Big-bore kits

This is really where reliability comes into the equation. If you done all the above mods, you would be looking at a power increase of up to 5bhp over stock, and a bit of a weight saving too. The reliability would be very similar to a standard motorcycle.

When you get to big bore kits, things begin to change. The first reason for this is that many big bores are done when the engine has been seized or damaged. The cost to rebuild the engine with standard parts of a big bore is similar, so that’s what many people do. But that leaves the question of why did the engine go bang in the first place? If the problem is not fixed, and it goes bang again, it is often blamed on the larger bore of the engine.

So, if it’s a big bore kit that you want, it is well worth thinking about doing it when your engine is working well. What can you expect from a big bore on your engine? Well, it depends. Some love ‘em some hate ‘em. If you have done the tuning listed above already, and your engine has been looked after and is in good condition, than you can expect a good increase in power and torque. The acceleration will improve, and usually the top speed too. Put it this way, if you have been trying to break the 100mph mark, with a big bore you should. But remember, that is with a good strong engine. If you have a worn out, smoking, grinding engine, you are likely to have it go pop reasonably quickly, and you will certainly not get the full benefit of the increased capacity.