800 Powervalve motor

[The other Alex]

Time to do some powervalve maintnance on my Yamaha's 800 motor. It's a 2001 Yamaha XL limited hull with the 800PV motor, Ive never dug into this motor so any pointers would be helpful.
I'm assuming I have to remove the exhaust. From there do I remove carbs or are the powervalves on the exhaust side of the motor..can someone please clear this up?
Once I get to the powervalves, are there any tricks to handling them so as not to avoid damage? Can they be cleaned and do I even have to remove them from the motor?
I plan on ordering the wave eater clips and links. I've never had any problems with the powervalves on this ski, and read that the powervalves were only a problem about midway through '01, not sure why that would make a difference. But lately the ski has been lagging a bit, especially in the midrange, I can hit the throttle in mid range, and there is a delay, then I can feel it snap open and the ski takes off. With that, its almost like there is no midrange. The motor also runs very rich at idle, more than it used to, and stalls if I let completely off the throttle (Idle is set at usual). Im assuming this could be caused by the powervalves, either sticking open at low speed and not opening fast enough in the midrange? Everything else on the ski is in tip top shape, Ive never touched the powervalves though and have heard a lot of bad stuff about it. Up until now, this motor has been great and reliable, I absolutely love it. Anybody have any tips, tricks to tearing into this?

 

[SuperJETT]

I bet the guys on greenhulk can help way better than me, but you shouldn't have to touch the carbs to get the powervalves off. Those are above the exhaust on the left side of the engine, not on the carb side. You may be confusing them with the reed valves.

 

[The other Alex]

I bet the guys on greenhulk can help way better than me, but you shouldn't have to touch the carbs to get the powervalves off. Those are above the exhaust on the left side of the engine, not on the carb side. You may be confusing them with the reed valves.

That clears one thing up. For some reason I had the idea that powervalves replaced the reed valves, and made for adjustable flow of fuel, rather than exhaust ports. This will be easier than I expected.
Does anyone know if the powervalves could be contributing to my motor symptoms? Or do I need to look more towards a carberation issue?

Thanks!

 

[Chester]

It's not likely that your power valves are causing the problem. You should go through your carbs. If it's running rich & stalling, you probably have a leaking needle & seat. Although, you should still clean your power valves & install the wave eater clips.

Chester

 

[JonnyB]

sounds like a carb issue. I would rec a manual before you dig into that motor trust me I have put many hours workin on my 800. and yes to get to the carbs you have to remove the exhaust. If its an 01 I would think its time to rebuild the carbs. And no the powervavles have been a problem forever not just till 01 thats why the 1300R doesn't have them. if your going to remove them I would buy R&D vavles or Rivas. Yes the waveeater clips will prevent the vavle from dropping into the cyl if the pin comes loose but if the shaft gets broken then the vavle will drop and the waveeaters will not do anything. This is a link for how to do a valve change on a 1200R but it will give you an idea http://www.cajundude.com/powervalvereplace.htm

 

[The other Alex]

Thanks for the reccomendations. I have a manual for the 1200 motor, that should suffice with a few exceptions...
After I do the powervalves, I suppose I will go through the carbs. Is removing the carbs on this motor any different and removing dual carbs from a 701 motor, assuming the exhaust is already removed? If not, that should be easy enough.
Thanks for the information, I looked over manuals and parts diagrams and have more confidence now going into it, now that I have an idea of where everything is/where everything needs to go/how the system works. Doesn't seem too hard, I have some experience with 650/701 motors in the area of exhaust and carb(s), but the 800 motor is intimidating for some reason...
However, I suppose anything is intimidating until you rip into the first time.

sounds like a carb issue. I would rec a manual before you dig into that motor trust me I have put many hours workin on my 800. and yes to get to the carbs you have to remove the exhaust. If its an 01 I would think its time to rebuild the carbs. And no the powervavles have been a problem forever not just till 01 thats why the 1300R doesn't have them. if your going to remove them I would buy R&D vavles or Rivas. Yes the waveeater clips will prevent the vavle from dropping into the cyl if the pin comes loose but if the shaft gets broken then the vavle will drop and the waveeaters will not do anything. This is a link for how to do a valve change on a 1200R but it will give you an idea http://www.cajundude.com/powervalvereplace.htm

 

[WFO Speedracer]

I would remove the carbs now since you are going to have to remove most of the exhaust anyway to do the powervalves.You will also have to remove the exhaust manifold to get enough room to get the power valve covers off.Definatly put the waveeater clips on there and replace the gaskets and seals while you are in there.The carbs should come off fairly easily once the exhaust pipe is out of the way.

 

[vomitspot]

carbs are diff than a 701
they use 4 allen bolts through the sides and 2 allen bolts in the mabifold
there are i series carbs
they come off as a set still bolted togather

 

[blaster800]

since you have to do both carbs and powervalves i would reccomend just pulling the eng and doing the rest on the bench ! you will thank me when your finished ! ! that eng is not hard to pull !!! i have that eng in my blaster and have pulled both carbs without removing the exhaust ! takes about 1 hour out and one hour or more to go in standing on your head ! JUST PULL THE ENG and save yourself much agrivation !!!!

 

[The other Alex]

I would pull the engine, actually thought of it since there is so much extra room in the hull, it will come right out. However, Im keeping this ski in my Grandmas garage, and there isnt a lot of room to rip everything apart and keep it apart while I venture back and forth to work on it between school and....well, if I decide to actually get a job...work. I'd rather just pull the exhaust, throw it in the storage bins, and work on the motor that way.

 

[Water Worx]

You can pull carbs on a 800 with exhaust on.:wink:

 

[JonnyB]

You can pull carbs on a 800 with exhaust on.:wink:

oh yeah don't let me tell you how much fun that is! (its not bad once you have done it)