Cleaned and adjusted my powervalves

CAM2

CAM2

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Dec 22, 2004
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Everything went ok, but I'm not sure if my cables are stretched or what. I took apart the whole power valve assembly including the cables ends attached to the PV's. Then I put it all together and used the bender tool to open the powervalves. I felt up the exhaust ports to make sure all ports were flush and had to adjust the cables at the servo. 2 of the cables needed to be screwed all the way into the servo housing to make the PV's flush with the cylinders. Are the cables stretched? I'm kinda concernd because with the cables adjusted all the way in, I have no adjustment left if they need it again.

any help is appreciated!
 

Did you happen to remember how much adjustment was left before you took them apart. Did you put the right cables in the right slots on the motor? Last but not least, and don't take this the wrong way (but I gotta ask) did you install the valves upside down? (I did it once, but caught myself halfway through the install).
 
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I was carefull to make sure the valves were in the right way. I've heard some horror stories about this. Next, I never took the cables off the servo motor, i took them off the valve side when I cleaned them. One other note, I had about a 1/4 to 1/2 inch of threads showing at the servo motor before the adjustment. Thanks
 
CAM2 said:
I was carefull to make sure the valves were in the right way. I've heard some horror stories about this. Next, I never took the cables off the servo motor, i took them off the valve side when I cleaned them. One other note, I had about a 1/4 to 1/2 inch of threads showing at the servo motor before the adjustment. Thanks
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I found the same thing. I actually replaced one of the cables and it ended up being adjusted way in, so there's no doubt in my mind that there's some significant cable stretching going on. IMHO, it means that Yamaha's recommended adjustment method of setting the gap on the valve body is useless if you want the valves themselves to be dead flush. OTOH, I'm not convinced that getting the valves dead-flush is that important from a performance standpoint. I think there's a wide variation in power valve adjustment setting before the average user would notice ANY performance change.
 
You don't want them to tight. If you have them to tight you can rob power from your bottom end and or top end.
 
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too tight? I had to tighten them all the way in to make the vavles flush.
 
you most likey have the cables in the wrong holes in the pulley, look they are offset, if the cables were stretched you would have to have them screwed all the way out, you're looking at it backwards, take the cables out of the servo, and have them installed in the cylinders, you will see that one of the inner cables is longer than the other 2, that one goes in the further hole and the other 2 go in the back hole, I just had a guy bring me a viper, he did the same thing.
 
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Thanks 800,
but i never took the cables off the motor. I only took them off the vavles themselves when i cleaned them. I will check it out anyway. thanks again.
 
you made it sound like you took the whole thing apart, any way the only other time you have to run them all the way in if everything is connected correctly is if you have a big bore
 
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I guess my first post did make it sound that way, but In reality only took apart the valve parts. ok i'll have to go over it tonight. thanks for your help
 
I did mine this week found that my middle cable on the servo needed to be adjusted all the way in untill I ran out of thread. I never took anything apart. I sort of feel like it could have gone a little more too.
 
this may sound dumb but when you take the pipes off where exactly is the top of the exhaust port??(the closer part to the exhaust or towards the piston??) & what part does the valve need to be flush with??
 
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you need too take off the exhaust manifolds too. then reach your finger up towards the top of the cylinder (towards the piston). It should be flush with the top of the cylinder. they will probably be closed if you don't idle down or send voltage through the servo.
 
yeah i know about the manifolds,& i used the tester.just wanted to make sure they were done right.which i dont think they are.the sled has a little bog & no mid range since i did them. but i re ringed it at the same time a long with some other work so well see.
 
do you HAVE to adjust, or can you just slide out the valves and clean them without a full disassemble??
 
u dont HAVE to adjust them every time you clean them...but u probably SHOULD check them to make sure they're not way off.....
i have always measured them using the method specified in the manual(tech pages on this site)which says the gap shoud be btw 2 and 3.5 mm....i use a drill bit (7/64") to check the gap and adust accordingly....never had any problems
;)!
 
I've been reading alot about the best way to adjust your powervalves. I think it is safe to say the "by feel" method is the most acurate, but the "cable housing gap" method is much easier and faster. I've heard it said that the cable gap method doesn't account for cable stretch but the way I see it, it does because what you're measuring is the position of the powervalve in relation to the cable housing. All cable stretch would be adjusted out on the other end. Right? However, this method does not allow for variations in the parts themselves which seems to be evident from the different results you get from each method. (each engine is not identical or even each cylinder on one engine)
All this said, I think the best would be to use the feel method once, then check the clearance at the cable housing. Just write these numbers down and then as long as the valves or cylinders are not changed, you should be able to use the easier cable gap method from there on. Does this make since to anyone but me? ;):D 700
 
I'm a little comfused about this thread.... When you use the adjustment coupler or if you let engine idle at 900rpm and then hit the kill switch the power valves should be fully open. If you using this metod and then adjust the valve flush with cylinder you are probebly loosening the wire so much that the valves will not open as much as it should. I'm thinking of using this metod you have to measure the gap as manual says or...? If you adjust valves flush to cylinder by feeling with finger trough exhaust you shold be doing this with valves fully closed and not have them fully opened in the way manual says...? Correct me if I'm wrong!
 
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