Hello to all, may I start with what a fantastic website thank you!! I have just got back my 92 mc21R I had sold to a friend a few years ago when I was in need of cash, he has seized the engine due to not putting one of the bolts for the oil pump back in when he was messing around with it and the oil pump has rattled loose and BANG. I have bought some second hand cylinders and heads but they are marked KV3L which I believe to be SP cylinders, the ones that came off the bike are KV3H R model. My question is will the SP cylinders and heads work with the R motor, does anything need to be changed to make them work. I have read not to mix them up, use L with L and H with H but is there any difference's with the bottom end except the clutch and gearbox, will they just bolt on and work?

Also I got carried away cleaning the power valves, they are shiny on the part where the exhaust gas flows over them. Now I started to worry that I shouldn't have and maybe it will rust?? any thoughts anyone

And now for the hard question, How to test the Air solenoids, when I got the bike 5 years ago I took it to the bike shop cause it ran like crap after 6000rpm. After a good carb clean and them fiddling around with the jets they told me the Air solenoids were not working, they disconnected the X piece and it ran pretty good and reved out all the way with no problems but started to loose power up top after a few weeks.
Do the air solenoids get power to them at a certain rev range or do they always have power to them that switches off at a certain rev range?? If so I can just check them with a multimeter when the bike is running right? also I don't have the original hoses for the air correction circuit does the diameter and length of the hoses matter if so could someone tell me the inside diameter of the hoses??

Thank you again NSW World, I have learned heaps from reading the forums Awesome site!!

Hello Dave, and welcome to NSR-WORLD.

http://nsr250.net/forums/viewtopic.php?p=98618#98618
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

dave robbo wrote:
And now for the hard question, How to test the Air solenoids, when I got the bike 5 years ago I took it to the bike shop cause it ran like crap after 6000rpm. After a good carb clean and them fiddling around with the jets they told me the Air solenoids were not working, they disconnected the X piece and it ran pretty good and reved out all the way with no problems but started to loose power up top after a few weeks.
Do the air solenoids get power to them at a certain rev range or do they always have power to them that switches off at a certain rev range?? If so I can just check them with a multimeter when the bike is running right? also I don't have the original hoses for the air correction circuit does the diameter and length of the hoses matter if so could someone tell me the inside diameter of the hoses??

The short answer is there is absolutely nothing wrong with the stock air correction setup, and to do any better, you will need the full HRC carb kit, and plenty of setup time/dyno runs. Even then, the HRC kit is only of use if you have a modified setup. It will do nothing for a stock bike.

The air correction solenoids switch on and off depending on throttle position, gear position, and RPM, controlled by the pre-programmed "maps" in the PGM. It's a rather refined system, and [generally] works very well. It is possible for the solenoids to fail, but rare. Also possible the PGM is faulty, but unlikely.

Disconnecting the X-piece is an awful bodge, and will have most likely made the motor run very lean at the top-end, and there is every possibility that caused detonation. Detonation generally leads to seizure. A partial seizure could be the cause of the lost power. The least you can do it pull the exhausts off and have a look up the ports at the pistons, but I'd recommend pulling the barrels off, for a closer inspection. (Leave the heads fitted, to save replacing expensive gaskets if all turns out to be in good condition.)
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

Thanks for the help Andy very much appreciated, the awful bodge you speak of cost me about $500AUD!! to have them mess around with it for hours and then disconnect a hose! Next time I need to go to a bike shop I will be finding somebody that knows about NSR's, I wish I had seen this site 5 years ago!
One of the Cylinder's is stuffed but I have 2 second hand ones in good nic. I will be putting them on when my new pistons and bits arrive in the mail and I will try to get the air correction system set back up to how it should be.
Thanks

anyone got any ideas about the powervalves I polished, I have started to worry it was a bad idea and they may rust? or will all the burning T2 protect them?

Give them a very light smear with 2-stroke oil upon reassembly, but I wouldn't worry too much. A stock bike pumps in a lot of oil, and they will soon get a coating of carbon and oil on them.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!