Eureka!  I guess 12 13 is the magic number.

So there's my 1974 GTMXA in all its glory.

Working now on getting the gas cap unstuck and removing the portion of the petcock that didn't come out of the tank with the petcock.  Both are soaking in periodic applications of PB Blaster.

Something is flopping around inside the tank but it doesn't feel like liquid.  I can deal with de-rusing the tank but hope there isn't a tank liner disintegrating or pealing apart in there!
ZT

I see pictures!

So do I, Sneezles.

"Eureka!  I guess 12 13 is the magic number."

And the picture has reached the UK as well!

If I want to "quote", I just copy and paste the relevant section of text at the start of my reply, and put it in italics or such like.  

Re emoticons/emojis, there are some site ones behind the smiley face on the toolbar within the text space. 

Look at you go! 

I love my little GT80B. It's an unrestored original in case you ever need me to check something for comparison purposes or if you just need photos of anything.

Unc said, "And the picture has reached the UK as well!"

Thanks Unc, for your suggested work-arounds.
ZT

@schu says, "Look at you go!
I love my little GT80B. It's an unrestored original in case you ever need me to check something for comparison purposes or if you just need photos of anything.
Schu"

Thanks Schu!  I appreciate your offer and know I'll have many questions.  I just put the GTMXA up on the lift and wondering where to start.  I got the gas cap off and it looks like I will need to use EvapoRust or Electrolysis to clean up the inside.

I'll need a new petcock as the finger (?) tube broke off inside the tank and is stuck in the bung hole.  PB soaking hasn't loosened it up.  I'm thinking that poking it through into the tank with a punch or drift would be better than trying to grab the little stub of tube to pull it out the bottom.  Please correct me if I'm wrong on this.

I also mentioned that the kick starter has never worked on the bike since I've had it.  We always bump started it. The kicker rotates down and springs back up freely but doesn't engage anything.  I can't remember if I put it in the state it is in now but I found a "Yamaha 80" box I had stashed away back in the day.  The box contained a new NGK B7HS spark plug, a shiny thin wire compression spring  (1-1/8"H x 11/16"D) AND what I've recently determined to be a damaged kick start idle gear (353-15651-00-00) that has 7 or 8 broken teeth.



I'm guessing the gear was removed long ago so as not to interfere with the non-functioning kick starter.  I'm not sure of this either.  How do these gears fail?  What may have caused the damaged teeth and will I likely find other damage when I open things up?

And then, how much needs to be disassembled to replace the kick start idle gear?
Thanks for any assistance.
ZT

As for the rusty tank……if it is not too bad you can probably try one of the many tank sealer kits. I have used KREEM tank sealer on three tanks. Two of which are still holding up and one that only lasted a couple months. Just follow the instructions carefully. Opinions on tank sealer kits can be like an oil thread….

As for the petcock….yes just poke or pick at the remains until they free up and fall out. If the tank floor is really bad around the petcock mounting surface you best start shopping for a better tank.

As for the kickstart gear….I’m no expert. I have replaced a kickstart assembly on a different bike but can’t help you on the root cause of your failure. There is a complete assembly on eBay right now. You obviously have to remove the side cover to replace the assembly. You best get a service manual before you get too far into it.

imgur.com/a/p8i9fA8

Ooooh! Schu!
I wish you hadn't posted that link.  I just ordered a new idle gear from that seller and told him I'd be back for more parts as I get into this resurrection.

Nobody pay any attention to Schu's last post.  Please leave those GT80 parts where they are until I'm finished.
ZT

Well folks, I've found the problem with the kick starter on my long-ago, hand-me-down GTMXA.  And now I know why it never got fixed and why it likely became a hand-me-down.  Popping in a new idler gear is not going to cut it.



I don't know if this is a common failure or not; but the idler gear end, of the transmission's "Axle, Drive" shaft (598-17421-00-00), was broken off long ago... about 8mm inside the external boss on the right side case.



It's actually amazing and a testament to this little motor that the case survived this traumatic event when the shaft broke and, once the broken gear and debris was cleaned out, except for the push starting, the little bike was still running good and introduced three families of kids that I know of, to motorcycling.

Other than a DIY "lift kit" on the rear shocks, I think the bike is pretty much all original and worth saving with matching frame and engine numbers and another generation of grandkids coming up.

I'm sadly assuming the cases will need to be split to replace the broken Drive Axle shaft BUT I do keep looking at this drawing from the GT80/MX service manual...



... wondering if the Drive Axle could be pushed out toward the chain sprocket with a slightly undersized dowel to hold everything inside... in place... until the new shaft was pushed back in to replace the dowel.  Could this work?

I'm also wondering, while studying the following drawing...



... how many, if any, of part numbers 18, 19, 20, or 21, are OUTSIDE THE CASE behind the kick start idle gear?

I know I'll have more questions but that's plenty for now.
ZT