Re: Yamaha QT50 crank seal replacement

Christopher Kimmel /
This single post is part of a larger thread. Start from the top or view this post in context.

From the link to add this info to our site:

Should have done this FIRST. Any of you with an old moped or ANY 2-stroke change crank seals from the start. If it sucks on the left it will get air in and mess up your attempts at jetting. Sucks on the right you pull tranny oil in and burn it. Mine was doing this and steadily getting worse.

Doing crank seals on my 81 QT50 (60) I looked high and low on the internet. Couldn't find if this could be done in the frame without separating the crankcases......IT CAN.

Service manual has a complete disassembly of the engine but doesn't tell you it's not needed for crank seals. Left side you have to pull the flywheel.

If you don't have or get the right tool Use this: ... 66868.html Automotive pulley puller. $13 from Harbor Freight.

Just also buy longer bolts and nuts to hold the jaws on (in one review on HF website). Be careful inserting the puller jaws in there are magnets and coils back there. If you're careful, no problems.

My flywheel (and crank seals) are original. Took some work to break that flywheel loose.

Remove the timing plate. BTW you'll need an impact screwdriver. Lots of JIS screws.

Take a small drill bit and slowly, carefully drill a hole in the crank seal. Crank seals are metal inside surrounded by rubber. The bearing is right behind so be careful. Run a wood screw in the hole and pull the seal out. There are videos online to watch how to do this.

For right side drain oil, remove cover, try to save gasket, if not order one.

Put an all copper penny between gears and break the crank gear loose.

Remove clutch, primary gear and all else in the way. This seal you can pry out carefully with a small screwdriver.

Drive the seals in squarely with a large washer and long socket. Or anything that will get the seals installed flush and straight.

This single post is part of a larger thread. Start from the top or view this post in context.

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account