FMF on there 2010

Who has put the full FMF system on there 2010 450? I would like some real world info on how it performs compared to stock! I would like some more top end but I really do not want to screw with the bottom end. I love how it pulls down low. I know I do not need one but just maybe I have to have one hehehe!!!

i just read in TWMX last night about a company called throttlebodymods or something like that and for $225 you can get the same if not more top end gain along with better throttle feel etc.

Yea I searched, and there is not much info so that is why I posted! eh!

Ok since this thread specifically mentioned the FMF system I have a scoop for you. I picked up a full 4.1 SS system from OEMCYCLE.COM for $448. You have to order the slip on (which is the same can as the full system) and megabomb header seperately. The full Ti system is around $600. I don't know if TT will beat it by another 10%, that would be awsome but tough to imagine. I waited until I received my system before posting because I thought they might say the price was in error. I got it now, I just need the bike. Before some one chimes in and tells me it's crazy to buy an exhaust before riding the bike, I allready rode my friend's white one. Frankly I can afford it and since this will probably be my last new bike, I went for it. By the way, this is the 4th 'last bike I'll ever buy'.

I have a Ti 4.1 full system . It smooths the low & seems to have more torque. it also seems to make the bike rev slower making the power seem longer . it does add top over rev . I don't even think about the power falling off like stock . it is not the highest reving bike but totally acceptable .. So in a nut shell smoother low end , less of an edge to the mid & more overrev . slightly slower rev feel to the engine . I ridden it with the jay marmont map, too much upper low & mid .I,ve used mellower maps ,with the pipe. I use the stock map most of the time. I had the bike & pipe for 4 months so this is not a back yard or on the stand test of the system. I only race mx no hs,trails . Jeff

Gray, I don't know which post you are referring to but NUMUKEN might be talking about the Simons Smart Body injector reviewed in Dirt Bike magazine.

The Dirt Bike web site has an update on how Simon's slide type body as opposed to a butterfly valve increases hp. They claim a large increase at half throttle due to less turbulence using the slide and a 'power now' type device. They also claim 6 hp on top for a KX450F due to no butterfly obstruction in the throat of the body. The update also states the original $800 has been reduced to $500 for this throttle body.

Also there's a company called Injectioneering that modifies the current injectors by drilling a hole in the butterfly and allowing it to close all the way. These mods supposedly reduce turbulance and increase flow at small throttle openings. Both companies have to recalabrate the fuel maps. Interesting times these fuel injected bikes are bringing.

Edited by NE14MX
updated info

I was referring to the info on the FMF pipe in the first thread, and the DRD in the second two links I posted. The DRD seems to address the sort of improvement the OP specified, while there were posts within that same thread that expressed being less than thrilled with the FMF. I'm sure there are other opinions out there, though.

The throttle body mods and alternative designs are interesting. The slide valve type obviously provides a cleaner through path at WOT, but the reduction in turbulence at part throttle is dependent on the use of the horizontal blade ("powernow") you mentioned. Otherwise, they are at least as bad, even if different. There have been designs using two such blades positioned so as to align with the edges of a partly opened butterfly which claim to address the turbulence issue. But there is a school of thought that regards all such devices as gadgetry, and holds that to the extend that air flow restriction resulting from the turbulence of a partially opened throttle can be addresses simply by opening the throttle farther, as long as the engine runs right at these intermediate positions. Only an advantage that exists at full throttle is truly significant. That's the camp I find myself in, too.

The advantage a slide valve would have (remember there would be no needle in the air stream) at full throttle can be largely adjusted for with a butterfly valve by going to a larger bore size. The opened butterfly will cause some disturbance, of course, but it shouldn't be so bad it can't be dealt with.

The hole in the throttle plate is something you see quite often in the automotive field. It improves "tip-in" performance coming off idle, as well as idle-down performance.

All in all, unless I were building a flat tracker or something, I doubt that I would see spending a bunch of money on adding power to a late YZ450 before I had addressed suspension and other stuff as something I'd want. If the mods are reasonably priced, and actually do something, it could be worth it, though.

Grayracer513,

With regards to your comment "Only an advantage that exists at full throttle is truly significant". Could you expand on this inlight of my comments below.

Concerning the Simon Smart Body, the dyno figures show what looks like a 10HP gain at half throttle, similarly a good increase in torque.

The motocross tracks I ride on are not flat out full throttle tracks, alot of tight corners and short straights. I rarely get to full throttle and would guess I ride in the 1/2 to 3/4 throttle range alot of the time. So in light of the gains mentioned above I would have thought that would have been an excellent product and full throttle gains of little relevance. Correct or not?

Grayracer513,

With regards to your comment "Only an advantage that exists at full throttle is truly significant". Could you expand on this inlight of my comments below.

Concerning the Simon Smart Body, the dyno figures show what looks like a 10HP gain at half throttle, similarly a good increase in torque.

The motocross tracks I ride on are not flat out full throttle tracks, alot of tight corners and short straights. I rarely get to full throttle and would guess I ride in the 1/2 to 3/4 throttle range alot of the time. So in light of the gains mentioned above I would have thought that would have been an excellent product and full throttle gains of little relevance. Correct or not?

You are only at 1/2 to 3/4 throttle because that is all the power you can use in that situation. If you wanted more power you would turn the throttle more. All 10HP gain at 1/2 throttle is going to do is make you turn the throttle less.

Full throttle performance being equal, part throttle performance can be increased at any point by simply opening the throttle farther, don't you think? Assuming the response is linear and predictable/controllable, I don't see paying for a device to gain power at half throttle as being advantageous when I can open up to 5/8 and do the same thing.

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