2-Stroke MUST HAVE Engine Mod! [YZ250 APEX Head Review]

[@chadrides914]

I’m impressed with your bikes super low idle yet it’s not dying or flooding out. Very nice job tuning the carb man. The lowest possible idle enhances the bottom in dramatically and prevents overheating.

[@RideEnduro]

Once it’s warm it runs excellently right from idle. That’s definitely thanks to the head and jetting like you mentioned. Apex helped with re-jetting after they did my head, all I have to do is fine tune with the air screw with the different seasons now. We ride year round, from -10c to +30c. Not having to mess with jets between seasons is nice!

[@michaelschwab9563]

THIS ☝🏻 Lowest idle possible. That's why race bikes don't idle

[@EarthSurferUSA]

I don't agree. The idle setting does not matter as soon as you open the throttle, and has nothing to do with over heating. I like to run a high idle on 2-stroke so they are harder to stall when braking hard for a corner if you get a bit sloppy with the clutch.

[@EarthSurferUSA]

@@michaelschwab9563 If you come across a racer of a dirt bike that does not idle, do not let him tune your engine.

[@chadrides914]

@@EarthSurferUSA you can disagree, but your still wrong. Low idling two strokes run cooler in a properly jetted bike and prevent overheating.

[@EarthSurferUSA]

You will notice good difference with higher compression with that bike, because it is pretty low on compression stock. But it is just a head mod. If you want some real low end power, (which I love for trails.), Put a 2010 head on it and lower your cylinder by removing the base gasket (seal the cylinder to the cases), to get about a .035" squish clearance. Then look for a lower rpm pipe, and I am adding a V-force reed also. This bike is built to run like a 125 for the very fast 4-stroike MX tracks, including the huge front brake, of which is so powerful, I am thinking about putting an air bubble in the brake line. :) I build 2-stroke engines for a living, and we can make this engine anything we want, except powerful enough to beat a 450 4-stroke MX bike. The FIM did that on purpose.

[@showtyme843]

@EarthSurfurUsa have you ever done a yz500 build? If so how did you like it? Also I have a 2019 yz250x so I'm wondering what can I do to it to give it more?

[@Pajero.m57]

@esp i already use your stuff for my baja engine and all i can say is that is amazing !! Could i do the trick with yamabond sealent instead of the base gasket? And my stock 2003 head? Thank you 🤟🤟

[@howardwoods342]

Its because Yamaha is king. Best bike ever

[@DariusBarazandeh]

Thanks man…. Great info. I’ll def talk to them. If I get a YZ 250 I’ll do it. If I get a 250x I’d probably do an SX head.

[@chrispewkreme]

I don't have much experience on 2 strokes. I ride a WR250R and I'm used to just letting the clutch go and finding traction with the throttle. I got my WR250 stuck in a muddy trail with supermotos on... A KTM 300 helped me get it out. He let me ride his bike, and just like my WR, put it in gear and use the throttle. Didn't even think about the clutch. Then I got a YZ250 all stock, and gawwwdamn, you HAVE to work that clutch. The hit feels like a on/off lightswitch, I want a dimmer switch.

[@RideEnduro]

Apex XC head will help, you can also swap out the power valve spring to one from a YZ250X as I have done also. Smooths things out a bit. A flywheel weight will also help a bit. I can no clutch ride this bike for the most part. But I learned to ride with the bike stock so I'm a happy clutcher. That's why I upgraded the clutch lever and Perch to a 1FNGR unit, it reduces the clutch pull by about 30%. You can also get the YZ250X clutch basket springs and washers if your struggling with the clutch pull as they are much lighter than the MX versions.

[@chrispewkreme]

@@RideEnduroI’ve got a hydraulic clutch which I like, but would like a one finger lever with a rear hand brake. Putting on the XC head here pretty soon. I already have a flywheel weight and was tempted to retard the timing a degree or so to be more like a 250X.

[@RideEnduro]

I have not played with timing yet. Ride it with the XC head first and then change the timing and let us know what you think!

[@chrismaddog8112]

Great video. Im putting my billet xc head on this week. Snappyness has been getting pretty tricky on the hard stuff

[@RideEnduro]

You will most surely enjoy! I’ve dropped down to a 13 tooth front sprocket and with the extra torque from the head I can crawl through some tricky trails in the low end of 2nd gear. First is for the real tricky stuff!

[@bentagliarini7918]

My 2000 cr250 when i got it, had wrong main jet, so set it up standard the carb 48,180 jets, then fitted 45 to idle quieter lower answel as 1 needle clip leaner, then 1.25 to 1.5 turns out on air mixture screw, boy it gave tons more bottom and mid range hit, like wow, still running 32 to1 still rich but not as much as standard, got fmf fatty and longer pc2 can sounds nice, gnarly will give it even more low and mid, was insane on 01 kx125 yrs ago the gnarly lol, running 13,49 stock 13,50 on cr250 2t occasionally fit 12,49 and absolutely monster but top speed 60ish rather than about 75 80 to before. Though tell you to give more ideas also, i hear new lectron carbs good to

[@sevenmilewhite1407]

Wow. I really want to do this to my 95yz250 hare scramble bike. It'd be so worth it.... thanks for the information.

[@RideEnduro]

Heck yeah! Correcting the squish is no joke, makes any bike run it's best with proper jetting of course!

[@soupysocksenduro]

wow, what a difference eh! I just ordered an 11oz flywheel weight for my RM125, but this looks like it would compliment that mod nicely! never heard of it, thanks for showing what difference it makes! I noticed my RM hated the elevation change when I moved to Pincher Creek, I agree with the starter & clutch! I can't afford my dream bike, a '21 TC150i, so I will add these game changers to the bike I currently have!

[@jacobhendrickson8935]

I’ve always used a Yz for the trails. I love having that hit.

[@RideEnduro]

It’s definitely a fun bike to ride. The X PV spring and head just smoothed it out a tad. It still wants hit the pipe and rip your arms off tho haha. Smiles for miles!

[@jacobhendrickson8935]

@@RideEnduro notice when it’s idling it almost sounds like it has a slight piston slap or rattle. I just bought a 2013 in really good shape that does this. Hearing it in my enclosed trailer intensified it making me wonder if something was wrong. After hearing yours I’ve decided that it’s either normal or we both have the same issue.

[@RideEnduro]

Every good running Yz I’ve been around has a similar sound. They are kinda odd sounding bikes at idle!

[@jacobhendrickson8935]

@@RideEnduro good to know, I was all paranoid. I still plan to tear it down and make sure it has a stock piston in it, and no issues with the cylinder or anything. Seller claims it was rebuilt a couple years ago so that always makes me worry about someone throwing cheap parts at it. I just prefer the genuine OEM parts for woods riding. If anything else a wiesco piston will do.

[@RideEnduro]

@@jacobhendrickson8935 That’s a good idea. Nothing but OEM inside my Yamahauler!

[@hugoross5749]

a vortex X10 CDI is more of a performance part but the Apex is great too

[@RideEnduro]

Hmmm haven’t put any research into a new CDI unit. I’m pretty satisfied with the bike as it stands right now but you can never have too much powwwwa!

[@gunnarhausherr5133]

Hey I love my YZ 250 for trails

[@RideEnduro]

Hells yes! 👊

[@RideWithTheWolf]

I got the MX cut and I seemed to loose some top end on my 06 yz250. I'll probably get the SC cut for my yz250x.

[@RideEnduro]

Did you get jetting specs from Apex? MX head should ring out pretty well! Get ahold of them and ask what could be happening.

[@ATMC-su7mv]

Thanks for sharing, I have just purchased the XC head and also want to run with the NECJ needle. Can you share your jetting specs, alt temp etc? Subscribed!

[@RideEnduro]

Nice, I’m sure you will enjoy it! I’m at 4500’ 91 octane, 20C temp, 168 main, 42 pilot, NECJ 2nd clip. Send Apex an email, they will send you the jetting chart for the NECJ needle for different elevations.

[@jeffgoetz7919]

thanks for the video on this

[@RideEnduro]

No problem. Best bang for your buck performance wise in my books.

[@jg6209]

Hi - great video. What Zuk needle, clip & jets you running - and at what altitude & temps? Have an Apex head and switched to Zuk needle as well - still trying to get it dialed. Thanks!

[@RideEnduro]

Thanks! I’m at 4500’ 70f (20c) 168 main 42 pilot NECJ needle second clip. If you email Apex regarding the Suzuki needle Matt will send you their jetting chart recommendations! And that is why I chose Apex. Customer service is on point 👍

[@usmc03]

Did you use Apex's recommended jetting?

[@RideEnduro]

Yes I Did. It was pretty spot on. I even swapped to the Suzuki NECJ needle and Matt from Apex sent me jetting specs for that setup and my altitude.

[@muiemunteanumuiebratuleanu3692]

hi , in this video , only apex head and jetting u changed or u have a flywheel weight on ur rotor ?

[@RideEnduro]

Yes I do have an 11oz flywheel weight as well. I will be releasing a new video shortly going over all of the mods I’ve done to my YZ to make it more trail compliant. Subscribe to stay tuned! Cheers 🤟

[@raywalsh5822]

ive gota yamaha research race and development head on my 06 yz

[@RideEnduro]

Is it from a race team bike?!

[@raywalsh5822]

@@RideEnduro i thimnk so i bought it with it on mouldedin the head which has cooling fins on it is YRRD.the bike is very quick full pro circiut and boysen rad valve

[@RideEnduro]

Sounds fun! 🤘

[@fasttoys99]

So if you did the jetting at the same time as the head. Are you sure the jetting didn't fix your problems with your bike?

[@RideEnduro]

No, I have owned and ridden the bike since 2015. It was jetted properly for my elevation from day 1. It ran good, but now it runs amazing and the power is where I need it to be. Checkout the reviews on Apex’s heads. Or any manufacturers heads for that matter. They make great improvements 👍

[@straighttimestirrups]

I’ve added an MX HEAD to my YZ125 and am having one for my 04 YZ250 on my way now. Great product and 100% agree in the Customer Support!

[@burtrumsburgermeat5473]

Higher compression means it’ll turn less rpm and slow your top end that’s why they gave it less compression

[@MotoPooch32]

I have both ktm 250xc and yz 250x and the yz is snappier and more playful and suspension is better stock. Rips Rediculous and mine lugs. I Have all the mods. The Ktm feels more like a race bike. Vibrates less and I feel more comfortable on the Ktm but the yz is just a huge smile on my face and is no joke. Rip your arms off riding all day.

[@RideEnduro]

Nice! The New TBI motors of the euro bikes are much more lively now. But I can't let go of my YZ!

[@fattie2550]

Would you need a new head of you bought a new 2023 YZ250X?

[@RideEnduro]

My particular head? I wouldn't swap it, I'd get the new one re-done and sell my current bike as is. My bike is an MX model, there's a possibility that the X dome characteristics from Apex would be different. Them 2023 YZ250X bikes are awfully tempting!

[@No_Budget_No_Problem]

Also bro, the magura hydro clutch on my 1999 YZ 250 has issues with not fully engaging the clutch

[@RideEnduro]

Google something about adding washers to shim up the actuator where it enters the ignition case. Thought I read something about that recently maybe it was on thumper talk. It might be a good idea to bleed the clutch to make sure there is no air trapped in the system too.

[@jacobhendrickson8935]

I’m still thinking that rattle we have at idle is piston slap from the piston skirt worn or cylinder one. Have you been in yours lately? I’ve heard several of the newer models that don’t make that idle noise.

[@RideEnduro]

I've got about 20 hrs on this top end. To be honest I don't think it has ever sounded any different 🤔

[@jacobhendrickson8935]

@@RideEnduro I guess I’m just paranoid. Wouldn’t doubt if every one of mine did to. I haven’t had a dirt bike in years. Last one was my 01 yz250. The older I get the more OCD I’ve become about anything and everything. Lol

[@RideEnduro]

Oh I hear ya in that one haha

[@jacobhendrickson8935]

Question, being every squish is different if I was to order the apex head how do they get the squish right on it ?? Do I do a squish test measurement with my stock head then they can make a new apex head to fit my unique cylinder?? I’m sure there not all the same and the whole reason for the new head would be to get the squish right. This makes me wonder if having them mod your head is the better choice. Unless they send you the apex head so you can do a squish test then return it to them for correction. Do you understand my concern??

[@RideEnduro]

When you order the billet head you should install it and then do a squish test. You will need a good set of vernier calipers. You can then adjust the squish if necessary by changing the base gasket under the cylinder to either a thinner or thicker gasket. This is right off their website: “On our 250/300cc billet heads, the ideal clearance is 0.050in (1.27mm). Values under 0.045in (1.14mm) should not be run unless its a race gas dome. Values under .045in or over .060in (1.52mm) can be corrected with different thickness base gaskets for some models. For clearance under 0.45in use a thicker gasket, and a thinner gasket if the clearance is over 0.60in. Please contact us if your squish in not in this range and we will advise.”

[@TheRealKlinky]

Why do ALL yz's have that 'rattle' at idle - mine does it as well

[@RideEnduro]

Yeah it's just a quirky attribute of the Yamahaulers 🤪

[@ryze6726]

What's the magic button he's referring to? @5:30

[@RideEnduro]

E-Start! “The magic button” Panthera Motorsports has released an aftermarket Electric Start kit for 2003+ yz250’s. It’s something Yamaha should seriously look into equipping on their 2 strokes.

[@ryze6726]

@@RideEnduro maybe on their 250x model, since it is more trail oriented, I agree

[@RideEnduro]

@@ryze6726 exactly

[@brianpolen1087]

Also, if you don't have a flywheel weight---that would also be the best money you can spend!!

[@RideEnduro]

It’s had an 11oz Steahly since I’ve started riding as well. But yes I agree, it helps immensely on the trails as well. 👍 I will be doing a complete video on trail worthy mods I have done to the bike shortly. Stay tuned!

[@endurotruckererniedesjardins]

I run the stealy 13oz. On my 2018 yz250. Love what its done for torque.

[@RideEnduro]

Send in your head to them! There is instructions in their website for doing the squish samples. There is a form you fill out as well so that they can mill the head to match your fuel octane (91 in my case) and your elevation. Ask for jetting specs to use with it too. You will be a happy man! Wads of torque!

[@endurotruckererniedesjardins]

@@RideEnduro i just don't want to be without my bike while its sent out. Lol...

[@RideEnduro]

@@endurotruckererniedesjardins oh I hear ya! I sent mine in when there was too much snow to ride.

[@innerfire-graham9016]

I had Matt cut my stock head xc as well best money spent. Did the washer come off the spark plug opening? Mine did, epoxy failed, hows yours doing?

[@RideEnduro]

No faults in mine. Haven't had it back off the bike since it's been done though. 👍 Were you able to repair it?

[@innerfire-graham9016]

I've yet to use hi temp epoxy, thats what Matt recommended. Great review btw. If you ever want to come ride in central Oregon let me know!!

[@RideEnduro]

@@innerfire-graham9016 good luck! Cheers

[@jacobhendrickson8935]

What exactly are you talking about? Washer that failed? Thinking of having my head done but plan to go with one of the other 2 versions. Not the XC being I’m looking for more mid/top end. What does apex epoxy some type of washer on your head?? If so is this just on the XC version?

[@RideEnduro]

The washer is on top of the factory head where the spark plug screws in. It looks like it is built into the head but is actually just epoxied on.

[@vwgtdturbo]

do you use xc dome is this with less compression than stock?

[@RideEnduro]

Yes my factory head was modified by Apex for XC. As far as compression goes, I’m not certain if it’s less or more than stock. I just know I told them my altitude, temp, and gas I use and they built the dome shape to account for all of it and it works amazingly.

[@vwgtdturbo]

@@RideEnduro awesome greets from austria

[@RideEnduro]

@@vwgtdturbo cheers, thanks for watching!

[@EarthSurferUSA]

@@RideEnduro It is higher compression, that is the difference. It looks like they cut about .020" off the gasket surface and polished the combustion chamber and squish band. If you took .0085" off the gasket surface, it would be the same compression as the earlier YZ250's. This may be the lowest compression 250MX bike made in the last 40 years, because they wanted it to burn any junk fuel around the world. I think I can easily get 4 more HP out of this engine with much more mid range and lower rpm power. But it is easier to get rev out of a grunter than grunt out of a revver.

[@RideEnduro]

Whatever Apex has figured out for thier YZ heads works very well in my opinion. I've got enough torque for the techy sections and it comes on instantly right off idle, and it's still a very Rev happy motor!

[@jacobhendrickson8935]

Gosh twist that throttle that baby has been idling for so long.

[@RideEnduro]

It’s amazing how well it idles and doesn’t load up.

[@jacobhendrickson8935]

@@RideEnduro no doubt.

[@terrybernard2870]

Do apex make xc dome ktm 250 sx thanks

[@RideEnduro]

At this time it looks like only the 300 and 150 cc bikes. atinno.com/ktm-products

[@endurotruckererniedesjardins]

So how does the apex xc head compare to the yz250x head. The yamaha head is really cheap to buy compared to the apex head

[@RideEnduro]

The factory squish on the X head is even larger than the MX version... the benefits of getting the head milled or replaced on the X is even greater than the MX bike! Even with shipping to Apex in the US, it cost me $165 cdn total to have them modify my factory head. Pretty damn cheap for the difference it made.

[@endurotruckererniedesjardins]

@@RideEnduro id say. Stock head was 177.00 last time I checked. If it makes that much difference its really worth buying a complete head from apex.

[@RideEnduro]

Yeah their billet units are super nice! They add more coolant volume to the head too. Keeps things a bit cooler.

[@sam71norton]

If you want to avoid the power curve coming on like a light switch it is really worth it. I have the XC dome. Before if I hit the power curve with the front end up it would want to come right over, or when coming out of corner with a slick surface it would hit the curve and break traction. Now that is not a problem. Love the new head.

[@RideEnduro]

Yeah it smoothed it out for sure! The X power valve spring did a great job of it too.

[@jacobhendrickson8935]

It sucks they don’t do this service anymore. Now they just sell the billet head. I want the custom cut and buying the billet head you don’t get that. You get put in a ideal range I guess but I want measurements then cut to exact specifications. Not an ideal range. And I sure have absolutely no interest in using some aftermarket base gasket.

[@RideEnduro]

Pretty certain you can order different thickness base gaskets from Yamaha or KTM or whatever brand you may have. That's how you custom correct your squish on a pre milled head. I think alot of guys skip that step, slap a new head on and call it good. Which I'm sure it's better than stock still just not perfect.

[@jacobhendrickson8935]

@@RideEnduro yes but wouldn’t a thinner/ thicker gasket also change your intake/exhaust port timing?? I want all of that in the stock position so thinking I’ll find someone who will cut mine. Really sucks I’d prefer a billet head but want it custom cut to my application.

[@RideEnduro]

@@jacobhendrickson8935 it will be so frign close, I doubt there would be any difference. You won't know till you try!

[@karlitosway4791]

Did you change the wheel from 19” to 18”?

[@RideEnduro]

Nope, still on the 19” rear tire. I do however run Michelin BiB Mousse tire inserts that are pretty soft. I haven’t found the need to get an 18” rear rim. Honestly I think the biggest draw back of the 19” is it limits your choices of Offroad specific tires as most brands are suited to 18”. However the Shinko and IRC tires I like come in 19” so No big deal to me.

[@chadrides914]

@@RideEnduro man, I’m telling you, in my opinion, the 18” rear tire was the single best addition above everything else for my woods bikes.

[@RideEnduro]

@@chadrides914 do explain! What about it felt so different?

[@chadrides914]

@@RideEnduro you can run lower pressures without damaging rims, they deflect off square edged bumps/roots/rock far less imo and most importantly they seem to absorb trail chatter better creating almost a feel like you’ve had your suspension upgrade. You do lose some nimbleness though.

[@RideEnduro]

Excellent explanation, thanks!

[@No_Budget_No_Problem]

Bro, you letting your bike idle like that, it just gums it up and it then runs like shit

[@RideEnduro]

A couple good blips of the throttle before taking it off the stand clears its throat. Bike runs and idles super crisp.

[@bradyhaskell8062]

bro don't just leave it idling like that .

[@RideEnduro]

When it runs this clean there is very little build up! One good rev to clear its throat is all she needs.

[@No_Budget_No_Problem]

Now put this, a lectron, and the flywheel weight

[@RideEnduro]

I’ve got a 11oz FWW on the bike 👍 I don’t ride enough varying elevation to justify a Lectron. The Keihin carb is a hangin unit, especially if you are jetted properly.