Originally Posted by JohnnyKZ1000A
Originally Posted by FOG
What ? once a month we get one of these. Anyone so experienced should be able to just look at this engine and see it is not suitable for Modifications to increase output.
Sorry FOG all engines are suitable for modifications. Just replacing the valves with Titanium ones, Forged light pistons with stock bores, carb modifications or flatside replacements, undercut gears, high performance crank, and rods, gas flow porting, etc. the list goes on, will increase the performance of any engine. Why do people modify Honda 50cc Monkeys? There is a whole aftermarket industry for those bikes.
There are many examples of successfull modifications done to a wide range of motorcycle engines.
As far as being experienced, if you were, you would not be writing a response like you did. I expected more from this site. I you have read my earlier comments, I said I was gathering information on a engine I am not familiar with and if no one knew or has done the modifications to the engine I was asking . I would have to go my own route.
So far everyone on this site has been helpful except for you.
Fact is, I'm the one with the most experience with this engine here. I raced one and managed a team of three riders on both stock and Modified EXs for 12 years.
You can do all that crap to a ex and it amounts to **** on a bull. All that stuff is aimed at increasing the revs. This is the one thing this engine cannot do.
I have listed the problems with this engine many times here in the past. but I do it again , Just for you.
Any attempt to raise the BMEP will result is gas blow by due to weak head clamping. (long bolts go all the way to the cases stretch like mad) Flat lapping helps but not if you raise the CR.
The Crank. Is too long and as a Result is wippy and will snap on a regular basis. New billet cranks help that but cost the earth and only transfer the weakness to other parts. Then that giant lump of an alternator
Rods are very bad They stretch and hit the head and the big ends open and spin bearings at any reves much beyond the stock 10.5K
Even the cases are too weak to support the crank loads in stock form. The output shaft bearing often levers them apart from chain drive loads.
The above problems stem from a design weakness that put the Cam drive in the center . This sl=plits the engine into to seperate singles held together by a very thin web of alum. They warp and distort due to this. Thais also adds a extra bearing to the crank making it way long.
Cylinders: They are already too thin being over bored from the 454 version . So thin that they are all out of round and you cannot achieve good ring seal even at the Stock BMEP or CR. New cylinders are out there
The Balance shaft is designed to quell fore/aft rocking couple by transferring that load into the cases. This causes bearing failure especially on the water pump drive end.
Fact is Kawasaki has already done all the cute trick you think your so smart with.
I have seen a few of these engines that make 60 + at the rear wheel
I have rebuilt about 100 of these engines for racing and I can testify in court to the above.
You can make it a little bigger as long as you don't over rev it.
As I said this engine is Not suitable for Modifacation