3XV Power Valve Bush

[FZRichard]

It looks like I am also on the hunt for, what Yamaha call, a Holder. It's the bush that the front power valve rotates in on the outside of the front cylinder, part number 3XV-1131F-00-00.

Mine has excessive, and I mean lots, of play and it sounds like the power valve is touching the piston slightly.

I have added a picture, it's the part in the blue circle.

[thump566]

I was going to replace the seals in mine when there was a minor oil weep but was then told that the holders tend to wear first causing the seals to weep so replacing the seals wouldn't totally solve my issue.

I wonder if its possible to use a small shim to reduce the play in the holder, has anyone tried this? I imagine the holders are pretty hard to come by and even then might have some play in them depending on the mileage they have done.

[FZRichard]

I am thinking of turning down the end of the power valve then making a bush to fit over the machined end and be tight in the end cap.

[thump566]

I am thinking of turning down the end of the power valve then making a bush to fit over the machined end and be tight in the end cap.

Not sure if it might be preferable to turn down the holder rather than the power Valve, maybe the more experienced guys on here might recommend either way?

[SouthCoastRich]

Mine has excessive, and I mean lots, of play and it sounds like the power valve is touching the piston slightly.

They all rattle bad 

[vinny]

I was having trouble  with powervalves breaking in the centre . (They were rattly but I wasn't overly concerned as they are know to rattle ,
I actually had two powervalves break so decided to try tighten everything up a bit and see would it prevent any more breakages.
I used a internal pullers to remove the brass  from the holder(  I'd say it might be possible to get it out with just  heat as the aluminium will expand more than the brass )
The Bush  had worn a little  bit plus im sure the powervalves I was using also  had also wear on them .
I made a new brass Bush  that was a tighter fit on my powervalve to compensate for the wear on the powervalve .
Pressed it back into the holder and refitted powervalve  and caps .
It's a good bit quiter now and no more broken powervalves. 

[James P]

I made a new brass Bush  that was a tighter fit on my powervalve to compensate for the wear on the powervalve. Pressed it back into the holder and refitted powervalve  and caps.

What Vinny said!

I would expect the bushes in the end caps to be bronze rather than brass. If the only problem is a worn bronze bush, have it pulled (or machined) out and fit a new one. As a variation, it may be possible to find a sintered bronze Oilite bush of suitable size, with its inner surface coated with Molybdenum Disulphide or other oil-absorbing coating, which can be pressed in (it will be necessary to machine the ID of the existing bronze bush to suit).
If there is any appreciable wear on the PV shafts, they may be able to be repaired by welding and remachining, or by machining and pressing on a bush.

Regards,
James

[SeaR1ck]

Don't expect them to happen anytime soon but the bronze pieces look removable. I asked my machinist mate the other day if he could make some of them and he said yes.

So when it comes time to happen I'll have him make a few sets. Maybe out of something stronger like steel?

[oldiggy]

In the past I fitted a chrome sleeve on the ends of my worn power valves but even those worn at an alarming rate on my 2MA which is why I changed the set up to ball bearings this time. I did consider a slim hard sleeve and needle roller bearings in the end caps. Vinny I am interested as to how you had two power valves break ?

[vinny]

In the past I fitted a chrome sleeve on the ends of my worn power valves but even those worn at an alarming rate on my 2MA which is why I changed the set up to ball bearings this time. I did consider a slim hard sleeve and needle roller bearings in the end caps. Vinny I am interested as to how you had two power valves break ?

All I can say is my power valves were rattling and I took no notice as they all rattle.
I needed to do some work on the exhausts  one day took a look in to check piston and noticed the powervalve was in two pieces .
I put in a replacement powervalve and thought no more of it really until it happened a second time  aproxx 12mths later .
This time the normal rattling powervalve had progressively gotten worse so I wasn't that surprised to find a second broken powervalve.
It's a testament to the design that there was no engine damage from  either breakage .
The only thing i can think may have contributed was Both of the valves were pretty worn and the bush's were worn also .
Since rebushing both cylinders I've had no issues in over a year and the p valve rattle is no longer .


Since