- Location
- Floridapunk
What mechanical post process makes the difference between light switch on and off and linear power on high output motors?
Xscream 12, others
Xscream 12, others
High output motors
- Thread starter SuperDrifter
- Start date
WFO Speedracer
A lifetime ban is like a lifetime warranty !
- Location
- Alabama
Porting , a two stroke motor can be ported to have great bottom end and no top end like on a Trials motorcycle, or great top end with no bottom end like on a motocross bike or anything between the two extremes.
Any twostroke with a tuned pipe will get an almost instant power increase when the pipe starts working.. Power is very broad and smooth without a pipe. The typical pipe starts working around 5000rpm where little thrust is produced. RPM and thrust will rise almost instantly after that. This makes the power feel like its all or nothing. Pump load is the primary factor, power will be much smoother when the engine is overloaded. Most riders want the fastest response and just fan the throttle to get whatever power they need.
DylanS
Gorilla Smasher
- Location
- Lebanon Pa
it’s really a package deal.
There are individual parts to the recipe that can make a difference but together really start to shine.
the “on and off” snap you’re talking about is generally the best imo when the power band comes on strong in what would be considered the middle of the rpm range and pulls hard through up onto the top seeing as most people spend next to no time on the “bottom” end.
Proper porting, a light flywheel, a good timing curve, high compression, pump setup, exhaust and intake/carb setup, etc, all play individual important roles in chasing the “hit”.
You can have a engine that pulls fairly mildly in the low/mid and crazy hard up top that feels snappy all around but in reality it’s just blasting off to 7k+ rpm as soon as you grab the throttle.
like mentioned above the height of the exhaust port plays a very large role in how linear that power is. One of the important major differences between big companies billet monster engines is the ports. Their angles, how many, the port timing, etc. Case volume. Rotating mass is also a big one.
Thats why power valve engines can perform so well across the entire rpm range. A smaller exhaust port at lower rpm and a nice open one at higher rpm.
In my youth and learning I once raised the exhaust ports on a 760 cyl considerably by accident and still had what I considered at the time a fairly snappy motor. Compared to what i have experienced later on not as impressive, but to your average rider pretty snappy even with a tall exhaust port.
My old 5 port dasa 1200 was incredibly violent from top to bottom for what some people would consider an engine more so ported to favor the top end.
There are individual parts to the recipe that can make a difference but together really start to shine.
the “on and off” snap you’re talking about is generally the best imo when the power band comes on strong in what would be considered the middle of the rpm range and pulls hard through up onto the top seeing as most people spend next to no time on the “bottom” end.
Proper porting, a light flywheel, a good timing curve, high compression, pump setup, exhaust and intake/carb setup, etc, all play individual important roles in chasing the “hit”.
You can have a engine that pulls fairly mildly in the low/mid and crazy hard up top that feels snappy all around but in reality it’s just blasting off to 7k+ rpm as soon as you grab the throttle.
like mentioned above the height of the exhaust port plays a very large role in how linear that power is. One of the important major differences between big companies billet monster engines is the ports. Their angles, how many, the port timing, etc. Case volume. Rotating mass is also a big one.
Thats why power valve engines can perform so well across the entire rpm range. A smaller exhaust port at lower rpm and a nice open one at higher rpm.
In my youth and learning I once raised the exhaust ports on a 760 cyl considerably by accident and still had what I considered at the time a fairly snappy motor. Compared to what i have experienced later on not as impressive, but to your average rider pretty snappy even with a tall exhaust port.
My old 5 port dasa 1200 was incredibly violent from top to bottom for what some people would consider an engine more so ported to favor the top end.
Last edited:
waxhead
wannabe backflipper
- Location
- gold coast
Way to many things to list. So often how often I see most basic mistakes. If you want liner power then get your squish right. So often a lot of people have this most basic thing wrong.