifolds then also check around the carbs themselves, check where the throttle shafts enter the carbs etc.
After coming back out and investigating some more, I am even less sure of what is going on. I sealed up my manifolds, so there is no longer a leak there. I didn't hear a leak around my carb boots leading to my airbox, but I am going to double check that once I get more carb cleaner. I never heard an increase in RPM's when I sprayed carb cleaner around the carbs with the bike running (but all of this was pre-rebuild). I am just going to double check everything. as Lilwrench mentioned about my choke cable, I eased it up so that there is a little "slack," per se, in the cable so that it fully closes.

Dan, I did split the carbs, and I re-aligned them to the best of my abilities. Someone mentioned realigning them properly to me before; is there a specific tool to help realign them properly, or could my quick level do the trick? I adjusted the free-play in the throttle yesterday, and I now have about 1/4 in. or so, maybe a little bit less of free play.

Thanks again guys for the quick responses, I appreciate it.

Oh, p.s. when I go to start it, I have to pull the choke out fully, and keep it pulled out for about 30 seconds then the bike finally runs on its own and slowly increases RPM's until it gets to around 2K. I figured this could be somewhat relevant info., but I don't know what this tells me. I am fairly certain that I shouldn't have to fully choke the bike for such a time period when it is Summer...!
 

·
Registered
Joined
·
72 Posts
Discussion Starter #10
[URL=http://i1295.photobucket.com/albums/b627/michael_henry14/DSCN0552_zpsf44fd521.mp4][/URL]

Sorry guys, I know it is not the most aesthetically pleasing thing staring at a badly painted bike, but this is the video of a semi-warm start-up. At about 26 seconds you will hear it click twice, usually once it is warm it clicks, and the idle picks up and it will idle steadily on its own. It does this a few more times throughout the video. At 38 seconds I throttle up, and you can see how it lags coming back down. The last up throttle, I let off and it just hangs for a few seconds. My pilot jets are both about 2 turns out. My throttle stop (I just learned this is the "idle screw") is all the way off, and it is surprisingly idling (although rough, and unsteadily) at about 1450-1500 RPM's. Hope this helps you guys help me! Again, I really appreciate the help!
 

·
Registered
Joined
·
4,033 Posts
After coming back out and investigating some more, I am even less sure of what is going on. I sealed up my manifolds, so there is no longer a leak there. I didn't hear a leak around my carb boots leading to my airbox, but I am going to double check that once I get more carb cleaner. I never heard an increase in RPM's when I sprayed carb cleaner around the carbs with the bike running (but all of this was pre-rebuild). I am just going to double check everything. as Lilwrench mentioned about my choke cable, I eased it up so that there is a little "slack," per se, in the cable so that it fully closes.

Dan, I did split the carbs, and I re-aligned them to the best of my abilities. Someone mentioned realigning them properly to me before; is there a specific tool to help realign them properly, or could my quick level do the trick? I adjusted the free-play in the throttle yesterday, and I now have about 1/4 in. or so, maybe a little bit less of free play.

Thanks again guys for the quick responses, I appreciate it.

Oh, p.s. when I go to start it, I have to pull the choke out fully, and keep it pulled out for about 30 seconds then the bike finally runs on its own and slowly increases RPM's until it gets to around 2K. I figured this could be somewhat relevant info., but I don't know what this tells me. I am fairly certain that I shouldn't have to fully choke the bike for such a time period when it is Summer...!
A flat surface should suffice to get them back aligned. Do you have Larry's book? Are you having to hold the choke to keep it pulled out?

If you had the carbs that far down, it's possible something isn't assembled correctly. When the choke is pulled (on, out, closed) there is a cam that opens the throttle just a little to give the bike a little faster RPM during warm up. It's possible this cam is stuck on high idle.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #13
A flat surface should suffice to get them back aligned. Do you have Larry's book? Are you having to hold the choke to keep it pulled out?

If you had the carbs that far down, it's possible something isn't assembled correctly. When the choke is pulled (on, out, closed) there is a cam that opens the throttle just a little to give the bike a little faster RPM during warm up. It's possible this cam is stuck on high idle.
Yeah I did realign the carbs on a work bench, so I think that they are realigned correctly, and I do not have Larry's book, I was just directed by someone who does. I know it's not too expensive, my funds are just quite limited haha.

When I start the bike I do have to keep hold of the choke in order for it to stay out. Is this an indication of a choke problem? I just figured with the spring that is connected to the choke it is supposed to automatically pull it right back to the closed choke.

I also found a pretty large air leak at my right carb boot where it leads to my airbox, so I put all new clamps on my hoses to tighten them down and the leak went away, and the idle dropped to around 1800 or so. It couldn't be that I just need to fine tune my carbs I'm assuming, because I would think that fine tuning occurs when the idle is only off a couple hundred, rather than 8 or 900. Also, Graywolf earlier mentioned turning the air bleeder screws; I do not know exactly where the bleeder screws are. I haven't tampered with anything but the throttle stop and pilot jets and that obviously has not helped me. But as Rocket said, I'll check out the choke clamp and see if its messed up.
 

·
Registered
Joined
·
7,223 Posts
If the choke cable has to be held then chances are the return spring isnt on right (too loose). I know that its not something you want to hear, but you may have to pull the carbs back off and go through them again. I sure know about having "limited funds" and am the epitome of cheap, but I would suggest getting Larry's book as it makes a huge difference. I use to rebuild car carbs for a living when I was younger, and after doing my CX ones 3 times with no joy I got the book. Did the carbs and have not had an issue since. These carb work very well if everything is perfect on them, but it only takes one tiny little thing to make them go right out to lunch. I can safely say that you will spend far more trying to fix this than you will on the book, best thing I bought when doing my bike.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #15
If the choke cable has to be held then chances are the return spring isnt on right (too loose). I know that its not something you want to hear, but you may have to pull the carbs back off and go through them again. I sure know about having "limited funds" and am the epitome of cheap, but I would suggest getting Larry's book as it makes a huge difference. I use to rebuild car carbs for a living when I was younger, and after doing my CX ones 3 times with no joy I got the book. Did the carbs and have not had an issue since. These carb work very well if everything is perfect on them, but it only takes one tiny little thing to make them go right out to lunch. I can safely say that you will spend far more trying to fix this than you will on the book, best thing I bought when doing my bike.
Yeah I have been contemplating on getting it, as it seems to be the greatest help to anyone who is trying to work on the carbs. I am uploading a video of the choke cable and throttle in action, and maybe if someone sees a problem they can point it out. But, I do think that the spring I have connected to my choke is pretty jacked up. I was not sure if it had much to do with my idle though, because it does not seem to have much to do with the choke (to an unexperienced eye, at least). Thanks for the input on the book, I think at the end of the coming week I will just go ahead and break down and buy it. If I am going to be doing things, I guess I might as well do them correctly!
 

·
Registered
Joined
·
72 Posts
Discussion Starter #16 (Edited)

·
Registered
Joined
·
7,223 Posts
If I remember right (and Im old so its a coin toss lol) someone had a similar problem and it turned out the spring wasnt wound enough, and one extra turn fixed the problem. With any luck one of the carb guru's (Murrayf or Larry) will be able to sort out your problem with a simple solution
 

·
Registered
Joined
·
72 Posts
Discussion Starter #18
Hey man, does "the older, the wiser" not apply anymore these days?? I still respect and learn from my elders! Thanks a million; I will give that a try, and if it does not work then maybe I can get in contact with Murray or Larry and see if they know the trick.
 

·
Registered
Joined
·
4,033 Posts
The choke not saying out is an easy fix. http://cxgl.wikispaces.com/Choke+Knob

IMO, the spring on the choke mechanism looks to be okay. If it was too loose, the choke butterflies would be allowed to open with the force of vacuum when trying to start the bike. Cable free play looks great.

IMO, here's the next step. I too would love to have Larry's book, but like you, the funds just aren't there. From reading this forum, the Wiki, and help from forum member Randall's ultrasonic cleaner I believe I've got my carbs fairly close. The information is out there. A bit of hunting is needed.


Search the Wiki and this forum for carb info. Perhaps something was assembled incorrectly.

Jets in the wrong place. Mixed up jets is normally a high speed problem, but who knows.

Check the slides to make sure they move freely and return to their seated position. Easy to do with the intakes off.

I believe one member had a runnability problem because they installed the seat for the needles on the slides incorrectly.

Just a side note on how things can be assembled incorrectly. I have a running '80 CX parts bike (no title). Seeing your video reminded me of this. When I took the carbs off, the choke cable was routed above the crossbar support! If one looks closely to the cross bar, there is a relief on the bottom side for the cable path. If you don't know, you don't know!
 

·
Registered
Joined
·
72 Posts
Discussion Starter #20
I will have to look into the cable position; I had no idea that there are paths for the cables like that. I just kinda figured do it however works! I did adjust the positioning of the choke cable and also tightened the spring and it did not seem to work either. So, I am back to square one. I am going to search the forum a bit more extensively though. I have only briefly skimmed through it. Thanks for the input Dan. I'll make sure my jets are all correct and everything else is assembled correctly.

Side note, anyone know of a cheap place to get some of the hardware? Like screws for the manifolds, the carb plates, etc.? Didn't know if somewhere like Lowe's or Home Depot would be the cheapest for it
 
1 - 20 of 32 Posts
Top