Hotrodden the Predator Part 1 of 3

Every once in a while a manufacturer of
these clones will change something that will make
any good cloner stop and say, “HEY, Maybe I can
use that for racing.” OK , maybe that happens all
the time and in this case it’s the new 212cc Predator
motors from Harbor Freight. Priced in the neighborhood of $159.00 and less if you can find them on
sale, these base motors come with some real nice
surprises.
The first one is obvious. Its 212cc’s compared to 196cc or 208cc for all the other 6.5hp
clones, making it the biggest so far. And bigger is
better, Right? Let’s see.
Coming in with a 70mm bore and a 55mm
stroke makes this bad boy “King of the Hill” when
it comes to size. The 196cc clones have a 68mm
bore and a 54mm stroke while the 208’s are 70mm
bore and 54mm stroke. OK, so I’m thinking this little
shining black gem is stroked and bored right out of
the box. How could I resist taking a peak to see what
else could be hiding beneath that menacing black
exterior?
Another pleasant surprise was the castings
and finish. Unlike the grainy castings of many of the
other clones, the Predator is closer related to the
Honda as far as detail and quality. It comes with
the usual features found on most clones. lt has a
governor system to 3900rpms, on/off switch, low oil
sensor shut off, gas tank, air box and filter system,
check oil caps at both ends, spark arresting exhaust
system, pull starter and meets EPA emissions standards. What a deal! Right? Let’s take a look.
First, we need a baseline horsepower and
torque number. That means a trip to see Dr. Dyno
and “The Search for the Truth” begins. Before starting any process that involves change, it’s always
good to have an idea of what you have to start with;
and a dyno is as good as it gets for this. In order to
meet EPA standards you will find these clones are
jetted very lean. In fact, they are too lean for what
we want. Usually, the clone’s main jet is #70. I have
found that #85 - #90 works better at most elevations and
should get you in the ballpark and on your way to making
safe and reliable power.
The other jet of concern is the pilot jet. And that is
located just under the idle screw adjuster. Normal pilot jets
Our Predator fired right up without hesitation and
ran smooth for its 30 minute break in. The new jetting was
much to her liking with smooth acceleration and crisp throttle response. Ungoverned, the Predator was very anxious
to turn more rpm’s than the manufacturer would like to hear
about. After warming up to a head temp of 275° I laid the
hammer down and let Dr. Dyno take over. The manufacturer stated 6.5 horsepower at 3600rpms. With the improvements we did, our test results were closer to 9 horsepower
at 3600rpm with maximum torque pulling 14.10 ft. lbs. at
2300rpms. The maximum horsepower of 9.83 was achieved
at 4700rpms. Power started dropping off at 4900rpms and
we hit a wall at 5600. I believe some valve float was limiting
our revs after that.
This Graph Printed:
6:00 pm 03-31-12
Page: 1
GARY
PHONE 1Performance Trends (C) 2007
Dyno DataMite v3.7
akra carS. CFG
Test:
Folder: AKRA carb test
c -
AIR FUEL RATIO , Corr Tq, Corr HP vs RPM
AIR FUEL RATI
Corr To
Corr HP
10.00
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2.00
800
TESTED as recieved , THOR oil
are in the range of .014”. We want .020”to richen up the bottom end, and help with acceleration off idle, and through the
low part of midrange just before the main jet takes over.
So off comes the gas tank to be replaced with an
aluminum top plate for added strength. Then the air box
and stock filter to be replaced by a K & N racing style air filter and adapter. Next, let’s complete this motor’s breathing
improvements and get rid of that very restrictive exhaust
system and spark arrestor for an open pipe into Dr. Dyno’s
exhaust analyzer sensors. Add some of your favorite oil
and we are ready for our appointment with the good Dr.
Test Summary and Comments for:
Operator: sneaks
4:31 pm 01/18/2012
Eng #: Predator
Corr. To: 29.92/60 dry
Customer: harbor freight
Corr. Factor 1.037
PREDATOR- Box Stock
I
Gas,
PkTq: 14.10 @ 2300
PkHP: 9.83 @ 4700
12.88 cid 4 Cycle
Su
lier - Johhn
2.755" Bore
2.160" Stroke
1 Cylinders
UPS
So before we can search for more power, we need
to address the issue of the valve train. I am targeting the
6500rpm range for this build and will be changing from gas
to methanol as our fuel. I will do another dyno run to see just
what the change in fuel alone will do to the power curve.
My Initial impression is some good power making
potential exists with this bored stroker as a base motor. Its
time to see what’s under all those aluminum covers and tins
starting with the head.
You don’t have to remove the head just to
us a bit more lift, and some mild cleanup of the ports.
To help support the valve trains extra spring
and rocker pressure we will replace the mild stock
steel pushrods with a set of chrome molys. Thanks to
the suppliers we now have choices from adjustable
change the springs. However, I’m going to install new
SI stainless steel valves while I have the Predator
apart. Like all clones, there are only 4 head bolts securing the head to the block. No surprises here. This
has always made sealing these motors challenging
when modifications to compression and bore have
taken place. There are many suppliers who have
seen the need for us cloners and have come to the
rescue and are making all kinds of high performance
“plug n play” go fast parts. Like modified heads, racing cams, forged pistons, roller rocker arms, light
weight flywheels, and the list goes on.
This Predator head will have stock size stainless valves, 25mm intake and 24mm exhaust with
automotive style split keepers. Those 10.8lbs stock
valve springs will be replaced with 26lb springs to
control that valve float. And 1.3 ratio rockers to give
aluminum to “Do it yourself” kits to make any length
you want. This will come in handy if you do any milling of the block or head.
Once you pop the top off, you will notice 2
more surprises. First, the piston position in the cylinder at top dead center is just .003”from the deck.
Now any cloner worth a roll of duct tape knows what
this means. Most clone piston positions are more like
.030” below deck requiring longer rods and different
pistons to get any compression. Even though this is a
dish style piston, a .003” “in the hole” piston is a huge
advantage.
The second surprise is the Predator comes
with a .050” thick head gasket. With the wide variety
of head gaskets from suppliers on the market today,
this is another area where we can pick up some compression by using a thinner one. In this case I will be
using a large profile .016” copper head gasket. Some
form of gasket sealer is always a good idea. Now that
we have increased the compression we need help
keeping the lid on. High strength metric stud kits are
available and do a great job in this area. Metric stain-
less steel bolt kits are also available and work well.
Now that we have made the needed changes to the head it’s time to reinstall and torque it all
back down on the block. The stock head torque values are
17ft. lbs. With the studs you can go up to 24ft. lbs.. This will
help in keeping the beast sealed.
The switch from gas to methanol will take some
carburetor jetting changes. However, there are many suppliers who will be more than happy to help you with this fuel
conversion. They sell “Plug n Play” carburetors that take all
the guess work out of choosing which jets to use. The price
ranges from $49.00 to $125.00 for blueprinted carburetors,
depending on your needs.
Now, if you happen to be a member of the “PoBoy’s Greasy nails” club, like me, then you’re going to do
jet size combo works best. Some experimenting will be
needed. The range for the pilot is .026” - .032”. This will
affect off idle and early acceleration out of the corners. The
main jet range will be from .056” - .064”. This controls the
mixture at wide open throttle or WOT. The E-Tube will need
to be bigger than the main jet. If it’s not already, then increase this to a minimum of .074”.
In case you haven’t figured this out already, then
let me tell you this isn’t going to be good for your mileage.
Expect to use twice as much alky as gas. That lost mileage
however, will be replaced by a big ole grin when you hammer down. Now, in order to “feed the beast” with its new
found appetite we will need to install a fuel pump.
All fuel pumps that we use for the clones are pulse
activated. So, we need to pick up a pressure signal from
somewhere. Again, our friendly suppliers step in with this
behind the carburetor pulse fitting adaptor that will give us
just the signal we need. You can pulse from the crankcase
or valve cover as well, but that gets messy keeping the oil
out of the pulse line.
this yourself and save the money for nonessential items like
clothes or rent.
And all you really need to do is drill out the pilot jet,
the emulsion tube or E-Tube, and the main jet.
Depending on where you live will determine which
One last issue needs to be addressed before we
can fire up. The cast flywheel is not intended for use above
4000rpms, so we once again turn to our clone parts suppliers for a safer flywheel. And this comes in many forms.
At the time of writing this, there seems to be some
issues on which flywheels fit the Predator best, so check
with your local dealers before you order. And while we have
the old cast flywheel off we can use modified keys that will
advance the ignition timing from 20 degrees stock to at least
28 degrees or more. These modified keys come from sup-
pliers in advancements of 2°, 4°, 8° and 12°. Alcohol
loves advanced timing and 30-32 degrees seems to
be the “sweet spot” for circle track racing. If drag racing your minibike is what you do, then 34-36 degrees
would be a better sweet spot for you guys.
let go. If it backfires, and they do, it will pull the rope/
handle right out of your hand and that really stings….
When we get this all done, our Predator will
start to look more like a racing motor than something
that belongs on a log splitter.
Now our Predator is ready to face Dr. Dyno
for the second time. With a new thirst for power there
is nothing left but the truth to tell us how we did….
Be sure when you install your new flywheel
that you move it clockwise so the new modified or
cut key rests against the left side of the flywheels
keyway. This will advance the position of the magnet
in relation to ignition timing.
All that’s left is to set the coil/flywheel air gap
as per the manufacturer spec sheet that will come
with the wheel.
A word of CAUTION is needed at this point.
If you’re going to pull start this modified Predator,
you will need to slowly pull the rope until you feel the
compression stroke before you yank, then yank and
The first thing you will notice is how long
it takes to warm up. Exhaust temps have been reduced from 1500 degrees to a near frigid 1200 de-
grees. Condensation will start around the carburetor as
little droplets of water when the cold mixture runs through
the bore. Head temperature was hard to get above 225 degrees when Dr. Dyno took over.
GARY
PHONE 1Performance Trends (C) 2007
Dyno DataMite v3.7
Test: 071811-19.CFG
Folder: clone
This Graph Printed:
4:51 pm 03-08-12
Page: 1
I
AIR FUEL RATIO , Corr Tq, Corr HP vs RPM
071811-19
#1
AIR FUEL RATI
Corr To
Corr HP
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a maximum torque of 16.03ft lbs. at 2200rpms. That’s an
increase of 2.3 horsepower over gas and it increased rpm’s
by 700. This beast on alky easily pulled over 6400rpms.
The torque not only increased by 1.93ft. lbs. but the maximum occurred 100 rpms lower. Lowering the torque’s rpm
range is always a good thing.
Any cloner would be very pleased with results like
this. With some carburetor wizardry , a pair of springs, and
a new fuel, our Predator is ready to be set free in the wilds
to prowl on any unsuspecting ANIMALS that may be lurking
around at the local tracks. And we haven’t even opened up
the crankcase.
Not yet anyway, but I’m having dreams of racing
cams, bigger carburetors, flat top pistons, billet rods, roller
rockers, chrome moly, and who knows what other ‘Go Fast”
parts are out there. I’m seeing a part 2 here.
Clones , They’re not just for generators anymore….
,
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To Be Continued. Part 2 coming next month...
4.00
1600
TESTED as recieved , THOR oil
Test Summary and Comments for: 071811-19 #1
Operator: GARY
4:29 pm 03108/2012
Eng #: MaxM5_002
Corr. To: 29.92/60 dry
Customer:
Corr. Factor 1.052
PkTq: 16.03 @ 2200
PkHP: 12.13 @ 4800
12.71 cid 4 Cycle
2.760" Bore
2.125" Stroke
1 Cylinders
212 Predator ...alk
While guzzling alky at an incredible rate your beast
pulled a maximum horsepower of 12.13 at 4800rpms and