Tell me now, before I start ripping needles out!!!!

 

Easy Michaelb2, go to your happy place..

Fueling requirements for stock header+slipon are exactly opposite of the requirements for the FMF system. ( lidless, near sea level)

I have found that the DJ2152 kit can serve as a "starting point" to properly fuel lidless, stock header+slipon bikes. Near sea level is 140/3N, 136/5N and probably 138/4N (not tested).. (Adding the MCM, IMHO, only increases the need for fuel everywhere.)

However, it's looking like the 2152 kit may be totally useless for the same bike running a Megabomb+PC4.

I guess I'm not going to quit until I have the FMF system fueled correctly.. So I'm considering the permutations between DJ and stock components to get the low/mid to stay in an acceptable AFR range. (Acceptable to me would be between 12.5 and 13.5 to 1.)

First, though, I'm going to remove my backfire screen and ride it a while..

 

Define "FMF System."

Then tell me, by the term "Slipon" do you mean "bolting on an FMF Q4 exhaust"?

<happy thoughts, happy thoughts>

 

Probably yes. Though, his testing with a slip on and stock header was with a DG Slip on. I'm sure the spread is minimal from brand to brand though.

When he says FMF system he means the header and slip on together.

 

Slipon = aftermarket muffler such as DG-R, DG-O, FMF Q4, FMF PC4, etc.. I also lump the KLX300 exhaust system (with the butt plug removed) in this group due to its' standard KLX 250 O.D. up to the midpipe connection.. I'm sure the differences in power levels are fairly close from one to another - except those that have managed to defacto reinstall a "soda straw" by the way of some kind of "quiet insert/tip"... I should note that I'm confident that my DG-R favors lower RPM power compared to my PC4 when used on the stock header due to the differences in the size of the midpipes - the DG carries a smaller O.D.

FMF System = Megabomb with a PC4 slipon. This is a larger diameter header and midpipe from stock. While I don't own a PowerBomb, it appears as though it is also a larger-than-stock pipe, same as the Megabomb. My FMF system greatly increases the "area under the curve" (higher power levels) starting at about 6.5k on up to redline- especially when fueled correctly. It is NOT capable of producing the same power levels as a stock header+slipon below 6.5K - at least as far as my testing can tell..

 

Can I ask then are you a fan of the DG with the stock header then ? And what are your thoughts about that with the larger snorkel mod and say a more breathable air filter ?

I am not looking at going crazy and expecting another 20 h.p. or anything. Just trying to help it breathe a bit better. My next question is what did it do to your fuel milage with all the testing you have done with different pipes and jets. If I put a slip-on on and rejet it will the milage go in the crapper ?

Thanks.
Lenman

 

I"m a fan of the DG-R simply because it's so cheap compared to the others. But, it is LOUD! Just the way I like it.. However, it seems all the slipons are too loud to "Hoon around the Hoods" with - my FMF PC4 (double the price of the DGR) certainly is also. You have to putt putt in the neighborhoods with all of them - so what is really the difference except price...?

I have no data with lids and snorkels. My idea with being lidless is that it is the most I can do to provide airflow to the carb (without cutting holes etc..) Since there is no information indicating increased water or other infiltration with the lid off, it is a "free" mod.. It is simply common sense (to me) to pull it and set up the carb for the better airflow. Which has been a daunting task but with great rewards..

I have no data on fuel mileage. Certainly, when you mod up to 22hp, what you do with those 22 horses becomes your fuel mileage.

 

I have somewhat similar mods on my '09SF and with my DJ136 4N I am getting mid 60 mpg where I got low to mid 70s with a DJ128 3N arrangement. This was before I did the MCM but power is noticeably better and lean surging is nearly gone. Plan to throw in the DJ140 3N soon and see. The other day I hit an indicated 95 mph at 9250/9500 rpm and she was out of steam.

 

Cool. Thanks. The noise isn't so much of a concern of mine for the neighbors. They are still getting off lucky. I sold the Harley I had for 14 years to get the klx. But I enjoy the threads you do and appreciate your time.

Also I am new to these kinds of mufflers but will all the slip ons need to be repacked at some point? None are maintenance free are they ?

Thanks again.

Lenman

 

I have the needle coming in the mail. Just need to source the main and pilot.