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How many here have ported their cylinder heads, results?

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Coming from mainly a car backround, I've noticed that not a whole lot of four stroke guys do extensive cylinder head porting. Any reason for this? It's one of the first major things to do when looking to either make more power or smooth out power in a car.

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i had my head mildly ported with a different cam along with valves and springs. made a noticeable difference on the SOTP meter. maybe 5hp. rapture had his done by RHC and had a huge gain over stock. maybe he will post. you do some porting?

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I ported auto cylinder heads for a long time, not motorcycle stuff though. Is this real common with the new four strokes? I've just been out of the whole dirt bike scene for about 6 years, right before thumpers made the big comeback, so I'm kind of behind the times. Have only ever ridden/owned two strokes.

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same thing for bikes. porting a head reshapes the air and fuel entrance to allow better velocity and flow into the cylinder.

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Yeah, I just had not seen a whole lot of hype about it, that's why I asked. Is it overpriced or something for bikes? I mean, 5hp is more than you'll get from most $500 exhausts, but you see everybody with aftermarket exhaust.

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5hp is more than you'll get from most $500 exhausts, but you see everybody with aftermarket exhaust.

You'll be lucky to see 1 HP and you usually give it (or more) up somewhere else. The stock systems are very well designed.

I still have a hard time believing people are paying close to a grand for some of these systems.

A good cam in the $150 range can do much more to modify the power of these bikes than these exhausts.

:thumbsup:

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5hp is more than you'll get from most $500 exhausts, but you see everybody with aftermarket exhaust.

You'll be lucky to see 1 HP and you usually give it (or more) up somewhere else. The stock systems are very well designed.

I still have a hard time believing people are paying close to a grand for some of these systems.

A good cam in the $150 range can do much more to modify the power of these bikes than these exhausts.

:devil:

I'll tell you why, they are buying bling. You can't see a port job or cam. Stupid but true in a lot of cases.

:thumbsup:

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I'll tell you why, they are buying bling. You can't see a port job or cam. Stupid but true in a lot of cases.

:thumbsup:

I agree 100%.

Made the exact same point in a post about the CRFX ... you can see the pipe but not the cam.

I was promptly scolded for being so truthful! :awww:

:devil:

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You have to be careful in the red forum, those guys mean bidness. :thumbsup:

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Owning six of them doesn't qualify me as one of them? :thumbsup:

(and I've had at least one for over 20 years) :devil:

:awww:

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I don't think you hear too much about it due to the fact that the bikes are already pretty [@#$%&*!] powerful. :thumbsup:

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I'll tell you why, they are buying bling. You can't see a port job or cam. Stupid but true in a lot of cases.

:thumbsup:

I agree 100%.

Made the exact same point in a post about the CRFX ... you can see the pipe but not the cam.

I was promptly scolded for being so truthful! :lol:

:devil:

And I third it. I built my first race car at 17 and my first road racer V-8 at 28. Heads and induction are where you make power, and bling and loud pipes ar total B.S. (Case in point: Buick Grand National. Very quiet. :awww:) Camshaft engineering is not as foolproof as opening up the heads, however, and it is more weight, use, and RPM-specific that a port job. Alot of guys charge major $$$ to POLISH the port job, but all this does is make gasoline slide off too easily for street applications and smooth idling. Do not let anyone sell you a polish job. That is a strictly-race preparation that is only useful in very high-rpm applications. The tiny lands and grooves in a rougher port job fill with fuel and help atomize and evaporate the stuff so that it is in a better mixture for slow RPM (esp. idle/startoff) and helps alot when running a rad cam, too. :lol::D

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I think the reason cams and heads aren't an issue with bikes is that they are already on the ragged edge from the factory. Most thumpers power curves are still on the rise when they hit the rev limiters. So basically, except for the diehards, the only way to go is more mild. You probably won't find a street driven car like that. Also by comparison bikes have no bottom end. My car has a fairly wild cam and will still idle at 900 RPM and pull from there. I guess what I'm saying is that for car engines you start at mild and you can choose any one of the many cams on the way to wild. On bikes you're already at wild so you open up the intake and exhaust to take advantage of it. Another thing, have you ever seen the cost of bike cams. They cost like 3 or 4 times what a car cam costs. I'll never understand how a reground six inch long cam with two lobes can cost more than a brand new one for a V8.

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I may sound nuts, but making the ports smaller (to a point) gives you gains in the lower end. Why? The gas and the air flow faster into the chamber.

I learned that from the break-in secrets site...

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I had mine done along with a 12.5:1 piston and a stage 2 Hotcam. It made a big difference. Definately more bang for the buck than any pipe could make.

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