im thinking about buying the powerbomb with the 4.1 muffler.my question is fmf makes 2 headers the supercross and motocross version.and also the megabomb im just wondering which one would be the best.my bike is a 056 crf450r and i ride mostly motocross all summer.i cant ride the bike on the top end either.one more thing is the supercross version powerbomb loopsway down like a low boy pipe.not really sure if i would like that or not.also some ideas of jjettting would be help full also.just for a starting point as far as pilot,needle clip,and main.thanks
is the fmf powerbom a good header?
- Thread starter thecount
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crf250rjcd5151
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- Dec 19, 2007
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I just bought the FMF Facory Dual Blue anodized slip on mufflers(they look and sound sweet!!!) for my 250r, then I just bought a week later the FMF Powerbomb stainless head pipe. a real b**** to get to fit but it looks good and sounds good, haven't really track tested it yet.
the longer pipe ( loops way down) will tend to shift the hp and torque peak rpms down a couple hundred rpms. Perception is more "punch" at those lower rpms. Coming off an corner, gear too high, base of a jump, etc.
The shorter pipe will move the rpm's the peaks occur at up and provide more over rev type power which can be useful for some tracks and rider styles.
One pipe doesn't really make more power than the other, it's more the kind of power, and many riders might not even be able to tell the difference. Also consider the length of the silencer also plays into the whole system.
The shorter pipe will move the rpm's the peaks occur at up and provide more over rev type power which can be useful for some tracks and rider styles.
One pipe doesn't really make more power than the other, it's more the kind of power, and many riders might not even be able to tell the difference. Also consider the length of the silencer also plays into the whole system.
crf250rjcd5151
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- Dec 19, 2007
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Here is a link to a pic of the final instal, for sure not an easy install. Just a tip, take the whole exhuast off, put the new head pipe on them work your way back. I tried to put the head pipe on later, not a good idea, almost impossible. Might be easier on your bike but I still had to use a rubber hammer to squeeze the mid pipe onto the headear, much larger diamater than stock and a tad too long at least on my CRF250R. FMF should really trim about a 1/4 off the end that mates to the mid pipe and would makes this install much easier. http://www.dirtrider.net/gallery/showimage.php?i=4144&c=3
thecount said:
None of these pipes change the power much. They are much more SHOW than GO. ;)
crf250rjcd5151
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- Dec 19, 2007
- 15
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I agree Rich, The slipe on Factory 4.1 mufflers helped plenty, once the header was on I didn't really notice much difference than when I added the mufflers. It does look good though. For sure no fun to install though!!!
I think the companies who sell these pipes are banking on the fact that with a 2-stroke the pipe can effect the engine a lot. Now that we have moved to 4-strokes, people are still stuck on the buy a new bike, then new pipe mentality.
Have you ever looked at a high performance, racing 4-stroke engine (say a nascar / top fuel dragster). They all have the exact same exhaust setup! Just a curved pipe to move the exhaust away. The thing that really matter in these is the overall diameter of the exhaust setup and the amount of flow provided by the mufflers (followed by the sound reduction of the muffler). Yes high performance 4-strokes can have "headers", but out dirtbike engine aren't multi-cylinder.
The camshafts, valve lift, overlap, timing, etc on these dirtbike motors are setup with the factory exhaust flow setup. The only time it would be really necessary to change pipes is if you were to make the motor more radical (if that is even possible, given how these motors come) changes to the engine.
Have you ever looked at a high performance, racing 4-stroke engine (say a nascar / top fuel dragster). They all have the exact same exhaust setup! Just a curved pipe to move the exhaust away. The thing that really matter in these is the overall diameter of the exhaust setup and the amount of flow provided by the mufflers (followed by the sound reduction of the muffler). Yes high performance 4-strokes can have "headers", but out dirtbike engine aren't multi-cylinder.
The camshafts, valve lift, overlap, timing, etc on these dirtbike motors are setup with the factory exhaust flow setup. The only time it would be really necessary to change pipes is if you were to make the motor more radical (if that is even possible, given how these motors come) changes to the engine.
Aftermarket pipes
Rich is right. Most pipes do not help out too much unless you have a yamaha with the new short silencer. Given the cost of the pipe, you will get better results for your money adding a CAM like a Stage 2.
Call and ask the maker to fax you a dyno curve of stock vs new pipe and check for yourself. You might find a bit more overev, but for the money a CAM is better money spent and way cheaper. If you want more overev you can purchase a $400 rev box and that is still cheaper and better performance than a $800-$1200 pipe.
Don't focus on looks, focus on end performance for dollar invested.
Spokes574
Rich is right. Most pipes do not help out too much unless you have a yamaha with the new short silencer. Given the cost of the pipe, you will get better results for your money adding a CAM like a Stage 2.
Call and ask the maker to fax you a dyno curve of stock vs new pipe and check for yourself. You might find a bit more overev, but for the money a CAM is better money spent and way cheaper. If you want more overev you can purchase a $400 rev box and that is still cheaper and better performance than a $800-$1200 pipe.
Don't focus on looks, focus on end performance for dollar invested.
Spokes574
