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Discussion Starter · #1 ·
Some backstory: Picked up a Gl500/cx500 (Can anyone tell me which?) for $80 bucks, it was missing the left side cylinder head and looks like it was sitting outside for a while. The ring of rust was so bad I couldn't get it to turn over manually, so I cleaned up the rust as best I could with some PB blaster and a scotch bright pad, shot some compressed air into it, sprayed it with wd40 and wiped with a microfiber cloth. There's a bit of carbon build up left on it but it turns over like butter now.

Can I run this as is or should I get this cylinder honed? Honestly don't really care if it burns a little oil because I'll be amazed if I can get it to run at all considering the state of the bike. This is my first bike and my first project!
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1981 CX500C
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$80 got you a DIY kit.

I wouldn't try to run a cylinder in that condition.

Find a ball hone. Pull the block. Run the ball hone with a drill. Use kerosene as a lubricant. Caution, this is flammable stuff, so NO Smoking.

It should clean up without changing the bore diameter significantly. You'll prolly need a set of piston rings too.
 

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If it was mine I would hone and rering it.

But this is a bit of a money pit.

Unless you're keen to pull it down I would just reassemble it and run it unless you are comfortable with doing the work.

You appear to already have done a pretty good job on the cylinder wall clean up. It doesn't look like there is any glaze left on the bore.
 

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It`s your first bike and your first project and the CX you have there will be an ideal start on the learning curve of motorcycle wrenching...
Getting it running perfectly will involve a LOT more time/money/experience and might be too much effort for what looks like a bike past it`s best..

It`ll run OK in that condition but as you say may burn a little oil and be down on performance. If all you want is to get it running to a reasonable condition i wouldn`t throw too much $$ at it and that means using the cylinders as-is.
Carefully inspect the valves and seats - the seats especially do not like sitting for years in damp conditions and will corrode to the point of them being not saveable.
 

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I often wonder what damage happens on those....."hasnt run for 30 years til now....a few kicks/ stabs of the button...wooowee....youtube posts"..
 

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'84 CX650E that is evolving into a GL500
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It looks like you have a CX500C but the way to tell for sure is by looking at the VIN plate attached to the left side of the steering head

I'd be very concerned about what is inside of that engine's crankcase and cooling system after sitting outside for years with the head removed.
 

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1982 gl500
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It looks like you have a CX500C but the way to tell for sure is by looking at the VIN plate attached to the left side of the steering head

I'd be very concerned about what is inside of that engine's crankcase and cooling system after sitting outside for years with the head removed.
Yeah my money is on the crank looking just as rusty, I'd pull the engine apart, clean it, and rebuild it.
 

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'84 CX650E that is evolving into a GL500
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Or find another and use this one for parts.

BTW: Welcome to the forum. When you figure out exactly what you have please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and while you are working on it go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).
 

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But don't throw money at another motor before you've looked at this one.

Capillary oil retention can protect the most important bits .... up to a point.
 

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Discussion Starter · #10 ·
Thanks for all the replies! Happy this is a super active forum. The consensus seems to be to pull it and hone it if I want a happy engine. I’m going to drop the oil pan and see how it’s faired, hopefully no rust and debris sitting at the bottom. If it’s real nasty I think I’ll just pull the whole thing apart, but if not I’m planning on replacing all the gaskets I can get to easily, changing the stator, checking the timing chain and guides, disassembling the oil pump and I think I have to pull the lower rocker arms on the exposed piston side - I’m able to push one of them way far up compared to the others so I think the spring is shot.

A lot of random stuff was parted out before I bought it so I need to source a radiator, both wheels and basically all the lines for the cooling and fuel system including the petcock. My fuel tank is rusted to shit on the inside so I’m planning on filling it with vinegar and bolts and giving it a good soak and shake.

Stock carbs need to be rebuilt and jetted for pod filters and I’ll need to run some lines for the crankcase breather holes. I’ll probably rebuild the forks, replace the rear shocks, pull the H box and get some shorter exhaust pipes. And a new wiring harness or rebuilding the current one, the plastic connectors are brittle and crumbling from sitting in the sun. Frame has a little bit of rust but not bad, wire brush + some gloss black rustoleum will clean it up. Planning on grabbing a cheapo Chinese digital speedometer and throwing some cafe style bars on, and I need to get some new brake lines, and a reservoir. I’ll stick with the disc + drum.

I think I’ll make a build thread at this point. Let me know if I’ve made any glaring omissions but I think I’ve got a pretty solid roadmap ahead
 

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I’m going to drop the oil pan and see how it’s faired...
You might have a hard time finding the oil pan :), unless it has had a 650 swapped in there.
 

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Ah I take it there isn't one... that might be a little problematic
Removing the front cover gives you access to the oil pump which can be removed, cleaned and inspected.
 

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'84 CX650E that is evolving into a GL500
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The first thing to do is download that FSM I mentioned and sit beside the bike while you go through the book to learn about the bike. Once you have done that you can think about picking up wrenches.

Re modifications, the best advice anyone can give you about customizing any vehicle is to get it safe & reliable in more or less original condition and use it for a while before you start making any changes so it can tell you what changes it needs to make it do what you want/need better. That approach almost always results in something you actually want to keep and use but making changes based on style or on what someone else (who may or may not really understand how the changes affect the way it works) has done often results in a piece of expensive yard art that you can't stand sitting on for more than a few minutes and might even be dangerous.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Given the number of missing pieces, I'd heed Bob's advice above. Find a more complete example and use this one for dissection and parts.
Unless you have a title for this bike and you find a complete, untitled of the same model. Then rebuild on this frame.
 
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By the way, the cylinder head that is missing is the right side of the engine right/left is determined from the seat as you look forward.
 
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