I have picked up the new toy - a 92 MC21SP. Fairly standard, with the usual signs of wear and tear for a 15 year old bike.
The good signs are that it appears to be a genuine Rothmans MC21, not a bits 'n pieces import/rebuild. It has a set of Tyga ss pipes and jetted to suit (according to the previous owner anyway.....), a drilled airbox with filter (my preferred setup).
Not so good is the dry clutch has been converted to a wet clutch arrangement using the existing cases (although I don't think my girlfriend is a member of the dry clutch appreciation society, as she will be riding it too). I will source a standard R cover for this to tidy it up. It also has single ring RM pistons, which I will change back to stock shortly. Each of the locks are different - I thought I could pull the barrels apart and swap the pins around like I did on my old RG. on closer inspection this doesn't appear quite so straight forward as first thought. Has anyone done this?
It has 36000Kms - high, but as I plan on keeping it for a while - I was going to up for a new crank at some stage anyway.
Anyway, the first problem I want to fix is the neutral light on the instruments - it doesnt work and there is no voltage at the connector. Looking at the wiring diagram, the wire goes to the PGM unit. Is there any other likely thing to check (where is the GPS?). Which connections/wires do I check with the multimeter on the PGM (the light green/red wire and???).
Congratulations on the purchase mate, hopefully you'll enjoy the bike
Download the wiring diagram from the technical section, and start tracing the stuff yourself.....sorry I can't be of much more help than that but I don't have my info in front of me.
Before you start checking the PGM, check all the electrical plugs are still plugged in.
I have a copy of the wiring diagram. I have checked the connectors at the globe and connector behind the instrument panel (no reading for the neutral light). The sidestand light is OK, and I assume I should get a similar voltage reading for the neutral light. According to the wiring diagram, the wire should go all the way back to the PGM (no inline connections). So, working back down the line, I want to check the output on the PGM, then the input side, then the GPS neutral wire (ie following the light green/red wire). I just want to know the best way of testing the wires into the PGM block. At the instruments/globe you have the light green/red wire and the black/brown (+) wire to measure across, but at the PGM which is the equivalent wire (black/white, 5th from left on the diagram?). I just don't want to short the PGM and fry something.
I thought that someone may have had a similar experience and be able to point me to possible problem areas.
I have been told by the previous owner that it had the wire splices as per this website. I have checked that the PGM O/B to Bl/W has been done. Looking at the condition of the GPS lead, it looks like the black sheath has not been cut anywhere (near the connector). I have yet to trace it all the way back to the engine sidecover.
Earthing the neutral wire from the connector gives a reading of 5V.
Battery registers 11.9V; when running a steady 14.4V across the terminals.
Front Cyl; Head has "KV3L FR2" cast into it; Barrel has "H1" cast in the circle on the bottom left side, is stamped "B" at the back, and has "0YH2 319" stamped along the base on the RHS.
I take this as an SP head on an R barrel, not the best setup....But it should be OK so long as I only run high octane premium ULP correct?
Rear Cyl: Head has "KV3 RR2" cast into it; Barrel has "L1" cast in the circle of the bottom left side, is stamped "B" at the back, and has "2MJ IL 106" stamped into the base on the RHS.
This I take as an SP barrel with SP head.
Both cylinders are "B" grade (and will take 'no mark' pistons).
Can anyone tell me what the code stamped in the base of the barrels is?
I have noticed some other things that are very unusual and will definitely require the assistance of the more technically minded NSR forum readers.............
Followed the wires back from the GPS connectors under the seat. Turns out that it isn't connected at all. It was cable tied to the wiring harness up near the servo motor. Looking under the sprocket cover, I can see about 3" of wires comming out of another GPS switch........
I tried to test the free switch by tunring the ignition on, bike in neutral, grounding the body of the switch against a bolt on the frame, and rotating the switch pin around. No luck with the neutral light. May be a dud switch.
Do you have to split the cases to instrall a new GPS?
Of greater concern, is the manual powervalve setup. It appears that the servo has been bypassed, with a short cable going from the carb throttle drum to the servo pulley. As soon as you start to turn the throttle, the powervalve cable is operated. Has anyone seen or heard of this sort of modification before?
I think I'd prefer the servo. I hope the PGM is all OK, and that it was a component failure that prompted this. Somehow, I have a gut feeling that may not be the case........
Don't know about the GPS I'm afraid, but I do know you won't be getting good power with the PV set up like that. It is meant to remain closed at low rpm, and open for high rpm, giving good power at all revs.
I'd be very suspicious of the servo, and wouldn't connect it to your PGM without testing it. Sadly I'm no-where near my bike so I can't give you any hints on which wires and what results to expect.
Anyone? _________________ MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball
Last edited by Dave Ett on Sat May 17, 2008 4:46 pm; edited 1 time in total
Middo wrote:
Checking the head/barrel configuration, I have:
Front Cyl; Head has "KV3L FR2" cast into it; Barrel has "H1" cast in the circle on the bottom left side, is stamped "B" at the back...
I take this as an SP head on an R barrel, not the best setup....But it should be OK so long as I only run high octane premium ULP correct?
The very least you can do is fit a 0.6mm gasket, but I would be more inclined to find an "R" head to bring the compression back in line. Not only is the front cylinder the most susceptible to detonation, but increasing compression on it without using AVGAS or similar is a recipe for disaster. (I.e. I strongly recommend against relying on 97 octane to keep it alive.)
The difference between the respective components is approx 0.2mm, this means an H (SP) barrel fitted with an L (R) head is 0.4mm under spec, approximately -0.8cc combustion chamber volume with standard parts. If the barrel has been replated at some time, then it's possible something has been taken off the deck height, and that will increase the compression yet further!
NSR's don't need high compression to make power (mine's set up at 66hp, and will make almost 68hp with peaky pipes/setup on standard compression ratio and porting), and unless you know exactly what you are doing with the various components, it will ALWAYS be better to run the Honda OEM specification parts. _________________ 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.
Middo wrote:
Do you have to split the cases to instrall a new GPS?
No, but be careful when fitting it. It's easy to bend the locating pin on the GPS shaft if it's aligned incorrectly. It's a bit fiddly! _________________ 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.
OK, agreed. Change the head, because it's easier and cheaper, or another SP barrel to return it back to original spec. I suppose I could just get a rear R head and the tyga hose for the better plug position to start with.......
Don't know about the GPS I'm afraid, but I do know you won't be getting good power with the PV set up like that. It is meant to remain closed at low rpm, and open for high rpm, giving good power at all revs.
Dave, yep, it's a bit gutless right off the bottom - and I have owned a few 2-strokes in my time.
Looks like I will have to hold off on some of the bling until I get the important bits sorted first. The 'To do' list:
Crank - at 36K it's on borrowed time. Are rebuilds worth it (how do rods hold up over time? I have access to all the bearings/seals), or should I just take the plunge for a new one?
Top end. Head/barrel swap for front cyl. I was going to replace the single ring RM pistons with OEM Honda.
GPS - get a new one, wire splice it.
Servo - test the spare one and hope it works (and that it's not the PGM).
A few things to work through - I hope the advice keeps coming.
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