Located in Menlo Park, California,
Motion Pro is dedicated to producing the most innovative and unique
products for the motorsports industry. The cables, tools, levers
and accessories they design are made to exact tolerances with the
highest quality materials and workmanship. Their products are the
result of years of "hands-on" experience in the shop and on the
race track. World Champion Racers and their mechanics rely on
Motion Pro to provide them with the right tools for the job. Their
products are the standard of the industry...
With
our cylinder installed and all the fasteners properly torqued to
spec, we are now ready for the most important, and often overlooked
part of the rebuild! The leakdown test...
The only way to determine a two-
stroke engines' overall health and well being is by performing a
leakdown test!
Leakdown Test
Procedure:
Motion Pro's Leakdown Test Kit is not only a first rate product with
flawless design, every fitting and adapter to test any modern
two stroke engine, and the highest quality construction and
components,
It is also a MUST HAVE tool for anyone
that want's to rebuild a two-stroke motor. The only way you can be
sure your motor is healthy before you start a jetting procedure is
to pressure test it. If you haven't, you are simply wasting your
time, and quite possibly, huge sums of money. A leaking engine will
almost certainly fail prematurely, if not instantly - and be
IMPOSSIBLE to jet correctly... Dune
It's so easy to use. Even a Glamis
squid with a brain that's been damaged from years of race gas
sniffing and sand eating can quickly perform... Just 1-2-3 simple
steps. If you have the skill to do the top end, the leakdown test
is a breeze... Or let's hope a lack of breeze coming out of your
300 buck overhaul!
The cost of Motion Pro's test kit is
less than an average top end job - and a more than wise investment.
With the cost of a big bore piston and rings hitting a 100 bucks or
more, plus gaskets, bearings, bore-job, etc, the cost of this kit
is more than offset by a failed top end due to an engine leak and
resulting seizure!
Install the proper flange cover or plug on the
exhaust...
Then the proper size pressurizing
plug/fitting in the intake boot...
Hook the gauge/pump assembly up and
start pumping! On a big motor like the 'zilla, it can wear your
hand out, so I cheat and blow air in through the intake on the pump
bulb with my mouth to get it started. Pump it up to about 6-8
psi.
What are the results of the
test? FAILURE! What you
say? It failed? Well gang, that's why you perform this VERY
IMPORTANT test!
At 2-3 psi, air started gushing out of the
right side crank seal! The engine would not hold pressure for more
than one or two seconds and the gauge would start to quickly
drop...
What now? Well... we pull the primary
drive and replace the seal, of course. No problem, done and
retested in 20 minutes. The big thing is that had we not done the
test, our engine would have sucked air and transmission oil in
through the crank seal, leaned out and burned up, provided we were
able to even get it jetted well enough to run... Some tips for testing your engine
with the Motion Pro Leakdown Test kit:
This is a precision instrument. Keep it clean,
and handle it carefully
When performing the test, it's a good idea to
have a mechanics stethoscope and a spray bottle of WD-40 (water
works ok, but tends to run off too fast) to look for leaks if
indicated.
A motor in good condition should hold pressure
for several minutes.
NOTE: They WILL not hold
pressure indefinitely. Most crank seals will allow some bleeding,
and on an engine like the LT500, which is equipped with a complex
power valve, frequently they will leak through them, particularly
if the O-rings are old or worn. This is not terribly serious but an
indicator you should service/overhaul the
valve.
Always perform a leakdown test when doing a
top end. The cost of Motion Pro's kit is far less than a spoiled
weekend trip due to a blown motor - not to mention jetting/tuning
and performance nightmares!
With the cylinder installed and fully
tested, we are ready to reinstall the primary drive, install the
flywheel and button up the side covers. In closing I have two last tips for you...
Before you install the flywheel, clean and
lubricate the inside of it with WD-40 and pay attention to the
tapered hub. This will prevent corrosion from forming, as well as
keep the flywheel from developing an odd molecular bond to the
crankshaft, as they are prone to do. If it does nuke itself to the
crank, it can be a bitch to remove down the road!
Using the same Permatex Hi-Tack gasket
sealant we used on the base gasket, glue the flywheel and clutch
gaskets to their covers.Use
sealant on the cover side ONLY! This way, if you have to remove a
cover in the field, it can be done easily, quickly and it will
leave the gasket intact for reassembly.
Your local dealer can help you get any of the Motion
Pro products you need!
Or...
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