79 GL1000 Restoration - Need help assessing cylinder wall

[LLRelease]

I acquired a 79 GL1000 that hasn't run and sat in the PO's garage since 2001. The right side intake tubes were removed, so I pulled the head off after un-seizing the motor. The timing belts were not broken and the timing was spot on. There was some rust in cylinder #3, but no evidence that the piston ring was stuck to the wall. I cleaned everything out, but there is some pitting which is barely perceptible to the touch. Nothing that catches a fingernail. I am trying to figure out what to do next and am hoping to get expert opinions from the community.

I think my options are to 1) try running it as-is, 2) remove some of the pitting with fine emory cloth and run it, or 3) do a full tear down and hone the cylinders. The later may be beyond my skillset and/or what is practical to invest in the project given the condition of the bike. I was planning to replace the timing belts, head gaskets, valve seals, etc, but I haven't spent any money on parts yet. The bike is rough and will still need lots of TLC including rebuilding the front master cylinder and lots of cosmetic work, but it's a cool bike and I really want to get her back on the road!

Cylinder 3 as found:

Cylinder 3 after cleanup:

Cylinder 1 as found:

Thanks in advance!

Bryan
'82 GL500 SilverWing

[Rambozo]

Not bad at all. Maybe a little Scotchbrite or steel wool, if you want, but not really needed. Check the valve sealing while you have the heads off. You can pour solvent in the intake and exhaust ports and see if any leaks into the combustion chambers. Scrape all the head gasket remnants off and check the head and block for flatness with a straightedge. I don't believe the OEM headgaskets are available anymore. I've been told Randakk's has a good alternative.

[Track T 2411]

Here's a link on ebay for OEM head gaskets. From the looks of it, Rambozo's correct, as the major parts houses list the OEM # as unavailable. I might say that an 1100 gasket would work, as the heads are identical; the 1100's just have a slightly larger bore, so the gasket ring would be slightly larger diameter. I can't say with assurance that this would not be an issue...

https://www.ebay.com/itm/174877324740?m ... media=COPY

[LLRelease]

Thanks for the help! I purchased a valve spring tool and valve lapping compound. I will try to get OEM head gaskets.

I am strongly leaning towards putting it back together to see how she runs. If I decide to pull the engine out and split the case to hone the cylinders at a later date, will I be able to reuse the head gaskets? At $75 ea., this is an expensive repair!

[Track T 2411]

No, you won't be able to reuse the head gaskets. There are also two small o-rings on the oil orifice you'll need to replace.
IMhO, a light 'buff' as Rambozo suggested above (and a thorough cleaning after) would be my choice. I have read of people doing a light hone 'in situ.' Splitting the cases is a major undertaking. Put her together and enjoy the ride!

[Rambozo]

You don't want to hone without removing the pistons as you will leave grit behind that will just cause wear. Check the valve sealing before lapping you may not need to do that at all. Typical auto parts store lapping compound is way too coarse. My favorite is Timesaver as it breaks down and gets finer as you work it. Clover is another good brand. You want around 600 grit. And again, afterwards everything must be cleaned spotlessly and flushed with plenty of solvent or water depending on your cleaning products.

[LLRelease]

What is the best way to leak test the valves? I did some research and it seems some pour the liquid in the top of the upside down head to cover the valves. Others pour the liquid in the intake or exhaust port to see if it leaks through to the top of the cylinder head. Also, should I use water, gas, or something else? Thanks!

[Rambozo]

I am in the fill the ports camp. Much easier to see leaks into the chamber. I usually use solvent (aka mineral spirits). Diesel would be a good substitute. I know some use alcohol, but like gas, I think that's too flammable, especially the vapors.

[LLRelease]

I have mineral spirits. I was a little concerned about leaving a pool of gas to leak out. How long should I leave the mineral spirits in the port? Also, do you recommend removing the carbon from the valves and head?

[Rambozo]

It only takes a minute or so. It will either leak or it won't. As to removing carbon, it depends. If there are deposits thicker than 1mm you should probably clean it up. Thinner than that, there is no real point as it will just come back when run. The back of the valves can get pretty bad if the stem seals are junk. Based on the cylinder pics, the engine looks pretty good. If you have the tools, changing the stem seals will be nice. Otherwise, I bet the heads are good to go back on for a lot of miles. If you want, you can post some more pics.

[LLRelease]

The carbon build up appears to be minor. I had read about oil pooling in the left side cylinders when parked for extended periods on the side stand, but was still surprised to find a gooey mess in cylinder #2!

[LLRelease]

Any suggestions for removing the leftover material from the head gaskets? This stuff is stubborn and I don’t want to get carried away with a razor blade and scratch the sealing surfaces. I am going to get a plastic scraper. Is there a solvent that will soften the old gasket material. I tried a gel paint stripper, and the old gasket was unaffected.

[Rambozo]

At one time there were chemicals to help with that, but I haven't seen them in a long time. A scraper is usually the best way, just keep the angle as low as you can to avoid scratches. Another option is to tape some emery cloth to a piece of glass or other perfectly flat surface, and rub the head on that. As a bonus that will also show you if the head is warped as some places won't touch.

[LLRelease]

I removed the valves on the right cylinder head after the leak test for all 4 valves failed. There was a significant amount of corrosion- especially on cylinder #3, so i am lapping the valves. I started with the exhaust valves. I have read to be careful because the valves are surfaced hardened, so I used only light hand pressure. The seats look a lot better, but there is still some pitting and the valves are still leaking. Is it OK to lap some more, or should I look at cutting the seats? I don’t want to spend money on another tool if I can help it. I do have a spare head, so I could use a different / sacrificial valve. Thanks!

As found

After lapping

[WingAdmin]

You've got to get that seal. If it's pitted enough that you're still getting leakage, that exhaust valve is just going to burn, and then you've got a whole other problem.

[LLRelease]

Thanks! That is what I thought. Any suggestions on how to remove the pitting on the valve and seat? I am concerned that lapping again will damage the coating on the valve. I was thinking of using a valve from a spare head as a sacrificial lamb for additional lapping / grinding of the valve seat. I could then do a final lapping with a fine compound to seat the original valve.

Nothing about this project has been easy, but I will keep moving forward and look forward to hearing it run!

[Rambozo]

Lapping won't true things up, it just averages the two uneven surfaces. If the seats are pitted, time to send it out for a valve job.

[LLRelease]

I found a local machine shop that gave me an estimate of $200 for cutting new valve seats and grinding the valves. Is this a reasonable price?

I told the guy the valves can’t be ground, so he said I may need some new valves. If that turns out to be the case, is it possible to find good quality and affordable non-OEM valves? The OEM valves are $50 and $120, which are outside of the budget assuming I will need more than one.

The costs are adding up and there is still a chance the rust in cylinder 3 will cause low compression. Should I start looking for a used motor?

[LLRelease]

Hi All,

I very much appreciate the help and support from this forum!

I decided to clean up the cylinder wall to smooth out any rough spots and better assess the extent of the damage. Below are before and after pictures.

I used 800 then 1500 sandpaper wetted with WD-40 and was very careful to get all of the grit and rust out. I used a circle cuter to make a tight fitting barrier at the piston, and flushed many times with WD-40 then brake cleaner. Finally, I coated all of the cylinders with oil and I manually rotated the engine to push any remaining debris then flushed some more. I feel good about getting all of the debris out, and I don't think I made it any worse as I can still see the original cross hatching.

I am at a point where I need to decide whether to move forward with this motor, or find a new one. I am tempted to put it back together and see how bad it smokes / burns oil, and check compression after a couple hundred miles. However, I am hesitant to risk having to replace the head gasket again after paying $80 each for OEM.

Should I try a less expensive gasket like the Athena set from Randaak's? The downside is that if the motor recovers and runs well, I am left with the OEM gaskets (which is OK), and I may have to redo the job if the gaskets don't hold up. I did purchase new OEM valve seals as well, but I think these can be reused if I find another engine.

Before

After cleanup

[RobbyMoto]

Hi LLRelease

Not sure of any way to verify compression without re-assembling and trying it.

I used Randakk's Althea gaskets on my '75 and no problems.

For removing the gasket I bought a motion pro gasket scraper and loosened the old gasket material with carb cleaner. It was quite a labor intensive job. Once I got the gasket material off I sanded very conservatively with some fine grit paper and used a straight edge to do a quick check for true-ness. Applied the Randakks gasket, torqued down the bolts and it sealed fine. It has compression. I cant speak to how the gasket will hold up over time but seems ok.

Make sure your dowel/ locator pins are still reuseable.

One thing to watch out for is that the old gasket material doesn't get into the coolant channels, which could cause problems later with clogging.

You can use a flashlight in the intake to see if there is a gross leak in the valve seat (bent valve, etc.). For the final leak test after lapping and re-assembly of the valves I used water in the chamber of the head. Left this for 1 hour and bone dry so i assume the valves were leak free.

Hope that helps.

[LLRelease]

I decided to split the cases to hone the cylinders, but have run into a roadblock trying to remove the main driven gear shaft. The Haynes manual says to tilt it up from the front end, but the end cap and / or shift fork (see arrows in photo) seem to be in the way. I tried putting it in gear but no luck. I am hesitant to forcefully remove the black end cap as it appears to be easily damaged. I am at my wits end and hope someone can help. Thanks!

[LLRelease]

I was able to remove the shaft with the shift forks, and pry the end cap up and out.

[LLRelease]

11/6/2024 update: The engine disassembly is complete, and the cylinders look good after honing. I measured the bore to make sure I didn't remove too much material. New rings installed. The old rings were stuck pretty good and may never have freed up.

I am currently rebuilding the oil pumps.

I also stripped the bike down to the frame to repaint it. It's been a much bigger project than I hoped for, but I keep telling myself it will be worth it in the end!

The pictures below were taken before I removed all of the old head gasket material.

[Rambozo]

Looks good. I'm curious, what was the final bore size and how much taper and out of round?