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Another tip for setting TDC on the compression stroke in case there is any confusion left is to watch the inlet valves as you rotate the engine. When the inlet valves are starting to close as TDC gets closer you are on the compression stroke required for valve clearance measurement.
 
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Discussion Starter #22
Another tip for setting TDC on the compression stroke in case there is any confusion left is to watch the inlet valves as you rotate the engine. When the inlet valves are starting to close as TDC gets closer you are on the compression stroke required for valve clearance measurement.
Thanks for the tip :)

I'm glad I found out why my valves wren't working right lol!

Now I just have to figure out what my next step is as far as diagnosing and fixing compression issues as the methods that everyone suggested were for if the bike was put together and running, which at the moment the engine is on the floor (still assembled)
 

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You can do a compression check with the engine on the floor. Do it with plugs removed and throttles wide open if carbs are still installed. Do a compression check, then repeat after adding some oil to the cylinder. If compression improves it suggests a piston ring problem. If compression doesn't improve it suggests a valve problem.
 

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My opinion is fix the cam tension bolt threads first. Do whatever you're going to do with the triple bypass and change out all the o-rings and gaskets with new. Especially the cam tension adjustment bolt o-ring. How pissed off will you be when the engine is all buttoned up and that leaks! The engine should at least run with that compression. 27k isn't alot of miles but it's usually where the original cam chain stuff starts going off. If the engine sat a while things will be a it sticky anyway. Now you know how to properly set the valves, do that. Put the engine in and get alot of oil for repeated oil changes to flush it out. Run the engine as is. Sometimes running it will free things up that have stuck from sitting. If oil consumption is still excessive after a few 100 miles and compression hasn't come up, then consider doing more as in refreshing the heads with new seals and lapping the valves or new rings. My opinion. Others may agree. Maybe not. I got sick and tired of replacing one tired engine with another so I'm in process of building a fresh engine, but have one to run in the bike in the mean time.
 
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You can do a compression check with the engine on the floor. Do it with plugs removed and throttles wide open if carbs are still installed. Do a compression check, then repeat after adding some oil to the cylinder. If compression improves it suggests a piston ring problem. If compression doesn't improve it suggests a valve problem.
The carbs are not attached right now so I think I'm good to go there. I didn't know you could do it with the engine on the floor, there's currently no oil in the engine, would it hurt the engine to do this without oil? I assume I can't do this by hand turning the crank and would need to connect the necessary electricals to run the starter right? I'll have to borrow my buddy's compression tester when I get a chance since I don't have my own.


Reset the valves properly first or you won't get true values.

As the engine will be cold spot it 20 PSI.
Oh interesting ok, why 20 PSI? Is that just a rule of thumb kind of thing?



My opinion is fix the cam tension bolt threads first. Do whatever you're going to do with the triple bypass and change out all the o-rings and gaskets with new. Especially the cam tension adjustment bolt o-ring. How pissed off will you be when the engine is all buttoned up and that leaks! The engine should at least run with that compression. 27k isn't alot of miles but it's usually where the original cam chain stuff starts going off. If the engine sat a while things will be a it sticky anyway. Now you know how to properly set the valves, do that. Put the engine in and get alot of oil for repeated oil changes to flush it out. Run the engine as is. Sometimes running it will free things up that have stuck from sitting. If oil consumption is still excessive after a few 100 miles and compression hasn't come up, then consider doing more as in refreshing the heads with new seals and lapping the valves or new rings. My opinion. Others may agree. Maybe not. I got sick and tired of replacing one tired engine with another so I'm in process of building a fresh engine, but have one to run in the bike in the mean time.
The bike did run before I ruined the tensioner bolt. I drove it about 1k-1.5k miles in the last 2 months. It just didn't run ever quite right. It kept running better and better the more I did to it (mainly improving the carbs). It ran the best it ever did before I dropped the engine, but it still feels like it's missing low end power my friend tells me (I have no metric to compare to as this is the only bike I've ever ridden so I'm only used to this bike and what I've felt on it so far). It ran well, I could take it at highway speeds no problem, handles up to redline well. It shifts easily and generally just works. But I know both based on my own feel of small things here and there and what my friend tells me and the fact that I have measured low compression and low mileage that it isn't running as well as it should. So oil has definitely been circulating through it for more than a few hundred miles.

I want to get this bike ready for a trip in about 1.5 months to ride in the mountains for a week with some old friends. I'm intending to do the triple bypass and the tensioner bolt fix for sure, but I really wanna address everything I can while I have the engine apart to minimize the chances of me having to open it again anytime soon. My buddy's dad said get new rings anyways if I'm opening the engine, but to check for a notch. If the notch is bad it needs to be rebored, otherwise we can rehone it. He is skeptical that the problem is valves right now without looking at them since nothing he has observed has made him think it was valves he mentioned.
 

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There's generally 15 - 20 PSI difference between hot and cold tests.

If this motor hasn't been running for an extended period of time the rings stick in their grooves giving lousy compression and oil control. I wouldn't be too quick to rip into it as this often sorts itself out in a few hundred miles.
 

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Discussion Starter #28
There's generally 15 - 20 PSI difference between hot and cold tests.

If this motor hasn't been running for an extended period of time the rings stick in their grooves giving lousy compression and oil control. I wouldn't be too quick to rip into it as this often sorts itself out in a few hundred miles.
It was sitting for an unknown period greater than a year, however, I got it running 2 months ago and have been riding it around as I worked on it and have since put about 1.5k miles on it myself.
 

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OK, it's not going to improve any further most likely.

If you decide to rip into it you might find some stuff here that will give you an idea what you're in for. I rip down to or three in this thread and rebuild them. There's one on my bench now waiting for me to get around to finishing it.

 

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Ooooooh, thanks, I skimmed through the beginning a bit and it looks really interesting....and horrifying LOL I'll read it thoroughly when I get the chance :) thank you for the resource :D
 

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If you did TR then the next TL, one side will have been on the exhaust stroke. Set the left side valves first, on compression (adjusting the camchain tension while you're there.) Then turn the crank to the next TR to set the right side valves.
 

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If you did TR then the next TL, one side will have been on the exhaust stroke. Set the left side valves first, on compression (adjusting the camchain tension while you're there.) Then turn the crank to the next TR to set the right side valves.
Thank you, I will make sure to do that when I fix the tensioner bolt and look at the cylinders. I have to wait for the parts from DSS to come in before I start working on things.
 

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Marvel Mystery Oil is known to free up stuck rings. They get gummed up and MMO has been know to unstick them. It wouldn't hurt to hit it a couple more times and turn it over by hand to move things around. You're going to tear it open any way. Just change the oil a few times when you've got it all together again to flush out all the MMO and sludge. Maybe it will use less oil and run better?

It's up to you. Your budget, your skills and probably courage. If you had all the parts and tools needed for a rebuild would you do it? I went for a "rebuild" because I'll need an engine when this one in the bike fails and I'm tired of tired replacement engines. It's never been taken care of properly which is just as bad as neglect. I found the harder to get parts first like the rod bearings, rings, stock head gaskets and a engine case with good cylinders. I'm familiar with the triple bypass procedures so I took a shot at tearing it down and having a go at refreshing a CX engine. I bought a trashed engine to learn how to take the engine down to just an empty case and put it together again before taking on the one I'm refreshing at the moment. This, a proper shop manual and this forum (thank you all. You all know who you are.) have all been extremely helpful. 1.5 months would be more than enough time to do it if you can. Again, just my opinion. Your mileage may vary.
 

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Marvel Mystery Oil is known to free up stuck rings. They get gummed up and MMO has been know to unstick them. It wouldn't hurt to hit it a couple more times and turn it over by hand to move things around. You're going to tear it open any way. Just change the oil a few times when you've got it all together again to flush out all the MMO and sludge. Maybe it will use less oil and run better?

It's up to you. Your budget, your skills and probably courage. If you had all the parts and tools needed for a rebuild would you do it? I went for a "rebuild" because I'll need an engine when this one in the bike fails and I'm tired of tired replacement engines. It's never been taken care of properly which is just as bad as neglect. I found the harder to get parts first like the rod bearings, rings, stock head gaskets and a engine case with good cylinders. I'm familiar with the triple bypass procedures so I took a shot at tearing it down and having a go at refreshing a CX engine. I bought a trashed engine to learn how to take the engine down to just an empty case and put it together again before taking on the one I'm refreshing at the moment. This, a proper shop manual and this forum (thank you all. You all know who you are.) have all been extremely helpful. 1.5 months would be more than enough time to do it if you can. Again, just my opinion. Your mileage may vary.
When I put the oil in the cylinders after testing compression it was MMO. I also put some in the oil fill port as well. Im confused as to what you are suggesting. What do you mean by "rebuild"? I am confused because when I hear rebuild I never quite know exactly what that means in which context. I hope I'm not alone in that confusion XD
 

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Taking the engine apart, replacing or refreshing any parts you can and putting it back together.
 

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Taking the engine apart, replacing or refreshing any parts you can and putting it back together.
That's what I was intending to do almost. I was intending on giving it a once over on anything I can get to, if it's in less than ideal shape then replace it, if it's ok then leave it. Basically inspect everything I can and replace what seems like a good idea to replace and leave what's fine. Is that what you mean?
 

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Basically, yes. I just took it a step farther because I don't need the engine to ride the bike at the moment. I can tell you these engines are easier to work on than some think. I've done what you're looking at doing and got plenty of miles out one. Do the triple bypass and fix the cam chain adjuster bolt. It runs at the moment like you've said. IF it turns out to be the rings you'll have to give some thought as to what you want to do as that's engine out again. Heads you can do with engine in if it's valve seals and/or guides.
 
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Basically, yes. I just took it a step farther because I don't need the engine to ride the bike at the moment. I can tell you these engines are easier to work on than some think. I've done what you're looking at doing and got plenty of miles out one. Do the triple bypass and fix the cam chain adjuster bolt. It runs at the moment like you've said. IF it turns out to be the rings you'll have to give some thought as to what you want to do as that's engine out again. Heads you can do with engine in if it's valve seals and/or guides.
Oooooh, I can service/replace valve seals/guides with the engine in??? I didn't know that, that makes things so much different :D
 
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