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mmcdan

'06 YZ450F Counterbalancer

12 posts in this topic

My YZF is eating water pump shafts, bearings and seals on a regular basis. About the only thing I can come up with is the end of the counterbalancer shaft that drives the water pump appears worn (internally where the water pump shaft makes contact). When installed, I can turn the water pump impeller/shaft about 1/4 turn back and forth before it makes contact.

Can the counterbalancer shaft and bearings be changed out without splitting the cases? Any other suggestions?

Thanks in advance.

Mark

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Can the counterbalancer shaft and bearings be changed out without splitting the cases?

Doesn't look like it.

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My YZF is eating water pump shafts, bearings and seals on a regular basis. About the only thing I can come up with is the end of the counterbalancer shaft that drives the water pump appears worn (internally where the water pump shaft makes contact). When installed, I can turn the water pump impeller/shaft about 1/4 turn back and forth before it makes contact.

Can the counterbalancer shaft and bearings be changed out without splitting the cases? Any other suggestions?

Thanks in advance.

Mark

i found on my 98 yz 400 that its normal for the shaft to do that:bonk: i ordered a new counter balancer because i was sure it was worn.i was amazed when i went to install the new one it was exactly the same as the old one.i just replaced it anyway along with the water pump shaft,seals etc.oh and i was able to change the shaft without splitting the cases.

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Are you sure "1/4 turn" isn't an exaggeration?

What's happening to the shafts, exactly?

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Thanks for your responses.

No exaggeration, it's about a 1/4 turn in either direction with the side case on, impeller mounted and water pump case off.

What I'm seeing:

- Water pump turning as described above.

- Water pump shaft has some "play" to it when mounted in the case with seals, plain washer and bearing. I can push-pull on the impeller and get about 1/16-inch movement (from impeller flat against the pump case to a gap between the backside of the impeller and the pump case).

- The water pump shaft is wearing on the large diameter portion where it passes through the seals within 4 - 6 rides of replacement.

- Counterbalancer has similar "play" as described above. I can push-pull on the gear and get a small amount of back-and-forth movement and a pretty good "thunk" sound.

- Rust inside the counterbalance shaft on the water pump driven end.

As for removal of the counterbalancer, the manual is a bit vague. I see that the bearings are held in place with tabs on the outside of the cases (right and left sides) and the tunnel where the shaft passes through the case is a pretty straight shot with no obstructions.

Mark

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As for removal of the counterbalancer, the manual is a bit vague. I see that the bearings are held in place with tabs on the outside of the cases (right and left sides) and the tunnel where the shaft passes through the case is a pretty straight shot with no obstructions.

Mark

That's the point I missed. If that's the case, you should be able to remove the weights and gears from the shaft, remove the bearing retainers, and drive the ball bearing out with the shaft. Note that many of the YZF balancer shafts have one flat side in the center, and have to be in a particular position to slide past the crank.

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my water pump is leaking coolant thru the weep hole. this has not happened to me on either of my YZ's. I used the TT search mechanism, hoping that NO ONE ELSE had this issue. Unfortunately, I found this thread. (I thought this was an earlier CRF450 issue--pffft)

Gray, since this is an unknown issue at this point for me, can you tell me if I dare and just replace the outer oil seal (order the seal now) or, should I investigate the 'free play' that exists on the impellar shaft and go from there?

Time is of the essence with a race this Saturday...

thanks in advance.

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The thing is that the right way to remove the impeller involves removing the right side crankcase cover entirely anyway. The impeller threads onto the impeller shaft (right hand thread) and "simply" unscrews. Many are tempted to crank it off in place, and many of those get away with it. However, the flat tab at the drive end of the shaft was not intended to handle this much load, and can easily be broken off by such shenanigans.

There is a pair of flats on the shaft that allow it to be held with a 12mm wrench, but the case has to be removed to get at them. As you disassemble, remove the impeller cover and check the vertical play at the impeller. It will be excessive if the shaft is a loose fit in the end of the balancer, the balancer bearing is bad, or the impeller shaft bearing is quite loose.

Look for a groove worn in the shaft by the old seal. If it has one, replace the shaft. Always replace both seals (they're too cheap not to).

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Gray,

I have found that my issues with my water pump/counter balancer shaft to be eerrily similar to what MMCDAN's has experienced:

I have found that there is about 1/4" of play in where the impellar shaft seats inside the end of the counter balancer shaft (rotating the impellar shaft left to right). Rust is apparent in the end of the couunter balancer shaft as well. Where the impellar shaft seats inside the end of the counter balancer shaft it has become gawled so much that is clear to see---the recess at the end of the counter balancer shaft has become an almost 'hour glass' shape if you will--obviously it should be square to correctly accomadate the end of the impellar shaft.

So, my first question is can the counter balancer shaft be removed without having to split the cases? (I believe someone else has commented that this is possible??)

Second question really is about how this happened. From my understanding of this issue, it is clear that there is nothing I could of done, to my knowledge, to prevent this from occurring. I maintain my bike impeccably. Oil changed every 2 hours, valves in spec, etc... Ultimately I will have the new counter balancer shaft installed, new impellar shaft, seals. What is to keep this from occurring again? Is it possible that Yamaha had a 'bad batch' of counter balancer shafts? If so, is there any way to determine if this issue has been corrected?

As a rep for a manufacturer I am extremely versed in the trials a manufacturer goes through with a given product. I would also like to add that if this is determined to be an issue with say, the quality of metals used, or the shaft to be known to be a 'little off' if you will, then by all rights a consumer would hope the manufacturer would, at the very least, supply the replacement parts a no cost to the consumer.

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The wear you describe at the balancer is, IMO, clearly caused by one or both of two things:

>The fit between the impeller shaft tab and the slot in the balancer is excessively loose.

> The slotted area of the shaft is not hard enough.

I would agree that that is something that should be considered a legitimate manufacturing defect.

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