Skip to content

FAQ: 410cc / 500cc J-Engine Big Bore Sets

This FAQ last updated: 27.05.2024

Please ask questions in the FORUM where issues are discussed in greater detail.

Q: When can I expect the 500cc set to ship?
A:  Now

Q: Do the 410cc or the 500cc BB kits require a widening of the engine body?
A: No – both are “plug and play” with regards to fitting.

Q: Do I need anything on top of the BB set for the 410cc upgrade?
A: No. This upgrade is very well handled by the OEM ECU of the bike itself. However, if you own a Meteor or a New Classic Bullet you may want to change to the throttle body/ecu combo of the Hunter as that one does not have the rev and speed limiter your bike will have. The part number for that particular TB is RLT00187. See also:

Q: What kind of piston do you use for the 410 and 500 BB kits?
A: We use a RE OEM piston for the 410 BB kit (which is cast) and a forged piston of our own design for the 500 BB kit.

Q: What additional ECU can I get for air/fuel and timing management of the 500 BB kit?
A: We only know of the Powertronic V4 made by Racedynamics in India at the moment. However, other vendors may come up with one in the future as the market for the J-engine is huge covering 3 of the best selling models of Royal Enfield.
Update: There is now the optional FuelX Pro+ for this engine and in our tests it showed a real improvement in torque and response.

Q: Are you offering maps for the J-Engine PT V4 and the 500cc BB kit?
A: Yes we do but we add the caveat that these maps where done for a Meteor and even then they may need additional tweaking to fit you specific bike if you have changed other elements concerning the fuel/air flow.

Q: Is there a appreciable compression increase with the 410cc or 500cc BB?
A: There is some. The 410cc has a 4% increase and the 500cc about 9%. In our experience the 410cc will run with 95 Octane fuel without knocking. The 500cc requires 100RON which would be called “Super” in most western countries. To completely avoid knocking issues we have opted to slightly modify the head by carving out a section that is very easy to work with, the pictures shown on this forum thread demonstrate this simple 30 minutes task:

Home of the 477 Big Bore
Translate »