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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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I'm still not finding where those small washers go.
Before installing the idle mixture screw, slide over the needle the spring, the washer, and the o-ring. When removing the screw, the o-ring and washer are often left behind and need to be extracted with a small probe. I use a piece of galvanized screen wire with a tiny hook on the end.
 

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'84 CX650E that is evolving into a GL500
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What he said^^^ Those are the tiniest washers I can think of.

It is a new vacuum petcock, I think I have the lines right.<<< There's the 3 barbs on the petcock, the large is supply line to the cross tube. The one in the center of the circle is the vacuum and the one small one in between those is drain correct?
Sounds right to me.

There was fuel when I drained the bowls after trying to start it.
Next question is was there enough fuel in the carbs for the engine to start? You need about 45cc (1.5oz) per carb and it doesn't have to be too much less before it won't start. If you were filling them by cranking the engine has to produce enough vacuum to open the valve and keep it open long enough for the bowls to fill enough before the engine can start so it is possible that you just didn't crank it quite enough. (This is one of the reasons many of us have changed to non-vacuum petcocks).

Note that I'm not saying that the problem isn't in the carbs, just that lots of people have had similar symptoms that turned out to be the carbs just weren't full enough.

Left side of the right-hand carb.
That's what it says (now). Thanks.
 

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1982 honda cx500c
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17 Posts
Discussion Starter · #23 ·
Good morning everyone, I pulled the carbs re cleaned everything. Put the old brass back in and got those tiny washers and o rings extracted and new ones in. Filled the bowls with 3oz of fuel. Tried to start it still won't kick over. Sounds like it wants to then nothing when I release the button. Had exhaust come out the pipes this time so it's an improvement. It starts to sound like it's running but only with the starter pushed in. It is cold outside here but I had the garage closed with the heater going all night. Maybe I should switch the new vacuum petcock with the old one or switch it to non vacuum? Thank you all I appreciate all the input!!!
 

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Squirt a little fuel in through the balance ports on the intake runners. It should start briefly if the issue is fuel.

Otherwise you might want to take a closer look at the spark or perhaps the compression.
 

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'84 CX650E that is evolving into a GL500
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If you have starting fluid (ether in a spray can, Quick Start is one brand) you could try spraying some into the air filter before attempting to start too.

If you filled the bowls it should start and run for several minutes even if the fuel line was disconnected so your problem isn't likely to be related to the petcock.

You mentioned replacing the camshaft holder gasket (behind the fan). Did you loosen the valve clearance adjusters to take the tension off of the camshaft when you did that? If you did did you re-set the clearances afterward and make sure you set them at TDC of the compression stroke?

How far apart did you take the carbs for your rebuild? If you separated them make sure you got the balance adjustment screw's parts back in the correct order.
Did you "bench balance" the carbs before installing them? This means making sure that both butterflies start to open at the same time (a good point to start doing a final adjustment from once it is running).
Also, how many turns out do you have the idle mixture screws set? You mentioned 1.5 turns but the Factory Shop Manual says to start at 2 turns out from lightly seated.
That leads me to ask if you are using the FSM or one of the aftermarket ones?
 

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1982 honda cx500c
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Discussion Starter · #26 ·
I didn't adjust anything when I removed the fan. It was the small cover on the motor behind the fan leaking oil. I followed a step by step online thing and read through the manual. I don't remember seeing anything about releasing tension. In the manul it says to have that screw 1 5/8 turn out for the cx500. I tried a little starter fluid in the air box nothing changed. I'll try some fuel in the balance port. All the butterflies operated properly, I'm not sure about the balance screw. I put everything back as it came apart I'm 90 percent sure
 

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1982 honda cx500c
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Discussion Starter · #28 ·
So we adjusted the mixture screws put gas directly into the heads. The engine is still stumbling smells really rich and the spark plugs are sooty. Compression is just over 150 on each side. Probably at the point I should have a professional look at it or buy new carbs. I think it's getting to much gas.
 

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'84 CX650E that is evolving into a GL500
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It is pretty common for people to loosen the valve adjustments to make it easier to push the end of the camshaft into place when they re-install the holder so I had to ask just in case you did.

The butterflies may operate properly but unless they open at the same time you can have problems. Also, there is a fast idle tab on the choke linkage that opens the throttle butterflies slight when starting and it may not run well if it is too far out of adjustment.
Another thought since you are pretty new to this stuff: Are you using the choke? The knob should be pulled out to enrich the mixture for starting and then pushed in as the engine warms up.

Page 4-10 of the '78-'82 CX500 FSM says 2 turns. Which manual are you using?
Font Adaptation Newspaper Paper History
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Page 4-10 of the '78-'82 CX500 FSM says 2 turns.
Check the addenda, Bob. It might have changed in 1980 with the restricted mixture adjustment.
Not that the Clymer isn't wrong. It generalized too much.
 

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Smelling rich and sooty plugs is sounding like it is receiving fuel but has poor ignition. You may have spark but it may well be weak.

I would have a closer look at the strength of the spark being delivered.

The bike is an 82? And has transisterised ignition and not CDI?
 

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'84 CX650E that is evolving into a GL500
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Randall: The only thing I can see about the carbs in the addendum is the high altitude adjustment.

Ram: Put the Clymer book on the shelf and use the FSM that I told you to download in post #17 of this thread.
The FSMs for many bikes are written in such a way that you pretty much need factory training to be able to get any useful information from them but the ones for these bikes are so well written & laid out that they render the aftermarket books secondary references at best and fonts of misinformation at worst.
 

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A 1/2 turn or so difference on the mixture screw setting won't prevent starting.

Staying on the subject of carbs and given the sooty plugs and smell I would be verifying the fuel levels in the float bowl.

Get a piece of 4 mm clear fuel line and stick it on the float bowl drain spigot. Turn the petcock to 'on', hold the fuel line up the side of the carb and open the drain screw a couple of turns.

Fuel level will show in the fuel line and should be about 2 mm below the joint between carb and bowl.

High level may be an issue and would cause sooty plugs.

Failing that I think you may have an issue with weak spark.
 

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'84 CX650E that is evolving into a GL500
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A 1/2 turn or so difference on the mixture screw setting won't prevent starting.
True, but who knows what else Clymer told him to do wrong.
 

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True enough.

But indications are that the issue may be an excess of fuel rather than a lack of it.

I wonder if it has aftermarket float needles?

Were the float levels ever set?
 

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1982 honda cx500c
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Discussion Starter · #37 ·
I don't know if the float levels were set. I did that clear tube test on the float bowls and they were both just under the seem. Would the accelerator pump cause it not to start if I didn't do something right with that? I will look into that other manual. The spark plugs a new so would that mean wires are bad or some electrical issue? The needles are still the aftermarket but I'm probably going to put the old ones back in just to see. I did notice a little fuel leaking around the accelerator pump so maybe I missed an o ring
 

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1982 honda cx500c
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Discussion Starter · #38 ·
We did watch the spark plugs out of there hole grounded with jumper cables. The spark was doing what it should expect it definitely seemed brighter on the first kick then it seemed to dim but was still steady
 

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Try taking the spark plugs out and leaving them out for a few hours. Sometimes when the motor is unwilling to start the plugs can become saturated with fuel and spark poorly.

The fuel levels sound correct. The black plugs suggest fuel is being supplied to the cylinder but combustion is poor.

Have the coils and plug caps been tested?
 
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