"new" 1971 Yamaha AT1

Recently aquired a 1971 Yamaha AT1 125 (photo below...hopefully!). Runs and is complete, except for the side emblems and the "guts" in the exhaust. First 2-cycle bike I've had since the late 1960's.

A couple questions...it has Auto-lube but I'm not sure it's working. Therefore I'm running a 32-to-1 oil mixture, using outboard 2-cycle oil. Is this a good mix to use...or should it be richer or leaner? Is there a good way to check if the Auto-Lube system is working?

The exhaust is VERY noisey. Hopefully I have a good complete exhaust coming from eBay tht will make it quieter and keep th neighbors from throwing rocks at me. if not, does anyone cut these apart and rebuild them with the proper baffles and silencers?

Finally, a question that has nothing to do with motorcycles...anyoneelse out there know what the "OCCO" on the red OCCO sign stands for?

It's easy!!!!!!

Put your pre-mixed gas in the bike.......

Pull the auto-lube hose off.........

Start the bike and rev it up..........

Clean-up the oil that came out of the tube with shop rags......

Put hose back on and run bike with straight gas in the tank.....

Easy!

I would use a better grade of 2 stroke oil, outboard engine rely on water cooling too.

the thing looks incredibly stock. looks like the screw is missing on the back of the exhaust so the baffle might be missing = loud.

I may be wrong, but my 76 DT125, has not only the expansion chamber part of the muffler, but a spark arrestor muffler thingy that attaches to it, routes inside the rear shock and out closer to the rear of the fender. You might be missing the actual muffler.

Looks nice, i gottta get mine running again!

on this model it should just have an internal removable arrestor/baffle. that one will be loud

Agree about the baffle likely being missing. The first thing lots of folks used to ddo it take them out, and without it the bike is very loud and lacking a spark arrester. You're also missing the tank badge, but it looks amazingly complete otherwise.

The autolube system is usually very reliable and is likely working OK but nake sure you check it to be sure. Running premix is fine for racing where you're running WOT most of the time, but if you're just putting around you'll foul plugs a lot more often than with the autolube system (in my experience).

Keep the air filter clean, use an excellent grade of oil, and those things will last a long time.

Nice bike!

As far as the autolube goes just make sure the throttle cable which runs to the oil pump is adjusted correctly. That way at least you know that the correct oil/gas ratio is being delivered at all RPM's. Probably would be a good idea to disconnect the pump and take it apart and clean it along with replacing/cleaning the hoses. That way you'll know that there isn't any debris anywhere clogging or restricting the oil flow.

I have the service manual for this bike in a .pdf file if you'd like I can upload it.

I did check the oil pump today and it does seem to be working afterall.

I do have a Chilton's Manual covering this model (among many other) but it does leave a lot to be desired, so I would definitely appreciate getting a more factory published manual. How do I do this...send you a personal message with my email address?

And speaking of the Chilton Manual, I was reading a description in it of how to bleed the oil pump and the description doesn't sound exactly correct. It says..."remove bleed screw, then turn the pump starter plate until no more oil comes out". Shouldn't that be "till no more AIR comes out"?

Thanks for the help.

Sent! Good luck.

Nice bike
As for the "Occo" sign. All I got as probably did you is air coolers and beauty products. And I used Occo oils. Occo petrolium products. And Occo pruducts.

I put the question about the "OCCO" sign out to see if there might be any others on here who might be from Iowa, USA...especially NE Iowa and remember the product. "OCCO" stands for Oelwein Chemical Company, which sold farm feeds and maybe other farm products like seed, etc. Oelwein being Oelwein, Iowa...a small town in NE Iowa. Wouldn't mean much to anyone unless you grew up a block from the distributor in Oelwein and watched a lot of OCCO trucks go by in the 1950's. It may no longer be in business or maybe under another name.

Great bike. That old AT1 reminds me of my Dad's. Do you still have it?

I found this artifact on a ride through Suntrana, near Healy, Alaska.


Suntrana was an old mining settlement and is now a ghost town, graveyard of old cars, trucks, snowmobiles and this tank. I wonder what else is decaying into the woods out there.

Your bike is a bit more complete. Dad had one of those.

Piston

My fifteen year old just bought a "barn Find" 1973 125 AT1. It had no spark until about an hour ago when we discovered a blown fuse. The fuse had kept everything electrical from working, probably for the last 14 years since somebody disconnected; removed, the rear brake light switch and maybe touched the power wire to ground. It has us confused for a while because the biggest power source went from the positive side of the battery to some type of round device. Well the round device turned out to be the starter solenoid! It's has an electric start! After that we looked on line for a schematic, tracked down the main fuse, it was blown, replaced it with the factory spare, we have power and spark.

It's very dirty, has 735 miles on the clock, who knows, and will almost certainly need a carb rebuild.

We started a parts list.

It weighs nothing....I can't wait to get it started so he can ride it.

Here's a good link. This forum just started up a few months ago and has a bunch of information on the Yamaha Enduro's.

http://www.yamaha-enduros.com/

Just because your shop manual shows and tells you to unscrew the short section of your lower fork leg that holds the fork seal; doesn't mean you should get lazy and try.

If you do you will ruin the race your fork seal presses into, ask me how I know.

1973 AT3 fork seal race is an integral part of the outer tube, it does not attach with a threaded section. The fork seal is held in place with a spring clip and a washer.

I just went by the book and cost myself an outer tube; right side.

There's a lesson for my kid hear someplace, I hope it's not that Ebay will fix a screw up.

EXCEPT, we repaired it this morning when cooler heads prevailed, using a large brass mandrel with ball peen hammer.

I got some really nice brass round stock from a scrap table lamp I found in the trash.

back on track.

We put new tires on this weekend. This gave me a chance to have a sixteen year old remove and then spoon on some new rubber with tubes. He went through two tubes on the front tire. A new one we had purchased and the existing ancient tube. We bought two mew tubes locally giving him the chance to get it done; both tires with three tubes.

It took some effort but I finally got him to work on top of the old tire on the ground. He figured out that 90 percent of the work is by hand and then last 10 percent is very gentle force with a flat spoon only.

When I was a kid at sixteen it would take me and two friends and we would use big screwdrivers, we all knew that a mistake would cost us riding time so it went carefully.

After that when we went into reassembly mode we noticed that one of the rear brake shoes had delaminated, so we are again waiting for parts.

This was supposed to take two weeks!

1973 Yamaha AT3 125, we are at $620.00, still have not fired up the bike.