2005 Yamaha YZ-125 FMF or Pro Circuit pipe & silencer, which one should I buy?

wfo4ever
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wfo4ever
I am looking to buy a new or like new FMF or Pro Circuit pipe and silencer combo for my 2005 Yamaha YZ-125. I would appreciate any info, feedback, and reviews on these products. Also on the Pro Circuit pipe is there any difference between the works and platinum other than looks, and the same on the FMF Factory or Fat Boy. Thank you to the Vital community members for any help on this matter.
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kmp1219
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kmp1219 9/6/2016 4:57pm
9/6/2016 4:57pm
Both will be similar. For 99% of riders I would personally suggest the pro circuit. If you look at the past magazine comparisons, the PC has been a little bit snappier and responsive right when you twist the throttle, but the power falls off a little earlier than the FMF. If you really know how ride the 2 stroke like a pro I say the FMF. The best 2 stroke riders know how to carry momentum through every corner and work their way through the entire gearbox, so if this is you, then the FMF will have more even power distribution in my opinion.

Really can't go wrong with either, though. Most riders wouldn't be able to notice a difference. I'd go with whichever you can get a good deal on. For what it's worth, the pro circuit works pipe is tough to keep from rusting, I used to use one on my 80.
MXTIME144
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MXTIME144 9/6/2016 5:19pm
9/6/2016 5:19pm
Tried them both and Neither one ran that much better than stocker.
Both of the short silencers suck and have no rev. FMF finally figured out longer silencers equal more more top end.
I have an DEP for short tracks and bud racing HGS for the fast ones.
Running leo vince silencer.
Came to conclusion for me this worked.
Testing 5 different pipes and 4 different silencers in all combinations
Gave me the combination I prefer!

Good luck with your choice
Insider347
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Insider347 9/6/2016 5:51pm
9/6/2016 5:51pm
PC all the way and they have always been a must for me on 125s, including yamaha. My bikes never leave the dealer without the pipe and shorty bolted up. You may need to change jetting but no biggie.
zehn
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zehn 9/6/2016 6:07pm
9/6/2016 6:07pm Edited Date/Time 9/6/2016 6:08pm
MXTIME144 wrote:
Tried them both and Neither one ran that much better than stocker. Both of the short silencers suck and have no rev. FMF finally figured out...
Tried them both and Neither one ran that much better than stocker.
Both of the short silencers suck and have no rev. FMF finally figured out longer silencers equal more more top end.
I have an DEP for short tracks and bud racing HGS for the fast ones.
Running leo vince silencer.
Came to conclusion for me this worked.
Testing 5 different pipes and 4 different silencers in all combinations
Gave me the combination I prefer!

Good luck with your choice
Yeah my experience with PC and FMF pipes and silencers on both a 2005 and 2006 YZ125 was that neither was necessarily better than the stock pipe and silencer, just different. The PC pipes definitely have less rev-out to them. They kind of fall on their face after a certain point but give snappier power when you're just cracking the throttle if you like that.

The FMF combo does pull harder longer but you need to carry more momentum and keep the bike right in the sweet spot (obviously, we're talking about a 125 2T here).

Personally I go back and forth between the stock pipe and silencer and the FMF Factory pipe and Powercore silencer. Most of our tracks up here are very slick, hardpacked and rocky, so the PC just makes the bike harder to ride IMO.

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Derek Harris 9/6/2016 6:24pm
9/6/2016 6:24pm Edited Date/Time 9/6/2016 6:26pm
our dyno says the 2004 model pc pipe was better than fmf for 2004.

For the 2005 and up yz 125, the fmf looks identical on dyno as oem, the shorty fmf with proper end cap can add over rev and a little peak, the pc pipe looses bottom, mid and power at stock peak hp rpm, then gains past that rpm. The pc seems to have better throttle response than oem.
On high hp builds, I have had the pc silencer hold back the combo... but not always. just an oddity.

The hgs and dep both perform decent, nod to dep imho.

The pipes all dont do huge things in the hp department. If you judged all the pipes vs the oem pipe on all conditions, rpms, rider abilities, the oem
on the track wont rank best in any category but will always be top 3. on a cumulative average the oem would win. thats how the Oem pipe gets selected at the manufacturer.

On our 134,144 and 150 builds, the oem pipe looses big time to the fatty and hgs, i cant stand how the pc turns shortly out of cylinder... it doesnt perform as well on those builds for us, the 04 pc on the 05+ (doesnt fit properly) is extremely good.

the bills hasnt been in any recent tests for me, so no comment yet, but Bill is sharp and usually his stuff performs well. I really like the hgs on our big bores for price, fit and finish, and performance
chump6784
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chump6784 9/6/2016 6:30pm
9/6/2016 6:30pm
Here is a review from 2003, I am not sure if the 2003 engine is the same as the 2005 but it should give you an idea.
I have found fmf generally broaden the powerband where pro circuit seems a bit snappier.
As for works vs plated, if you wash the bike and spray some water repellent like wd40 or my favorite, inox, you will be all good with the works
http://www.dirtrider.com/tests/parts-accessories/141_0302_2003_two_stroke_exhaust_test
Jonesboys819_828 9/6/2016 6:33pm
9/6/2016 6:33pm
Stock pipe and PC304 shorty. Seems to be the sweet spot for me. If you want that factory look, get the stock pipe acid cleaned, then just blue the welds and use a high temp clear sealer. Works and looks great for cheap.
deltadestroyer11 9/6/2016 6:44pm
9/6/2016 6:44pm Edited Date/Time 9/6/2016 6:46pm
Pro-Circuit is what every pro rider chose when the two strokes ruled..The guy that said FMF is more top end than pc got that one backwards.Pro Circuit has always been the go to pipe for pro's wanting a long drawed out potent topend pull..And FMF didn't figure out long silencers made more top end power...the average local racer knew that a long time ago..I'd still mate the the pc pipe with the shirty silencer...til make that 125 very snappy with instantaneous throttle response..
I had the works pro Circuit and shorty on my Kx250 and that pipe made my bike rock..And cleaning it just takes a ill WD 40 with a scotch brite every two or three weeks...very easy..
Radical
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Radical 9/6/2016 7:25pm
9/6/2016 7:25pm
The FMF SST is supposed to scream out an extra 500 RPMs, but I believe it's harder on the engine and must be jetted properly or it'll damage the engine. If I remember right many people have said that FMF's recommendation to go leaner on the jetting is wrong and you'll fry the top end. You need to go richer.
If you do go for it and get the jetting right, it's supposed to be the best pipe out there for a 125.

I bought one on Craigslist and haven't tried it yet. When I can ride in the power band all of the time with the stock pipe, I'll install it.
MotoX85
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MotoX85 9/7/2016 1:23am
9/7/2016 1:23am
FMF fatty if you are looking for bottom end. FMF SST if you are looking for mid to top. Pro Circuit if you are looking for mid to top

95% of YZ125 owners get the FMF fatty, it is also the same as the GYTR pipe which is a fatty with a GYTR logo on it
Question
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Question 9/7/2016 3:42am
9/7/2016 3:42am Edited Date/Time 9/7/2016 3:43am
Derek Harris wrote:
our dyno says the 2004 model pc pipe was better than fmf for 2004. For the 2005 and up yz 125, the fmf looks identical on...
our dyno says the 2004 model pc pipe was better than fmf for 2004.

For the 2005 and up yz 125, the fmf looks identical on dyno as oem, the shorty fmf with proper end cap can add over rev and a little peak, the pc pipe looses bottom, mid and power at stock peak hp rpm, then gains past that rpm. The pc seems to have better throttle response than oem.
On high hp builds, I have had the pc silencer hold back the combo... but not always. just an oddity.

The hgs and dep both perform decent, nod to dep imho.

The pipes all dont do huge things in the hp department. If you judged all the pipes vs the oem pipe on all conditions, rpms, rider abilities, the oem
on the track wont rank best in any category but will always be top 3. on a cumulative average the oem would win. thats how the Oem pipe gets selected at the manufacturer.

On our 134,144 and 150 builds, the oem pipe looses big time to the fatty and hgs, i cant stand how the pc turns shortly out of cylinder... it doesnt perform as well on those builds for us, the 04 pc on the 05+ (doesnt fit properly) is extremely good.

the bills hasnt been in any recent tests for me, so no comment yet, but Bill is sharp and usually his stuff performs well. I really like the hgs on our big bores for price, fit and finish, and performance
These dynos charts on your profile pic are impressive, just 1 thing I dont understand, what do you mean by long rod, 134 or still 125 ?
chump6784
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chump6784 9/7/2016 3:43am
9/7/2016 3:43am
Someone above suggested the stock pipe with shorty silencer, this is a pretty popular set up as the stock pipe is pretty good and the shorty gives it a bit more snap. If you sill want the works look just hit the stocker with a wire brush attachment on an angle grinder. Here is my yz250 pipe



Frodad78
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Frodad78 9/7/2016 8:36am
9/7/2016 8:36am
I'll add that I use the stock pipe and PC shorty for trails and sand.

I use the PC pipe and shorty for Moto.

I'd like to experiment with cutting a little off the stock silencer so I can pick up a little more top end, but I'm not sure how much to take off.

I've read that the R304 silencer is a nice compromise between the shorty and the stocker.
Missing_Muffs 9/7/2016 9:14am
9/7/2016 9:14am
chump6784 wrote:
Someone above suggested the stock pipe with shorty silencer, this is a pretty popular set up as the stock pipe is pretty good and the shorty...
Someone above suggested the stock pipe with shorty silencer, this is a pretty popular set up as the stock pipe is pretty good and the shorty gives it a bit more snap. If you sill want the works look just hit the stocker with a wire brush attachment on an angle grinder. Here is my yz250 pipe



I second that works look stock pipe! just did that a kx250. only I'm lazy and took it to a sand blaster and it was done in 3 minutes and only cost $10.

once you get some time on the pipe it starts to get the nice colors on it.
plus it doesn't make you hurt inside when you get a dent in it because it didn't cost you anything.

Derek Harris 9/7/2016 11:14am
9/7/2016 11:14am
Derek Harris wrote:
our dyno says the 2004 model pc pipe was better than fmf for 2004. For the 2005 and up yz 125, the fmf looks identical on...
our dyno says the 2004 model pc pipe was better than fmf for 2004.

For the 2005 and up yz 125, the fmf looks identical on dyno as oem, the shorty fmf with proper end cap can add over rev and a little peak, the pc pipe looses bottom, mid and power at stock peak hp rpm, then gains past that rpm. The pc seems to have better throttle response than oem.
On high hp builds, I have had the pc silencer hold back the combo... but not always. just an oddity.

The hgs and dep both perform decent, nod to dep imho.

The pipes all dont do huge things in the hp department. If you judged all the pipes vs the oem pipe on all conditions, rpms, rider abilities, the oem
on the track wont rank best in any category but will always be top 3. on a cumulative average the oem would win. thats how the Oem pipe gets selected at the manufacturer.

On our 134,144 and 150 builds, the oem pipe looses big time to the fatty and hgs, i cant stand how the pc turns shortly out of cylinder... it doesnt perform as well on those builds for us, the 04 pc on the 05+ (doesnt fit properly) is extremely good.

the bills hasnt been in any recent tests for me, so no comment yet, but Bill is sharp and usually his stuff performs well. I really like the hgs on our big bores for price, fit and finish, and performance
Question wrote:
These dynos charts on your profile pic are impressive, just 1 thing I dont understand, what do you mean by long rod, 134 or still 125...
These dynos charts on your profile pic are impressive, just 1 thing I dont understand, what do you mean by long rod, 134 or still 125 ?
we build a version of the yz that uses a longer rod.

It applies to a 125, 134, 144, or any other combo. its just a longer connecting rod, doesnt change displacment. our long rod 125 cc bike holeshot mammoth in 125 schoolboy both motos a couple years back. now our non lon long rod matches our long rod... so no real point to it
dedi684
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dedi684 9/7/2016 11:26am
9/7/2016 11:26am
Frodad78 wrote:
I'll add that I use the stock pipe and PC shorty for trails and sand. I use the PC pipe and shorty for Moto. I'd like...
I'll add that I use the stock pipe and PC shorty for trails and sand.

I use the PC pipe and shorty for Moto.

I'd like to experiment with cutting a little off the stock silencer so I can pick up a little more top end, but I'm not sure how much to take off.

I've read that the R304 silencer is a nice compromise between the shorty and the stocker.
I added a normal length fmf instead of the usual shorty's i have always run. Im pretty happy i threw an 11oz flywheel weight as ive only used a 9oz or stock on my other 4 yz 250's lve had.
wfo4ever
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wfo4ever 9/7/2016 1:38pm
9/7/2016 1:38pm
Thanks for all the info everyone, it is very helpful. Any suggestions on getting the cylinder ported and the head done also?

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