Quote:
Originally Posted by jimmy101
If you really want more top end - port the head - these engines really take to improved flow by all accounts from the ex500 racers out there. You would then be looking at way more power everywhere (4 stroke power is all about the head flow).
cya
|
Hmm, somehow I doubt that. A question about porting and polishing the cylinder head were asked at EX-500.com some days ago. The question was...
Quote:
I was just wondering if porting and polishing the 500R head would be a good idea? i have done it on a few of my vehicles and have gotten outstanding power gains...... would it be worth my time to do"
|
and the answer he recieved from FOG (he has raced these machines for years, tried more or less everything to improve HP, and his response was...)
Quote:
This is another No No, The shape of the intake runners has been created to obtain the best flow already and polishing it will make it worse. The rough cast surface is better than a smooth polished one. Read up on Laminar flow. Essentially the smoother surface causes greater drag in the airstream.
FOG
|
FOG more or less knows this engine "in by out", so I'll take his word for it, and I doubt SPYE (me included) wants go get every last piece of HP from the engine as possible; reliability is also of importance!
According to FOG; if you want to get those extra HP, do the following...
Quote:
If you really want to help get all there is . you need to get internal. DO a valve job, this way:
Get a set of after market intake valves, The heads are thicker.
Re cut the valve seats till the seat angle(45) reaches the very tip of the valve. This gives the maximum valve opening area,
Make the (60) angle to reduce the actual seat line to .030 wide.
Lightly radius the top edge at .01R max.
Lightly lap the valves in place
Remove each valve and cut the bottom away till you just reach the lap line.
Reset clearances to .005 in .006 EX
Slot the cam chain wheels mounting holes .12 in each direction.
Degree cams after installation to 100 intake lobe centers 105 exhausts.
Note the valve info applies to intakes only the exhaust don't matter.
With good compression this will produce 54 HP at 9800 RPM
Coupled with good carb tuning (fog Box Mod and proper adjustment of pilot screws) the best power under the curve.
FOG
|
(the last quote may not work with the KLE 500, as the KLE 500 has 254 degrees camshafts, instead of 290 degrees (GPZ/EX 500))
source:
Port and polish cylinder head
The reason why SPYE's KLE will max 165km/h, and not more, is most likely due to the exhaust system AND the lower compression (9.8:1). By changing exhaust, you will probably increase the speed, and it will vibrate less.
My KLE runs just fine; but I somehow got the feeling that the 115 main jet is a bit too large, as it runs fine when cold, but as it gets warmer, I can feel "low speed stumbling" going WOT @ ~3000rpm (there's no power down there, but it shouldn't stumble (doesn't stumble when cold, which is a sign of it going rich)). It runs better now than with the 112 main jets, but I didn't use the big snorkel with the 112 main jets anyway, so perhaps it were asking for "more air"(pressure balance) with the 112 main jets.
edit: opened up the airbox with 2x8 mm holes (not much at all), and the low speed stumbling is now gone, and it still goes perfect at the highway. Can't say much about the top speed just yet, but got to 180km/h, before I had to roll off the throttle (still had a little bit more to give), so I am quite sure the jetting is more or less perfect now, but will have to do some more testing, when it's not windy (yes, windy today too) and raining
/Mollrik