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Elan

What about the FMF?

12 posts in this topic

I bought the FMF power bomb header and Powercore IV2 muffler (after crushing my stocker in a fairly high speed slide out). A little lighter and much better boost from off idle thru the mid-range with just a slight loss up top. Sounds great too!

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I just installed the powercore IV2Q. It's claimed to do just what Tom says about the regular powercore IV2, but is supposed to be quieter. I haven't had a chance to track test it yet, but I've had the bike running int the driveway and it is quieter. Of course this is just a seat of the pants judgement. I don't have a sound meter. Both versions are spark arrested (which is why I bought it). FMF 's recommended jetting for this muffler is 45p, 168m and 2-3/4 turns out on the fuel screw. The latter of the two sound a little rich to me though. Tom, what jetting changes did you make?

I'm seriously considering getting a Dubach exhaust system as soon as they're available.

I just got an e-mail from them last week stating that he's finished testing the final proto-type and is ready to start production.

You can check them out at http://www.dubachracing.com/

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00 YZ426F

01 TT-R125L (my son's)

91 CR125

83 YZ490

74 Hodaka Super Combat(gone but not forgotten!)

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I have had the FMF Powercore IV^2 for almost a year now and it is great. It makes super power across the board and sounds great. I really liek the fact that you do not need the asbestos gasket between the header pipe and the slip-on. Fit and finish are superior. Here's what my machine looks like with it.

DCP01538.JPG

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I have the PowerBomb header on my '01 426 and once I put the 168 main in, it made a world of a difference! The stock jetting is too lean for the pipe. As for the pilot jet, they recommend testing the bike with the stock jet before making the jump to the #45. I for one found the stock jet to be fine.

BTW, the jetting was tested at around 2000 feet in the San Diego area.

--Milo

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thanks for the info Milo.

------------------

00 YZ426F

01 TT-R125L (my son's)

91 CR125

83 YZ490

74 Hodaka Super Combat(gone but not forgotten!)

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Roostn, What jetting changes did you make? FMF 's recommendations for the main jet (168) and fuel screw (2-3/4 turns out) sound kinda rich to me.

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00 YZ426F

01 TT-R125L (my son's)

91 CR125

83 YZ490

74 Hodaka Super Combat(gone but not forgotten!)

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Dirtdad, when I installed mine it was about 30-40 degrees cooler than it is know and I had to go richer on top (168) but as it is heating up I have dropped back to a 165 main, the next leaner needle (I can't remember the number and it seems to run funny if I go more than 1 clip position away from the middle) and a 45 pilot about 1 1/2 tirns out.

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Thanks Tom. I put the 45pilot and the 168main in, but haven't had a chance to test it yet. I've got my front forks off to MX-Tech for a re-valve. FMF 's recommendation for 2-3/4 turn out on the fuel screw seemed way to rich to me. I left it at 2 where I had it for now. I may go back in before testing and replace the 168 main with the 165 to start with too. By the way, what do you do in the Army? Thanks again for the info.

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00 YZ426F

01 TT-R125L (my son's)

91 CR125

83 YZ490

74 Hodaka Super Combat(gone but not forgotten!)

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I must have the wierdest jetting out of anyone. I have a 152 main with my FMF Powercore IV^2. Stock needle, stock airscrew. The thing runs like a train. I do want to Dyno it before Pikes Peak to see where I'm at. I got those jetting numbers from my local shop where I bought the pipe.

Roostn

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Dirtdad, I am an active duty Infantry type assigned as the BN Ops Sgt/Bradley Fighting Vehicle Master Gunner for a Texas Army National Guard Infantry battalion. Yes, it is a rather unique experience to say the least!

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Tom, I was just wondering as I'm a retired Navy Intel Specialist. Thought maybe you did something similar.

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