Right, in the pic below you can see the powerjet pipes. One part it blocked off, the other is open with nothing attached. I do not have the solenoids plumbed in and cant even see the connector for them!!

I had the carbs off just before I took that pic and removed the screw from the float chamber to reveal the powerjets were 'not' blocked.

So, with this setup, will the powerjets still come into operation and give me the top end fueling I need. The bike runs and rides absolutly fine, but I've not gone over 9k rpm yet as I didn't know what the top end fueling was like. With one of the pipe open to the atmosphere, would this be just like the solenoids being permanatly open and allowing air flow in?



Image edited by Admin


Last edited by Barry_MC21 on Tue Jul 12, 2005 1:07 pm; edited 2 times in total

I doubt you are going to get many replies until people can view the page without waiting for X minutes for the image to download with a dial-up modem!

Please reduce the image size or I will have to remove it.

Thanks,
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How's that, 300k down to about 130k.?

Better, but if it's resized to less than 800 wide, it'll save the aggro of scrolling accross the screen to read the writing!

As for an answer, I dunno. Sorry!
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What you mean you dont know, I dont want to hear that answer!

I guess I'll just get it on the dyno and see whats going on!

Unless Mr Tyga can shed any light?!

I could make up an answer based on how I 'think' the power jets work, but that'd be supposition, and I'm thinking you probably want a correct answer?
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Well thats all I'm doing at the moment.

I guess that as that pipe is not blocked, its the same as the solenoids being constantly open and supplying air?!

Whats your theory?

OK Barry, have you checked the diagram in the Technical section yet?

I would strongly suggest the air corrector circuit is reverted to stock before you try and go any further, if this means sourcing another X and Y joint, then it's the way to go really.

The top of the black connector that is currently open is (well, was!) the X-piece - there should be a small brass jet visible in the top. This normally goes to a little 3-way connector that presses into a little filter on the underside of the airbox, which in turn branches off to the bottom (large) connection on the solenoid block.

The blanked off pipe should go to the Y-piece. The straight section on the Y-piece should go to the right solenoid (closest the frame rail) and the angled part of the Y-piece to the left solenoid.

The soleniods bleed air into the emulsion tubes. If this isn't set up properly you will NEVER get the mixture correct, and trust me, I've seen the results first hand when you get it wrong!

I would expect things to be extremely rich with this current setup - even with the X-piece open to air.
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Andy,

So what your saying is the powerjets will be constantly supplying fuel?

But it runs really well low and mid range!

I suppose the best thing to do is block the power jets and go HRC. I'm using a PGM2 F3 ignition, and couldn't see any connectors for the solenoids.

Fecking bike!

I'll see what the fueling is like on the rollers hopefully this weekend.

Right, in the pic below you can see the powerjet pipes. One part it blocked off, the other is open with nothing attached. I do not have the solenoids plumbed in and cant even see the connector for them!!

I had the carbs off just before I took that pic and removed the screw from the float chamber to reveal the powerjets were 'not' blocked.

So, with this setup, will the powerjets still come into operation and give me the top end fueling I need. The bike runs and rides absolutly fine, but I've not gone over 9k rpm yet as I didn't know what the top end fueling was like. With one of the pipe open to the atmosphere, would this be just like the solenoids being permanatly open and allowing air flow in?

Don't see anything in there mentioning an F3 PGM-II!

The power jets provide fuel depending on the air-flow (or rather depression) across the top of them - fuel is drawn through them. As I see it, the solenoids vary extra airflow (timing) and the X & Y pieces the extra airflow (volume) to the emulsion tubes weakening or richening the mixture as per the program in the PGM unit.

If you have power jets fitted, they will supply fuel regardless of whether the solenoids are connected. What mains do you have fitted? What size are the power jets? How about the size of the slow jets?

I will know a lot more about air solenoid timing after the next dyno session, but only have an MC21 and an MC18 to test. Quite what an F3 PGM is doing at certain RPM is a mystery to me I'm afraid.

Cue Matt...
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The main / slow jets are stock, I'm not sure about the power jets as I dont have a small enough screw driver at the moment to get them out.

I think I'll just get it on a dyno and see what it doing, then go from there.

Might just go for the HRC jet kit and block the power jets!

Cheers guys..

You really want to check the power jets before any high speed runs if you are using otherwise stock jetting.
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Andy wrote:You really want to check the power jets before any high speed runs if you are using otherwise stock jetting.

I've just had a very interesting chat with a tuner, powerjets, according to them, have nothing to do with top end, especially as they are so small (#70, 75 etc..). He said that it is not even used in anything over 1/4 throttle, and its there just for when you snap the throttle open at low revs to give a better responce.

Have booked my bike in with them so will have a good chat with them about it then.

I don't think you'll find the NSR power jets work the same way as bikes like the RS and TZ, where they can be cut off or triggered at certain RPM.

What I can tell you however is that while setting up StephenRC45's MC18/300, different size power jets had a huge effect on the way the motor performed (or didn't perform) whilst trying to get the top-end jetting correct.

I will admit though, we are still not entirely sure exactly how and when things are happening regarding the power jets and solenoids, which is one reason why we have booked the dyno for a day in a few weeks time.
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If only the guys at Honda who designed all this stuff would frequent the site!
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