Hi there...I will start by saying, I don't have a lot of background knowledge in working on vehicles.
I recently bought my first bike in over 20 yrs, a 2010 KLX250SF, with what I thought where some nice upgrades....I should say that in my book, the bike is real nice, seems to ride fine, and I love it!
After riding a few hundred miles and getting the feel for it, I began reading up, wanting to learn and become competent at working on and upkeeping my bike.
After some research and poking around, I determined that the PO had installed a DG muffler, FMF Megabomb header, and had it set up lidless with a K&N air filter. I don't know about jetting yet, and I assume no MCM, but not certain.
Fast forward to me reading threads late at night, and I ran across a warning that if your SS header is turning purple, you might be too lean, and running hot. My header has a nice purple hue.... Then Werloc warns Ditch Pickle that " they run great lean, until they kaboom" or something of the sort...
So, I PM Klxster and start asking for advise. His first reaction to the setup on my bike was that the DG muffler doesn't belong on that header, it is too small and thats why a wad of fiberglass is in there. So I'm looking for the best deal on an FMF slip-on to go with my FMF header, when I realize that I think the PO has notched and "necked down" if you will, the mega bomb header!
At this point, I am starting a thread, so that I can throw some pics up, for Klxster and everyone else to see, opine, and hopefully I can sort all this out.
Thanks in advance for any help and input, AND, thanks for all of the good reading and resource already on this site, it is overwhelming at times, and there are only so many hours in the night, but I am learning everyday reading old threads etc.

 

In the pictures above, you can see the purple tinge, as well as the crimped end on the FMF to fit the DG. I measured both pipes, and they both measure at 1.48 o.d...knowing that, I wonder if I could get a piece of SS with a 1.5 i.d and have it my friend weld it to the DG portion(after cutting back the bottle neck of course), and then eliminate the funky crimp on the FMF end and be good to go?
Also, the one picture is looking into the exhaust port, and I would like to know if the valve stem normally has that white lumpy build up on it?

 

Well the first thing I would do while the exhaust is off is check the jetting. You can remove the one screw the holds the throttle cables , loosen both boot clamps and rotate carb bowl 45* towards pipe side and remove bowl.

let us know how you plan to run your air box and your sea level. We will get you close.

looks like the PO did a number to that pipe. I wouldn't worry about pipe color. It's thin stainless and too rich can also make exhaust heat . If the air injection is still intact that doesn't help burning the extra fuel in the header.

If you need a header I have my stock one. You are more then welcome to it.

 

Firstly, please take s10gto up on his very generous offer. This will get you "up and going" with a proper performance exhaust system. Stock header + DG will make tons of TRQ, especially with MCM added, in a lidless CVK setup.

Your High Dollar Megabomb has been butchered. No doubt it could be repaired. Perhaps there is enough of the original bell left to allow a seal onto a FMF slipon. The hacksawing looks like it does not run the full length of the bell..

So your choices, as I see it :

Repair the Megabomb, add a FMF slipon - With a lidless CVK setup it offers biggy power 7k-10.5K with a loss below, compared to stock header + DG .. The lack of heat shield on the Megabomb is a burn hazard, IMO, a serious one.(I run a Megabomb, I know..)

With s10gto's stock header + your DG and a lidless CVK setup, you'll get biggy power idle - 7k rpm with a fairly strong top end 7-9k.. Not much use in revving it past 9.2K though..

Also, you could sell the Megabomb as is - someone in here may want it and be willing to "go the distance" with any needed repairs. The megabomb will greatly lower the sound level emissions from any FMF slipon as well as add biggy power as described above..

 

O.k!! thanks for the quick replies! My thoughts are this:...
S10, that is indeed a very generous offer! I thank you, and will PM you. In regards to airbox and sea level, I would like to keep it lidless, and I live and ride locally at 235 ft, and rarely would go above 1000. If I got ballsy there are a few passes to head east as high as 4800.
Looking at the carb while it is apart, is a good idea. I will do that. Am I correct that I won't be messing with the diaphragm by taking just the bowl off? It will take a few days as my garage is under construction.
Klxster, in regards to that header, my thought is, if I had a stock one to use, I could take my time and see what I could get done on repairing it. If I could get it fixed, would cutting the bottle neck off the DG and just extending it to mate to the bell on the FMF be a bad idea? (without the bottleneck the DG looks like it would mate perfectly with the megabomb)


E.T.A...I didn't know if that valve was normal looking, but included it just in case that was a "bad sign"

 

The internal diameter of the DG midpipe is smaller than the FMF's midpipes.. You can verify this yourself - the FMF midpipe is "same material" as the megabomb and is same size to the megabomb "piping" just in front of the megabombs' bell. That Megabomb bell is barely identifiable as the wall thickness of the FMF stuff is "thin".. When you mate FMF to FMF, there is no "neck down" at all, at the slip joint - no impediment to gas flow at all..
You'll see that rigging up the DG to the Megabomb will still create mismatched I.D.'s - and in this case(header larger than midpipe), the mismatch is counter productive..

Just to be clear, counter productive means, IIRC, you loose power everywhere compared to stock header + DG.. Don't ask how I know..

 

You are correct on the diaphragm. Removing the bowl will not bother it one bit.

 

Hi guys.... In the time since last posting, I have received that stock header from s10gto (THANK YOU!!), and just now, following advice, twisted the carb to access the bowl without removing the entire carb. My smaller jet is 35(with a little star pattern), and the big one is stamped 132. I haven't cross referenced that with anything yet as far as educating myself, just pulled them and am posting up now.
Any input is, as always, appreciated. And tonight I will be reading up on related posts. Thanks!!

 

With your current mods, for max power, near sea level, you'll need a DJ140 or K152 main jet, a DJ needle, and #40 pilot jet. You can find all the information about such items in here..

You probably already have a DJ needle in your CVK. It will need to have the clip moved to the top notch (1N) and the two DJ washers super glued on top of the clip..

Add in the other items, pull the airbox lid, and feel the goodness...

 

If you still have that pipe I'd do the following

• Get a piece of 3/4" steel galvanized or black pipe clamped up tight in a bench vise
• Get a propane torch
• Get a ball peen hammer and maybe a small sheet metal body hammer
• Slide the end of the header on the steel pipe and hammer on it a bit to start to take out the crimp
• Heat the crimped area up some to make it a bit more malleable for working the area out round again.
• Carefully work the end back out round trying to be careful not to stretch the metal making the diameter bigger. The reason for gentle hammering versus whailing the snot out of it.
• then when good, do what was said, get a 1.5" ID piece of tubing welded on to make the pipe slide on the muffler or weld the sleeve on the muffler to slide on the header.

This description is actually more complicated sounding than the work actually is. It is what I've had to do to round out flattened expansion chambers in the two stroke off roading days.

Besides you already have the head pipe so it's not costing anything to play.

One other thought too. If you can get it out fairly close to round you might be able to have a muffler shop flair it to the needed size to go over the muffler (or vice versa).

And final possibility that will work... Measure how long a piece you need, get a piece of tubing that long and the right size for the slip fit, cut the bad part out of the header and weld on the step up slip fit sleeve.

May as well try, better than having the thing hanging in the rafters for ever. And it's always fun to try to fix things you didn't screw up yourself, while throwing curses on those foolish enough to try that sort of rigging. Then you can either use it or sell it on ebay for a bit of gain.