• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

1980 GS1100ET pistons/moly coating question

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

Guest
Hello, Merry Christmas to all...

I am in the process of doing a top end on a GS1100 ET. I bought this bike ($3k/10k miles indicated), seemingly straight and solid, albeit a bit faded and down on power, attributed to CV carbs with pod filters, running rich. That was the first thing I dealt with. (And in my parts hoard I found a GS1000 airbox from way back when, shared with this bike, thumbsup.....)

Opening up for valve service, I found that the motor had been molested, 15 aluminum retainers and one OEM steel, cams in bad shape, so it came apart.
All new valvetrain components have been sourced, found some high volume oil pump gears along with a lockhart cooler and the head is at EdCo in Petaluma California.

Bore is stock, cylinder nice (although it would appear it sat for some time), ring end gaps measured ~.010-.012", well within spec. I was planning on honing it myself. (new OEM rings in hand)
But I realized today during parts cleanup and inspection that these pistons were coated from the factory. The coating is uniformly gone from all the pistons except in the wristpin region. Otherwise they look pristine.
Can anybody tell me if this is a problem for these motors? The coating seemingly very thin, thinner than the armorglide on the latest wiseco (and other) pistons.

And an internet search doesn't reveal any info on the (GS coating) subject. Or the armorglide for that matter.
Any info and real world experience appreciated. Seems like it shouldn't be a problem with modern oils, high volume gears, and a cooler.
Not thrilled at the prospect of throwing another >$1000 at it.


And if anyone is looking for a Martek440 ignition, free to a good home...
 
The stock pistons were not coated. Can you post up some photos?

You might want to measure out of round, taper, and piston to wall clearance. No more than .0010" out of round or taper allowed. Piston to wall clearance is less important; the manual states that .0047" is the service limit. As long as the specs fall inside these numbers, I'd run the engine, regardless of piston coating.
 
thank you for the reply, and see the attached. the gentleman who sold me the GS750 gears and oil cooler mentioned this in passing as we discussed other aspects of my build. but he recalled that it was on later models only..
I will take some measurements this afternoon. but the original finish on the piston is still discernable.
 

Attachments

  • photo60402.png
    photo60402.png
    52.5 KB · Views: 0
  • gs1100 piston coating snippet.png
    gs1100 piston coating snippet.png
    52.5 KB · Views: 0
Last edited:
Thank you. Some improved measuring tools en route, but my inside micrometer tells me the bores are round and well within spec, Ring gauge to verify its accuracy coming, and the pistons will be double checked when the 2-3 micrometer arrives. And ring groove widths are spot on.
It was also suggested that a feeler gauge can also be used with a naked piston inserted in the bore. A new one on me, will explore that tomorrow...

And I saw those ebay pistons, tempted, but not wanting to spend.
 
I agree with Nessism​ about the coatings being for break in. With only 10K miles on it, unless he ran it out of oil, I wouldn't think the bottom end would even be an issue. Best of luck and many miles. ;)
 
You must log in or register to reply here.
Back
Top