Upgrading A 400 Cc Bike To 600cc

[Kf6vci]

Do the Japanese manufacturers use identical engine casings, drilling just smaller holes for their 400 cc models? Can owners easily upgrade their 400s to 600 cc engines, like with a Sportster 883 to 1200 cc? Just wondering... Chris

[submaniac]

Not quite the same as new jugs on a Harley. Was looking at doing it on an FZR400 (wanted to put in the 600cc engine). Mounting bolts are the same, but engine is not.

[BigBikeBKK]

Much much much easier to just buy a 600cc machine. If you put a 600cc in a 400cc frame you'll soon discover that the rest of the bike was never designed to handle the extra power. More headaches than it's worth IMO. Ride On! T

[BSJ]

I've done engine swaps and it's not to hard if you stick to the one model. It's when you decide on a different engine from another bike where it gets.....interesting!

Some of the things to watch out for if your swapping parts from one to the other:

1/ Exhaust ports and exhaust system different inside diameters.

2/ Gearbox or output spocket different ratios.

3/ Carb venturi different size or jetted differently. Inlet port/valves different.

4/ Added frame reinforcing on bigger engined bike not on 250cc frame.

5/ 250cc head on 400cc engine can raise compression.

6/ Starter motor on 250cc not powerful enough for 400cc.

7/ Brakes/rims/tyres/spokes/swingarm on 250cc to light for 400cc.

You need research on every little thing!