The basic principle of the combustion motor
is drawing fresh air into the cylinder while mixing it with fuel, next
compressing it, then igniting it, and lastly expelling the waste (or exhaust)
and then starting again. In general the tighter you compress the fuel and air
mixture, the more efficient and powerful the combustion. Stock pistons in
the V-Star 1100 deliver an 8.3 to 1 compression ratio. This is generally
considered a low compression engine. It is able to use low octane gas, and
actually a stock engine will run better using low octane gas. Also lower
compression engines are generally easier to tune for mass produce from the
factory.
Installing our 10.6 to 1 or 10.25 to
1 compression pistons are the essential building blocks to begin building a
performance engine. We have spent many hours testing and retesting many
compression ratios of pistons. Both higher and lower. We have found that with
the V-Star 1100 engine 10.6 is the ideal compression for performance,
reliability and longevity. 10.25 to 1 is ideal for customers that are
looking for increased performance, but do a lot of traveling (i.e. higher and
lower altitudes). A bit less compression will allow more variance in tuning as
oxygen levels change with altitude levels, etc.
Many people ask, well if 10.6 to 1
compression is good, then why not go higher? Why not 11 to 1 or even 12 to 1?
The main problem with going higher is pre detonation, or what is commonly called
pinging. This is caused because the tighter you compress the fuel/air
mixture the more volatile (or explosive) it becomes. Add to that, the fact that
higher compression also develops more heat and you chance of pre detonating are
greatly increased.
Detonation of the air fuel mixture is
started by the spark plug just before the piston reaches Top Dead Center (or
TDC). The reason the fuel is ignited just before TDC is because all of
the fuel in the cylinder does not ignite instantaneously. The explosion actually
starts as a small ball of flame created by the spark plug and then rapidly expands to
fill the entire chamber forcing the piston back down, creating the power that
ultimately pushes your bike forward. The amount of time it takes for all
the fuel to ignite, should be the time it takes for the piston to fully reach the top
of it's stroke and begin its travel back down the cylinder. So going with a too high of a
compression piston creates 2 compounding problems: 1) Increased heat, and
2) The increased volatility of the air/fuel mixture because of the higher
compression. When these two conditions combine, the probability of
spontaneous igniting of the air and fuel without the actual ignition being
caused by the spark plug is greatly increased. This happens before the piston
has a chance to fully reach to position necessary. This is called pre-detonation. Pre-detonations
causes a pressure wave, which reverberates
throughout the cylinder, causing adverse effects to the combustion cycle, and
high amounts stresses on the engine. If it happens too soon before the piston
reaches TDC, it also pushes down hard AGAINST the piston on its compression
stroke. This causes a sudden loss of power and bucking of the pistons, rings,
pins and rods, not to mention very high stresses on the bottom of the engine
including the crank. Even if pre-ignition does not cause
audible knocking, it causes higher temperatures and pressures in the cylinder
that can cause rings to fail and even cause aluminum-alloy pistons to melt. Not
pretty. Keep in mind at just 4000 rpms the piston is firing at and amazing
33 times per second!
Don't be fooled by competitors that
promise more power by higher compression. It simply isn't true, or it isn't safe.
Do a bit of research before you purchase from us or anyone. You will notice that
even the most renown cruiser engine builders very rarely ever use compression
ratios over 10.25 to 1 for v-twin motorcycles. This is why
we have done many, many hours of testing and retesting to be sure that we are
producing a product that is going to provide plenty of enjoyment. Oh, so you
caught that.... So you ask... If these engine builders rarely use higher than
10.25 to 1 compression pistons, why do you recommend 10.6 to 1? Great question.
The simple answer is this, remember the comments about the creation of heat
causing an increase in pre-detonation? Well most cruiser ( V-twin) engines have
cylinders which are quite close together (45 degrees or even less), so they require a
long y type intake manifold for
the side mounted carburetor, meaning the air/fuel mixture must travel nearly 6
inches or more before entering the hot combustion chamber. The V-Star 1100 (with
a 75 degree motor) on
the other hand has two carburetors situated between the cylinders. Each of them has about 1 inch
of intake
manifold, and the carbs are situated in position that fuel is able to
be almost direct sprayed into the cylinder. When the cool air/gas hits the
top of the cylinder and piston it creates additional cooling which helps delay combustion
which allows the 1100 motor to safely use 10.6 compression. Hopefully this helps, if you have any more
questions feel free to call us!
V STAR 1100 HIGH LIFT CAMS
Since the V-Star 1100's engine is a Single Over Head Cam (or SOHC),
changing the cam is a very simple process when compared to doing other internal
engine work. Changing the cam does not require pulling the engine or highly
advanced tooling. Basically, if you are mechanically minded, and know how to gap
your own valves you can change your cams.
Here's how the cams work (the V-Star motor has 2 cams, 1 for
each cylinder). Each of the cams have 2 lobes on them. These lobes press against
the rocker arm which in turn presses against the intake and exhaust valves.
There are 4 main working positions of the valves,
1) Intake valve open as the piston moves down, which draws in the
air/fuel mixture from the carburetor.
2) Both valves (intake and exhaust) closed to create compression
as the piston rises to the top of its stroke.
3) Both valves closed as the piston returns back down under the
power created by the combustion of the air/fuel mixture.
4) Exhaust valve opens as the piston returns to the top driving
the burnt air and fuel out of the cylinder and into the exhaust pipe.
Those are also the 4 strokes of a 4 stroke engine. As you can
deduct, the farther you open the valve the more air is allowed to rush in.
Therefore creating more available combustible mixture, and thus generating more
power. This is what a high lift cam does better than a stock cam.
So you may ask, why not use a very high lift cam? Wouldn't opening
the valve all the way possible be the best? In short, not necessarily. First,
too high of a lift creates more potential of piston to valve interference. It
also creates more potential of floating a valve at higher RPM. Floating is when
the motor is turning fast enough that the valve springs do not have enough force
to keep the cam against the rocker arm, in turn not closing the valve quick
enough. Stock valve springs are capable of safely handling a 450 lift cam. All
of our X series cams achieve a 438 lift and are designed to work with stock valve
springs.
Our Triple Z cam provides nearly a 500 lift! This camshaft
must be used with our dual valve spring package to provide the force needed to
close the valve safely with the added lift. This camshaft is arguably the most
advanced cam for the V Star 1100 on the market today with much less valve
overlap than the competitions ultra high lift cam. Less overlap means less
decompression, which means more bottom end torque. Unlike the X series cams, the
Triple Z cam will require pulling the motor in order to install the dual valve
spring setup in your heads.
All of our cams utilize a hardface nickel based welded lobe
containing complex microscopic bi- and tri-metallics. This is by far
the most dependable and longest lasting way to build a cam. This process
requires the return of a stock cam set (called a core) from each sale. These cores are then sent
off to WEB CAM and prepped, hardwelded and then grinded to our specifications
and then delivered to the next customer. Aside from hardweld cams, another type
of cam is a Billet Heat Treated cam, we do not use this process. This type of cam is relatively inexpensive
to produce, and does not require a core (because you are purchasing a
cam out right). Billet heat treated cams wear down much quicker (we have seen
complete breakdown of a Heat treated billet cams in under 5000 miles!) and are not
nearly as
durable as hardweld cams. Because of that we only offer highest quality hardweld cams. Since
we choose to only offer hardweld cams, during some seasons when many people are
doing engine modifications, you may experience longer delays in receiving your
order as we wait for cam core to be returned. But we figure that is better than
waiting for a replacement for a failed cam or prematurely worn cam. Please call
us regarding any further questions you may have.
V STAR 1100 FLAT SLIDE CARBURETORS
For years Keihin has be known
as one of the top carburetor builders in the industry. And the Flat Slide style
carb is one of the most responsive style of carburetor made by any company.
These carbs are so advanced, when our competition first purchased them from us
(yes you read that right) to put on their V-Star 1100, they complained these things are junk,
sold them, and put
the stock carburetors back on. Well interestingly enough they now only sell the
EXACT same carburetors they purchased from us that he initially called "junk".
Well, obviously the carbs didn't change, maybe he just learned (oh yeah, and
bought a second set!).
Keihin carbs are used by
race bike manufacturers all over the world, and we spent allot of time designing
them to fit on the 1100 engine. The stock V-Star 1100 comes with CV (or constant
velocity) carburetors. These carbs have no direct connection with your hand to
the slide. The slide in the stock carburetor is pulled up using vacuum created
by the engine. CV carbs were basically designed to be very easy to tune on a
mass production scale. As you can figure, this style of carburetor generates
very sluggish acceleration. For example, when you give the throttle a full
twist, the slides do not come up, until the engine creates enough force to pull
them up. Only then after that delay do you finally begin to get response.
On the contrary, with
the Keihin FCR carbs, the slide is directly connected to the throttle cable,
which means when you give the throttle a twist, you get instantaneous throttle
response, anywhere from partial to full "hold on to the grips" throttle. In
addition the carbs we offer are 39 mm as opposed to the 37 mm stock setup.
This allow the engine to obviously pull more air and fuel in when requested. The
main benefit from these carbs is advancing and increasing the performance power
band in the normal driving range. Although overall hp will increase 7 hp +/-
over the stock carbs, actual power of the engine in normal driving rpm ranges
will be even more significantly increased. Another benefit is increased gas
mileage when touring. People that install the carbs notice that gas mileage goes
up, unless of course your throttle happy, and then all bets are off!
Furthermore when packaged together with the
rest of our performance products, hang on!!!
These carbs have almost limitless adjustability, with a large range of
available adjustable needles and jets for the ability to fine tune your engine to
perfection. Please call us regarding any further questions you may have.
V STAR 1100 DYNA
3000 IGNITION
In 2004 Yamaha changed their
V-Star 1100 ignition setup in some models. Mostly the California models. But
some of the changed models appeared randomly elsewhere across the country. In
2005 the remainder of the states changed to the new version. The change was from
a 2 plug setup to a 1 plug setup (the actual function of the box basically
remain virtually unchanged). To verify which Dyna 3000 ignition will work
for you, simply remove your drivers seat. The ignition module is right
underneath it. If your stock module has 2 separate sets of wires that plug into
the module with 2 plugs (as the picture shows) you will need the Dyna 3000. If
it has only one wire plug set, you will need the Dyna 3000 Single
Plug (V2).
CYLINDER REPLATING
Modern motorcycle cylinders are Nickel Ceramic
plated. This precision process allows much better heat dissipation and much
tighter bore tolerances (from less heat expansion and contraction) than the
older method of steel sleeving a cylinder. In addition, Nickel Ceramic plating
is much harder than a steel sleeve (its common to cylinders with 70,000 or more
miles that still show the original hone "cross hatching" in them!). When over
boring or repairing a compromised cylinder, re boring or repairing involved
"sleeving" a cylinder with steel, and then boring the steel sleeve to the proper
spec. This often led to over heating problems as a result since the steel sleeve
now created a barrier between the piston and the cooling fins of the engine. Over time
this robs
your engine's performance and worse, compromises it's longevity.
Our process of Re-plating your
cylinders ensures your engine is performing with
maximum precision, reliability and longevity with all the benefits of a Nickel
Ceramic cylinder.
