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Discussion Starter #1
Hello everyone!

My 81 CX500C (cdi ignition) cafe project is so close to the finish line, but I keep getting held up. Let me explain.

Bought it two years ago as a Craigslist find for $300. The odometer had 25,XXX miles on it, but it was definitely not running. Tore it down completely and stripped/rebuilt each piece (not the most meticulous job, but enough to satisfy my own standards - ever heard of the Pareto principle?) Engine was rebuilt as well to the best of my ability - followed the FSM as well as all the available information I could find online. (this forum, motofaction, etc.)

Engine tear-down #1 & 2:
  • New bolting
  • New gaskets
  • New oil seals (all of them)
  • Replaced every O-ring I came across
  • Replaced mechanical seal
  • Replaced piston rings (did not gap the rings, but I did set them @ the correct angle apart per the fsm)
  • Replaced piston big-end shells
  • Honed the cylinders
  • Lapped all the valves
  • Replaced all the stem seals
  • Adjusted valves

I think the point is made - I did everything to bring it back to life. The ONE thing I didn't do was mess with the timing. PO looked to have a brand new chain/tensioners and I didn't want to mess with something that wasn't broken.

Fast forward to a few weeks ago: Bike put together, wiring checked, stator checked, carbs rebuilt twice w/ an ultrasonic cleaner; wheels, tires, brakes, shocks all rebuilt and installed. And i'm ready to do the first start-up and a no go. Turns but no fire, and this has been the case ever since.

I know what I need is:
  • Spark at the right Time
  • Compression
  • Fuel
  • Air

I've confirmed spark:
I was grateful to Consubandon to give me some advice! He even recommended I post here, but I didn't want to waste anyone's time before doing the most I could on my own.

I have fuel. Every time I pull the plugs, I smell fuel. (I've even let the engine air out a few times in case the engine was "flooded". Didn't work.)

Air is a given.

Compression Test:
Left Cylinder: 90psi dry, 95psi wet.
Right Cylinder: 118psi dry, 125psi wet.

Leak Down Test:
Left Cylinder: Leaking through intake valves & into engine past the piston rings.
Right Cylinder: Leaking into engine past the piston rings.

I read on the forum that folks have bikes which run @ 120psi, so I thought i'd keep trying. I rebuilt the starter motor (much needed), and I replaced the starter solenoid. One of my buddies also let me borrow his Ignitech, which I installed and tested here:
You'll notice how much better/faster the engine turns when trying to start.

STILL NO FIRE!?

So, yesterday I dropped the engine for the 3rd time and i'm going to check the following:
  • Verify valve timing is set correctly.
  • Re-lap the left intake valves
  • Verify piston ring gap (left & right)

Here is where I humbly ask for your help.
1. Is there anything anyone can identify that I've missed?
2. Is it realistic for me to have to verify the piston ring gaps? Especially since they're brand new rings. I wouldn't expect them to perform as well as rings that have been broken in - but I may be wrong.
3. If the valve timing is off by even one notch, would it put me in my current situation?

Any help/advice is appreciated. Apologies for the long post - just wanted to get it all out there so you have the full story.

Thank you,
Samir
 

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When you had the pistons out, did you mark them as to which cylinder they came from?
Also, did you do a quick hone to break the cylinder wall glaze?

Next thing I would do is to verify that it can fire by shuttinf off the fuel tap and remove the air filter and spray some quick start into it and see if it will even try to fire off.
 

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Discussion Starter #4
Thank you so much for the responses!

When you had the pistons out, did you mark them as to which cylinder they came from?
Also, did you do a quick hone to break the cylinder wall glaze?

Next thing I would do is to verify that it can fire by shuttinf off the fuel tap and remove the air filter and spray some quick start into it and see if it will even try to fire off.

Yes, I marked the pistons L and R when I took them out. Both went in exactly as they came out. Honed the cylinders for like maximum 15 seconds - I was warned not to overdo it. After i landed this Ignitech for testing, I got a single, monstrous backfire from the right cylinder (which I had never gotten before) when I sprayed quick start into the carbs. Tried switching my ignition coil wires (pink/yellow) still nothing.



Sweet link - it makes me sad and happy at the same time to know others are going / have gone thru the same issues that I have now. I'll double check my grounds this afternoon. I've used a grinder down to the metal for my ground points to make sure there's contact. I'll do a check again tho, could have easily missed something.
 

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Discussion Starter #5
So I checked my grounds and made sure they all are cleaned/connected. I'm going to bench test the motor this week and maybe I'll find a culprit. Thanks again for the suggestions.
 

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Random thoughts, and at this point I'm just potshotting:

Put the bike on the centre stand so as to be level.

Back up your bike's battery with a jump from a car battery.

You say you smell fuel. Let's look closer: Can you confirm flow to the float bowls of the carbs? Open the float bowl drains, then open the fuel tap? You have a vacuum-operated fuel petcock, I believe, so maybe open a drain into a jar below the drain tube, and suck gently on the diaphragm hose that applies vacuum from the carbs to the petcock to allow flow. No vacuum to the petcock = no fuel supply. With either drain open, each suck should allow some fuel to drain into the jar.

Is your petcock screen clean? Is your tank pretty devoid of grit?

Take the petcock and tank out of the equation: Briefly replace the fuel tank with a small quantity of fuel in a plastic cup rigged to flow into a fuel hose going straight to the carbs. Suspend the cup like an I.V. bottle, about at the level of the tank.

Is the fuel level too high or too low in the float bowls? Install clear tubing on the drains to each carb float bowl, bend and hold the clear tubing up in the air beside the carbs, open those float bowl drains, open the petcock (suck it, as required, or bypass it), and see that the fuel applied at the inlet hose to the carb rises to a level just about the height of the seam between the top of the float bowl and the carb body.

When you shoot starter fluid into the intake, can you get it to catch, perhaps, after a few rounds? How flooded might "flooded" be? Liquid gasoline spraying out the exhausts?

Not enough fuel? When I'd rebuilt my bike and it went to Taka, the Honda Whisperer, to get his blessing and a full check-out, he told me that from a cold start I was to roll the throttle six times before pulling out the choke and pressing the starter button. I did not do this ten years ago with my old '81 CX Custom, so I'm not sure why he ordered me to do it with my '81 Deluxe. I could not ascertain if he had made any carb changes beyond altering my crankcase breather tubes. Both bikes were/are completely stock. As it happens, I pump the throttle a half-dozen times when cold and it always starts. On hot days (like it's been much of this summer), I find I can interfere with starting by applying too much choke, so I ease off. Air is not exactly always a given. Of course, if you are flooding out, pumping the throttle would not be addressing your problems.

Which plugs are you using? Stock equivalent is NGK 2120 D8EA. I once had a brand new plug result in an engine that would barely idle because the box had likely been dropped and the gap changed ever-so-slightly. Swap in different plugs?

Then we get to electrical system tests, about which I have had less personal experience. If your spark is weak, I'd refer you first to the Factory Repair Manual.

You did download a copy of the Factory Repair Manual, right?

https://drive.google.com/drive/fold...MGYzY2QzNDcyNzJh?sort=name&layout=list&num=50
or
https://coodie.com/cx/

Also: https://cx500forum.com/forum/general-discussion/10-quick-reference.html

"Texas" is a pretty broad description of your location! Can you use the Member Location Map on this forum to find a CX-ing buddy down there? Maybe swap carbs if none of your other experiments bring joy?
 

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Discussion Starter #8
Annuit.Coeptis - The bike's on the center stand, and I am using my car's battery for extra juice.
Yes, fuel flows to the bowls and drains when I unscrew the drain screws. Here's a picture of my carbs as they were when I first went through them. I don't have any vacuum hose - maybe they're the wrong carbs for my model year?

20170404_205441.jpg

IV fuel delivery is what i'm currently working with.
I can check this weekend how high the fuel is in the bowls - I'll post a picture as well.
When I shot starter fluid...I realize now I probably was putting in WAAY too much. Fluid was misting out of my exhaust.. I haven't been in the garage since my last post, so I'm hoping that the cylinders would be dried out by now. I've read that it's only supposed to be a few light sprays to vaporize it into the carbs, the engine should do the rest. Only once did I ever get a single loud backfire. Right after I swapped in the ignitech unit. Just so it's out there - my mixture screws were turned all the way in, then turned out 2.5 turns.
Currently i'm on the NGK (2923) DR8ES-L plugs. I read on motofaction that they are the plugs for our bikes along with the D8EA's. I'll swap in D8EA's that I can buy locally to avoid shipping damage.
Yes, I've got the FSM. I'll review the troubleshooting page again for sure.
I've added my location to my signature. Also, I had no idea we have a Member Location map!! Updated my location - looks like I've got a two members close. I'll reach out maybe they can help. One of them might be the friend of mine who lent me his ignitech.


Murrayf - I have spark when the plugs are outside of the cylinders. I've read that if spark is weak, once it's under compression, it is basically nothing - but I thought the ignitech would fix that issue, if I had it? I also have compression when I use a compression tester - the values in my first post. However, the most recent time I tried to turn the engine I saw smoke coming out of the spark plug hole!? I ended up turning in the towel out of exhaustion, but i'm ready to get back in it. It might be that my plug holes were shot all along, and I actually don't have compression. The compression tester uses an o-ring for a tight seal, which the spark plug doesn't have. Maybe I could try a spark plug o-ring combo? I know that adjusting the valves affects compression. I'll also re-verify my adjustments when I get back out there this weekend.

I really appreciate your willingness to help me figure this out! :D
 

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Discussion Starter #9
I've been MIA for a few days. My car took a dump on me last Friday. Took all my time to find a replacement. Anyway. I was able to get in the garage for a few minutes yesterday. I have pics of the level of fuel in the carbs. Looks like the right carb fuel level is higher than the left.

Readjusted the valves @ TDC of the compression stroke. +5psi compression in both cylinders Dry. Tried go start it with starter fluid (two light sprays per carb) and it fired up for a glorious 3 seconds..

Then couldn't replicate.

That's where I'm at.


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OK, so to recap.
It did fire up once but when it ran out of fuel (starting fluid) it would not do so again when given an equivalent dose.
When you squirt it, are you also holding the throttle wide open?
This will allow more to enter the passage and get into the combustion chamber.
Will it continue to run as long as you can squirt more in while it is running?
 

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^^^^^^^^^^^^
I was simply wanting to know it would continue to run or if it would quit and then not restart.
A couple of brief squirts while it is running can tell a lot.
 

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Discussion Starter #14
IT FIRED!

Let it sit for a few days.. reset the mixture to 1.5 turns out just for kicks. Two bumps of ether with the throttle pulled in each carb. Then let her rip. Didn't keep it on too long as I'm missing my vital readings (oil pressure, tacho, temperature, etc).

Im running 90/120 jets set in the right ports based on what I've found online. Main vs secondary. I did replace my rubber idle passage plugs.

Currently not running pods or exhaust as you can see from the vid. But I will be running pods and exhaust soon enough.

You can hear my excitement in the video lol... but quickly subdued because of the smoke..any ideas? I'm hoping it's just burning oil because its newly rebuilt...




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