Jump to content
Sign in to follow this  

DRZ headers?

Recommended Posts

I'm looking for more low to midrange torque but want to keep my '02 DRZ400s quiet so will stay with stock muffler for now. I like to be able to leave the camp site early without pissing every non biker off plus it's easier to sneak up on things. Question is, will the larger diameter header such as FMF make any difference and is there anything to be gained with powerbomb vs non? Is the powerbomb worth more money power wise or sound wise? I've already done 3x3 and Dynojet, good mod and noticeable and seems to run cooler in side by side comparo with buddies stock DRZ. (judging by fan on & off time). Would like more low to mid power so I don't have to be up in the rpms as much when just trailing..Mark

Share this post


Link to post
Share on other sites

Well gears will help a little but I did notice a huge difference with the powerbomb.... :thumbsup:

Not that much louder either.

Share this post


Link to post
Share on other sites

Kman, when you say powerbomb do you mean the complete FMF system? I suppose that's what Q2 means? with quiet core? I don't want to shift power range any higher just enhance what's there, especially low to mid. Got to be quiet so I can go fast without attracting attention, Mark

Share this post


Link to post
Share on other sites

The complete FMF is what I have, Powerbomb and Q2. I love it. I too need to not attract attention. Assuming you ride off road like I do, 99% where you are not supposed to, it is a good choice and it was an amazing change in bottom end.

It cost $$$$ but I think it was worth it.

Obviously if you ride in 2nd WOT there is not too much you can do but attract attention....

Share this post


Link to post
Share on other sites

True and my yellow is hard to hide anyway but I like the better bottom end yu report, Muzzy pipes got a good write up here but I don't know about their decibel output, maybe someone with one will add something. I do need to keep it quiet though.

Share this post


Link to post
Share on other sites

If you need it quiet you will have to stay with the stock system.

The FMF PowerBomb header will fit, but you will need to make or buy a non standard size gasket for the mid pipe join.

I found the FMF header to be a good move, it gave a good improvement to lower and mid range power and throttle response.

It did however need re-jetting, for me at least.

Neil. :thumbsup::ride::applause:

Share this post


Link to post
Share on other sites

Neil,

Elaborate a little more on using the header and stock s can.

I would like more bottom without the noise.

Shawn.

Share this post


Link to post
Share on other sites

Neil,

Sorry one more question what did you have to jet to?

I am at 1000 feet and have the 3x3 with burneds jetting.

Share this post


Link to post
Share on other sites

Jetting worked out to Eddie's spec's accept for the main, I ended up with the 142.5 with a stock silencer, (and the stock pilot jet, but that is a UK thing)

That may not apply to the US spec S silencer, don't know, never seen one.

The FMF header is the same OD as the E header, but thinner gauge tube.

The S silencer is a smaller ID than the E (but still bigger than the FMF header), so you need to make or buy a spacer to suit.

I made mine from alloy tube, just skimmed to fit, on a lathe, and sealed with silicone.

If you do a search all the dimensions have been listed, but from memory, the FMF header is 42 or 43 mm diameter. (can't remember, had a glass or two of wine)

Neil. :thumbsup::ride::applause:

EDIT: FMF Header is 41mm O/D, just did a search.

Share this post


Link to post
Share on other sites

Neil,

Thanks, so all that I have to do is turn a piece of Al or SS to the ID, OD of the pipes and I am good to ride.

Simple 15 minute job on a lathe.

Thanks for the quick answer and have an extra glass for me.

Shawn

Share this post


Link to post
Share on other sites

camster- i just got done doing the total muzzy, 3x3, and jetting and was surprised at the noise level- if you wind it out it's louder but i think actually quieter at lower rpms and i don't have the quiet core. just my experience.

Share this post


Link to post
Share on other sites

Thanks for input, may have to look into either FMF or Muzzy and see if I can add or delete the quiet core version at will.. I just pulled the muffler to see what midpipe seal looked like, it's a cylindrical graphite feeling thing, rather slippery to the touch. Probably could open one up without to much trouble for the SS powerbomb header. Just wondering if the powerbomb actually does anything measureable besides increase the price over the non powerbomb...anyone know for sure? I believe price jumps from $150 to $250 just for the powerbomb header. May as well spring for whole system at that point...hmmm have to think about it...Mark

Share this post


Link to post
Share on other sites
Neil,

Thanks, so all that I have to do is turn a piece of Al or SS to the ID, OD of the pipes and I am good to ride.

Simple 15 minute job on a lathe.

Thanks for the quick answer and have an extra glass for me.

Shawn

Thanks, I had a few extra glasses, but I have just done a forum search, and it seems the FMF is 41mm O/D.

So it is still just a spacer needed.

Neil. :thumbsup::ride::applause:

Share this post


Link to post
Share on other sites
Thanks for input, may have to look into either FMF or Muzzy and see if I can add or delete the quiet core version at will.. I just pulled the muffler to see what midpipe seal looked like, it's a cylindrical graphite feeling thing, rather slippery to the touch. Probably could open one up without to much trouble for the SS powerbomb header. Just wondering if the powerbomb actually does anything measureable besides increase the price over the non powerbomb...anyone know for sure? I believe price jumps from $150 to $250 just for the powerbomb header. May as well spring for whole system at that point...hmmm have to think about it...Mark

You might as well buy a stock 'E header rather than go with the powerbomb. They are basically the same size.

You won't see much if any performance increase until you go with either the Yosh or Muzzy full system.

Grant

Share this post


Link to post
Share on other sites

1. If you want to maximize your low end, you may as well stay with the stock header. The curve and smaller diameter reduce topend but maximize low end.

2. Don't think you are going to increase the ID of that seal. It looks like it could be easy but it is more like an aluminum/graphite composite with a wire mesh entwined inside of it. If you try to modify, it will be wrecked. I had to make a new seal for the change I made.

Share this post


Link to post
Share on other sites
1. If you want to maximize your low end, you may as well stay with the stock header. The curve and smaller diameter reduce topend but maximize low end.

And you have tried the FMF PowerBomb header on an S silencer to prove this, yes ??? I think not !!!!

I have, and it works well, makes a bigger difference than a slip on.

I now use the FMF and a UK spec E silencer from preference, better than any other I have tried.

Neil.

:thumbsup::ride::applause:

Share this post


Link to post
Share on other sites

Yes, normally I also would have thought that the smaller header would make better low end but from being on this forum I will have to lean towards the experience of the members here. I beleive Eddie S. said the S header was one of its biggest restrictors. Sounds like either a full sys. or perhaps Neils route is best option for a little more power and quiet.

Thanks for input on seal Stu35, I looked closer at seal and you're right about possible difficulty in modding, does the E model exhaust use a similar seal? Mark

Share this post


Link to post
Share on other sites

I have an complete E pipe on my S. IMHO, I think it improved my lowend torque, it seems smoother at low rpm's and less inclined to get "bucky" when I accelerate from those low rpm's. I don't really run high rpms except at 75 to 80mph on the highway. That's as high as the rpms go for me.

BTW, for comparison, the S head pipe fits inside the E head pipe and can. The E pipe would not fit into the S can without modification to the gasket and the gasket is fragile and breaks apart easily. I considered using the aluminum from a soda can to wrap around the E pipe. After pulling the stock gasket material from the inside of a S can, something will need to be added to seal the E pipe to the S can. I just used the E can but then you need to modify for the mid mount by the foot pegs.

Share this post


Link to post
Share on other sites

this talk of long headers and low rpm power may have something to do with a post I made a while ago and I feel I should add a bit.

In theory, long, small diameter headers favour low rpm power and short, large diam headers favour high rpm power. This is a general truth of flow dynamics and wave energy bouncing around in the pipe. Add in the variables of port size and shape and cam timing and mid-pipe length and and muffler restriction and you have enough to mess up the generalization.

I find that big, short headers work well on the drz and the difference between them and long small headers is not significant, and for some, maybe not even noticable. Any major reduction in back pressure is going to make the engine breathe so much better at any rpm that there will be a major gain.

The bomb in the fmf is a resonance chamber with a bit of a function as a pre-muffler. It should work well when new and clean but I doubt it works well enough to show up as more than a small hiccup on a torque graph around 8000rpm (judging by its distance from the valve face)

I dont know how restrictive the stock S header is. It is small and a full system really makes a difference. The general wisdom of this site is that the stock S header is the main restriction in the system so slip-ons are a waste of money. I remember reading a magazine article when the drz came out and they tested several bikes as they would be run (might have been dirt rider-for shame!) so they had aftermarket systems or slip-ons. The drz E lost power with a slip-on and only gained over stock with a full system when the insert was removed:stock was the best set-up for power/noise.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

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

Reply with:

Sign in to follow this  

×