|
 Serious about speed.
The connotations of that statement imply a great degree of
enthusiasm, dedication, knowledge, and experience. Each of
those factors can be found within MP Racing in Salem Oregon.
Serious about speed is MP Racing’s motto. They believe that
each engine they do is a representation of them, and therefore
must run hard and do such for a long time. However, MP Racing
takes it a step further and on most weekends can be found out
riding in the dunes. Testing and improving upon existing
designs as well as creating new and exciting creations. Those
very test rides and thoughts have lead MP Racing to their
newest line of engines.
 Their
new engine, whose nickname is now The Polonda, has emerged and
proven to be a potent engine indeed. Team Source met up with
the MP Racing Team for a great weekend of riding at the Oregon
Dunes National Recreation Area in Florence Oregon. Our
objective; test ride the new Polonda engine. Polonda? Well,
the name halfway gives it away. A Honda ATC/TRX250R is the
donor engine. MP Racing skillfully crafts a Polaris Scrambler
400 cylinder to fit upon the 250R bottom end. Current
displacement ranges from 389cc’s to the latest generation of
Polondas at an astounding 440cc’s. No replacement for
displacement is indeed true.
The actual conversion itself is rather simple
when compared to other hybrid engines. In most true hybrid
engines, case welding and repositioning of case bolts and
studs is required which does not allow for retro-fitting the
stock 250R cylinder back on the bottom end. In the case of
the Polonda this is not required. The majority of the work to
allow the fit up of the Polaris cylinder is done to the
cylinder itself.
Dave
Moore, owner of MP Racing, explained in great detail to Team
Source what all was involved in creating this hybrid. A
straightforward procession of steps involving welding,
machining, and ultimately porting and head configuration
alterations. The engine is completely disassembled, and with
any big bore cylinder, the case halves are machined larger to
accept the larger sleeve to slide down into the cases. With
that complete, Dave then begins to work over the cylinder
altering it to what he has found to be the best
configuration. The cylinder water outlets are re-positioned
and welded to better accommodate the 250R cooling system. The
cylinder itself is built up and welded around the stud holes
and exhaust port for much greater strength. Additionally a
spacer plate is fitted to the cylinder to get the port opening
heights corrected. The 389cc variant utilize the stock
Polaris piston at 83mm’s, whereas the 440cc variant that has
been built uses a Yamaha YZ490 piston at 89mm’s. Currently
Dave is researching using the new Aaen piston which is 91mm’s,
which would take the displacement out to 490cc’s on the stock
stroke!
The next steps in creating a Polonda are
considered normal in any high output modifications. The
porting arrangement is skillfully re-worked to suit the power
delivery needs of the customer. Additionally the head
configuration is re-worked as well. Dave recommends running
100+ octane fuel due to the larger bore size. In our
conversation he did say that it could be ran on pump gas, but
for the best in performance and reliability, higher octane
fuel is preferred.
With the greater displacement of the Polonda, a
tuned pipe that can handle the greater exhaust gas volume is
required as well. Dave through many test rides has found that
there are 2 commonly available pipes that work best with the
Polonda. The ESR TRX5 Centermount works extremely well for
all around power, where the ultimate in top-end power is
needed, for instance a greater proportion of drag racing, then
the FTZ fat in-frame drag pipe is used.
The intake side is handled by an MP Racing
worked over Mikuni TM 39mm carburetor coupled with a Moto
Tassarini V-Force reed cage. The advantage of the Mikuni TM
carburetor is that with some additional modification the
carburetor can run both gasoline and methanol. Once converted
to run alcohol, unlike Keihin carburetors, the Mikuni TM can
be easily swapped between the two fuel types. The V-force
reed cage is as designed for the Scrambler cylinder. No
re-work of the intake is required. The intake angle and
direction is handled via a custom intake plate and boot. MP
Racing also offers nitrous systems for the Polonda(or any
engine that you wish) as well. The intake system is simple
and efficient; again designed, tested, and perfected by MP
Racing.
The Polonda utilizes the stock stroke of
72mm’s. Dave has found that a modified YZ250 rod is stronger
for increased strength and longer service life. Dave is
currently in development with a newly designed and
custom-machined rod that far surpasses any rod available to
ensure the ultimate in crank and rod life. This ensures that
the higher output generated does not reduce the reliability or
increase the maintenance required.
The MP Racing Team had arrived in the
campground the evening before and we all had the chance to sit
around and chat quite a bit about everything. However, as
most that have ridden the ODNRA know, the weather can and does
change for the worse, and often. Saturday morning arrived
under grey skies but no rain. Lets go!!! We all get geared
up to ride as a few light sprinkles begin to fall and as we
rode out the rain really started to come down. We had hoped
that it was a passing squall. We got out to the flat and I
watched as Dave and several other guys lined up for a quick
drag race or two. Dave and another member of the MP Racing
Team touched wheels about 40 ft out and Dave wound up taking a
hard digger over the bars. Living up to his moniker of Krazy
Dave, he chose to ignore the fact that he likely had broken a
couple of ribs in the crash. Dave gingerly stood around and
regained his breath.
The rain
wouldn’t subside and with Dave all sandy from his crash we
headed back to camp to get dried out and let Dave clean up
some. Later that afternoon the skies cleared some and the
rain stopped. Capitalizing on the break we headed out again
to the flats.
 The
first generation Polonda that MP Racing did was for their good
friend Jason Maisel. His bike is named Gang Green for it’s
very bright green paint job. This would be the one we were
going to review. I had Jason line up and race some other of
the MP quads and make several passes for me and I noted how
easily the front end would lift even with a 10 inch over
swingarm -
View Mpeg Video
(size 125 kbytes). After Jason had made several good
passes, I took over the controls and lined up to drag race a
couple times myself. I was surprised at how potent the engine
really was. It launched out off of the line extremely hard,
and as Jason had demonstrated getting the front end light with
such a long swingarm was still easy. The
weight transfer was excellent, the rear squatted, the front
end got a little light, and it rocketed off.
 I was very impressed with how well this engine
pulled. Not only did it have that great large displacement
torque to moving well; it had excellent hi-rpm’s too. The
contention that some people hold is that bigger bore engines
will not rev out as nearly as high as a smaller displacement
engine. In the case of the Polonda engine this is not the
case. It revved up and out very well. In this MPEG video
watch the comparison in shift point between the hi-revving
Banshee on the left, and myself on Gang Green on the right.
This really is an excellent real world comparison -
View Mpeg Video
(size 125 kbytes).
Not everyone drag races all the time, so to see
how the Polonda would ride for a dune rider oriented engine I
headed off towards the trails and small hills to rip around a
bit. I was very surprised to see how well the engine
performed. The power delivery was consistent and smooth.
While at times the corner would come up faster than I had
expected –BRAKES!!! I found that riding it in the tight
trails was equally as impressive.
A true testament to Dave’s testing and
development- an engine that could do very well drag racing,
and then cruise off to go play ride in the dunes. It would
not be a stretch to say that this engine could be suited for
just about any type of riding.
Jason later demonstrated the hillclimbing
ability of the Polonda engine. He lined up deep down in an
hillclimb on the edge of the dunes and showed how well it
could climb. Here Jason rips it up pretty hard coming out -
View Mpeg Video
(size 240 kbytes).
 Overall,
Team Source found the Polonda to be a truly great engine. A
hybrid engine, whose cost is on par with all the other big
bore engines, yet having the capability to go straight from
drag racing to trail riding. The amount of modification
required to the engine is an asset to the Polonda as well.
The engine can be retro-fitted with the stock 250R cylinder if
you chose to, whereas with other hybrid engines that is not
the case, it’s a one way deal. This engine is easily above
the performance levels achievable with a Pro-X engine set-up. The Polonda
we rode was only 389cc’s; Dave has built a 440cc, with plans
for even larger displacement engines sure to come.
Our test rides and the dyno graphs both support that notion.
The engine is potent, but very rider friendly as well.
MP Racing can build these engines for all
applications and years of experience and many hours of testing
and developing the Polonda becomes apparent with how strong
these engines run.
[This company is no
longer in business]
MP
Racing
1550 4th Street
Salem, Oregon 97303
Phone: 503.361.7666
|
