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woot -> RE: 2000 F4 horsepower (1/28/2007 9:30:05 AM)
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Stage 1 and Stage 2 are mostly bullshit names that people don't understand... You hear a few people throw them around as if you *should* know what they're talking about, and that it makes a big difference. They just represent a kit - that's it. You could just say you installed the right jets/needles for your bike as it is setup currently - or just say jetted.
A stage 1 kit is for a stock or slightly modified bike. Maybe a slip on exhaust with the stock headers for example.
A stage 2 kit is for a bike that you've changed some stuff on - for us it's pretty much only the exhaust as the stock airbox is pretty good.
A stage 3 is available for some bikes... but I don't think for ours. This is a designed for a more tuned bike than ours, potentially running individual air filters instead of the stock box.
For more reading:
http://www.dynojet.com/carbjet.shtml
Now - for the other stuff. If you think of a bike in three parts - intake, motor, and exhaust. To get hp you want to run as much fuel through the engine as possible. To make the fuel burm you have to have the right ammount of air. Setting up the carbs sets the mixture - lean and it gets hot, rich and it bogs.
The limitation of more fuel (and therefore more air) is the intake and the exhaust. If you're exhaust is too restrictive you can't put more fuel/air through the engine. After market exhaust and voila more potential for airflow. Some bikes are intake restricted from the factory - some are exhaust restriced.
So you go ahead and install a better flowing air filter. ( don't throw out the airbox as it's very scientifically/carefully designed to get more airflow through it's mouth than would be possible with a straight pipe... resonance.
So far we've added k&n filters, and some sort of full exhaust in our hp quest - we are running nearly $1000 in parts. To make use of the extra flow we've also jetted the bike - replaced the stock needles and jets with some nice adjustable ones perhaps.
Now the intake isn't just the airfilter, and the exhaust isn't just the exhaust pipe. The ports in the engine that bring the air mixture from the carbs to the top of the piston at the intake valves, and the ports in the engine that bring the exhaust from the exhaust valves to the exhaust pipe. These ports can be honed and polished... a really knowledgable person would understand the science here (either from books or practice) to get the biggest flow through the available space... sometimes that doesn't mean the biggest hole either. So they polish them up, and now they've reduced the restrictiveness here and suddenly we've really got something for airflow.
Now a port and polish varies in cost and advantage from bike to bike. The new bikes are really well built and I don't think you could do that much more... you'd need a really good guy to get the extra ponies here - and there is the possibility you work will be in vain... or worse you loose hp. This is probably going to run you over $500 for a cheap guy and over 2000 for a good guy.
Anyhow - that's the rundown of the air/fuel performance mods off the top of my head.
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