1976 Engine Rebuild

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bronko37

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Ok so I have begun my engine rebuild, which I mainly think is only going to consist of re-ringing the motor. I believe that all of the bearings and such will be fine. So instead of just pulling the engine I am reworking components as I need to remove them. First I removed the carb rack so I could replace all the buttons with the black delron as I have in other mods that I have shared on the forum. I also removed all the lettering from the caps so they look super badass now, Ill post some picks later.

Next I began to remove the heads so I could take them all apart, clean the valves, and machine or lap them as necessary. So far the lapping is working just fine. Now, here comes the question, upon inspecting the cam lobes for wear I discovered something that you may or may not be aware of. In the Clymer manual, which is what I have, it shows that the specs for both the intake lobes and the exhaust lobes are the same for years 75-77 and different for years 78-79. However when I check the Honda manual via the forum it shows that they are different and gives no discrepancy between model years.

Here is what my cams measure:
Intake 1.460 on all 4 lobes. The book shows a size range of 1.459-1.465 with a service limit of 1.448 so all good there...
Exhaust is 1.440 on all 4 lobes. This is where I get confused a little bit. Here is why....

The Clymer manual shows a size of 1.459-1.465 with a service limit of 1.448 for years 75-77 and sizes of 1.445-1.451 with a service limit of 1.437 for years 78-79. So when I measured my exhaust lobes I'm sayin to myself "man those lobes are nearly .020 below factory and .008 below the service limit". Then I went to the forum and checked the Honda manual which shows sizes of 1.445-1.451 with a service limit of 1.437 with no difference between model years.

The bottom line is I believe, according to the Honda manual, that my cams are indeed just fine. So, does anyone have sizes on thier cams that I can compare to? Is this hickup in the Clymer manual well documented like the jet mixup they have published?

It seems as though I should really ditch this Clymer manual and invest in a Honda manual. I'm just looking for some affirmation that my cams are indeed fine and are actually within spec.
 

bronko37

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I should also note that there is absolutely nothing to indicate major amounts of wear on these cams. All the lobes look to be in really nice condition with no burrs, galding, or scratches. The rockers are also nice and smooth with no burrs are scarring. It didnt make any sense to me that the Intakes would be perfect and all 4 exhaust lobes would be worn nearly .020 and all within .002 of one another.
 

bronko37

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Yea Joe its gonna be fun...2 years ago I was learning how to remove and clean a carburetor, this year Im gonna get into the internals of the engine. I never would have thought it, but here I am. I will be sharing progress along the way. Im hoping for a significant boost in my compression. The bike runs great for as low as it is so I cant imagine what bringing it back to spec will do.
 

Terry

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Curious question:

Why do you need a overhaul or rering?

Low compression?
Burning oil excessively?
Ultra high mileage and just tired and worn out?
 

Terry

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I see,
90 psi is low now it makes sense.
Running surprisingly well makes less sense, but hey it's a Honda.
 

bronko37

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[url=https://classicgoldwings.com/forum/viewtopic.php?p=164081#p164081:317khu1t said:
joedrum » Tue Dec 08, 2015 12:11 pm[/url]":317khu1t]
yep runs good for 90 lbs compression ....sheesh i guess the c5 is making the best of it ...how do plugs look bronko ...like to see pic of that .... :popcorn:

Plugs range from coffee color to carbon n oil black. Ill try n post a picture of them later when I get home. I also cant wait to see what this c5 does with a proper engine.
 

bronko37

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Here are some pictures of the plugs. There is also a pic of one of the cylinders. They all look really good from top to bottom. I just think the rings are stuck. Ridding the shit out of it didn't fix it so im aiming to get her back to the original glory, probably better. My compression is only 90psi per cylinder. Runs great but I gotta be losing out on a good helping od power i would think.

Let me know what you guys think...
 

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bronko37

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[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=164082#p164082:1nlxqtpw said:
Terry » Tue Dec 08, 2015 12:13 pm[/url]":1nlxqtpw]
I see,
90 psi is low now it makes sense.
Running surprisingly well makes less sense, but hey it's a Honda.

I was sure I was wrong and it would be ok but nay. One time I got a cylinder to read 140psi but the next day it was 90psi. It's like it broke free, just a little, and when it cooled it locked up again. I was sure I was doing the test wrong but all signs point to low compression and sticky rings...no matter how i do the test or what tester I use. Im thinking a 60-80 pound boost in compression should be quite noticeable :music:
 

slabghost

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How many miles at a time and total did you ride it? What did you add to the oil during that time? Did you use ATF in the fuel during that time? Did compression go up significantly when oil was put in the plug hole? Cylinder walls look great! Might be just a bit of clear glaze present but hard to tell in the pic.
 

bronko37

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[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=164095#p164095:3i1x1rlz said:
slabghost » Tue Dec 08, 2015 5:16 pm[/url]":3i1x1rlz]
How many miles at a time and total did you ride it? What did you add to the oil during that time? Did you use ATF in the fuel during that time? Did compression go up significantly when oil was put in the plug hole? Cylinder walls look great! Might be just a bit of clear glaze present but hard to tell in the pic.

I rode it on short rides, 10 - 25 miles at a time. I took it on a few rides where I went 80+ miles round trip. I would ride it every day to work when the weather permitted. I probably put about 3,000 miles on it over the season. I've used MMO and atf as fuel additives, not at the same time of course....I never added atf to the engine oil in any significant amount, but have changed the oil a few times. When I did the compression tests i never added fluid to the cylinders and rechecked...rookie move, im still learnin...however, I have had the heads apart before and they appear to be in great shape. I've done leak downs throught the intake and exhaust ports and got no leaks. Everything seals up tight. Also, while I have the bike comming apart i am lapping the valves in and going through them, leaving no stone unturned...
 

slabghost

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Had you asked before tearing into it I would have advised a few all day rides. Including some intermittent high rpm runs with 8oz of atf in the oil. That alone may have cured the issues. Unsticking and reseating the rings and bringing compression up to normal. Stuck rings need time at operating temperature to break loose.
 

bronko37

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Man, trust me, this bike lives in the high rpm range. This is the best way, plus I just kinda wanna do it....will be a great learning experience. With my machining back ground there isn't really anything here that I haven't already done in one form or another. This way it will not just break free, it will be absolutely correct.

I was well aware of the "add atf and hope" plan, just not worth fiddling with when I can do it right..., for the record this is just my own version of "doing it right" not to be deminishing toward anyone else's methods of "doing it right"....just the way im doin it... :read:

:music:
 

bronko37

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[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=164100#p164100:tea3fd74 said:
dan filipi » Tue Dec 08, 2015 6:44 pm[/url]":tea3fd74]
Tearing it down, honing and new rings would be more fun to me actually.
Though I don't have the spare time lately, it's what I'd do if I did.

That's prezactly what im sayin.... :Egyptian:
 

slabghost

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Different strokes as they say. I'm in the "if it isn't broke. don't fix it " camp. As long as runs good I'll add oil as needed and run it. I don't fear rebuilds but I will put them off as long as I can.
 

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