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Discussion Starter · #1 ·
Hello Hive Mind,

Long story short, I`ve a 500 that refuses to fire into action.
Longer version: Bought the bike, which had stood for a few years. Checked/changed the fuel, filters, oils, fuel pump, starter motor and coolant, gave the whole thing a good once-over and proceeded to go for lift off.
I blasted easy start type spray down the air intake and eventually got it firing..woohoo. I repeated this trick a couple of times and it would run with the spray, then...something popped and produced fumes back up the air intake.
The pop/crack (like a backfire) sounded as though it came from the front, down the bottom. Bear in mind, both my ears are goosed, so it could have come from almost anywhere.

Since then, the bike has refused to fire up. That`s with it`s own fuel or with any kind of easy start spray.
The engine turns over as it should but simply refuses to start. Fuel system light comes on and the system pressurises just fine.

I`ve changed the right hand bar control/kill switch (twice), changed the coils, checked fuel is getting to the plugs, made sure there`s a spark on each side, removed the main Honda fuel filter and inserted an in-line filter in its place, checked/replaced fuses, changed over the starter solenoid, checked all visible connectors/wires, checked the ECU lights (W comes on/goes off as it should..no other lights come on) oh and swapped the ECU today.
Nothing has made a difference.

What has happened and what can I do to remedy it ?
 

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Probably your camshaft NE speed sensors are both broken.
Fuel pump should run 3 seconds after power on, then it should start again as soon as the ECU gets a signal from the NE speed sensors.
Check if the fuelpump is running during starter engagement.
 
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Discussion Starter · #3 ·
Probably your camshaft NE speed sensors are both broken.
Fuel pump should run 3 seconds after power on, then it should start again as soon as the ECU gets a signal from the NE speed sensors.
Check if the fuelpump is running during starter engagement.
Fuel pump runs as it should before and during starter engagement.
 

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1982 cx500tc turbo
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Hi
Do you have spark when cranking

Is the new fuel pump wired right
make sure its wired proper
remove the fuel pressure port plug and cycle key to see if the pump is pumping fuel
if you can for safety reasen install a hose so it don't spray all over

TLD 🇨🇦 🇩🇰
 

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Discussion Starter · #5 ·
Hi
Do you have spark when cranking

Is the new fuel pump wired right
make sure its wired proper
remove the fuel pressure port plug and cycle key to see if the pump is pumping fuel
if you can for safety reasen install a hose so it don't spray all over

TLD 🇨🇦 🇩🇰
Both sides have spark and the fuel pump (now an original replacement) is wired correctly and works fine. I had fitted a brand new pump but sourced an original, so used that.
 

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I had a problem with a rebuilt 650T one time. I used the little port right at the intake to shoot some gasoline in there. After that it started fine every time. Sadly with 40 year old bikes the wiring can cause issues too. The ignition, kill switch and others can go wonky and be royal pains to sort out. Keep us posted.
 

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  • Ignition switch on
  • wait until the fuel pump stops
  • blip the throttle
You should hear the injectors clicking
 

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Discussion Starter · #9 ·
I had a problem with a rebuilt 650T one time. I used the little port right at the intake to shoot some gasoline in there. After that it started fine every time. Sadly with 40 year old bikes the wiring can cause issues too. The ignition, kill switch and others can go wonky and be royal pains to sort out. Keep us posted.
Kill switch has been changed. Ignition switch hasn`t, yet. I have a full lock set for the bike, so I guess now`s a good a time as any to fit it.

Stripped the fairing off this morning and double checked all the connections I could find. I now have zero dash-lights working, to add to the non firing engine. So I guess it`s wiring that`s playing up.

Still don`t understand why it fired up, then backfired and then refused to start :unsure:
 

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I'm not a huge fan of starting fluid. Try putting some gas in the port right where the intake goes into the cylinder head. There is a small 5mm bolt there, get a spray bottle, a syringe, a straw, whatever, and put some gas in on each side to prime it to start. When the systems are run dry they are often a b*tch to start. Be sure to fasten the bolt afterwards.
 
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Discussion Starter · #11 ·
I'm not a huge fan of starting fluid. Try putting some gas in the port right where the intake goes into the cylinder head. There is a small 5mm bolt there, get a spray bottle, a syringe, a straw, whatever, and put some gas in on each side to prime it to start. When the systems are run dry they are often a b*tch to start. Be sure to fasten the bolt afterwards.
You Sir, are a sanity saver!!
Just tried your suggestion with starter fluid and got the reluctant little beast to fire up. It wouldn`t however fire without a constant stream being fed it.
I`ll try it with petrol, as I`m running low on starter fluid now...once I figure out a method.
There`s fresh petrol (from the tank) getting to the junction just before the injectors but not seeming to get into the pots. Am I being premature in suspecting blocked injectors ?
 

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1982 cx500tc turbo
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Hi
Get a test noid to check for injector pulse
The fuel pump will prime the system and circulate the fuel to the tank

I have a hard time believing the injectors are plugged
Pull the tail of or pull the ECU out so the codes can be read on the ECU

TLD 🇨🇦 🇩🇰
 

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Discussion Starter · #13 ·
Hi
Get a test noid to check for injector pulse
The fuel pump will prime the system and circulate the fuel to the tank

I have a hard time believing the injectors are plugged
Pull the tail of or pull the ECU out so the codes can be read on the ECU

TLD 🇨🇦 🇩🇰
When you say the ECU codes, do you mean check what lights are showing? If so, as mentioned, there are no fault codes showing. The W light comes on with the ignition and then goes out, as it should.
If the bike fires when the injectors are bypassed but dies as soon as that bypass is stopped and there`s definitely fresh tank fuel getting up to the splitter behind the injectors, what does it point to, as far as you are concerned ?
 

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So if the injectors makes the clicking sound and you have a working fuel pump there are basically only two things which could prevent from fuel going into the engine :
1 - clogged injectors
2 - broken fuel pressure regulator
 

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In your write up I did not see that you had the injectors serviced, if not that is your next step. Also resist the temptation to buy some cheap Chinese replacements. As Pim and others will tell you, a rebuilt Japanese injector is much more reliable. There are numerous injectors from the 70's that will replace these as well, just make sure to get the low ohm version. I am betting that the fueling problems is what caused the bike to be sitting so long. Keep us posted.
 

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Discussion Starter · #16 ·
In your write up I did not see that you had the injectors serviced, if not that is your next step. Also resist the temptation to buy some cheap Chinese replacements. As Pim and others will tell you, a rebuilt Japanese injector is much more reliable. There are numerous injectors from the 70's that will replace these as well, just make sure to get the low ohm version. I am betting that the fueling problems is what caused the bike to be sitting so long. Keep us posted.
I agree on the injectors needing cleaning out.

As for the reason it was left standing, I think I found that this morning.
When I had it turning over, there was evidence of a bad oil leak at the front of the engine. I guessed at either the left head gasket or the transmission cover gasket. On digging through to the front, I`ve found a previous owner has rounded every one of the exhaust manifold nuts/bolts, making it impossible for me, at the minute, to get to the source of the oil leak. I assume this is as far as said owner got, as the heat shields were undisturbed.
I`ve had to leave it as is for now, as I`ve zero way of getting those nuts off.
I`ll get to the injectors in time and also sort the oil leak out but as things stand, I`ve got other things to sort in the meantime.

Thanks for the help and advice everyone.
 

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Oil leak at the front is probably the Turbo oil supply hose
 

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Discussion Starter · #18 ·
Update: After my little tantrum finished, I bought a nut/bolt extractor kit and got the manifold etc off this morning.

The oil leak/s are (definite) both rocker cover gaskets and (fairly certain) the camshaft gasket. Can`t properly test the Turbo oil supply hose or for that matter, the camshaft seal..without firing the engine up. So I`m going to go with what I`ve judged from where the oil has travelled and gathered. Time will tell if I`m wrong.
(Anyone know a cure/replacement for the Turbo oil hose ?)

Only sheared one heat shield bolt (quite impressed with that) and binned one shield..the oddball, manifold one that always rusts first.
A few days of cleaning up and repainting will now follow, while I await the new gaskets.
 

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Update: After my little tantrum finished, I bought a nut/bolt extractor kit and got the manifold etc off this morning.

The oil leak/s are (definite) both rocker cover gaskets and (fairly certain) the camshaft gasket. Can`t properly test the Turbo oil supply hose or for that matter, the camshaft seal..without firing the engine up. So I`m going to go with what I`ve judged from where the oil has travelled and gathered. Time will tell if I`m wrong.
(Anyone know a cure/replacement for the Turbo oil hose ?)

Only sheared one heat shield bolt (quite impressed with that) and binned one shield..the oddball, manifold one that always rusts first.
A few days of cleaning up and repainting will now follow, while I await the new gaskets.
We have numerous posts on the turbo oil hose, just use the search feature at the top of this page. The camshaft gasket is different from the stock CX. Murray sells them, or if you are in a hurry you can make them with gasket material, a hole punch and an Exacto knife. There is a little "U" shaped section on the regular gasket that will leak on the turbo, so do not cut out that section. Also, do not force the cover back on. Rotate the engine if needed to get it to fit. If you try to pull it down with the fasteners you will be searching ebay for another cover.
 
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Discussion Starter · #20 ·
We have numerous posts on the turbo oil hose, just use the search feature at the top of this page. The camshaft gasket is different from the stock CX. Murray sells them, or if you are in a hurry you can make them with gasket material, a hole punch and an Exacto knife. There is a little "U" shaped section on the regular gasket that will leak on the turbo, so do not cut out that section. Also, do not force the cover back on. Rotate the engine if needed to get it to fit. If you try to pull it down with the fasteners you will be searching ebay for another cover.
I`ve replaced the Turbo oil feed now and I`m just waiting on the camshaft gasket and replacement injectors to arrive from the U.S. (hopefully in about a week`s time). Once they land, it`s spanner time and hopefully a successful update post.
 
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