07 wr450 help

5 replies to this topic
  • Alb84

Posted December 11, 2013 - 08:14 AM


Hi guys

More questions I'm afraid.

Seems the seal on my clutch rod needs replacing, does anyone know how to do this?
Looks like it can be done from the outside but I have no idea.

Also have coolant in my bash plate but can't work out where it's coming from, any ideas?

  • GuyGraham

Posted December 11, 2013 - 10:28 AM


clutch actuating arm seal can be done after removal of the clutch actuating arm

the clutch push rod holds the arm in, so you need to remove this first. Remove clutch cover, remove clutch pressure plate and pull out the push rod

The actuating arm will pull out now

Just lever the seal out


Your coolant is coming from the water pump weep hole, located on the underneath side of the water pump

The seal on the water pump has has failed / is failing. Most likely weeps at engine start up then stops when engine gets warm


Plenty of threads on here about changing it


  • Alb84

Posted December 11, 2013 - 12:39 PM


Thanks for the reply.

I did check round the weep hole for the water pump and there was no sign of a leak.
However the coolant is below and further back from the weep hole.

Is it possible its dripping out and leaving no trace at the waterpump weephole?

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  • GuyGraham

Posted December 12, 2013 - 12:22 PM


you wont see any trace at the weep hole

start engine from cold and watch for the leak

  • Alb84

Posted January 16, 2014 - 09:36 AM


Thought I'd just post an update.

Seems the coolant was leaking because the muppet that had the bike before me had attempted to remove the water pump without taking the side case off which just resulted in grinding out the square drive on the balance shaft.
Meaning the water pump wasn't working at all and the coolant was boiling out.

A new balance shaft was needed which ment a complete engine rebuild. Had a funny feeling about the bloke I got the bike from so I guess the lesson is if it dosnt feel right walk away.

Anyway got the bike back and it's 100% so hopefully I'll get to ride it now.

Next thing is supermoto wheels

  • grayracer513

Posted January 16, 2014 - 10:51 AM


For anyone else finding themselves in this predicament, be it known that it IS NOT NECESSARY to remove the engine or split the cases to replace the balancer shaft on '07 or later WR's, or YZ450's from '06 to '09 (this may also be true of the later YZ450's but I haven't looked at that situation yet). 


FIrst, drain the oil and coolant, and remove both the right and left crankcase covers.


Next, remove all the drive gears and weights from both ends of the shafts, then remove the retaining plates from over the bearings.  Place the weight retaining nut on the left (ignition) side of the shaft and run it on until it's flush with the top thread.  The shaft must be removed from left to right.


IMPORTANT: During this process, the crank must be kept at about 60-90 degrees after TDC so as to position the "short side" of the crank nearest the balancer shaft.  The crank counterweights extend too far outward from the main bearings to allow the shaft to move past it.  The area ~45 degrees or so on either side of the crank pin is closer to the crankshaft center, and that part of the crank is also narrower, thus has more clearance with the balancer. 


The bearings are a slip fit on the shaft, but they are press fit into the cases.  It will take a pretty good swat to "break loose" the water pump side bearing, so use a sturdy punch that will center itself on the left end of the balancer, give it a couple of good sharp whacks to get it started, and begin working the shaft toward the right side, driving the shaft and bearing out on that side.  A bit of prudently applied heat may help here. 


IMPORTANT #2: As the shaft begins to move, the bearing flange on the bearing flange on the left end of the shaft will come close enough to the crank to run into it.  This will occur just about the time that the bearing is about to become free of the case on the right side. TO AVOID CRANK DAMAGE, rotate the balancer shaft so that the key way on the left end faces back toward the crank, as there is a flat ground into the bearing flange that allows the shaft clearance to slip past the crank (see the attached picture).  The shaft can then be driven the rest of the way out until the bearing is free, and then removed from the engine.  At least the water pump side bearing should be replaced following this procedure, as the races are likely to have been damaged by hammering on them. 

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