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Power Valve Adjusted?


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cgallant
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Power Valve Adjusted?

Mon Jun 06, 2005 5:12 am » Post: #1 » Download Post

Okay,

So my race NSR has always been a bitch on the starts. It really doesn't like to launch, but once its going, the power is really good. I was at first thinking I would "dink" with the needles, as this seems to be the jet that it would be on at the time of starts.

But while I was going through the bike after the last race, I took the pipes off to inspect the top end, and noticed that the power valves are closed a good amount. I rotated the servo, and turned the kill switch on, and it went back to where it was (arrow is sitting nearly at "lo" on the servo motor), and the valves are closed (they are blocking the exhaust port to their max).

Well, my TPS isn't attached to the carb body, so I decided to come up with a way to attach it (I am missing the little clip, but Matt P said this is okay for a race bike). Well I made a clip of sorts, and the TPS is now attached to the carb body. I went through the standard adjusting, and it's now sitting on "lo", so they are all the way closed (with the TPS wire disconnected, as per standard Honda adjusting instructions).

Now I am trying to figure out if the valves should be closed (blocking the exhaust port), or open (recessed into the body of the cylinder). And what should "lo" and "hi" represent in terms of the valves themselves? I am basically wondering if the cables are crossed, and they are working in reverse.

Thanks
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Dave Ett
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Mon Jun 06, 2005 8:11 am » Post: #2 » Download Post

Without re-reading the setup proceedure, I think the valve is supposed to be open with the TPS disconnected.

It should certainly be open above 5/6 ish, and closed below that.

I belive the valve should be closed with the TPS connected, ignition on and engine off.
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Andy
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Mon Jun 06, 2005 9:11 am » Post: #3 » Download Post

OK Dave...

You know that your technical assistance privallages regarding RC Valve adjustment have been revoked since the weekend! STOP IT! Laughing
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Dave Ett
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Mon Jun 06, 2005 9:12 am » Post: #4 » Download Post

Heh heh, do as I say, not as I do! Laughing
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cgallant
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Mon Jun 06, 2005 5:55 pm » Post: #5 » Download Post

Dave Ett wrote:Without re-reading the setup proceedure, I think the valve is supposed to be open with the TPS disconnected.

It should certainly be open above 5/6 ish, and closed below that.

I belive the valve should be closed with the TPS connected, ignition on and engine off.


So is your "open" the same as my "open"? I am thinking that "open" means the power valves are recessed into the cylinder body, allowing maximum exhaust port.

thanks,
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scottvor

 
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Mon Jun 06, 2005 10:21 pm » Post: #6 » Download Post

chuckie, correctomundo. when i recently checked and set mine, fully open
was completely recessed into the cyl. (they swung open towards the head).

the markings on the brackets is crap. neither motors i have had were very close to mark. i used a sharpie pen as a reference when i had set them long ago. worked ok. i think hi on the servo was open.

i ought to have a talk with matt p. 'bout this. i noticed that the valves opened
up early in the revs (6-8K?) 125s don't run power valves. how 'bout welding
'em up all nice and smooth. how you fancy that? "we don't need no steenking mid-range!"
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Matt@TYGA
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Tue Jun 07, 2005 4:18 am » Post: #7 » Download Post

Hi means open and Lo means closed.

When you're setting, don't overdo the open bit or you'll not only lose top end , but also bottom end as the valves won't close the proper amount.

Do as Scott V says and scribe a mark on the plate where you can plainly see, and do so when the valves are fully open.

Fully open means that they've just cleared the top edge of the exhaust port, NOT hard up against the roof of their chamber. You should be able to stick your fingers into the exhaust port and feel a smooth transition from the port edge onto the valves. no steps.

Run the open/close procedure several times to set up and ensure that every time they are opening to exactly the same point, and they do it reasonable fast. If you're not sure then remove the cables completely and run the preocedure and watch how fast the servo works. You need minimum drag through the cables, so if the movement is slow when it's connected then you're cables are either too tight or need lubrication or replacing. Any drag will not only affect the performance, but could also overload the PGM and POP.........that's another bunch of cash out the window.

NSR's are all about careful setup. Get it right and you'll be rewarded with reliable power, but if you don't love it then it'll be a dog.
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