XR engine rebuild

Ok, all the parts should be in, so it is now time for the rebuild! I started with the head, cleaning up and shaping all the ports as well as cleaning off some of the flashing around the fins.

 

The head and new valves after Alex did the seats.

 

The right side case apart, getting the new oil pump, tensioner guide and clutch components.

 

I ran into a problem, with the oil ring not fitting into the groove cut in the piston. I am not sure if it was a mis-machined piston, wrong piston or wrong rings, but XR's Only ended up sending me a new piston and rings after verifying that they did fit together (normally they are stored and boxed separately). With that resolved, the bottom end could finally be assembled.

 

Ok, on to the head. Here is a comparison of the stock cam to the Hot Cams Stage 1 cam, and the engine being assembled to check for piston-to-valve clearance.

 

We used solder to display the clearance since it is easier to read than clay and the valves are plenty strong. For an engine with smaller valves, clay would be the smart thing to use.

 

With valve clearance checked and looking good, it is time for final assembly!

 

Progress! The engine is finally back in...

 

Time to bolt on some of the other fun new parts :) Keihin FCR 41 pumper carb.

 

FMF header, midpipe and Titanium 4 silencer (plus a quiet core insert).

 

The engine started fine, though I kept checking for oil pressure and was not getting any. I had primed the oil pump when installing it, but that had been several days prior and likely had drained out. I went through the steps to re-prime the pump, but it just would not take. I finally ended up pulling the side cover off and checking the pump. After removing the transmission feed line and turning the pump, I got a few gurgles and then a steady flow of oil. I reassembled and everything was fine. Perhaps it would have eventually burped the air on its own, but I did not want to risk damaging the new engine if it had not.

 

Finally back in business!!!!!!! I am so excited to have this running again. Super huge thanks go out to Alex Frith for all his work, patience and knowledge during this rebuild :)