Bottom end increase for YZ250?

Looking to get some more power off the bottom, but without losing any power up top....

I find myself really struggling to find power in lower speed corners and already geared the bike taller (52R) so I just need a little boost at the bottom. Anyone have any recommendations? Thanks.

Good luck, other than porting or a FWW it will be tough to find power down low without losing a little up top.

If you just need a tad more try a shorty silencer. I run a shorty on my 250 and it gave me just enough bottom without causing the bike to suffer at all up top.

FMF Gnarly pipe FTW! If it does take a away from up top, its very minimal and I don't notice it. After riding my brothers stock yz250 this past week I couldn't believe how on off the power band is. The gnarly pipe gives its torque from the very bottom, makes hill climbing, putting around in higher gears and going slow much easier. I find the power delivery similiar to my friends yz450f actually. My bro was riding my bike while I rode his, he is now currently in the market for a gnarly pipe :smirk: I've heard good things about the FWW too, specifically in steahly's 13oz fww but have yet to try one. And I run a turbine core II with my gnarly. Couldn't be happier.

A FWW will take away throttle response and make the bike rev slower, not what he's looking for if he's wanting more snap out of corners...

Exactly, its extremely hard if at all possible to gain noticable bottom without losing any top end.

you can get a gnarly and retard your timing one degree to get more over rev??

also tuning your airscrew for optimum throttle response helps alot with bottom end power. i tweak mine for every ride depending on the weather. 1/4 turn here and there makes a big difference in the throttle response from idle to 1/4 throttle. just my 2 cents. everybody is probably tired of hearing this but if you have the dough the eg 295 kit did lots for the bottom end.

Power now wing gave me bottom and quicker throttle response.

I would of never bought one, but it was given to me and now I can't live without it.

I agree, making sure the jetting itself is dialed in 100% will help the entire RPM range. I also adjust my airscrew every time I hit the track. Its amazing what minimal adjustments to it will do if your jetting is correct and likely the most noticable.

I feel that the Gnarly helps on the bottom and I don't feel like there is any sacrifice on top. I also run 52 sprocket in the rear. Truth is, a little bit of finesse with the clutch hand will give you everything you need.

hp bikes 350cc kit when available should do it!:smirk:

My impression of the gnarly was the exact opposite. On the track I felt as if I lost quite a bit of over rev with the gnarly... maybe it was just my imagination? Nuudle hit it spot on though, clutch/ throttle control will get you anything you desire. All depends on the riding style however, the pipe that works for one person probably wont work for the next.

Rem. too much down low and youll do nothing but spin the rear and break traction unless your on the road, thats the reason I ended up running the stock pipe and fmf shorty on my current race bike for about 90% of my races although I have 5 other pipes hanging on the wall in my garage. Smooth power everywhere with no losses anywhere... good low end, great mid range, and slightly above average top end when compared to other pipes in those specific areas. I think the stock pipe makes its best power at about 3/4 throttle. Id prefer my power to be made throughout the top half of the throttle range rather than the bottom half if I had to chose however. I can control the rest with the clutch since I never lug the bike, but in order for that to work jetting needs to be spot on so throttle response is there.

Not to insult you but maybe you just need to put in a little more clutch work and you may be suprised at how much these bikes really have down low. Correctly feathering/ dragging the clutch will help with this. Thats why the really fast guys at the local track will smoke me out of corners on a 125 when Im on my 250. Not to mention they have better overall corner speed than I do so they dont worry about breaking traction.

Sorry for the long post... got a little carried away.

BB will do it for you, I second the Power Blades also.

j-bo's comments reflect my experence exactly.

Hi there

Reading through the forum it should be best to get the EG 295 kit for more power. And the DEP pipe seems to be the best. I did not try the 295 neither the DEP. Also what I have is the vortex cdi. It is nice and the cost is almost the same as the 295 kit.

Good luck


Zach, what pipe are you running now? And what year is your yz?

I'll echo what many have already stated.

My 09 250 currently has a 13/48 (it was a freebie otherwise I'd run a 14 and +1 in back for most riding), jetting and air screw are spot on, stock pipe with either stock silencer or PC 304. And I remember to be in the meat of the powerband and momentum at all times. It came with VForce reeds but the jury is still out on that.

My other bikes have kits or flywheels, etc., but for the YZ250 and my general all-around riding needs from tight woods to open desert the aforementioned combo is near perfect from top to bottom.

I did put a 13 and stock rear sprocket for more down low snap but it was too tiring or had me shifting too much on all but the slowest tightest trails. I'm only 170 before gear.

I had a pro circuit platinum 2 with the pc shorty and man what a big difference in bottom end.

Zach, what pipe are you running now? And what year is your yz?

Found this

Stock setup is my 2nd choice. I lost no bottom end power with the DEP/PC 304 combo (but didn't gain any) gained great mid range and a lot more overrev. If you want something with more bottom end, get the PC pipe.

Another thread he said he was getting the squish mod'd last year, but no follow up. So we dont know if he did it or not. 2010 yz 250.

I'm thinking the next step in low end without giving up anything else is more displacement....

Edited by adam728

. I'm thinking the next step in low end without giving up anything else is more displacement....

Im thinking EG 295 kit:

Found this

Another thread he said he was getting the squish mod'd last year, but no follow up. So we dont know if he did it or not. 2010 yz 250.

I'm thinking the next step in low end without giving up anything else is more displacement....

I never did the squish mod, was told it would take away from power up top. Yes I have a 2010 with a DEP/PC304 combo.

Squish only takes away from top end if the bowl isn't opened back up to give stock compression. Just cutting the head down for squish clearance increases compression, which generally makes it harder for a 2 stroke to breathe at high rpm (again, generally). Proper squish and proper compression will give better power everywhere. Do it!

How's the jetting dialed in? Perfect pilot and needle will go a long way towards quick throttle response and low rpm power.

How's the top end? As compression goes away, so does low end. I rode a friend's 04 that was down around 190 psi on compression, it really felt like a big 125, VERY weak low end compared to my bike.

I'll also add:

Flywheel weight - made my bike feel like a slug out of corners. Slower to build revs means slower accel when traction is good. Made me want to use the clutch more to get things ripping.

FMF Gnarly - went to it from a FMF Fatty, definitely moves peak power down in rpm some, and over-rev suffers greatly. Now I'm used to it, but it was a huge change at first. I'd say the engine peaks easily 300 rpm sooner, then just signs right off, doesn't taper into over rev smoothly....

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