So I was discussing with a good friend of mine about carburator and discussing things whether or not to put on an after market Carburetor and right on the spot he immediately suggest the Lectron HV Carburetor, well at first I was quite hesistant since lectron only build their carbs for dirt bikes and the closes thing I can get is the CR 250 kit but lectron will be calibrating it up for what the customer requirements needs but I do not know if it will be more benificial/ideal to put it on my NSR project since I've seen one folk did it on his mc18 but for tracked used only which is parallel to what my bike will be more used to which is road use only for most of the time.

So it will be worth of an investment or should I just stick on stock Carburetor and braaaap on?

Phantom wrote:So I was discussing with a good friend of mine about carburator and discussing things whether or not to put on an after market Carburetor and right on the spot he immediately suggest the Lectron HV Carburetor, well at first I was quite hesistant since lectron only build their carbs for dirt bikes and the closes thing I can get is the CR 250 kit but lectron will be calibrating it up for what the customer requirements needs but I do not know if it will be more benificial/ideal to put it on my NSR project since I've seen one folk did it on his mc18 but for tracked used only which is parallel to what my bike will be more used to which is road use only for most of the time.

So it will be worth of an investment or should I just stick on stock Carburetor and braaaap on?

HRC invested years of development and untold amounts of cash to develop the MC21. Power wise it is made up of a super fine balance of cylinder/crankcase/carburretor/exhaust working in absolute perfection to deliver peak performance and reliability.
No other manufacturer really came close to the fine balance HRC created (Suzuki were closest), which is why the RS series of race bikes dominated on the race tracks of the world for more than 20 years and more than 150,000 NSR 250's were sold...I would say leave it well alone and spend your cash on something else...an MC28 maybe?

Max wrote:

Phantom wrote:So I was discussing with a good friend of mine about carburator and discussing things whether or not to put on an after market Carburetor and right on the spot he immediately suggest the Lectron HV Carburetor, well at first I was quite hesistant since lectron only build their carbs for dirt bikes and the closes thing I can get is the CR 250 kit but lectron will be calibrating it up for what the customer requirements needs but I do not know if it will be more benificial/ideal to put it on my NSR project since I've seen one folk did it on his mc18 but for tracked used only which is parallel to what my bike will be more used to which is road use only for most of the time.

So it will be worth of an investment or should I just stick on stock Carburetor and braaaap on?

HRC invested years of development and untold amounts of cash to develop the MC21. Power wise it is made up of a super fine balance of cylinder/crankcase/carburretor/exhaust working in absolute perfection to deliver peak performance and reliability.
No other manufacturer really came close to the fine balance HRC created (Suzuki were closest), which is why the RS series of race bikes dominated on the race tracks of the world for more than 20 years and more than 150,000 NSR 250's were sold...I would say leave it well alone and spend your cash on something else...an MC28 maybe?

I'm ok with the Mc21 maybe in near future I'll secure a 28 too. So to say you're voting on just stick on stock and braap on.

Phantom wrote:

Max wrote:

Phantom wrote:So I was discussing with a good friend of mine about carburator and discussing things whether or not to put on an after market Carburetor and right on the spot he immediately suggest the Lectron HV Carburetor, well at first I was quite hesistant since lectron only build their carbs for dirt bikes and the closes thing I can get is the CR 250 kit but lectron will be calibrating it up for what the customer requirements needs but I do not know if it will be more benificial/ideal to put it on my NSR project since I've seen one folk did it on his mc18 but for tracked used only which is parallel to what my bike will be more used to which is road use only for most of the time.

So it will be worth of an investment or should I just stick on stock Carburetor and braaaap on?

HRC invested years of development and untold amounts of cash to develop the MC21. Power wise it is made up of a super fine balance of cylinder/crankcase/carburretor/exhaust working in absolute perfection to deliver peak performance and reliability.
No other manufacturer really came close to the fine balance HRC created (Suzuki were closest), which is why the RS series of race bikes dominated on the race tracks of the world for more than 20 years and more than 150,000 NSR 250's were sold...I would say leave it well alone and spend your cash on something else...an MC28 maybe?

I'm ok with the Mc21 maybe in near future I'll secure a 28 too. So to say you're voting on just stick on stock and braap on.

👍 BUONG GAS!! Braaaaaap

What Max said, spend your money on a good suspension overhaul and set up, remember, these bikes are 30 + years old and these are often overlooked, you will probably get more benefit from this than swapping out the carbs, just riding on the road, remember the old saying, " if it aint broke ".
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Lesviffer750 wrote:What Max said, spend your money on a good suspension overhaul and set up, remember, these bikes are 30 + years old and these are often overlooked, you will probably get more benefit from this than swapping out the carbs, just riding on the road, remember the old saying, " if it aint broke ".

I see, I've the Ohlins and Nitron+ rear shock suspension already and gonna get the front suspension checked too.

The MC21 (and MC18) carbs are actually very good, and very difficult to better. The D shape venturi acts more like a 34mm [maybe more!] carb at 50%+ throttle opening, and like a small round-bore 32mm carb at low RPM and throttle openings, giving the best of both worlds.

Putting larger carbs on an NSR250 almost invariably destroys the bottom-end and mid-range. Unless you've done substantial supporting work to the crankcases, barrels, heads, and exhausts to reap any potential benefit it's just not worth it. Even then, you are still more than likely to only gain some over-rev and still lose bottom-end. Another thing to take into account, is you lose any provision for the stock air correction, making setting both fussy and more difficult. (Remember, the TT-F3 setup is designed around the removal of the air correction, but the standard PGM-III is not.)

Something we've always wanted to do, but sadly never got around to, was fit 32mm HRC TT-F3 carbs to an NF5 on the dyno. I reckon the results would surprise a few people!

As an aside, the 300 conversion does seem to respond better to larger carbs, but the problem I see most often is people thinking the answer is always to go too big. Personally I think a 36mm would be perfect on both a very hot 250 and a 300, but I've seen people using (trying to use!) 39mm and even 40mm. Much to many owner's chagrin, we've never seen an NSR (250 or 300) with big carbs out perform an equivalent one on the '88-'93 32mm carbs... and we've dyno'd dozens and dozens of NSRs.

Not saying you couldn't make it work for you, or that you shouldn't try, but in my experience you're better off spending your money elsewhere... unless it's really important to you, or you're loaded and have nothing better to do!
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Andy wrote:The MC21 (and MC18) carbs are actually very good, and very difficult to better. The D shape venturi acts more like a 34mm [maybe more!] carb at 50%+ throttle opening, and like a small round-bore 32mm carb at low RPM and throttle openings, giving the best of both worlds.

Putting larger carbs on an NSR250 almost invariably destroys the bottom-end and mid-range. Unless you've done substantial supporting work to the crankcases, barrels, heads, and exhausts to reap any potential benefit it's just not worth it. Even then, you are still more than likely to only gain some over-rev and still lose bottom-end. Another thing to take into account, is you lose any provision for the stock air correction, making setting both fussy and more difficult. (Remember, the TT-F3 setup is designed around the removal of the air correction, but the standard PGM-III is not.)

Something we've always wanted to do, but sadly never got around to, was fit 32mm HRC TT-F3 carbs to an NF5 on the dyno. I reckon the results would surprise a few people!

As an aside, the 300 conversion does seem to respond better to larger carbs, but the problem I see most often is people thinking the answer is always to go too big. Personally I think a 36mm would be perfect on both a very hot 250 and a 300, but I've seen people using (trying to use!) 39mm and even 40mm. Much to many owner's chagrin, we've never seen an NSR (250 or 300) with big carbs out perform an equivalent one on the '88-'93 32mm carbs... and we've dyno'd dozens and dozens of NSRs.

Not saying you couldn't make it work for you, or that you shouldn't try, but in my experience you're better off spending your money elsewhere... unless it's really important to you, or you're loaded and have nothing better to do!

Thanks andy for the response.
Looks like a small dent of benefits is what I can get with if I put a Lectron HV 36mm on my NSR, I guess I'd just divert the fund on other necessary stuff for my mc21 that can be both beneficial on me and the bike.

I think big carbs are the sort of thing you try and do on your "second" NSR. It's really, and I mean really difficult to better the OEM carbs, and for a daily/streetbike, I can never see the point.

There's a guy in Japan who's put fuel injection on an MC18... that's pretty trick, seems to run OK in the videos, so pretty much anything is doable, but I bet it's not as good as standard carbs.

The PGM is just so well integrated with the ignition and fuelling. Bear in mind too, that the PGM controls the RC Valve, and takes an input from the TPS (which most big carbs don't have). While setting the TPS to a fixed position "works", the way the PGM reads the TPS and translates the input to RC output isn't as simple as that.
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Andy wrote:I think big carbs are the sort of thing you try and do on your "second" NSR. It's really, and I mean really difficult to better the OEM carbs, and for a daily/streetbike, I can never see the point.

There's a guy in Japan who's put fuel injection on an MC18... that's pretty trick, seems to run OK in the videos, so pretty much anything is doable, but I bet it's not as good as standard carbs.

The PGM is just so well integrated with the ignition and fuelling. Bear in mind too, that the PGM controls the RC Valve, and takes an input from the TPS (which most big carbs don't have). While setting the TPS to a fixed position "works", the way the PGM reads the TPS and translates the input to RC output isn't as simple as that.

Forgot about that PGM thingy stuff to do. I guess I'd be buying zeeltronic to change my PGM will that be ideal to do so?

My understanding is the Ignitech is better for the NSR, but I don't have personal experience. That information does come from a trusted source though. I trust about 3 people when it comes to NSR information... and one of those is me!
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Andy wrote:My understanding is the Ignitech is better for the NSR, but I don't have personal experience. That information does come from a trusted source though. I trust about 3 people when it comes to NSR information... and one of those is me!

I see I guess I'll try to source out the ignitech for good.

I admit I have had same thought to try either Lectrons or SmartCarbs. The idea of not having to pull the carbs every time a main jet needs changing really appeals to me. The ideal situation would be a fuel injector with a data cable to plug into a laptop to make jetting adjustments..

But then I start to think about how much time and tinkering its gonna take to get the bike to point where it is right now with stock carbs/HRC jetting which is damm near perfect. I'm sure you will come to your own conclusions. I have read on forum others have used Lectrons with success so I am anxious to hear your story should you use them. Hopefully you can get them to put a TPS sensor on them.

For now my NSR sits by itself while I start on a new project. I recently came across an original BMW GP frame circa early 70s that I am building into a custom bike. The donor bike arrived yesterday. But that is for a different thread on a different forum.

ericandchi wrote:I admit I have had same thought to try either Lectrons or SmartCarbs. The idea of not having to pull the carbs every time a main jet needs changing really appeals to me. The ideal situation would be a fuel injector with a data cable to plug into a laptop to make jetting adjustments..

But then I start to think about how much time and tinkering its gonna take to get the bike to point where it is right now with stock carbs/HRC jetting which is damm near perfect. I'm sure you will come to your own conclusions. I have read on forum others have used Lectrons with success so I am anxious to hear your story should you use them. Hopefully you can get them to put a TPS sensor on them.

For now my NSR sits by itself while I start on a new project. I recently came across an original BMW GP frame circa early 70s that I am building into a custom bike. The donor bike arrived yesterday. But that is for a different thread on a different forum.

I've seen some few folks do convertion from stock carb to lectron HV on their NSR mc18,21 and 28 with good success on the internet but they are purely used more on track than what I'll normally do which would be in road use and rarely on track, some of them haven't replied back on my inquires about what they've gain on upgrading on Lectron carb the only responses I got is "Fuel efficiency" and that's all.

Putting a Lectron HV on my 21 will be a hefty job since some of the descriptions they've stated is that it takes tons of $$$ and time consuming to calibrate it out to what they really wanted to achieve and make the bike perform to what they wanted it to be.

As of now I'm only exploring and tinkering with the idea whether to get Lectron HV 36mm to replace and preserve my stock carb or just rethink my decision and spend it to other valuable spare parts.

ericandchi wrote:
I admit I have had same thought to try either Lectrons or SmartCarbs. The idea of not having to pull the carbs every time a main jet needs changing really appeals to me.

The MC28 TB carbs are a ball-ache to work on compared to the earlier TAs, so I could see why you'd consider changing!

In all seriousness though, as you say, you can get the OEM carbs near perfect with a little patience and the HRC jet kit, and unless you're absolutely set on running them on the ragged edge, it's not like you're not swapping mains every 15 minutes.
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