Litestar/Pulse Engine Temperature
by Bob Cervero
As we know all too well, the greatest weakness of the Litestar/ Pulse
vehicle is the lack of efficient cooling of the engine. No matter which engine
is being used, cooling is a problem. My Pulse, #61 and Don Muddimans #199 are
both powered by the Yamaha 400 cc twin. Believe it or not this engine is
actually quite powerful and will more than keep up with normal traffic.
My Pulse was delivered from Oklahoma in October, 2000 and Don
got his from Texas in December, 2000. We both work for Lockheed Martin in
Orlando Florida so we have been helping each other and exchanging ideas for
improvement since Don got his Pulse. It has been amazing how similar our Pulses
are in problem areas. We both have experienced problems with cooling, starting,
charging systems, tires and suspension. We are both extremely pleased with our
Pulses but realize that they do have a few shortcomings.
In my opinion the major problem
with a Pulse in a hot climate is overheating of the engine. Dons Pulse in
particular showed evidence of extreme overheating (the side case covers were
golden brown in color) which resulted in destroying his alternator, clutch
plates and starter.
What is the cause of this
overheating? As we all know, a motorcycle engine lives in the open air,
completely surrounded by moving air as the bike goes down the road. This is a
perfect environment for an air-cooled engine. The air goes over the cooling fins
and removes enough heat to keep the engine in a safe temperature range.
Well, in a Pulse, what do we have?
We mount this air-cooled engine in a very tightly enclosed, streamlined box away
from any air flow. We also enclose the extremely hot exhaust pipes in this box.
Don and I have come up with several options to help our engines survive this
torture.
A simple
modification to increase the airflow around the engine is to elevate the cover
on top of the engine. I built a very simple wood spacer to raise the cover on
top of the engine about 6 inches. Before this mod, the head cylinder head was
less than 1 inch from the insulation on the engine cover. All the engine heat
was being trapped in this confined space. Now the cylinder head has 6 inches of
clear air space over it. This also opens the cylinder head compartment to the
rear airspace in front of the rear tire. This way the overall airflow is greatly
increased around the engine. Don has done a similar mod, which includes a fan to
pull the hot air out of this area. Even
doing this still did not correct the overheating in traffic on a 90 deg. day.
The
hottest item in the engine compartment is the exhaust pipes. They add greatly to
the overall high temperature within the engine compartment. They run in excess
of 750 Deg F. Wrapping your exhaust pipes with an insulating material will lower
the temperature inside the engine compartment. The thermal wraps will keep a
good portion of the heat inside the pipes and allow it to be blown out the end
of your exhaust pipes instead of being dumped inside the engine compartment.
Raising the exhaust temperature will also make your engine more efficient. J.C.
Whitney has everything needed to wrap your exhaust pipes.
Another method to lower your
engine temperature is to switch over to a motorcycle synthetic lubricating oil
such as AMSOIL.
Neither Don nor I have switched yet but we will do so at the next oil change.
From what I have read and from some comments from Litestar/Pulse owners,
switching to a synthetic oil can decrease your engine operating temperature at
least 20 degrees. There are two reasons for this. First a good synthetic oil
will reduce friction in your engine. Friction generates heat. Reducing friction
will reduce the heat in your engine. Secondly, synthetics have a greater heat
capacity. This means they will carry more heat away to the cooling fins or oil
cooler if you have one. Every little bit helps.
One caution about whatever oil you
put in your engine. Make sure you use an oil designed for motorcycle use. In a
motorcycle, the oil lubricates the engine and the transmission, including the
clutch. This is called a wet clutch as it actually sits in the oil supply. Well
guess what? Oil designed for a car has friction lowering additives in it. They
are very slippery. Synthetic oils designed for cars are even more slippery than
petroleum based oils and they also contain these same friction reducing
additives. These oils can be just too slippery for your clutch to work properly.
The clutch in that Pulse has a hard life as it is because of all that extra
weight it drags around. Don’t make it any harder by using the wrong oil. Use a
special motorcycle oil.
The absolute best thing you can do
to lower your engine temperature is to add an oil cooler. My Pulse came with an
oil cooler. An oil cooler generally mounts between your engine and its oil
filter. The oil cooler takes the oil that was going to the filter and routes it
through a radiator and then back into the oil filter.
This is
accomplished by using a spacer between the engine and oil filter. This spacer
has oil channels drilled in it to direct the oil to the radiator and then back
into the filter and back into the engine. In a normal air-cooled engine, the oil
has provides lubrication and cooling. Believe it or not, the oil provides 40% of
the engine cooling, the rest is done by the cooling fins. The goal here is to
cool the oil outside of the engine, just like the water in a car radiator. This
is the most effective method for cooling your overheated Pulse engine.
The earlier SJ single overhead cam
400cc Yamaha engine has an external oil filter. This makes it very easy to add
an oil cooler. You can buy everything over the counter. The later RJ dual
overhead cam 400cc Yamaha engine has an internal oil filter which complicates
this a little. Don Muddiman has designed and built a slug of aluminum which
replaces the oil filter on this engine to route the hot oil through a very large
oil cooler. During this you also
have to use a remote mounted oil filter which give you the advantage of using
automotive oil filters. The original center bolt that holds the oil filter was
used to retain the oil cooling adapter. This
bolt has a pressure by-pass valve built in. The by-pass valve is designed
to open when the restriction to the filter increased, sending the oil directly
to the engine by-passing the filter. When
installing the oil cooling system you add a slight restriction to the normal oil
flow. By watching the oil temperature during a long run it was discovered the
valve was by-passing the add oil cooling system and filter.
To fix this problem the spring pressure on the by-pass valve was
increased by shimming with .160 thick washers.
Don
has found that this oil cooler, actually a transmission cooler, dramatically
reduces his engine operating temperature over all ranges of operation.
It now never
exceeds 210 deg F. even on a 90 deg day with no fan running in stop and go
traffic.
My oil
cooler is mounted in the right side NACA duct. Don has mounted his oil cooler in
the nose of his Pulse, under the headlight with a scoop and a fan to assist.
This is really the way to go with an oil cooler as it gets the radiator away
from the hot engine compartment which cools the oil better and keeps the hot air
from the radiator out of the engine compartment, which keeps the engine cooler.
It’s a winner both ways. I plan on moving my radiator to the front the next
time I tear it down.
Well, thanks for listening and I
hope that these ideas that Don and I have come up with about cooling are some
help for your Litestar/Pulse when the hot weather shows up. If you have any
questions about cooling your engine or anything else about your Litestar/Pulse
just E-mail Don Muddiman or Bob
Cervero. We might be able to help. Thanks
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