Jump to content

1971 ATI 125


richard83642
This post is 1117 days old and we'd rather you create a new post instead of adding to this one. You can't reply in this post.

Recommended Posts

Bike set for 30 years, only 4k miles, blows oil out of case, exhaust,  and smokes real bad. Will use up all the oil in the case in about 15 minutes. Changed piston and rings, no difference. Will start with starting fluid, won't rev above 3k, changed points and timing settings no different. Replaced carburetor,  no difference.  HELP ME PLEASE!

Link to comment
Share on other sites

Do you want an ad-free experience? Join today and help support the Yamaha Owners Club.
  • Moderator

Make?
Model?

Have you checked the valve seals?

You might wanna introduce yourself first...

Link to comment
Share on other sites

  • Moderator

Doesent have valve seats, what it does, or rather did! was have crank seals, they are long dead. I would bet just about every seal on that motor is split or has shrunk to the point of failure. Would be a VERY smart move to fit new crank bearings at the same time as having sat that long they may well be toast so while your there for an extra tenner. Check the other significant bearings too. They can sometimes rust if they have been left without a covering of oil.

Depends on where you are but as you haven't given us ANY real information to work with I'm guessing.

You can get full seal and gaskets from fowlers. Bike has been in production as far as the engine goes for donkeys years, parts are readily available. Cycle parts not so much.

  • Like 2
  • Thanks 1
Link to comment
Share on other sites

  • Moderator

Aaah! The bike is the title!
No wonder I couldn't see any info...

Link to comment
Share on other sites

My bad, Richard here, Meridian Idaho. Would the seals pump oil through the cylinder and piston? Or would seals cause external leaks? I have removed the exhaust and disconnected the injector pump. When I start it it still pumps oil through the piston and out the exhaust port. Any ideas anyone?

Link to comment
Share on other sites

2 hours ago, richard83642 said:

My bad, Richard here, Meridian Idaho. Would the seals pump oil through the cylinder and piston? Or would seals cause external leaks? I have removed the exhaust and disconnected the injector pump. When I start it it still pumps oil through the piston and out the exhaust port. Any ideas anyone?

Good call on the crank seals, thanks. Got them ordered.

Link to comment
Share on other sites

  • 4 weeks later...

Well, after replacing the crank seals,  piston and rings, I found the real problem.  The oil drain plug was too long and plugged the oil passage causing pressure to push oil through the crank seal. Replaced with a shorter plug and works fine. Next problem, pops out of first gear. There is a bolt next to the neutral indicator with a spring on it. Could a weak spring cause the problem. Anyone know what the spring and bolt is for?

Link to comment
Share on other sites

  • Moderator

It's called a detent. The spring and ball work on the selector drum generally so the drum only moves one 'click' at a time. 

  • Like 1
Link to comment
Share on other sites

  • Moderator

Generally.. No. Once it's in gear the dogs on the gears should hold things. It's when these gears wear that gears pop out. 

Sorry. 

Link to comment
Share on other sites

The only thing that I wonder about is the bike only has 4000 miles on it. I have another one just like it with over 9000 miles and still no tranny problems. This bike sat for over 30 years and I just got it running. Is it possible that rust on the gear is not letting it go in properly? What else could do it? I have had both side cases off to replace the seals and everything else looks like new.

Link to comment
Share on other sites

  • Moderator

you can get the dogs recut as race peeps get theirs undercut to lock the gears together under acceleration.

Link to comment
Share on other sites

×
×
  • Create New...