Rear Head - Removal/Replacement Thoughts and Experiences

[RedRider]

Goldenrider and I got the rear head reinstalled and timed up yesterday.  Hoping to have it roadworthy later today.

Hopefully, no one will need to deal with this.  But if you do, here are some things we found (in no particular order):

- The rear head can be removed without pulling the engine.  You get about an inch of clearance and it comes out easily. Don't know about the front head, but it looks like it should make it.

- The Yamaha replacement head gasket has a coating already on it.

- The inside edges of the head casting are very sharp,  This makes it very difficult to slide in the long chain guide (front side).  We used a jeweler's file (Harbor Freight set is nice) to put a small chamfer on the inside edge.  This allowed the chain guide to slide in much easier and without damage.  It is a really tight fit getting this guide in place around the frame neck.

- The small rolled positioning pins for the cam shaft caps are easily damaged - AND VERY SHARP.  We found using the smooth end of a drill bit to roll the edges back out works.  A 1/4" bit should just fit inside.  Be wary of these pins while spinning the wrenches.  They can, and do, leave a nasty cut on your knuckles. 

- Put a little oil on the pins before installing the caps (you are also to oil the journals and inside of cam caps).  This helps the caps slide on much easier.

- Setting the correct timing positions is a PITA.  It took a couple of tries as the positions of the cam shafts move when the chain guides are put in place.

- Use a paint pen to mark the cam shaft sprocket and chain position.  This helped to judge moving the sprocket teeth one tooth in the chain.

- Having never done this before, we preinstalled the head with the old gasket just to see how it would go.  This was a good thing as we weren't experimenting with the good head gasket.

- Have a good service manual.  We had both a Yamaha Service Manual and Clymers.  They were in general agreement but one or the other will have the illustrations/pictures you want to see.

- Don't set the labelled muffin tray of bolts on the floor next to the bike. 

As we were really concentrating on what we were doing (radio-and-TV-off level of concentration), pictures were not taken.  Sorry.  I will add additional points to this list as I think of them.

RR

Edited March 28, 2021 by RedRider

[Marcarl]

All good things to know for anybody in the future. Hopefully nobody will need it, but then we are all humans and machines don't always co-operate.

Thanks for doing the write up.