The idea behind the mods that I will do are simple things that will
improve the performance of the bike. I have opened up the airbox, set
the carb up with a oxygen sensor, both which helped the bike in the
power and ride-ability. The idea for removing the cylinder base
gasket came from Suzuki. There are two models of DRZ400's (sweet
bikes!), the more road worthy one has a thicker base gasket to reduce
the compression ratio. I figured I could do the opposite to give it a
little boost.
The 0.016" number came from the compressed thickness of the stock
gasket. I am certain the thin coat of RTV will seal the base no
problem with a gasket. I'm trying to get a tube of
http://www.permatex.com/motorcycle/PermMotoSeal.asp?
automotive=yes&f_call=get_item&item_no=30304 which is engineered
exactly for this purpose. Actually I think this sealant is designed
for 2-stroke motors because it has a higher tolerance to gasoline
that is inside a 2-stroke case. There is no real load on the gasket
here, no pressure, just keeps the oil in the crankcase. The area is
quite wide and very well machined, the sealant should work fine.
There is no ridge in the cylinder, so a light deglazing and a new set
of rings will be all I need. The deck height is plenty, way over
0.025" so the piston will not extend out of the cylinder on this mod.
I still have to check clearances of the valve to the piston, but I'm
85% sure that will not be a problem.
I did measure the cam profile (I will post the curve) before the mod
to see what effect dropping the cylinder will have. I don't suspect
anything significant. I'm going to do the math as well on that one.
I don't intend to port the head by "hogging" it out. I haven't
figured out exactly what I'm going to do there yet (just got the
valves out yesterday), but the first thing is just to clean up the
obvious casting flaws etc. without changing the port volume or
profile. I will "polish" the exhaust port to improve that flow, and
roughen the intake to get some tubulence in there to reduce fuel
separating from the air. There is an interesting protusion in the
intake port behind the valve stem. My theory is thats its KHI's way
of getting more velocity for better low and mid range torque. I'm
going to measure the choke area of the intake port to see how
theroetically close it is to reaching supersonic at high RPM's before
I decide to do anything with increasing the flow velocity by
decreasing the port area with expoxy.
So far the major mods are all reversable so I'm not too worried about
do anything bad to the bike. If it runs like crap, I'll put it back
the way it was.
As far as the claims on the MotoTune web site, I mostly agree with
what this guy says, although how he says it is a little strange to
say the least. He stuff is nothing new, it's all well known, Good
tuners don't just measure the flow of a port but the velocity and
swirl as well to try and find the best balance.
Bryan K
A14
--- In DSN_klr650@y..., "Arden Kysely" wrote:
> --- In DSN_klr650@y..., "Bryan Kowalchuk" wrote:
> > Doing engine work for a bunch of reasons:
> >
> > 1) Fix the dohickey.
> > 2) Check the cam timing, maybe modify it because of item 4.
> > 3) Port the head, clean up the exhaust, possibly do a high-
velocity
> version
> > of the intake (
http://www.mototuneusa.com/homework.htm ). The
> middle of
> > page
http://www.mototuneusa.com/the_2007_superbike.htm says he
got
> about 7%
> > increase in power on a KLR.
> > 4) Remove the cylinder base gasket, drop the cylinder 0.016" to
> increase the
> > compression ratio, check to see if there is valve/piston
clearance
> issues.
> > 5) Clean out the oil pump screen.
> > 6) New rings and valve seals to fix increase in oil consumption
> problem.
> > 7) Give the valves a light lapping to clean them up.
> > 8) Set the valve clearance.
> > 9) New oil filter, spark pluc etc.
> > 10) Check the general wear and tear on the engine.
>
> If my KLR was running good and I wanted to prepare it for a trouble
> free season next year, I'd do 1, 5, 8, and 9, then lube the
> swingarm/uni-trak linkage, run a larger wire to my headlight and
call
> it a winter. No one seems to have much luck with performance mods,
> and I'd definitely avoid them if I wanted reliability. Just my 2
> pennies worth. My A11 with 20k miles is going strong and I don't
plan
> to mess with success.
>
> __Arden