Big Bore Kit, NSR300, Wiseco, VHM
This 300cc Big Bore Kit is identical to the TPER-3007 NSR300 Big Bore Kit, but uses VHM cylinder heads instead of the cast TYGA cylinder heads. See dyno charts for performance details for TPER-1007.
Bore & Stroke is 59mm x 54.5mm giving a total displacement of 298cc.
Parts included in the NSR300 kit.
- Cylinder x 2 (includes head studs, RC valve, pulley & nut and washers)
- VHM Rear Head x 1
- VHM Front Head x 1
- Wiseco Piston kit x 2 (Includes Piston, rings, pin & circlips)
- S/E Bearing x 2
- Head gasket x 2
- Cylinder gasket x 2
- RC Valve cables x 4
- Water hose x 1
- Exhaust Manifold x 2 (to fit TYGA pipes)
Please select your piston preference from the option dropdown below:
Short Skirt (default):
The short skirt type piston is a 'bolt on' solution for the big bore kit. In this case we modify the piston by shortening the front side skirt to allow clearance from the crankcase at BDC. Therefore, no crankcase disassembly or modification is necessary, and the top end can be assembled in the usual way of doing a top end overhaul.
Full Skirt:
The full skirt type piston has a very slightly increased longevity compared to the short skirt type, however, this necessitates that the crankcase is completely disassembled, and some grinding of the crankcase is required to allow for piston clearance from the case at BDC. Please see the guide for how to perform the necessary modifications.
Technical information:
Exact Jetting requirements for your area and application cannot be provided due to differing atmospheric conditions around the world. However, following are some base settings to work from:
MC21 Std bottom end, Wire splice, TYGA Pipes, Airbox lid mod with filter.
- Temp: 29 C
- Press: 1015mb
- Hum: 65%
- Alt: 30m
- MJ - #182/#185
- JN - Std./Std.
- SJ - #38/#38
- AS - 1.5 turns out
- PwrJ - Std./Std.
Tip: Cooler temps, higher pressure and/or lower humidity require richer jetting. High altitude requires leaner settings. Starting off with rich settings will in the worse case foul a plug. Too lean a setting may destroy the engine.
This jet set-up is for guidance only. TYGA Performance cannot be held responsible for any engine damage incurred due to incorrect settings.
At present, this kit is available by special order. Each kit takes approx. four weeks to prepare.
Torque Values:
- Cylinder Head: 22Nm
- Cylinder: 24Nm
Fiiting Instructions RC Cables: 
There is no problem about the RC valves hitting the piston due to thin cylinder wall thickness. This is not an issue on our kit as it's using different
cylinders, not modified NSR250. They are genuine OEM Honda cylinders, made and plated in Japan to their typical high quality.
The RC valves are easier to adjust than ever on the 300 kit, as there's only one adjuster screw to play with, and each cylinder marked at the correct 'fully open' position for simple setting.
In the case of the Honda NSR250 MC28, to realise the full potential of the big bore kit, you really need to use the HRC ignition card, as without this the ignition timing is quite retarded and you will not reach full power.
If using the standard ignition card, then we suggest following the modifications that can be found on out power up kit page: HERE
The power up kit mods will be most helpful and will increase power all through the range compared to the 250cc setup, but will not reach what is possible with the HRC card.
Be sure to take the time to set up the carbs properly. This is most important
Contact us for more details
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This product contains the following items: |
 | 2 x | (12192-KV3-680) Gasket, Cylinder, MC16~28 | $6.41US |
 | 2 x | (14320-KW6-840) RC Valve Cable guide, NSR150SP | $1.99US |
 | 1 x | (TPER-1033) RC Valve Cable A, NSR150SP | $10.55US |
 | 1 x | (14340-KW6-840) RC Valve Cable B, NSR150SP | $8.10US |
 | 4 x | (90035-KV3-950) Stud, Exhaust #2 8x22, MC28 | $2.33US |
 | 2 x | (90310-634-980) Nut, 6mm, L/H thread, MC28 | $1.38US |
 | 2 x | (90437-GM0-000) Washer, 6X12.5X2, MC28 | $1.75US |
 | 4 x | (90555-KV3-000) Washer, RC Valve, Special, MC28 | $3.47US |
 | 2 x | (91102-KV3-771) Bearing, Piston, MC28 | $6.81US |
 | 12 x | (92900-08040-0E) Stud, Cylinder, 8X40, NSR150SP | $2.88US |
 | 20 x | (94050-08000) Nut, Flange, 8mm | $0.74US |
 | 4 x | (94301-10160) Dowel, Cylinder, MC28 | $1.23US |
 | 1 x | (TPER-0035) RC valve cable kit, 300cc big bore | $31.81US |
 | 2 x | (TPER-0026) Wiseco Piston, TYGA 300cc Big Bore Kit * | $155.04US |
 | 1 x | (VHM-NSR300) VHM Cylinder Head Set, NSR300 | $595.90US |
 | 2 x | (TPER-0028) Cylinder, NSR300 Kit | $703.64US |
 | 1 x | (TPER-0038) TYGA 300cc water hose, top cylinder | $15.40US |
 | 2 x | (EXMC-0001) Clamp, Manifold, NSR150/250 | $5.00US |
 | 2 x | (EXMN-0300) Collar, Manifold, Stainless, NSR250 | $25.58US |
Cost of separate parts: $2,554.41US | | You save $0.00US |
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