Forgive me if this bean beat to death, but both of my R5K's have a single black wire that comes out of tail harness and just sits there, no connector, just ends. Looks like antenna for my garage opener... not on the diagram. don't feel like cutting the harness open just to satisfy my curiosity, anyone ever traced it?

Also while asking questions, what does oil pump solenoid do? All the bikes I've seen before only have a cable to meter the oil, does it simply override the pump?

Last question is about PJ solenoids, do they have anything to do with cold idle? My bike will idle at least 1000 rpm higher when cold and when warms up idle will come down, don't have another running bike to compare it to.
My theory is that PJ solenoids like EFI on later cars/bikes raise cold idle or
I simply have a bad seal and it sucks air when cold, air leak stops when engine warms and expands

Any way to check PJ solenoids? what to expect if they fail?

Thanks in advance

The power jets are all about supplying extra fuel when the throttle is wide open - something you should avoid with a cold engine!

They are air correction solenoids.

20 years ago, when we knew no better, they were dubbed power jet solenoids, and the name has stuck ever since. There's no doubt references still dotted around the Main Site and all over the forum misnaming them. I change the references as I come across them.

The power jets are controlled by atmospheric pressure, not electronically, on the NSRs.

The solenoids are linked to throttle position, and RPM on the MC18. I believe they are also linked to gear position on the MC21, but can't say for sure.
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Excellent questions Dmitry!
I probably won't find time to answer these questions.
I think an NSR wiki would be a great place to store answers to questions like this (no pressure Andy )
But for now just searching the forum works not too bad.

I too have seen that black wire and wondered...

Sorry for what is basically an unhelpful post.
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So, what do air correction solenoids do? I assume air mixture control, so how will I know if they fail?

Started working on cars couple decades ago, done plenty of 80's Honda cars where carburetor is attached to a black box by no less than 40 vacuum hoses, each controlling some air circuit or another essentially last step before EFI. This 2 solenoid NSR thing seems much simpler I was hoping someone has a clear idea how it works and what symptoms to expect when it fails.

I know it is all tied in to PGM2 and provides 3D ignition and fuel mapping (I assume air correctors work based on RPM and TPS so that would be a 3D fuel map)


And back to my high idle question: I get 3000 rpm on a cold bike with no choke, comes down to 1500 after it warms up a bit, any ideas? Is it normal?

I think there's a section all about testing them in the Workshop Manual.
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Andy wrote:I think there's a section all about testing them in the Workshop Manual.

I get the hint

Dmitry wrote:what does oil pump solenoid do? All the bikes I've seen before only have a cable to meter the oil, does it simply override the pump?

When the engine is running between 0 to 7000 rpm, current flows to the oil pump solenoid. In this state the movement of the oil pumping piston is slightly restricted and the oil pump pumps oil at a restricted rate.
Above 7000 rpm the current to the oil pump solenoid is turned off. In this state the movement of the oil pump piston is no longer restricted and the oil pump pumps oil at a higher rate.

Typical road use seems to give a fuel:oil ratio of approx 37:1.
However, this ratio will change depending on whether you cruise around at revs below 7000 rpm or not. (supposedly NOT )
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Took Andy's advice and searched the manual, found the description of operation, diagrams and testing flowcharts

Amazing resource available at your fingertips

What I have not found is symptoms that may indicate air solenoid failure, don't feel like pulling the bike apart is it's not broken, but I would have no clue if it is since I never ridden or even seen another NSR250 up close. When I purchased my RG500 the power-valve servo was fried and for the longest time I just assumed that it supposed to run like sh*t all the time till it gets on the pipe, having never ridden one before I had nothing to compare it to. last owner had it for 15 years, didn't know either!

Start bike making sure the hoses are all connected as per the diagram and maybe replace the little filter connected to the air hoses.
What symptoms make you think its a solenoid fault?
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