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Discussion Starter · #1 ·
Hi, I've done the risky thing and bought a cx500 I know little about. Seems like I got screwed over... it's seized! :nightmare:

It won't turn over in gear even with the spark plugs removed. A tell tale sign something was up when I drained the old oil and just under a litre came out (2 pints) when they're meant to hold 3L. I've noticed they've screwed the head cover threads that hold the rubber gasket down so maybe it leaked oil till it seized.

Anyway, I'm thinking penetrating oil down the spark hole therapy for x number of days to maybe try and free the crank. Any other suggestions and advice would be much appreciated. Presumably I can try this without dropping the engine out at this stage? would it help to heat gun the outside casing to expand it slightly?

Thanks, Jonny
 

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If you still have the oil and filter you removed, inspect it for shiny metal particles and what colour they are, silver or goldy. Then use a dental mirror in the timing inspection hole to see if the chain has snapped and jammed up in the rear cover preventing it from turning over.....also, get it out of gear to see if the motor turns over at all.

Do this then get back to us
 

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Discussion Starter · #3 ·
I already replaced the oil and filter; there were no metal particles I could notice, I just saw some fine black particulates captured by the filter so the signs indicate there's no metal wear. It's an 81 cx as well so it shouldn't have the came chain tensioner problem. It's at my parent's place at the mo so will be able to check at the weekend if it turns over in neutral using the crank bolt on the front behind the cap. Thanks for the help so far
 

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If it's overheated the big ends could equally wear into nothingness pretty quickly, and that would ruin the crank, and quite possibly promote piston slap and severely wear the piston if not bore as well. This has happened to my brother. Good thing I keep spares! xD


Anyway, does the rear wheel turn freely in neutral out of interst, that could sometimes indicate a gearbox problem. take the rockers off, inspect the valves, they could also be bent stopping the piston from making a complete stroke. It might have just overheated, it could be an accumulation of things.

Does it even attempt to turn over? or does it simply do nothing. Can you hear any metal upon metal sounds?
 
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mix some atf and pb blaster and put in the spark plug hole and let it soak a day, then turn the 17mm bolt on the front of the engine to loosen.
take it out of gear:)
 

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Discussion Starter · #7 ·
Good news, I took the wheel off and after turning it over in neutral with the crank bolt I realised it's not seized after all! :icon_thumbright: Clicking it in gear turned the output drive around so the transmission is fine. I dropped a little engine oil into the spark plug hole to help lube things up in there for the time being.

The back brake was locked on pretty heavy heance why I couldn't push it, and so the engine problem must be to do with the stater. When I press the starter button, it hums noticeably but does not turn over (battery is new) so maybe a problem with the relay or starter motor itself. Will find a volt meter and go prodding around the wires. to try and see the problem. I will have to take the engine out anyway as there's clearly a badly leaking gasket as there were a few drops of oil on the floor when I arrived home. If it managed to leak without any oil pressure I can only imagine the mess when it gets runnning!

Thanks for the advice guys.
 

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Discussion Starter · #8 · (Edited)
I've taken the starter motor apart (after a bit of hammer persuasion) and found this inside! :disgust:


Auto part Gas Auto part Metal

Pretty awful! I turned it upside down and what looks like a pile of ash poured out! Will try cleaning in the ultrasonic cleaner with some hot oxalic acid solution and see if that helps.
 

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Well if the starter is in that bad a shape, you probably want to check the engine out well. You stated your taking the engine out to fix a oil leak. If it was me I would pull the engine apart to see just how bad (or good) it is. when I got mine it was a barn bike and had hay in one sparkplug hole. Wasnt sure till I pulled the heads and found virtually no wear at all (once cleaned)

I would plan on getting a full gasket kit for the engine (around $100, so dont order it until your sure the engine is alright) when needed, but would start by pulling the heads and then the engine (engine is lighter without the heads on it). This will allow you to see (and post pics) of the valves, piston, (and when you pull the front and rear engine cover) the cam chain, starter clutch, stator .......

This will give you an overall idea of what shape the engine is in (without having to do a full tear-down of the internals) and if it is good to go. It will also give you a chance to check the stator, as this is the best time to do a triple if needed. (if not I would still replace the oil and mech seal)

Anyway, pics you can post here will let all the really smart guys help you determine whats the best thing to do
 

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I use a bore scope to look inside engines. Gives a good indication of cylinder walls and the piston tops.
Sounds like the heads need to come off since the engine is an unknown. You can do a quick compression test when you get the started working.
While you are out buying things you might as well get Larry's carb bible and carb rebuild kits from Radakk's
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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I would plan on getting a full gasket kit for the engine (around $100, so dont order it until your sure the engine is alright) when needed, but would start by pulling the heads and then the engine (engine is lighter without the heads on it). This will allow you to see (and post pics) of the valves, piston, (and when you pull the front and rear engine cover) the cam chain, starter clutch, stator .......
I'd leave the heads until I knew there was a problem. Front and rear covers are easy, though, and worth pulling to inspect and replace seals, chains, etc.


R
 

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I had a 1980 cx starter that was not quite that bad. But it was bad. I cleaned it, lubricated it. Found the bearings were good. Installed it on the bike I still ride today. Mine is a 1981 cx500c from michigan. I bought here in florida. Unroad for five years.
I bought the 1980 cx for it's egine and parts.
 

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if the engine is not seized and turns through smooth

then change the oil adjust the timing chain and valves and get the old girl started up

run it till normal temp a few times then see where you are at this take it all apart before you know what is what is expensive and silly

its a honda have faith and do fix what is not broken !!
 

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Discussion Starter · #16 · (Edited)
That sounds like good advise. I gave the starter back case (2nd photo) a good ultrasonic clean with hot oxalic acid solution and it did a very good job on it. Not perfect but was impressed. It cleaned up most of the rust and tarnished copper, but isn't much good at grease but an ultrasonic turpentine pass would help if required. Heavy pitting on the corroded steel remained but I couldn't do much of a better job of it with power tools as the thing is just hard to get at. After cleaning results are shown below:

Auto part Clutch Rotor Clutch part

Result is: not shown in the photo but there was a hole in the back casing which has obviously let water and subsequently havoc into the motor unit hence Armageddon was unleashed and the fire and brimstone gave rise unto ash that are now the innards of my starter motor!!!!

Anyway long and short all this malarchy is that an Ebay special starter motor was order and so elbow grease will be kept for the more serviceable components on the bike. At £25 inc delivery ($37 US) from a reputable breakers, tested and free of corrosion I'm definitely not complaining.

Upon peering into the engine starter motor pinion hole with a flashlight I could see the internal engine surface is without burn oil hallmarks and thus I'm relieved that the evidence before me suggests the engine had not overheated in past years.

A full gasket kit had been previously purchased for the princely sum of £32 ($47) which, considering the number of gaskets involved, I think is pretty fair. Having suspected a gasket leak I made the purchase in anticipation of an engine break-apart.

As mentioned earlier a head gasket bolt has ripped a thread:dontknow: any suggestions of how to cure this please disclose!!! I will need to find a fix for this to ensure a working sealed engine for the many cheek-to-cheek smiling miles I intend to get out of this cafe-racer project (anyone who's watched racer-tv on youtube should get this :p) www.youtube.com/watch?v=E87nG_NcGW4
 

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Discussion Starter · #17 ·
Just saw the recent messages. Application of elbow grease to machines like these is one of the those things in life which makes sense only to those endeared to the project they're undertaking. My brother thinks the work is a financial waste of time and I should have bought a closer to show room quality machine for a few extra pennies but he does miss the point a bit. Half of the fun is the learning experience and the satisfaction of reviving an old tired piece of history and breathing fresh life into it. Plus the clocks are only showing 20,700 miles which for a machine registered in 1981 is pretty good (if the dials hold any truth) so it could last me well.

I'm all for the "if it ain't broke don't fix it" approach - life's busy enough as it is' but though it is currently broke, I only intend on mending the actual sources of strife for this bike's mechanical physiology. At a glance it actually appears in good overall condition considering it's age.

BTW, Apologies for a slightly odd tone of narrative if I am portaying one, but mother's day supper saw me get through a good full bodied bottle of red so just typing off the effects currently. As always the help is much appreciated and I'm surprised and impressed at the amount of helpful chaps/chapettes on here. :icon_thumbright:
 

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Look below this post there are 2 links in my signature 1 for the wiki.

There is 1 for a thread that every newbie should read to help make a better decision

about what to know before they start off in the wrong direction.
 

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Discussion Starter · #19 ·
Yeah I'm not planning on a full strip down as the motor looks like it should run with the new starter motor. Will get her running, see which gaskets are leaking then drop the engine and replace them without touching any of the delicate stuff like cam timing, clutch or gearbox etc. I think it's one of the two main large side gaskets as there is what looks like a silicone sealant on them from a previous engine break apart. The bike was apparently running until storage 2 years ago and it doesn't look like it has been tampered with since then.
 
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