exhaust pipes

[Rcannon]

I have been wondering what the various exhaust systems do. It is easy to buy into the ad hype and hope they do what they say.

To make a long story short , I ended up trying aStock system, Pro Circuit pipe, an FMF Gnarly, and an FMF fatty on my YZ 250.

The differences between all the pipes are very slight. The Pro Circuit and stock systems fit really well. The fmf pipes do not fit quite as well.
I wish I could tell you the performance differences, but there is nothing worth mentioning. The gnarly MIGHT have a tiny bit more low end, but not 199.00 dollars worth.

I setteled on the gnarly pipe because it is the easiest puipe to deal with. Some of the others did not gie enough clearance around th eoil filler hole. As you know, the 1997 YZ's had the filler cap designed by someone with a serious drug/alcohol problem.

My honest opinion is to save your money until the stock pipe gets smashed. Then buy whatever aftermarket pipe is cheaper.

None of them change power characteristics as much as a flywheel weight kit.

 

[KLRay]

Thanks for the info! I was thinking about getting the Gnarly for my 03 YZ but I think I'll wait till the old one's shot now.
Where'd you get the flywheel weight and is it hard to install?

 

[Rcannon]

I used the zip-typ flywheel weight kit. Installation is not a big deal. You do need a flywheel puller.

Other than drilling and tapping some holes, no problem.

 

[KLRay]

Thanks, again!

 

[jmics19067]

good post, I have been meaning to try out that experiment myself on my 94 yz. you have basicly concluded what I suspected and what most of the knowledgable people on this site reiterate, modern stock pipes work pretty darn good and the big aftermarket pipe manufactures are mostly advertising hype. ATleast the mass produced ones they put off to market.

they are a great alternative to a smashed stocker but you will get better returns from a ported engine from a good builder and keeping the bike well maintained and fresh.

heard that more than once in here and I am not surprised in that you found that out to be true

 

[RM_guy]

All a pipe can do is shift the power around. I have said for a while now that if you want better power, get it ported. Eric's prices are way cheaper and a pipe anyway.

 

[Rcannon]

The porting would have been a much better value. The only thing I found more useless than the pipes was a reed spacer. It hurt throttle response, and added virtually nothing anywhere else.

I will probably have eric port my cylindr as soon as I decide what it is that I need and what I want.

I was lucky to be able to try this for very little money. A friend that owns a shop let me have these pipes for very little money. I can get most of it back selling them on ebay.

I think people buy pipes and are embarrased to have to say..."It did nothing."

 

[marcusgunby]

Some bikes respond well to pipes and others dont-the 01 Cr125 is one that doesnt.

 

[jmics19067]

I think people buy pipes and are embarrased to have to say..."It did nothing."

well in all actuality for me anyway everytime I bought a pipe it was a great improvement ....... but then again the stock exhaust system from a '38 Packard is probably better than the waffled accordians that usually adorn my bike. :eek:

 

[jirvine]

Originally posted by marcusgunby
Some bikes respond well to pipes and others dont-the 01 Cr125 is one that doesnt.

The KDX is one that really benefits, whole lot more revs and power with the PC on it.

 

[Rcannon]

jirvine, I understand what your saying about the KDX. I agree that the stock pipe on that bike is pretty restrictive.

I wonder how the aftermarket gets off claiming all these improvements on the MX bikes?

 

[Studboy]

Originally posted by Rcannon


I wonder how the aftermarket gets off claiming all these improvements on the MX bikes?

Well,  they've gotta make a living too!!! Even if it is off of that 0.3 HP increase between 6200-6500 RPM's which in pipe ad talk means:   DRAMATIC MIDRANGE IMPROVEMENT!!!  :debil:

Pipes can be a good thing if you know what you are looking to get from them.

 

[anderstj]

I added an fmf desert gnarly (top end pipe) to my 03 kx 500 with a dynoport barker bigbore silencer. bumped compression by 2 points and had verner do the port work. the differance was quite noticeable, the power comes on later and and a lot harder. geared 1 tooth biger on the countershaft. my bike is bordering on obnoxious in power delevery dept. after the mods. prior to that i used a procircuit pipe and it sucked! i beleive that is is designed to slow this beautiful bike down. this setup is not for everone especialy if you are using your kx5 for a woods bike, great on long out door tracks and over any distance you need to shorten.
tom

 

[jmics19067]

I added an fmf desert gnarly (top end pipe) to my 03 kx 500 with a dynoport barker bigbore silencer. bumped compression by 2 points and had verner do the port work. the differance was quite noticeable,

If you did all these mods at once how do you know the effect the pipe itself had?

It would be very difficult to give a fair description of a specific pipe if the tuning of it was outside the perimeters of the tuning of a stock engine.

It would also be very ineffective to have massive amounts of engine work done if it fell outside the characteristics of a stock pipe.

to say that the pipe itself was effective is unreliable to most of the people looking to buy a pipe , to say that the combination of engine work plus pipe is awesome is different.
I am not sure how you mean about the pro circuit pipe. It is very possible that the PC pipe works very well for taming a stock 500 and yet sucked on your modified brute.

Did you try either pipe on a stocker or try the mods with a stock pipe?

Please excuse me for picking apart your statement. I do know and realize you said "this combination works great for me". Iam just curious if you have done any back to back testing with some type of a control or just stopped when you found a system that works for you.

 

[marcusgunby]

Some pipes add power, some move it and some loose power compared to std-its all bike and pipe dependant,what you want is power to suit your riding style-doesnt matter if its more or less as long as its suits you.

 

[anderstj]

jmics, the pc pipe was good on a stock motor but as you said sucked the life out of the mod motor, the stock pipe seemed slightly better on the mod motor than the pc and the fmf helped it all come together. that being said you are correct. without testing individual changes who is to say what the benifit is, as for me i have never seen the need to change the stock pipe on a stock 2 stroke, untill the motor gets hopped up or i bash the stocker to death. having said all of that, ill say this, for the money get port work, you reep more benifit per dollar spent, and you can have the power whare you want it. then get the craftsmen that ported the motor to recomend a pipe for his pice of work. this is a great websight!!! thanks for making me explane my previous statement, it was quite subjective.
thanks again
tom

 

[Lorin]

I agree mostly with the post above, especially on the newer bikes. FWIW, my 98 yz250 is using the stock pipe along with porting, delta valve, and different silencer. On the other hand, my wr 500 noticed differing gains from both FMF and PC pipes (over the stock one). The FMF helped power, along with freeing up the motor to rev a little faster. I then tried the pc pipe and was impressed even more. It seemed to allow the bike to rev considerably faster than the FMF did. It almost felt as though the bike had flywheel weight removed. That said, I see no reason to replace the stock pipe on my 98; it keeps the sound down (double-wall pipe) and still maintains a good spread of power. I did spend some judicious time with the jetting. I think proper jetting is responsible for more gains than most pipe swaps.

 

[jmics19067]

Good stuff!

 

[SpectraSVT]

A good way to decide which pipe would work best for a particular bike is try to find the dyno chart for the pipe and your bike. The FMF sst pipe for my bike claims huge gains everywhere but on the dyno you could see it almost mimicked the stock power band with a little gained here and a little lost there. BUT basically the same. Thats what helped my decision.