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Old 02-02-2013, 12:47 AM   #52953
Sierra Thumper
Studly Adventurer
Joined: Oct 2012
Oddometer: 641
Laugh First quick street ride with powerbomb and cut air box

I wanted to give some feedback on my results so far with the addition of an FMF powerbomb header and cut airbox to my bike....I know adding a header is a fairly expensive and debated topic, I just wanted to help anybody reading by sharing my experiences so far. I did manage to pick the header up for an awesome price, which helped my decision a little

I'll start out by saying that yesterdays quick ride was pretty windy, compared to my last ride which was pretty much windless. Also I'm still running my 20/50 oil, which is a little thicker in the cold than it was on my last ride which was warmer, and I suspect is robbing me of a few ponies.

Anyway, besides the powerbomb header, and hole I cut on the top right side of the airbox next to the stock opening, here are my other engine performance related mods-
Stock motor
Daves mods
Uni filter
Big Gun silencer and mid-pipe
58 pilot/155 main jets
5000ft above sea level

Just a quick warning, if you cut your airbox be prepared to adjust your mixture screw substantially richer, or even possibly having to go up a size on your pilot jet. My pilot is already big for my elevation, and I had to turn my mixture screw from 1/4 turn out to about 3 turns out, just to cure a big flat spot just off idle The hole I added REALLY helped the airflow tho, and definately helped the low end response, and seemed to work very well with the powerbomb.

First thing I noticed when I took the bike for a quick street only ride, is that it winds up through the lower gears quite abit quicker than before the powerbomb, I was needing to shift sooner than before, and the motor wanted to spin up much quicker. The low end throttle response and revability of the bike is noticeably better. I didn't notice as much of a difference in fifth gear tho, but I was fighting a pretty stiff headwind, which I didn't have on the last ride pre-powerbomb. When I did get a small break from the wind it seemed to want to wind up quicker in 5th as well.

I haven't got to hit the dirt yet, but from this ride I think its going to be much snappier and quicker revving in the lower gears, which should add to the off-road fun factor substantially

I haven't changed any jetting or needle settings at all, haven't even opened the carb, all I've done is adjust the mixture screw......with that change alone the bike has no flat spots anywhere, no decel popping, and the same crisp, smooth throttle response all the way up as before the header and cut air box. I did have to richen the mixture screw to the point the idle started dropping some to cure the off idle flat spot, and I've had to raise the idle up so the bike doesn't want to stall coming to a stop.
But with that fixed she runs the same as before, just stronger
Also the powerbomb mellowed the sound out noticeably, just like FMF claimed it would.....that was a nice suprise

Its not a drastic improvement in power, but so far its substantial enough to make me happy......and imo it was worth the money and time

I might be able to get more power if I play with the jetting, but I'm going to run it as for awhile and do a plug reading to see where I'm at jetting wise.

I would recommend opening up the air box with some cutting (I wouldn't go crazy tho) along with adding a header....from the reading I did it supposedly helped, and from the way my bike's responded so far I'm pretty sure the cut air box did help the power gain along with the header.
"Don't get so concerned with the slab that you choose a turd for the dirt"- The Gospel as spoken by itrack
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