Always sad to see an engine in this condition.
However, help is at hand and we have the tools to make it all nice and
new again.
This chap wasn't sure why it stopped going, but if you have a look at
the pics you'll see why. It could have been a lot worse, just quietly.
Once the cases are separated it's important to measure the web to web
(see pic 3) with great accuracy, for when it goes back together if the
rod doesn't have enough side clearances it will be back with the same problem
very quickly. You need a good press to push it apart and make sure you're
not standing to close in case something flies out.
Putting the new rod kit in is very tricky - I have seen guys damage
rods pressing things together incorrectly. Once it's together and the conrod
side clearance is spot-on then it needs to be trued to within .05mm at
the end of the shaft, that is both ends.
See pic 10, there's a big copper hammer there ( I like to call it my
persuader), because we hit the web to move it all into place. Ever seen
those medical shows where surgeons are drilling and hammering, it looks
rough when in fact, done correctly its very accurate. Again this is very
precise work, one wrong move and it's all over, very important to get the
run-out within .05mm to ensure long life and minimal vibration. This job
is best left to the experts.
Crankshaft main bearings are replaced - they also need to be carefully
pressed into place, along with the crankshaft, then you can fit the cases
together make sure the crank is not stressed. Always make sure it turns
freely once the case are bolted together, if it doesn't pull it apart,
check everything and start again.
/ "feel the difference"
Article on a WR/YZF250 Hotup
Article on a WR450 Hotup
