2 replies to this topic

[pauly_denham]

Hi Guys,

I have recently purchased a 2003 R1 5PW R1 engine. The engine has come with basically no ancillaries just the gearbox, block and head. I have been told that the head has been ported and polished, which looks to be true, and the valve seat angles have been re-cut to 3 degrees. This apparently helps with the flow etc (The head was an ex-beale virgin Yamaha head?).

Basically my question is: What would you guys buy (new or used) to get the best possible performance out of this engine.

I have been told the regular stuff like power commander and a good air filter etc but if you could suggest the best set-up to gain the most amount of power (Exhaust back box, commander, filter make, plugs etc) I would be very grateful. I am only just entering the world of bike engined minis and only have a basic knowledge so the more specific you could be the better :)

Also is it true you can set these engines up on either carbs or injectors? If so which would you suggest? I am looking for a small degree of reliability too

Cheers Guys and look forward to the comments!

[Alex_B]

I dont have much experience in bike engines but am doing a motorsport engineering degree, and there isnt a set order for doing things which give x horsepower gains, the best way if you are serious about doing it is learning how an engine makes power, and how various items can be tuned to give the best performance for what you want, things like ram pipes, they can be tuned to give more torque, more hp etc,

A power commander type system is very good for tuning fuel air, spark timing ect as you can plug a laptop in, go for a drive see how it works and just tweak settings, I believe ITG filters are very good, exhaust pipe tuning is science, and yeah you can follow other peoples examples but that doesn't mean it will meet your specific needs.

There is a very good book for minis about tuning the a-series, it might be worth looking for one that specialises in short-stroke high revving engines which bike engines fit into.

things you may struggle with is torque or lack of, short stroke over-square engines suffer from low torque but high power so pulling away can be an issue, so may need to look into gearing it more for torque.

Sorry if this isnt what you were looking for, but hope it is of some help. :)

[pauly_denham]

Cheers, yerr I will have a look to see what I can find out about the short- stroke high revving engines! I'm sure there must be something out there! I hear that the R1 engines are just ok for torque, and easier pulling off if you have a Barnett clutch fitted. I am looking at building my mini as lightweight as possible so that should help in that department.

Cheers :)