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MC21 tuning: Preparing your MC21 for Track Days

 

There's a few simple things to do yourself, and a selection of bolt on goodies to turn your 45hp MC21 into a 65hp track weapon. The list below is by no means all you can do, but it'll get you enough gee-gees to give your bike a new lease of life.

 

There's no particular order to the procedure. I've just started from the back and worked forwards.

 

Wire Splice

 

This is necessary to remove the PGMIII restriction, and is fully documented, with pictures, in the link below.

 

Airbox

 

If it's going to be a track only bike then you may as well junk the airbox. It does nothing but restrict the high speed airflow. Open carbs are the way forward.

 

Oil Pump

 

You'll also want to remove and block off the 2T oil injector and go to premix. This gets rid of all the unsightly and 'in the way' 2T oil tank and associated parts and gives a solidly reliably feed of oil to all the moving parts. Use a quality oil mixed at 30:1. There's many good oils to choose from, but one of the best in my opinion is Castrol A747. You'll also need to block off the oil feed holes to the carburetors.

 

Carbs

 

For ease of setting up the carburation, an HRC carb setting kit is recommended. This includes three sizes of adjustable needles (A, B & C), a selection of main and slow jets, and replacement air corrector X & Y pieces. We can supply TYGA #0 power jets at no extra cost if the jet kit is purchased through TYGA, as these are not included in the MC21 HRC jet kit.

 

Reed Valves

 

The next step is to fit TYGA Hi-Flo reed valves and carbon reeds. These are always good for some instant ponies. Fitted with HRC style rectifiers and lifter plates to improve power and throttle response.

Crankcase

 

If you've got the cases apart then there's plenty to do here. Radius all those nasty sharp edges, and smooth off the casting flashing. This removes any restrictive lumps and bumps and keeps flow restricting turbulence to a minimum.

 

Cylinders

 

Don't worry too much about changing the timing of the transfer ports on the NSR as they're pretty good as stock, and more harm can be done than good if you just go hacking away! Just clean up the overhanging Nikasil plating in the port windows. This is a delicate job so make sure you have all the correct tools and be patient.

 

The exhaust port is the culprit in the NSR's relatively low peak power. It's a very conservative shape and could do with some attention. Cut the roof of the port flat to 28mm from the top of the cylinder, and then cut the RC valves to match. Leave a generous radius in the out side corners of the ports to preserve ring life, and don't go wider than the stock dimensions. Again, make sure that you have the right tools for the job, and leave a nice chamfer on the port edge to stop the piston ring catching on the way past.

 

Heads

 

No real need to start messing around here if you just want a reliable track day tool. The stock compression ratio is fine for unleaded pump fuel. One thing to consider doing though is fitting rear heads to both rear and front cylinders. This requires a special HRC water hose, but the benefits are better spark plug positioning compared to the stock front head. Less chance of detonation, a better burn which means more power.

 

Expansion Chambers

TYGA Pipes are a must! Designed with the help of TSR's computer design program and manufactured in Stainless Steel in either SS or GP designs. Silencer available in either aluminium, carbon, carbon/Kevlar or titanium. Fast and simple to fit with guaranteed increase in horse power over the stock pipes.

Well, that's about it. Pay careful attention to the jetting at all times. If in doubt, start rich and lean off as necessary. Make notes at every track day for weather condition, best jetting etc. and you should be rewarded with a fast but reliable track day bike.

 

All this can also apply to the MC28, but the PGMIV restriction is obviously more expensive to overcome, as the HRC 030 card is required.

This advice is offered as assistance only. TYGA Performance cannot be held responsible for any machine damage, personal injury or death incurred by following the above mods.

Show: 

Set, Exhaust Chamber, GP Type, Stainless Steel, NSR250 MC21

Set, Exhaust Chamber, GP Type, Stainless Steel, NSR250 MC21

Constructed in stainless steel, TYGA Performance  combine modern technology and traditional techniques to bring you the best in…

Model
EXCS-0006A
Quantity
5
Set, Exhaust Chamber, Side By Side Type, Stainless Steel, NSR250 MC21

Set, Exhaust Chamber, Side By Side Type, Stainless Steel, NSR250 MC21

Constructed in stainless steel, TYGA Performance  combine modern technology and traditional techniques to bring you the best in…

Model
EXCS-0005A
Quantity
12
Silencer, Aluminium, Two Stroke, (Special), Assy.

Silencer, Aluminium, Two Stroke, (Special), Assy.

This aluminium two stroke silencer offers the same excellent value for money that our silencers always have but now…

Model
EXSL-9005
Quantity
100+
Silencer, Carbon, Two Stroke, Assy.

Silencer, Carbon, Two Stroke, Assy.

This high quality lightweight (0.47 kg) silencer is made from CNC machined end caps joined by a carbon fiber tube.…

Model
EXSL-0003
Quantity
46
Silencer, Carbon/Kevlar, Two Stroke, Assy.

Silencer, Carbon/Kevlar, Two Stroke, Assy.

This high quality lightweight silencer ( 0.47kg) is made from CNC machined end caps joined by a carbon/Kevlar fiber…

Model
EXSL-0004
Quantity
33
Race Air Box Lid (Carbon), MC21/MC28

Race Air Box Lid (Carbon), MC21/MC28

Race Air Box Lid Carbon, MC21 The stock air box is restricted by the size of the inlet holes…

Model
BPCX-9010
Quantity
6
Race Airbox Lid (GRP), MC21/MC28

Race Airbox Lid (GRP), MC21/MC28

The stock airbox is restricted by the size of the inlet holes on the lid which limits the amountof power…

Model
BPFX-9010
Quantity
1
2T Blank Plug

2T Blank Plug

Replaces the 2T oil injector pump for pre mix use. Secure with liquid gasket such as…

Model
TYLY-0012
Quantity
40
Blank Plug holder

Blank Plug holder

Secures plugs TYLY-0012 and TYLY-0014. Secured to engine case using existing M6 hole FREE SHIPPING  by Airmail* if ordered individually (please…

Model
TYLY-0015
Quantity
24
Gasket, Cylinder, 0.4mm NF5*

Gasket, Cylinder, 0.4mm NF5*

Gasket, Cylinder, 0.4mm NF5 Fits MC16~28. Use to adjust deck height/squish/compression ratio.…

Model
12191-NF5-610
Quantity
39
Gasket, Cylinder, 0.6mm NF5*

Gasket, Cylinder, 0.6mm NF5*

Gasket, Cylinder, 0.6mm NF5 Fits MC16~28. Use to adjust deck height/squish/compression ratio.…

Model
12193-NF5-610
Quantity
23
Hi Flo reeds, MC21/MC28, Assy.

Hi Flo reeds, MC21/MC28, Assy.

Kit includes: * HRC style stuffer for improved intake mixture flow. * Reed stopper lifter plates to increase intake…

Model
TPER-0001
Quantity
11
Power Jet #0, for NSR250 MC18/21/28.

Power Jet #0, for NSR250 MC18/21/28.

Power Jet #0, for NSR250 MC18/21/28. Replica part to replace HRC part: 99106-NKD-970   Use this jet to blank off the power…

Model
TPER-0005
Quantity
1
Water Hose, Head conversion, thermostat

Water Hose, Head conversion, thermostat

Use this hose when converting from the standard front cylinder head to a rear cylinder head. Connects inline with the…

Model
TPER-0021
Quantity
12
Woodruff Key, Offset, 1 Degree, NSR250

Woodruff Key, Offset, 1 Degree, NSR250

1 Degree offset woodruff key for NSR250. Allows simple advance/retard of stock ignition timing. *Important* Modifying ignition timing from standard setting may…

Model
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Quantity
46
Woodruff Key, Offset, 2 Degrees, NSR250

Woodruff Key, Offset, 2 Degrees, NSR250

2 Degrees offset woodruff key for NSR250. Allows simple advance/retard of stock ignition timing. *Important* Modifying ignition timing from standard setting may…

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Quantity
51
Woodruff Key, Offset, 3 Degrees, NSR250

Woodruff Key, Offset, 3 Degrees, NSR250

3 Degrees offset woodruff key for NSR250. Allows simple advance/retard of stock ignition timing. *Important* Modifying ignition timing from standard setting may…

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Quantity
41
Woodruff Key, Offset, 4 Degrees, NSR250

Woodruff Key, Offset, 4 Degrees, NSR250

4 Degrees offset woodruff key for NSR250. Allows simple advance/retard of stock ignition timing. *Important* Modifying ignition timing from standard setting may…

Model
TPER-4044
Quantity
57
Carb Setting Kit, MC21

Carb Setting Kit, MC21

Carb Setting Kit, MC21   Comprehensive HRC style carb setting kit for the Honda NSR250 MC21. …

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Quantity
4
Water Pump Shaft/Gear, MC18, MC21

Water Pump Shaft/Gear, MC18, MC21

Water Pump Shaft/Gear, MC18, MC21 High quality hard anodized aluminium gear, on precision ground shaft. Manufactured by T2 Racing…

Model
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