Porting & Polishing:
The
process is somewhat different for 2-strokes and 4-strokes but the basic
idea is the same: Improve the flow through channels (ports) where the
air/fuel mixture enters and the exhaust gasses exit the engine. Porting
and polishing a 2-stroke or and 4-stroke head is the ultimate engine
customization. Porting & polishing fixes the manufaturer's flaws
that result from mass production of engine components, there are often
blemishes and surface imperfections that remain because they are "within
specs", these imperfections, in the intake and exhaust ports hinder
engine performance. Porting & polishing fixes these issues and provides
the individual attention to the cylinder or head that the factory was
unable to do.
Once the porting process is complete, the next step is to polish the exhaust port, this promotes just a little more air flow, lessening resistance for the burnt mixture to escape from the engine. We do not do this to the intake side, as doing so would actually take away from the engine's efficiency. The reason being that after the intake ports are complete they are left with a slight texture, a roughness, that helps to tear apart the fuel droplets as they pass over the surface before entering the cylinder, this causes the air and fuel to mix better causing a better ignition. If the intake ports were to be polished the same as the exhaust ports the increase flow would not compensate for poor fuel mixture, which in turn would be wasting the fuel power that still had to be pumped through the engine, but didn't burn to full potential.
Porting Stages:
Performance upgrades give you the option to go as far as you want to, or at least as far as your engine can go. Following is a list of different porting stages that are available and which is appropraite for your application.
Stage I: Recreational or Clean-Up Port Job
This stage is also known as a Recreational Port and Polish or a Clean-Up Port job. Every decently tuned stock engine can gain performance from this type of port job. Naturally, it will be noticeable on some engines more than others due to the "fixes" that this stage provides. If you were one of the few lucky people who has a head or cylinder with minimal "defects" then you won't notice as much of a difference as if your 2-stroke sleeve was a millimeter or two offset on every opening or if your 4-stroke head has severe casting blemishes. Another factor is the type of riding you do, but whether you notice a dramatic difference in your riding or not your engine will run more efficiently.
Stage II: Trail/MX
Stage 2 or a Trail/MX Port and Polish is great for anyone who takes (or wants to take) their riding past the everyday recreational riding to something more of a passion. This is also applicable to most off-road racing applications.
The engines that receive a Stage 2 Port job the best usually have several other performance modifications already in place. If you have upgraded your exhaust or intake system in other ways, or changed crank, cam, bore size, etc... then a a Stage 2 is exactly what you need to get full potential out of your engine.
This stage covers a complete Stage 1 Port job, and also adds expanding port size. This is where we begin slightly raising/lowering ports in 2-stroke engines as well.
Stage III: Trail/MX Expanded
This stage expands on the Trail/MX Port job and probably includes the addition of "boost" ports (which are very tedious to preform, but the effect in a high output engine is fantastic).
This is the "biggest" stage of porting and also known as All-Out-Drag. It is specifically for engines with major internal changes and not designed for casual everyday riding. Basically, if you need this level of porting done, you already know it, and have been planning for it since day one.
Warning: You Need Experience
For every "ultimate" gain that can be achieved through porting and polishing there is an ultimate risk factor. It takes a lot of experience, testing what works and what doesn't, and careful planning to be able to complete a successful port and polish job. Even then, it takes many hours of tedious work and extreme attention to detail to complete each specific component modification. Porting involves physically removing material from the casting and material can't be replaced once it is removed. A very small (think in terms of millimeters, sometimes less) modification can have a huge impact on performance. If the modification was done incorrectly or a hand slipped, there might be a huge negative impact on performance rather than an increase.
Please Call (814) 929-5332 for more information and pricing