FMF Megamax II- help!

I just brought home an FMF megamax II spark arrestor muffler for my 99 WR. The parts manager made me an offer I couldn't refuse- $190.00 + tax. Well, I got it home and it doesn't seem to fit with the stock header. The header diameter is a little too small and it doesn't fit into the little sleeve in the muffler pipe. Since that doesn't fit, the whole thing doesn't slide forwrd all the way for all the mounting brackets to line up with the holes in the frame- about 1/4" off.

I know some of you out there have used this pipe with the stock header. How did you do it. Any help would be appreciated.


Rich Bumar

The complete Mega Max II exhaust tail section system in its origonal box comes complete with:

1) A quiet core

2) sleve to be used with FMF headers

3) a second sleve to be used with the stock header. The two sleves are of different thickness.

4) a excellent clamp

5) Rear mounting band and bolt

5) FMF Stickers

6) complete instrucions

You should have gotten all of the above. Sound like you did not get the sleve to go with the stock header. Rag on your dealer or call FMF and get one.


Clark, was is your opinion of the Megamax II pipe? How does it compare to the uncorked stock at low, mid, and top-end? How about sound levels. Can the pipe be quite a bit quieter than an uncorked stock pipe with similar performance?

I bought Clark's megamax II and header and I'm going to install it in a week or two. At the same time, I'm going to switch to yz timing. I have a canadian model 99 street legal so noise is important. By the way, here the dvp needle is back-order for the moment. I'm waiting for it to install the pipe and convert to yz timing. When I'll finish the installation, I'll post my impression but I'm not use yet to the power of that bike so comparision is hard to do.

Well, I went ahead and installed the pipe. I had to use a hacksaw and cut off about a half inch of the stock header to get it to line up right. All I had to do was align the stock header pipe properly and there were no problems.

It has completely transformed the way the bike rides. Since I bought the bike used, I got it as-is. That meant that there was no stock exhaust baffle and no packing inside the muffler- basically an open pipe. Very loud and there was no bottom end at all. It rode like a two stroke (rev it up and feather the clutch.) It's not like that anymore. I pretty much leave the clutch alone now. Just put it in gear and roll on the throttle. The powerband has basically moved lower down in the rev range, so there is much more low and midrange power/torque in comparison to the open pipe. I also noticed that I want to upshift more often to keep the revs lower in the meat of the powerband. I road some high speed fire roads and the top end power doesn't seem to be lacking either. It is so much more enjoyable to ride.

The added bonus is that with 8 plates and the quiet core insert, it is very quiet. No rejetting was required. Bottom line-- I like it!

[This message has been edited by Rich in Orlando (edited 06-04-2000).]

Is 8 disks with the quiet pipe quieter than the stock pipe with baffle in?

I can't say whether it's quieter than stock, since my bike came with no baffle and no packing inside the muffler.

Which brings up a question I have had: What's inside a stock muffler?

I bought mine used and it came with, basically, an open pipe with a spark arrestor, and no baffle. I tried to buy a stock baffle just to find a cheap noise fix, but my local dealer told me that Yamaha only sells the entire exhaust pipe as a unit, which would cost $469. (Not worth it in my opinon.)

Does the stock muffler have any packing or baffles inside it, other than the removable baffle in the tailpipe?

I installed my megamax yesterday with 6 disk and the quiet core. the pipe is just a little bit louder than the stock canadian pipe. Inside the canadian stock pipe, there is just baffles and no packing (no maintenance is this way). I was surprised to see that both the megamax and the canadian stock pipe are around the same weight. By hand I cannot say which one is heavyer and this is the same thing for the headers (stock and fmf one). In any case, the pipe transformed the lawmover noise is strong but quiet noise and I love that!

I was surprised to have the front wheel in the air in second gear (geared 16/45 with street tire) without trying to raise it!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now