Power Valve Question & Piston Identification. RZ5 Therapy

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tonyhes
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Power Valve Question & Piston Identification. RZ5 Therapy

#1 Post by tonyhes » Wed May 17, 2017 12:24 am

Hello!

I am helping a friend who is recovering from a bit of bad luck by having motorcycle rebuild Monday nights.


We have 2 questions.... which we hope for pro's like you will be very easy! :)

1) The rz500 fiche seem to indicate there are 2 different kinds of power values. And for the sake of keeping things simple... I believe there should be two 1-1 valves and two 2-2 valves. (1-1 & 2-2 Refers to the casting on the PVs themselves). The pair of uppers should have installed a 1-1 & 2-2, and the lowers a 2-2 & 1-1

Now here is the problem... We took the two upper cylinders (reed cylinders) apart and found... two 1-1 power valves. This was NOT what we expected.

What power valves should we be expecting?


2) Can anyone identify this piston. It has a single ring, is definitely not a standard RZ-500, did not have ports in the piston, but did have a crescent moon machines out of the bottom.


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tacky1
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Re: Power Valve Question & Piston Identification. RZ5 Thera

#2 Post by tacky1 » Wed May 17, 2017 1:20 am

I would check the lower cylinder valves. I bet the last builder put the number 2 valves in there side by side. Not the first time this has happened. I had a set of cylinders and the valves were backwards. Number 1 on top and number 2 on the bottom.
Sorry. No idea on the piston.
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1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
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silverstrom
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Re: Power Valve Question & Piston Identification. RZ5 Thera

#3 Post by silverstrom » Wed May 17, 2017 3:46 am

Lower left is #1 Lower right is #2

Upper left is #2 Upper right is #1

The parts list is clear, as you have read.

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jackson.40
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Re: Power Valve Question & Piston Identification. RZ5 Thera

#4 Post by jackson.40 » Wed May 17, 2017 5:45 am

How was the power valve linkage fitted?, with the two no.1 power valves side by side the angle at the end of the power valve for the clamping bracket would be wrong hence the need to have a no.1 and a no.2 power valve side by side.

The piston maybe a YZ125?

Steve

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Rick Lance
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Re: Power Valve Question & Piston Identification. RZ5 Thera

#5 Post by Rick Lance » Wed May 17, 2017 9:21 am

The power valves form the roof of the exhaust port tunnel which should be tapered, constricting toward the pipe (unless some fool ports it to death and removes this feature in the pursuit of NASCAR like flow...). Because of this taper, the valve has a specific orientation in order for the contour to match the port tunnel. If the valve is mounted backwards, the mismatch is very evident if one simply looks at it. The valves have only one end that is compatible with the linkage mounting. For this end to be located in the center of the cylinder pair while offering the proper contour position of the port roof, there must be two different orientations of the valve ends, hence the 11 and 22 type valves.
If I disagree with everyone, that doesn't make me right. If I take the side of only one, it doesn't end the fight. If my position's strong enough from exposure to the light, you may see things my way when we share the same highway.

tonyhes
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Re: Power Valve Question & Piston Identification. RZ5 Thera

#6 Post by tonyhes » Thu Jun 01, 2017 11:42 pm

Hello!

Sorry... I did post a reply earlier and well... looks like I screwed up... Anyway here goes.

Everyone is correct 11 & 22 plus 22 & 11 in front and rear banks are the only way to assemble the motor.
If you put a pair of 1-1s together... you can obviously assemble... But I bet it runs like P*#P! (No idea how any of this happened).

Thank you for the help! I have a new question but will post in a fresh message.

:)
Tony.

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