Thrust plate screw...you suck....

[bcssrmz250]

I've worked on this thing for days.  Impact screwdriver has failed, correct bit and all.  Screws stripped and I'm not sure what the next best step is.  Screw extractor kit?  I'm so mad at Yamaha right now.  Isn't this thing only like 0.5" long, and can I just drill it out?  Just trying to remove the valves so I can press in a new dowel pin.

[arnego2]

a chisel and a hammer, put the chisel sideway onto the remaining screw and wack it, a few hits and it should loose itself. good luck

[Hans Schmid]

I would use a dremel and cut a flat blade screwdriver slot...

[kijen]

Yes to the dreml cut a slot for a flat blade screwdriver. Patience is key

[UncleLuke]

Did you use a JIS screwdriver?

[moto2000]

a chisel and a hammer, put the chisel sideway onto the remaining screw and wack it, a few hits and it should loose itself. good luck

 

Yep...chisel will turn it out quick

[BRM]

I would say that is operator error not yamaha error.

Cold chiesel and hammer works for me in those situations.

Also wire cutters

[1987CR250R]

Got access to an acetylene torch?  Rapidly heat the head of the screw until it glows red.  This anneals the screw which removes the tension in the threads and allows it to be backed out almost with your fingers.  It also melts down any retaining compounds such as Loctite that may have been used (Most Loctite products release between 350 and 450F).  It should back out easily from that point unless it was overtightened to the point the threads are distorted or bottomed out in the hole.  Otherwise, Craftsman Bolt-Outs (I know "As Seen on TV") actually work extremely well for this case.

[MANIAC998]

Got access to an acetylene torch?  Rapidly heat the head of the screw until it glows red.  This anneals the screw which removes the tension in the threads and allows it to be backed out almost with your fingers.  It also melts down any retaining compounds such as Loctite that may have been used (Most Loctite products release between 350 and 450F).  It should back out easily from that point unless it was overtightened to the point the threads are distorted or bottomed out in the hole.  Otherwise, Craftsman Bolt-Outs (I know "As Seen on TV") actually work extremely well for this case.

We call that a "Hot Wrench"! And it works almost every single time!

[RiderX]

If heat doesn't work try carefully drilling the head off.

[arnego2]

Heat on the cylinder? Apart from the seal sitting behind the PV shaft there is that possibility of developing an issue of distortion.

[1987CR250R]

Heat on the cylinder? Apart from the seal sitting behind the PV shaft there is that possibility of developing an issue of distortion.

 

That is why you HAVE to use an acetylene torch and you HAVE to heat it quickly.  Drilling the head off the screw also works but with such a small screw its kind of a pain to recover the remains of the bolt.  You have to use tiny drill bits with tiny easy outs.

[jesel]

A small vice grip worked for me. Then I replaced the screw with a hex head bolt for future service.

[PETE24]

yamaha is mad at you for working on a dirty bike

[bcssrmz250]

I would use a dremel and cut a flat blade screwdriver slot...

 

Worked perfectly.  Thanks Monk!

 

I would say that is operator error not yamaha error.

Cold chiesel and hammer works for me in those situations.

Also wire cutters

 

This issue is common on Yamaha 2-strokes....funny how a simple 8mm hex head would've probably kept this from happening.

 

Now I'm trying to press in the new push-pin; I referenced an older thread where most people used a bench vise.  Any advise from folks having done this before?  I really don't want to break a valve considering they're $$$.  Also, I purchased new pins that have slits in them for contracting, and I have one that seems the perfect size.  However, only one of the original solid push pins has come out.  Should I replace both while I'm in there or will one be fine?  The main reason I ask is they're different weights; otherwise I'd probably leave the stocker in the unaffected side since it's not loose.

[ldon400]

See if you can grab the head with vice grips. If you cannot, cut a slot for a flat bladed screwdriver with a dremmel. If you use the red wrench Be Careful.  Easy outs are nice, just be sure you get the drill hole centered and drill STRAIGHT. Off center and not straight will turn into a five tylenol day. Good Luck.