Hi,
We are a shop in Austin TX, and have a customers Japan 'spec' M21 in right now. We had to wait a long time to get a rear brake m/c repair kit - which was sourced out of Australia. The customer wanted the bike 'de- restricting', so -- that was achieved with the help of the detailed mods to the wiring (orange ground at the PGM-111 unit, and 4/5/6th gear sensor wires spliced into 3rd gear) (Thanks!!)
The customer wanted some dyno figures - after the wiring mods, so - last week the bike was dyno'd. I did the wiring mods - but wasn't there for the dyno work. Apparently the dyno guys said the RC valves weren't operating properly, and between them and the mechanic that took the bike, they 'fudged around with it - and supposedly got some appreciable readings (We are still waiting for the figures!!).
Whilst they were checking things out, they opened up the RC valve servo motor - to make sure it was OK inside.
Back at the shop, I have been trying to ascertain exactly what the bike should and shouldn't be doing !!
Here are my observations so far ---
The bike is a pain to get started, especially after sitting for a couple of days!!
When the tank was taken off after it being run - the RC valve servo motor was pointing to HI. When the key is turned on, the pulley rotates counter clockwise and stops mid way between Hi -LO, then after about 5 seconds, turns clockwise -- a little further than HI. After unplugging the TPS plug, and turning the key back on, the pulley moves slightly anti clockwise and stops. The pointers on the RC valves are lined up at this point.
I have only had the bike running once since it was dyno'd, and - during warm up - and subsequent blips of the throttle - the servo motor remains static.
We have a Honda workshop manual for NSR250R G-N, SP J-N, SE L-N - however it does not have any reference to the M21.
In one of the troubleshooting tests on the RC servo motor - it refers to a W/BL wire in the coupler plug -- and there isn't a wire that color on this plug!!
I sincerely hope anyone can help us better understand this a little clearer, as it would be nice to see the bike back with it's owner!!
Thanks in anticipation!!
Brid.

Hi Mate
There is a section on this site that tells you how to adjust the rc valves here http://www.nsr-world.com/tuning/250-tuning/engine/
I adjust mine the HRC spec way
The normal operation of the power valve servo when you run the bike turn it of and then turn the key on the motor should turn to the lo position turn of unplug the t.p.s and turn key on should turn to hi possition
Hope this helps

Maybe some use?

http://nsr250.net/forums/viewtopic.php?p=71833#71833
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Vampire?

Thanks for the input guys!! So -- if I'm reading things right -- the servo pulley should be pointing to the LO position for starting ? I sort of suspect the TPS unit as being faulty - however, don't know of any static test that I can do? Getting a new one also seems to be like looking for Rocking Horse Droppings Maybe we'll just opt for disconnecting the servo, and pinning the valves --- if we can get it started that way!!
Again - thanks, and any further input will be greatly appreciated.
Cheers,
Brid.

brid wrote:Thanks for the input guys!! So -- if I'm reading things right -- the servo pulley should be pointing to the LO position for starting ? I sort of suspect the TPS unit as being faulty - however, don't know of any static test that I can do? Getting a new one also seems to be like looking for Rocking Horse Droppings Maybe we'll just opt for disconnecting the servo, and pinning the valves --- if we can get it started that way!!
Again - thanks, and any further input will be greatly appreciated.
Cheers,
Brid.

Brid,

If you disconnect the TPS connector (turn off the ignition switch before doing this!), and then turn on the ignition switch, the servo motor should rotate to the "HI" position.

If it does not do this,check the battery voltage is good (below 10 v, servo motor may not work).

To check the TPS, disconnect the RC Valve servo motor and measure the resistance between the BU/G and the Y/R terminals on the Black PGM connector (wire harness side), should be 4-6 kohms

While measuring the above, also measure the resistance between the BU/G and the Y/BU terminals. TPS fully closed should be 0-1.5, , fully open should be 4-6. if the resistance is above, disconnect and check at the TPS sensor plug. If okay, then it's the wire harness, if not, then the TPS needs to be replaced.
_________________
Charles Gallant

Charles - Thanks. Here's what I found.
Brid,

If you disconnect the TPS connector (turn off the ignition switch before doing this!), and then turn on the ignition switch, the servo motor should rotate to the "HI" position.
Yes - it did - RC valve pointers lining up correctly

If it does not do this,check the battery voltage is good (below 10 v, servo motor may not work).
Battery is at 12.6V

To check the TPS, disconnect the RC Valve servo motor and measure the resistance between the BU/G and the Y/R terminals on the Black PGM connector (wire harness side), should be 4-6 kohms
This is 4 kohms

While measuring the above, also measure the resistance between the BU/G and the Y/BU terminals. TPS fully closed should be 0-1.5, , fully open should be 4-6.
Fully closed is 0 -- fully open is 3
if the resistance is above, disconnect and check at the TPS sensor plug. If okay, then it's the wire harness, if not, then the TPS needs to be replaced.
At TPS plug, static reading between BU/G & W/R is 4, and between BU/G & W/BU is o to 4, as throttle is 'cracked' - then it quickly drops back to 3
Does this tell you any more?
Again - many thanks for the help here - it's much appreciated!!
Cheers,
Brid.

Hi Charles,
Been gone a couple of days - and not seen my mail. I assume from your no reply to my previous mail - that the TPS is at fault here? Can you please suggest a source for a new one? Part# 04101-KV3-770
Thanks,
Brid.

brid wrote:Hi Charles,
Been gone a couple of days - and not seen my mail. I assume from your no reply to my previous mail - that the TPS is at fault here? Can you please suggest a source for a new one? Part# 04101-KV3-770
Thanks,
Brid.

Can anyone help here? My searches for a TPS haven't been successful. Does the part cross over to a TPS used on other models?
Thanks,
Brid.

The TPS is just a variable resistor, so if you can't find one, then maybe you can find something suitable to substitute.

Perhaps you could try sending a PM to Moriwakiman who buys things from the Japanese auctions for guys on here - may be your best bet for finding a replacement TPS.
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I'm pretty sure that I saw a new one available on Yahoo - Moto Parts Sapporo have lots of new OEM parts.

The MC21 T.P.S. part number is 04101-KV3-770.

While they have been known to fail, it is extremely uncommon in my experience. The T.P.S. is actually rather expensive new to replace, but I would be very surprised if you sourced some used carbs and they too had a faulty sensor.

Personally, I've come across it probably twice in 15 years.
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Andy.
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Andy wrote:The MC21 T.P.S. part number is 04101-KV3-770.

While they have been known to fail, it is extremely uncommon in my experience. The T.P.S. is actually rather expensive new to replace, but I would be very surprised if you sourced some used carbs and they too had a faulty sensor.

Personally, I've come across it probably twice in 15 years.

Andy -- I did the tests suggested by Charles - and posted my results, however - haven't heard from Charles? Can you please take a look at my post (a few back from here) and see if my test results made any sensible conclusions. From what Charles advised - and what I found -- it appears the TPS is at fault?
Thanks for the help,
Brid.

Middo wrote:I'm pretty sure that I saw a new one available on Yahoo - Moto Parts Sapporo have lots of new OEM parts.

Middo - I tried googling them -- but nothing. Do you have any contact info for them?

Dave -- I went through the entire members list - and couldn't find Moriwakiman?

Here is maworkiman http://www.nsr250.net/forums/profile.php?mode=viewprofile&u=1446