Anyone ever see this before?

C

Champion750

XS650 Addict
Messages
100
Reaction score
0
Points
16
Location
Los Banos, CA
What am I going to do? The first inclination is to use an easy out but I'm sure these pins are hardened and pressed in. Not like removing a broken screw. Now here's a dumb question, is it possible to run without these? Seems like its what keeps the crank bearing from spinning in the cases. I am not looking forward to this chore. How am I going to pull this thing out without ruining the hole that it is in? It just amazes me that this sort of thing is even possible.

BTW the pin measures .180 DIA.

Anyone ever encountered this problem before?

Thanks for any help/advice in advance
 
Forgot to add pics :laugh:
 

Attachments

  • IMG_0895.jpg
    IMG_0895.jpg
    178.6 KB · Views: 266
  • IMG_0896.jpg
    IMG_0896.jpg
    152.2 KB · Views: 242
You're correct re. function; the pins keep the main bearings from spinning. I've never seen one sitting flush with the case before--wouldn't recommend running that way. The others look to be correctly positioned, no need to disturb them.

If that case were mine I'd be heading for the local automotive machine shop with it. If you're really committed to a DIY job, I wouldn't recommend an easy out, but you might try this: Clamp the case on your drill press table, drill the pin for a 3 mm. tap, run a screw into the tapped pin, heat the case to 300* in an oven (I wouldn't try heating with a torch, you don't want to warp the case), and pull the pin with a pair of pliers.
 
Strange, it really doesn't look like the pin is broken. It looks to have the same rounded edge on top as the other pins.
 
Yep, doesn't look broken or deformed. It would be interesting to know the history of that motor; I'm guessing this isn't the first time those cases have been split.
 
It's possible it could be heated and merely lifted out with a magnet. I heat nose forks for Cessna Citations that have a 1.5" piston for the front oleo to 250 degrees and the .002 oversize piston falls into the bottom of the recess in the fork. We just hold it in place for 20 seconds and it shrinks and grabs it. Works out perfect because we have time to properly align the Schrader valve hole in the piston with the one in the fork.
 
grizld1 said:
Yep, doesn't look broken or deformed. It would be interesting to know the history of that motor; I'm guessing this isn't the first time those cases have been split.
Click to expand...

grizld you are correct. These cases have been split before. I'm guessing the previous builder installed the crank bearing without aligning the pin in the bearing hole then clamped everything down and it just pushed the pin deeper into the hole. I'm just surprised Yamaha made the hole deep enough for this to happen.

So today I tried using a center punch on the pin to mark it for drilling. Not a scratch. Nothing. Those pins a pretty hard. Trying to drill and tap it?.....I don't know. I might have to make some phone calls. I don't know if I want to try this myself. Maybe I'll try heating it up in the oven just to see if it will fall out or come out with a magnet.
 
Yep, try jd's suggestion; the pin may lift right out once you heat the aluminum that holds it. Be sure to check the mating surfaces on the cases and make sure they're flat. If the PO cranked down hard enough on the cases to drive that pin flush, he may have warped them.
 
You mean just like a body shop dent puller pin welder 2many?

Another "suggestion" drill a small hole from the back side, use a chunk of drill sized rod to tap on the back side of the pin?


case pin 001.JPG case pin 003.JPG


Don't run junk chain and sprockets, why this engine died. When the chain slipped a tooth it cracked the upper case.

case pin 004.JPG
 
When you break off a bolt flush with the surface they often weld a nut to it and then unscrew the bolt.

How about welding a nut to the pin and then pull on the nut?

Small nut over the pin protects the case as you weld down inside.

Need a good welder though.

Like JD's idea of lots of heat. With a rare earth magnet it may just pull right out.
 
Why not just build the pin up with a bit of weld, shape it enough to hold the bearing and leave it. 2 of mine were pushed down, but enough to hold the bearings..got lucky i guess.
 
Ok so after some thought I decided to try gggGary's suggestion first by drilling a hole behind the pin and then trying to drive the pin out from there. Then, when I'm poking around in there trying to get a fix on where to start drilling, look what I found!! The pics show some cracking on the back side of the bearing boss. The arrow shows a hairline crack below the machined surface.

Soooo.....I drilled the hole then put a little screw down in there that I ground down to a point and after some light tapping the pin did indeed move to the proper position. Quite easily I might add which concerns me a little. I'm worried that when the engine is hot that pin might move.

So now my question to the almighty forum vault of knowledge is this: should I have that cracked area ground down and then built back up with weld bead or should I leave it the way it is? I realize that the crank cheeks come pretty close to that area of the cases so whoever does the work might want to have the crank handy to check for clearance. What do you all think?

P.S. I can't thank you all enough for all your help. I never would have been able to solve this problem on my own. Many heads are better than one :)
 

Attachments

  • IMG_0909.jpg
    IMG_0909.jpg
    141.6 KB · Views: 198
  • IMG_0915.jpg
    IMG_0915.jpg
    160.9 KB · Views: 181
  • IMG_0913.jpg
    IMG_0913.jpg
    155 KB · Views: 210
  • IMG_0914.jpg
    IMG_0914.jpg
    139 KB · Views: 183
Well that is a big chunk of steel embedded in the case there to support the bearing. How long since the last overhaul? That crack hasn't hurt anything yet. If I were going racing I'd be looking for different cases, if it's a street cruiser... Carry on. Might try a wanted in the local CL MC parts and see if there are any engines kicking around cheap.
 
Myself, I'd be gyrating between two options.
- Weld-fill the hole
- Conduct penetrant-dye test in that area to see how far the crack has progressed.
 
That pin also index's the bearing to the oil gallery.
 

Similar threads

C
XS750 question, starter not engaging neutral
Replies
4
Views
639
Bruno_c
B
toglhot
Single points conversion, how to.
Replies
0
Views
522
toglhot
toglhot
Britman
Dreaded Cam Chain Guide
5 6 7
Replies
131
Views
9K
zrx1100
zrx1100
C
Electrical gremlins - blown main fuse, melted connectors, bad neutral switch, and dead turn signal
Replies
6
Views
498
5twins
5twins
M
SOS ... Some crank truing help required please!
2
Replies
20
Views
4K
MikeDodd
M
Back
Top