Hi guys new to the NSR and obviously this forum.
My ride is a MC21 SE, possibly SP as it had “spare” rims but couldnt find them for the sale, barrels are marked L and the VIN is within the SP numbers, but to me it simply a track bike, full track conversion (by previous owner)
Kick start delete
No airbox, just open carbs,
HRC jet kit,
VHM heads,
Full TYGA exhaust,
Basically previous owner ticked all the TYGA boxes and followed the HRC power up documentation to the letter. Then rode it three times and put it away for the last five years, and then I stumbled across it.
Came with all the road gear including the factory Rothmans fairings (still has the Japanese writing stickers on all the fairing parts.
Inline with all that the RC servos have been removed, I presume that side of the PGM lll failed, and RC valves fixed into the halfway position. The GPS is also removed, so do I still need to rewire the GPS side of the PGM? The wire splice on the other side has been done.
Also it is not running a battery, does it require one for the PGM seeing as there is nothing on the bike that actually needs/requires battery power?
I have tracked the bike and in the second session it point blank refused to rev past 10000 rpm, was fine in the first session tho. Any suggestions?
I apologise for the long first post.
Ty again

Hello "Rowanvtr", and welcome to NSR-WORLD!

Sounds like it could indeed be an SP, but to be honest, it's impossible to be 100%. Only Honda would be able to confirm it, but experience over the last 20+ years says it's very difficult to get specific information officially out of Honda. People have claimed it over the years, but very few, and none have every shown the evidence.

Yes, the PGM-III will require a battery to function fully. In fact, a poor battery or charging systen has been tracked down as the culprit for misfires and inability to rev fully before.

The RC Valves will need to be fully open to attain peak power/RPM, but pinning them open can do a pretty good job on shorter/twistier circuits. They're the best system out there though, so if you can gat it all back up and working it's well worth it. Yes, you will need the GPS, and TPS for them to work correctly. The PGM takes inputs from those plus RPM. It was a very advanceed system for its time. The PGM also controls the air correction. When it's all working as intended, the NSR power delivery is incredibly linear.

This is a typical graph for a standard delimited MC21



With the mods you've described, and with it all back in fully operational condition, I'd usually expect to see around 63-64rwhp for a fresh MC21. More than that would need internal work on the crankcases.
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Ok question on the battery, I have read in a few posts about the battery required to be fully charged and in good condition, this I’m confused with, as the NSR is not 12v dependent, so technically once the bike is running it has no requirement for a battery (by definition a battery is simply a storage device for energy) so as long as the electrical circuit is in good condition it will supply up to 14v to the system.
Now the reg rec will obviously do it’s job not to over or under charge, so is the battery required only to supply a constant and uninterrupted constant flow 12v to the system with no peaks or troughs? The battery will receive up to 14v but only out put 12v.
I have attached an “under the bonnet pic to show what has been removed.

We've seen MC21s misfire or drop in performance on the dyno with a bad battery, but they have all still utilised the complete RC Valve and charging system. We've seen several MC21s and MC28s with the lightweight aftermarket "disc" flywheels that have rapidly dropped off too, because the battery hasn't been absolutely 100%. (Obviously those bikes had no starot, so charging system.)

The same has actually happened on a full HRC TT-F3 we ran a few years ago. One of the wires on the NiCad connecter broke away inside its connector, and the bike barely limped back to the pit. The F3 uses the same small flywheel and stator as the RS250R NF5, but absolutely does need the battery pack.

If you find it works for you, that's great, but we always recommend using the battery, just as for the majority we say keep the oil pump. Unless you're the fastest of the fast, and really need all the bells and whistles, the OEM setup is really very good, and so eaily optimised.

My MC21 with the standard charging system (lightened flywheel), standard PGM-III (with wire splice), 2T pump, stock compression & porting, with slightly reshaped transfers, matched to the cases, and our crankcase work, HRC kitted carbs with Ramair foam filters, makes a little over 66rwhp. It launched faster than the full HRC F3 (on the same HRC gearing), but would then lose out in 4th/5th/6th as the greater HP of the F3 overcame it. Hard to better the OEM setup though.



I can sort of understand the simplification of the setup for some, particularly if they've come from less sophisticated bikes previously, but I think it often leads to far more questions than it warrants.

Someone will always come along and contradict the above, but I only speak from personal experience. Additionally, I am unsure if you are aware of our credentials here, but aside from the NSR250Rs, we also ran six NSR500V NX6s for several years, each utilising PGM-IIIs, and I can state categorically, they will not run without a battery pack.


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On the topic of needing a battery, i can say that i ran my track MC21 for many years, with HRC loom & derestricter, HRC jet kit with ram air filters, tyga reeds & stuffers, and lightened flywheel, with no problems whatsoever, with no battery, just a battery eliminator fitted. I wouldn't expect a fully road kitted bike needing lights and all the gubbins that comes with it to run without a battery. But i know of other track only NSR's that run fine with no battery, just a battery eliminator fitted.
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Proud Father of , 05 ktm 400exc supermoto 2018 honda crf rx supermoto

There you go, as I said, someone will always come along and contradict the above.

However, an eliminator is just a big (well, smallish... big relative to those in the PGM!) capacitor, which takes a charge from the AC generator and stores it... erm, kind of like a battery does! It's doing the same job effectively; it just weighs a fraction of a lead acid battery. The difference is it won't hold a charge in the same way as a battery.

As I say, I only speak from my personal experience. The NSR500V won't run without a battery pack, the F3 barely made it back to the pits (you should know that, Les, you were there!), and we've had to replace old batteries on MC21s and MC28s when they wouldn't run cleanly on the dyno. Just my experiance.
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I’m new to the NSR, this is how I got the bike, and I’m trying to get my head around the little details as well as the larger details (as to why the bike has been “gutted” so much etc. I have a track day next weekend so I’ll certainly try a battery (they are not expensive) if it fixes the issue I will be ecstatic if not I guess I’m back to square one.
Thx for the all the info. The day you stop learning is the day you should give up.

You are right Andy, but like you i was only speaking of experience, and the eliminator is only any use to someone seeking the last ounce of weight saving, ie, an over weight jockey like me.
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Lesviffer750 wrote:
You are right Andy, but like you i was only speaking of experience, and the eliminator is only any use to someone seeking the last ounce of weight saving, ie, an over weight jockey like me.

Overweight??? I wish I weighed as much as you, Les! 🤣🤣🤣
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Rowanvtr wrote:
I’m new to the NSR, this is how I got the bike, and I’m trying to get my head around the little details as well as the larger details (as to why the bike has been “gutted” so much etc. I have a track day next weekend so I’ll certainly try a battery (they are not expensive) if it fixes the issue I will be ecstatic if not I guess I’m back to square one.
Thx for the all the info. The day you stop learning is the day you should give up.

We find they've often been "gutted" for one of two reasons... first is components die, and can be difficult and often extremely expensive to replace if you're outside of Japan, and second, people often think they can do it better/simpler than Honda! They can't!

The truth is, you can indeed simplify it, as someone's clearly done in your case (I've done it myself before!), but I can absolutely guarantee it's nowhere near as good as it should be now. Someone's basically taken away everything that makes it so much better than its contemporaries. If you have the chance to acquire the missing parts, I'd definitely advise it, but it won't stop you enjoying the bike for sure. Just keep it in your mind, "it could be better".
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Andy.
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Andy wrote:

Rowanvtr wrote:
I’m new to the NSR, this is how I got the bike, and I’m trying to get my head around the little details as well as the larger details (as to why the bike has been “gutted” so much etc. I have a track day next weekend so I’ll certainly try a battery (they are not expensive) if it fixes the issue I will be ecstatic if not I guess I’m back to square one.
Thx for the all the info. The day you stop learning is the day you should give up.

We find they've often been "gutted" for one of two reasons... first is components die, and can be difficult and often extremely expensive to replace if you're outside of Japan, and second, people often think they can do it better/simpler than Honda! They can't!

The truth is, you can indeed simplify it, as someone's clearly done in your case (I've done it myself before!), but I can absolutely guarantee it's nowhere near as good as it should be now. Someone's basically taken away everything that makes it so much better than its contemporaries. If you have the chance to acquire the missing parts, I'd definitely advise it, but it won't stop you enjoying the bike for sure. Just keep it in your mind, "it could be better".

Problem of no rev past 10000 fixed, Andy you were 120% correct it needed a battery, put a battery in for a track day today and she freely reved.
Thx for the help.

Rowanvtr wrote:
Problem of no rev past 10000 fixed, Andy you were 120% correct it needed a battery, put a battery in for a track day today and she freely reved.
Thx for the help.

Excellent news!

Hope we get to see some more of it here soon. (But without problems, of course!)

Maybe consider adding it to our "Members Garage" section, with spec and photos?
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Andy.
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