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The ultimate normally-aspirated engine.


Here we will take a somewhat brief look at what it takes to build a 190 rwhp engine that would 

scare the shit out of you...let us look at it in stages.


Stage 1:

We start with a stock production bike (say,135 rwhp) fresh out of the showroom without any mods.

Lets start with the basics which are:

-A slip-on (any brand that rocks your boat: round for big noise, oval for less noise)

-A jet kit or power commander (Ivan's, Factory, PC3/3R, YOSH EMS)

-An air filter (K&N or BMC)

Those simple bolt-on mods can net you a gain of between 2 and 6 hp depending on the slip-on choice or

if you choose to go with only one, two or all the above mentioned mods...the job can easily be done by the average backyard mechanic.

This gets expensive if you have to go with a PC2/3/3R, so expect to spend between $1000 and $1500 usd.


Stage 2:

This is getting interesting now.......lets say you had enough of the stage 1 mod and want more......

If you were clever enough to buy a PC3/3R or Ivan's kit, good for you...if you bought those "stage 1"

jet kits, then you are just looking at more money to be spent...I'll get to the point now.


The stage 2 mod is not really extensive, but don't forget that we're going toward that 190 rwhp engine!


Ok, time to shop for a full race system now.

The choice is yours, there are many good and bad choices to be made, but most are good systems...ask

 around, the same brands keep popping out, so there must be something good there!

4-1 for top end power

4-2-1 for more midrange oriented power 

I've noticed through the years that this so-called "oriented-power" thing is not that true...

Most full systems makes about the same peak hp. (Yosh, Graves, Hindle, Akrapovic, etc)

So, with the addition of that nice, ultra-light full race system you can add an aftermarket airbox!

There are a few choices out there, they are all good. Its only a matter of build-quality from there.

These additions can net you a gain of between 10 and 15 rwhp from a stock bike, again depending 

if you choose both mods or not. That bring us to around 145-150 rwhp...for between $800 to $1400 usd.

Stage 3:

Now its getting interesting!

We are looking at semi-serious engine mods now.

-Head milling job for a higher compression ratio


-Cleaning of the ports (commonly referred as porting job)

Now this brings us to the neighborhood of 170 rwhp...not bad!

Costs: Around $1500 to $2500 depending of the shop/tuner/quality of parts.

Recommended tuners: Graves, Attack, Brock Davidson.

Stage 4:

The final frontier....

You want the ultimate, you want to keep this motor in one piece...

Follow me in the most expensive part of the adventure.


-Oversized valves (although the space is very tight) Recommended: APE

-Heavy-duty valve springs (APE)

-Race ignition box (good luck finding one)

-Connecting rods (Falicon, Carrillo)

-Heavy-duty clutch basket (APE)

-Forged pistons -not oversized, just higher compression is enough- (JE)

-Clutch modification from diaphragm to springs (even a lock-up clutch can be thought about)

-Heavy-duty studs -to squeeze the lot in one tight package- (APE)

-Flat slides carburetors (Mikuni FCR`s)

-Coils and leads (Nology)


-Optimized squish band (to bring the intake charge closer to the flame, creating a bigger bang)

-Valve seats job (3 angles or 5 angles, no choice since you choose the oversized valves)

-Balancing of the crankshaft/rods/pistons (reduces potentially lethal vibrations)

-Blue-printing of the whole motor i.e.:

>Careful measuring of the crankshaft bearings tolerance

>Removal of all casting marks inside the crankcases and head

(to make the oil slosh around easier and to prevent cracking in the case of the crankcases)

>Polishing of the crankshaft/rods assembly (again ,to prevent cracking and make both slosh around easy)

>Transmission undercut job (more power needs a more positive engagement)

Recommended tuners: Graves, Attack, Brock Davidson.


Now you are looking at a 190 rwhp engine that is not only peaky, but usually also needs a brain transplant to be

ridden like its meant to be! (just joking!)

The costs involved in the stage 4 engine is can easily look at a $5-6000 usd job...

The price of a turbo kit (mcxpress)  is about the same, and still 6-7 times more than a nitrous kit...(hint)

Brain transplant not included. (For a transplant, read more about it here )


Note that you still have a stock chassis/suspension setup with a 190 rwhp motor, which is not the way to go.


For the really nutty/wealthy only.


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