Years ago a company called Design Performance made compete performance conversion kits for the VT750 including ported and polished heads, high compression pistons, custom cams, roller rocker arm lifters, single carburetor, etc. With all of the above installed a VT750 was able to dyno 62HP at the rear wheel. Unfortunately Design Perfroamnce are not longer making these parts. The good news is that AFT Customs is now selling performance kits including aftermarket pistons and camshafts.
Here you will also find sources and part numbers for some of the parts DP used.
To really bring the VT750 Shadow Spirit motor to life AFT Customs has a high compression piston and camshaft kit available. The AFT Customs kit is composed of 11:1 CPR pistons and bigger Cams and can add up to a 20% increase in HP over stock if tuned properly.
The AFT Customs Performance Kits for the VT750 can be purchased HERE, they also sell a plethora of other custom parts.
These kits can also be purchased through Hellriser Customs.
Thinking beyond pistons and cams, having the heads ported and polished including a custom larger exhaust valve will help maximize the power from this kit.
Also consider inner valve springs from an early '90s model Hawk NT GT650 as the outter spring is the exact same as the current spring used on the VT750. If you can find one used a carb swap to the NT GT650 carburetor which is larger would also net more airflow/fuel which can equate to more power.
NT GT650 part numbers:
Intake Inner Spring: 14751-MR1-003
Intake Valve Spring Seat: 14775-MF5-000
Exhaust Inner Spring: 14752-MR1-003
Exhaust Valve Spring Seat: 14775-ME9-000
It has been noted that CBR 900 Aftermarket clutch springs fit the VT750 and stand to be stiffer than the aftermarket options currently available.
Magnum Tuning Appears to make Adjustable Rev Limiters for the VT750 product lines of bikes including the Spirit DC, Spirit C2, Phantom, Shadow RS, etc. This requires disassembling and modifying your ECM to interface the adjustable device but after some serious engine mods such as cams and or pistons increasing the rev limit from the stock 5000 RPM to say 7000 RPM is a game changer. Note that VT750DC.com knows of no one who has actually done this mod successfully. We are inquiring with the manufacturer.
Click this link to find the model that suits your VT750: Magnum Tuning Search at Amazon
part #: 55-999
grind #: 453 HWD
79mm (3.1105) Cylinder bore
18mm (.708) Pin Diameter
(There is a recess on top for valve clearance)
not sure of part number
Dyna 3000 Performance Ignition
(This item has been discontinued)
Part #: D3K1-3
Dyna 3000 wiring