What 2 Stroke pipe has the best top end power

[Kesler Seifert]

I have a 2005 cr125r and the top end power is lacking for sure, I love the way the bottom end power is but I could definitely use some more top end. I’m just wondering what pipe would do that for me without taking a lot of the bottom end power, I’d like to buy an exhaust before gearing and jetting it. 

[GreenHills]

I'd gear and jet a bike WAY before i tried to buy a pipe to make more power.

You also very rarely more power across the board, more top end = less bottom end, and vice versa.

As for the best? it's probably something along the lines of a Scalvini pipe.

[ThePit]

Jetting it isn't a one time thing, an action to be scheduled before or after this or that, it is an ongoing passion.

Go order some brass and start jetting now, get it from rmatv or motosports OEM parts section, jets aren't expensive and you want to know they're exactly right.

[mlatour]

Aside from jetting, if you feel a lack in top end;

-make sure the power valves are operating correctly

-check for worn / damaged reeds (ideally avoid all-fiberglass ones in a 125)

-check for any restriction in the intake/exhaust tracts (including an over-oiled air filter)

-confirm the ignition timing is set correctly

-don't run a 'Shorty' silencer

-if you've milled the cylinder head and/or, are running a thinner base gasket etc.

  anything that could have considerably increased compression,

  that will improve low end but sign off sooner on top.

 

If you really want to have a crisp running 125 engine all the time, fine-tuning the jetting is almost a daily task.

Just a 10° change in ambient temperature will require a bit of tuning for it to run optimally.

 

Edited June 8, 2022 by mlatour

[69fastback]

How long ago was the last piston?

[CR250-2007]

Any pipe that gives you a noticeable increase in top end will sacrifice low end.

[Woodzi]

What is confusing me is how anyone could think an 05 CR125 has good bottom end power. That certainly was never their claim to fame. 

If its a pipe you want, most (probably all) aftermarket pipes for a 125 are tuned for high end power. Probably splitting hairs between the popular brands. 

If your current pipe has large dents, then you might notice a significant improvement.

 

[flat lobes]

11 hours ago, Kesler Seifert said:

I have a 2005 cr125r and the top end power is lacking for sure, I love the way the bottom end power is but I could definitely use some more top end. I’m just wondering what pipe would do that for me without taking a lot of the bottom end power, I’d like to buy an exhaust before gearing and jetting it. 

Get a low end torque grunt pipe to help pull faster gearing. keep the motor in the mid range power. 

[UG_ALLSTAR]

PC platinum is the expansion chamber of choice

FMF/PC/Scalvini works are all racing expansion chambers

FMF Gnarly caters to bottom end.

[mlatour]

The FMF Gnarly has never been offered for any 125 so the OP definitely doesn't have that option.

While it wasn't the case before, with the advent of the YZ125X, FMF might have a market for one if there was enough demand.

[Kesler Seifert]

4 hours ago, 69fastback said:

How long ago was the last piston?

I just got done breaking it in

[Kesler Seifert]

3 hours ago, Woodzi said:

What is confusing me is how anyone could think an 05 CR125 has good bottom end power. That certainly was never their claim to fame. 

If its a pipe you want, most (probably all) aftermarket pipes for a 125 are tuned for high end power. Probably splitting hairs between the popular brands. 

If your current pipe has large dents, then you might notice a significant improvement.

 

It’s not that it has “good” or “bad” bottom end power it just has a nice amount of pull that I enjoy and I’d like to get more top end power without changing the bottom end

 

[Kesler Seifert]

1 hour ago, UG_ALLSTAR said:

PC platinum is the expansion chamber of choice

FMF/PC/Scalvini works are all racing expansion chambers

FMF Gnarly caters to bottom end.

What I was looking at getting was the gold series fatty with the shorty muffler but I haven’t really looked into pc pipes, what makes it so good. 

[Kesler Seifert]

7 hours ago, GreenHills said:

I'd gear and jet a bike WAY before i tried to buy a pipe to make more power.

You also very rarely more power across the board, more top end = less bottom end, and vice versa.

As for the best? it's probably something along the lines of a Scalvini pipe.

I’ve heard the benifits of fmf and pc, but what do scalvini pipes benefit?

[UG_ALLSTAR]

19 hours ago, Kesler Seifert said:

What I was looking at getting was the gold series fatty with the shorty muffler but I haven’t really looked into pc pipes, what makes it so good. 

PC's are known for their top end. You could do a quick google and most will agree that the PC has stronger over-rev

FMF's are great, the fatty is more of an all-around expansion chamber. More of a stock feel.

 

Neither is going to add much without the silencer and proper jetting to open up the top end. The 304 or powercore are good mates to their expansion chambers.

 

Really it all comes down to personal preference. Both systems are better than stock and will make your bike ooze with style. 

[Kesler Seifert]

2 hours ago, UG_ALLSTAR said:

PC's are known for their top end. You could do a quick google and most will agree that the PC has stronger over-rev

FMF's are great, the fatty is more of an all-around expansion chamber. More of a stock feel.

 

Neither is going to add much without the silencer and proper jetting to open up the top end. The 304 or powercore are good mates to their expansion chambers.

 

Really it all comes down to personal preference. Both systems are better than stock and will make your bike ooze with style. 

Thank you for the feedback I’ll look into pc pipes now