So I'm about to install my FMF Q4 and Mega-bomb header this weekend. When I looked at the directions, I have a few questions I'd love some help on before I dig in.

1. I was not clear on whether or not there is a slip in insert at the exhaust port end of the header, or just pull the old one off, bolt the new one on? Seems like maybe spring versions have it, other's dont? But I'm not sure how a good seal happens on that end.

2. Should I use some kind of sealer at the exhaust port end regardless and if so what?

3. I know I should use a high-temp silicone for the joint between header and actual muffler to avoid leaks. I bought the highest temp my local automotive store had which was a flexible high temp copper stuff. Does anyone know what range of temp is required here?

4. I'm swapping my main jet and planning to start at a 130, but keeping my stock pilot. Will I need to back off the pilot screw to get it to start and begin testing my tuning? It seems to be that I would need to open it up at least a little but then maybe at idle there's not much difference?

5. I wanted to order the nifty Kouba Screw for my pilot, but it looked like they required a bulk order? Any one know how to get just one?

(For reference, at this moment, I'm planning on keeping my box lid on, my screen intact, and my snorkle cut significantly, but still in place.)

Any tips or suggestions for the install are welcome (like easy carb removal techniques and how many turns out to start at. If I can get my camera back from repair I'll document the process, hopefully it comes back before then.

 

1.
There Should be a copper gasket between the header and engine. When I had mine off I annealed it before re-using it.
2
just the copper gasket
3
not sure of the temp range but the permatex stuff I have used is a copper hi temp silicone
4
Can't remember but mine is at 2.5 turns out.
5
No bulk order reqired on the Kouba screw. min order of $25 is all. So instead of paying $20 for one screw, you pay $25. If you have a buddy that wants one, you can get 2 of them for $40. Mine just came the other day (cost me $25 because I only bought one)
Dan

 

I was looking for a little help too! I only bought the slip on and it does look like it will make the long stretch. Does this mean I have to loosen up the header? I think I'm answering my own question while saying it out loud. But... Its weird that doesn't even come close to fitting, It is an Q4 FMF pipe. It looks like the pipe actually fits over the head pipe. Do, I have the wrong size pipe? I will keep searching and hopefully I will find something. If any body knows let me know! Thanks much!

 

Do a search on this and I believe you will find that the pipe is designed for a bigger header so you might need an adapter or different header? As I recall though, the pics I've seen of just a slip on show the pipe going over the header. Hope we both get it right on the first try!

 

Looks like Dan answered all your questions. But I'm wondering why are you not allowing more air into the engine by at least removing the snorkle. You will be opening up the exhaust, but keeping the stock snorkle will continue to limit the amount of air flowing into the engine. Even if you trimmed the stock snorkle, it still has that small opening where it passes through the airbox lid.

 

The FMF fits over the stock header and needs a sealant. I used Permatex muffler and tailpipe sealer. One word of caution if you haven't seen this, you will have to bend out the guard at the right side passenger foot peg. You can use a hammer handle as a pry bar and it won't scratch the paint. I also noticed this past weekend that the FMF pipe was extremely close to the air box. I'm talking about 1000th of an inch and may have melted the air box some. Has anyone noticed that on theirs.

 

Hey jackson, how big is the openning on your header? The slip on I have is 1 3/4".

 

Just thought I would give an update! I ordered a klx300 header from four stroke works. Hope it works! I'm at 700 ft elev. I'm removing the screen and the complete lid. So, with that being done and a complete klx300 aftermarket does anyone think a 132 jet is too much? Should I start with the 128? Also tips for getting the carb off. I think I'm going to have to take the gas tank off. Is this correct? I'm also keeping the stock pilot jet. Any input would be appreciated!!!

 

That's pretty large compared to mine. My megabomb header is 1.5" OD at the slip on end, my Q4 slips tightly inside of that (it's narrowed to slip inside). To fit 1 3/4 I think you'd need some kind of adapter.

Based on what you're saying I think you may have the wrong pipe for this bike (or I do and just haven't found out cuz weather is not cooperating with my install plans). The part numbers on mine are as follows
Header: 042251
Exhaust: 042156 (stamped very lightly on the pipe, it's the last of the string, I believe first four digits and slashes are production date eg 10/09/042156

Seen herehttp://www.fmfracing.com/Products/MX/380

I measured from the most forward tip of the most forward mounting bracket (the narrow steel one) to the farthest away point of the slip in pipe and it was 10" on mine and as per the link part number on mine is what they recommend.

 

Acehol, Check this link. It helped me. https://www.kawasakiforums.com/forum...lx250s+exhaust