With complete engines showing up cheap on the bay, I was wondering what could be done to one for street riding.
Anyone know? Obviously, a big bore/stroke kit isn't possible and going nuts with compression won't work. Is there room over the factory build level that a good balance and blueprint with lighter and stronger parts would be worthwhile?
I'm assuming the 1k motor wouldn't fit...
I don't understand why big bore/stroke is obviously not going to work?
You can bore the 954 1mm to 980cc but the cost of pistons, boring and replating makes the bang for buck very low - possibly as much $500/hp. The old rule of thumb was the percentage of extra capacity is worth around the same in horsepower.
Consider that boring the 929 1mm to 954, the extra 26cc or 2.8% was worth about 10hp _including_ the 2mm bigger throttle bodies and lighter pistons. 5-6hp purely from the bigger bore would be reasonable I reckon. Of course, there'd also be a gain from the new rings, so you could see double that on the dyno depending on how worn the engine is to begin with.
I don't know how far it can be stroked but you would need custom rods and/or pistons. Stroking gives a bigger midrange improvement than boring but increases piston speed so you'd want to reduce your redline. With crank work and rods the cost per hp is similar to boring.
Compression provides minimal power gain at the expense of a lot of heat so I wouldn't recommend it for purely road use. You should be able to go to around 13.5:1 on pump fuel. That might score you 2-3% but expect to have to deal with combating heat - probably needing a bigger radiator which adds weight. The rule of thumb is 2% per 1.0 increase in ratio I think.
Cams would be the biggest gain I think without having to go into the engine.
Whatever you do inside the engine I think you'd want to start with a full race exhaust system and cams regardless.
The dual-injection off the 1000RR could be a step up as well but would require the ECU, harness and instrument cluster.
You could also make a stock 1000RR engine fit the 954 frame and swingarm mount but for the cost of getting an engine and modifying the frame to take it I don't know that the extra 10hp or so would be worth it.
The cheapest option would be bolting a turbo on and just run low boost. Without even going into the engine you should get an easy 200hp without over-stressing the engine. You can wind the boost right down when you don't need it so the bike behaves like a standard 954 and you can keep it for your next bike when you sell this one.