Honda CX 500 Forum banner

1 - 20 of 35 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
ive tried reading other threads but cant seem to find a solution
I'm not super mechanically inclined but I bought this bike not too long ago as a project bike, its a 1983 honda gl650 with a little over 50k miles on it and I just replaced the battery and headgaskets. The bike ran fine for awhile but now I'm having trouble with it over heating on rides about 25 minutes or better, I read that its probably the thermostat so I found the correct part on eBay that was still new in the packageing. But after replaceing it it still over heats.
Anyone have some helpful information?
 

·
Registered
Joined
·
8,510 Posts
Did you follow any retorquing procedure after replacing the head gaskets? At a minimum, you need to retorque after the engine has been run up to operating temperature. Some will recommend doing it again at certain intervals. If not, you might have exhaust gases escaping into the cooling system. Is the reservoir overfilling? Do you see bubbles in it while the engine runs?
Welcome, Sean. Where are you? You might find some experienced hands nearby.

Randall
 

·
Registered
Joined
·
7 Posts
Discussion Starter #3
I did follow all of the torque specs when putting it back together, but i havent touched it since. I have seen bubbles in the resivor once but I havent since.
And I have had it get hot enough to over flow once but i didnt let it get hot enough to damage anything.
I will try to retorque everything next.
 

·
Registered
Joined
·
8,510 Posts
Retorque the head bolts in the sequence given in the FSM (or in a star pattern, if it isn't specified.) Run it up to temp again, and repeat until the bolts don't move anymore.
Hopefully, you haven't run it enough to erode the fire rings of the new head gaskets.

Randall
 

·
Super Moderator
Joined
·
13,801 Posts
Note that the procedure given in the manual was correct for the original head gaskets BUT they were made differently than modern ones (among other things, asbestos has been banned) so the newer ones require a different procedure, including re-torquing them several times after running the engine through heat cycles (search the forum for more details).

BTW: Welcome to the forum. Please add your location to your profile and your bike's model and model year to your signature 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 the Previous Owners may or may not have done 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 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 because 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).
 

·
Registered
Joined
·
585 Posts
Don't forget to check valve clearance after re-torquing the head bolts.
 

·
Super Moderator
Joined
·
13,801 Posts
To retorque, you loosen each bolt about 1/4 turn, then tighten it to spec again. If the nuts move past where they were before loosening the gasket becomes thinner, moving the rocker arm pivots closer to the heads but the pushrods stay the same length so the gap between the end of the valve and the adjuster gets smaller.
 

·
Registered
Joined
·
8,510 Posts
To retorque, you loosen each nut about 1/4 turn, then tighten it to spec again. If the nuts move past where they were before loosening the gasket becomes thinner, moving the rocker arm pivots closer to the heads but the pushrods stay the same length so the gap between the end of the valve and the adjuster gets smaller.
I strongly recommend against backing off the head bolts (not nuts, btw). I ruined a set of replacement headgaskets doing that very thing. They both blew out 2/3 of the way to Rochester for a group ride. That was around 2009, before being a poor mechanic helped make me a better mechanic.

Randall
 

·
Super Moderator
Joined
·
13,801 Posts
Yeah, sorry. I corrected it.
Loosening each bolt and then re-torquing it to spec is the procedure that Joe Hovel (among others) recommends for the currently available CX/GL650 head gaskets.
1) In 2009 you would have been using original spec gaskets (unless you had aftermarket ones and then all bets are off) so re-torquing wasn't necessary but even so, as long as you only loosened one at a time and immediately re-torqued it how could that cause the gaskets to fail?
 

·
Super Moderator
Joined
·
13,801 Posts
If you don't loosen it slightly you can't set the torque correctly. If a bolt (or nut) is at close to the spec torque and you put the wrench on and lean on it you will always increase the torque to a higher value before it clicks.
I don't know how to explain this but it has to do with the way torque wrenches work. I think it is something like this: The wrench is designed to click when a moving fastener reaches a specific resistance to turning. If you loosen it slightly first the fastener is moving when it reaches the spec torque and the wrench clicks but if you don't loosen it has to move the fastener before it can click, which can increase the torque significantly, especially if repeated several times.

Truck wheels coming off at speed and hitting moving cars was in the news here some years ago after a couple of people died as a result. They initially blamed lug nuts coming loose so truckers started putting a wrench on each lug nut every morning to make sure they weren't loose. When incidents of wheels coming off increased it was traced to lug studs breaking because after a few weeks of being tweaked every day they were under so much pressure they broke. After that they were told to loosen every nut before tightening (a while later plastic indicators that fit over the nuts and indicate whether they have moved).

BTW: Here's Joe's explanation of why the new gaskets require re-torquing with additional info from Murray & others
 

·
Registered
Joined
·
8,510 Posts
The wrench is designed to click when a moving fastener reaches a specific resistance to turning. If you loosen it slightly first the fastener is moving when it reaches the spec torque and the wrench clicks but if you don't loosen it has to move the fastener before it can click, which can increase the torque significantly, especially if repeated several times.
I can't agree with that. My wrench will click without moving first, if the fastener is already at or above the value set on the wrench. Maybe it's your wrench. Regardless, I don't see any value in backing out the bolt, and great potential harm in doing so.
It's possible that I had backed off all the bolts first, rather than one at a time. It was a long time ago, and I don't remember the exact procedure. Since then, though, I've been wary of releasing compression on a head gasket and expecting it to reseal.

Randall
 

·
Registered
Joined
·
8,510 Posts
They initially blamed lug nuts coming loose so truckers started putting a wrench on each lug nut every morning to make sure they weren't loose. When incidents of wheels coming off increased it was traced to lug studs breaking because after a few weeks of being tweaked every day they were under so much pressure they broke.
How many were using a torque wrench? It's easy to over-torque with a lug wrench.
Sorry, this example doesn't apply here.

Randall
 

·
Super Moderator
Joined
·
13,801 Posts
It may be that yours clicks before you notice that you are turning it. Perhaps someone that knows more about why it is necessary to loosen them slightly can give a better explanation than me.
 
1 - 20 of 35 Posts
Top