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Discussion Starter #1
Hi all,
I'm currently in the middle of a CX500 project and the engine is out.
I have limited engine knowledge but what I've got planned is:

rebuild the clutch (gears weren't engaging)
Reset cam chain tensioner
Check valve clearances
Check water pump housing as there was crystalized coolant in the pipes

Is there anything else I should check or replace whilst it's out?
 

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Without some more information, it is hard to say, but I would at a minimum remove the rear cover, replace the mechanical seal, carefully evaluate the cam chain, guides, tensioner and replace if worn, and do all of the electrical checks on the stator in addition to a visual examination and replace it if you are not sure it is OK.
In other words, consider a triple bypass after being sure the rest of the engine is OK.
 

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Crystalized coolant???? Never heard of such a thing. Is this like powdered water?

I agree with Nolimtz. What is the mileage? Yes, perform the "High Mileage" maintenance schedule in the FSM.

Then step forward. Engines are not affected by age. Engines are affected by mileage and maintenance.
 

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Discussion Starter #5
Apologies, it's at 35k miles.
I bought it as a project bike and it was a state (I don't think it's ran in over 20-30 years)
I did get it running although the idle was rediculously fast and it was backfiring through the carbs.

The main reason the engine is out as everything is getting sandblasted and powdercoated.

I didn't notice any issues with leaks but again, the cooling system was blocked so hard to tell.
 

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Before we can give much suggestions. Please share the year and model.

Off hand.
The carbs will likely need service. Get a copy of Larry Cargill's Carb book. Follow it by the letter.
Download the FSM (Factory Service Manual). Perform the High Mileage service.

Resist taking it apart until you find a problem, then diagnose and repair.
I'd suggest looking at the ignition system but until the year and model are known, bad suggestions will come.

Check the date code on the tires. If made before XX10, then consider replacement.
Check your brakes. Working? Probably should replace the pads and shoes at a minimum.
 

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You need to state what year your bike is . Also does it have a manual cam chain tensioner or the later automatic one ? They require differant treatment to check and adjust.

Your clutch is probably stuck due to lack of use . That should be an easy fix , doable in the frame . Its accessable from the front so no big drama . Probably just needs using to free off.

The carbs will be blocked with 20 year old fuel debris. Get them cleaned by someone who knows and understands CV carbs. Your buddy down the street who fixes lawnmowers probably doesnt have the knowledge to fix these , specially if his name is Bubba ...

Like Knute says avoid taking the covers off . You can do static testing of the electrical componants without pulling anything apart. If it aint broke , dont fix it .

And good luck. Keep us posted.
 
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Check the stator and big ends. Check the camchain either with a mirror or with the cooling fan. Check for rubbish in the oil and oil filter. If good, fill with cheap oil and coolant and start the thing. You may not need to do anything.

And Knute, some coolants will form crystals or jelly. I see it from time to time.
 

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Discussion Starter #9
It's a 1980, I've cleaned the carbs as they were completely blocked and will be getting a rebuild kit.

I've been hoping to avoid taking the casings off under the rules of "if it ain't broke don't fix it" but because I've not had it running properly, it's hard to tell.

The stator is under the back casing isn't it? Does anyone know why the backfiring through the carbs might have been happening? I was thinking valve clearances but I'm not sure.

So the list stands so far is:

rebuild the clutch
Reset cam chain tensioner
Check valve clearances
Check water pump housing
Check cam chain condition
New mechanical seal

Anything else anyone can think of?
 

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Discussion Starter #10
Oh and I'm not sure on the exact model. It had no paperwork.
It's not the Custom model that's all I know.
 

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Service the spark plug caps. they're another possible cause of your backfire. Does it start or only backfire? If not starting make sure the yellow wire goes to the left ignition coil and the pink to the right. If the coils are fitted to the wrong side and then connected by colour code you get lots of backfires.
 

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Oh and I'm not sure on the exact model. It had no paperwork.
It's not the Custom model that's all I know.
What are the frame number and engine serial numbers? You can xxx out the last few digits, but the prefix and first few should tell us more about what you have.
 

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Discussion Starter #14
It starts and runs but it backfires loudly through the right side (silencers and airbox were removed during the tear down process)
I replaced the coils and it seemed to be wired correctly.

This is how it arrived

image.jpeg
 

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If it starts and runs the coils are correctly wired. Service the plug caps and run through this.

I'll get the stator chart up in due course. Photobucket is apparently doing some maintenance.



Swap the coils side to side to see if the backfiring follows.
 

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If the coolant has solidified, I would certainly remove the cylinder drain plugs and see if you flush the motor and get water from the drains. If left standing a long time I have seen them fur up around the cylinder causing overheating.
 
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