You're a great presenter! Very clear and concise. I ride an 03 yz250 that I built from being all torn down in boxes. The only real modification I had done to my bike was head work of the OEM head by RK Tech, and my gosh what a difference it made! I will NEVER sell this bike! Thank you for showing all of this. I always love to learn!

Love learning about race engines. Thanks for the videos coming out of your shop!

@HPRaceDevelopment

3 ай бұрын

Thanks for watching

It’s a lot of work that most don’t understand. Testing testing testing. I had 5 pipes and 4 silencers and tested all before came up with combo I LIKED

@HPRaceDevelopment

3 ай бұрын

well said

never clicked on a video faster when I saw it in my recommended. Keep up the good work and thanks for all the info in your videos

You try and explain why a top supercross bike is so expensive and i had a guy say he could buy everything he see's on the bikes so they aee not that expensive. I said oh you have no clue the internal parts and custom ine off parts that are not available to the public. This is a great video just explaining a bit that goes into that. Great job!

Sweet. Love the 2 strokes, long live em.

Amazing videos am a fan and about to my own yz250 build thanks to you

@HPRaceDevelopment

9 күн бұрын

If we can help with performance side of things and a piston kit, let me know. Leshar piston now in stock and ready to go

Always look forward to your videos!!

Pretty trick, nice work Derek

I like that last part u said about the cdi box lol… 👌🏼

And also on the ceramic main bearing from my experience there not all the same I’m no expert but I’ve had them fail on the dyno before so I run oem and just replace them when motors apart

Great stuff...!

It always amazes me how rough some engine builders are on their precision measuring tooling. never the less this guy knows WAY more than me. And I appreciate the video, also that 412 piston looks awesome. Nice build.

@HPRaceDevelopment

3 ай бұрын

rough????

@HPRaceDevelopment

3 ай бұрын

The way the dial bore gauge works - is a replaceable dial indicator is mounted up top - and the mechanism that operates it is within the tubes spring loaded its pretty durable - and our bench is wood with a plastic mat on top. the micrometers are cheapo - we only need them to be the same size as the piston then lock in place to measure relative piston to bore size - so the actual measurement is of no real value (it is in other instances when specing parts for design) really high end measurement tools also require climate controlled rooms, and good knowledge of use and calibration - not something im a pro at. I just do the basics to ensure we dont have problems and when i need serious measurement accuracy i phone a friend who has an incredible set of measurement tools for his business and pay him to do it

@eriksforestryvision8751

3 ай бұрын

@@HPRaceDevelopment Copy that, your doing a great job im sub'd. I would say the way you moved the dial gauge and caliper was a little rough. Just based off some experience in how precise measuring tools are treated. My bad

It is the first piston I have seen where the ring end gap traverses a port. I have transformed (on small production basis) Piston port engines to reed valve engines by adding the 5th transfer port, that was traversed by the ring ends. Real small bore engines, (34-36mm), that sometimes let us get away with murder. So I am glad to see I was not just getting lucky. :)

Good old 2 smoke Race engine!!! brings out memoriesss :) . I'm not to sure about the OEM water pump delete tho, you trade .1 horsepower for a possible electrical pump failure, and a DNF...

Good video.

Do you have info on the electric water pump? I have a 05 CR125 with a broken water pump housing and the side case is discontinued by Honda and not 9n eBay. Thanks!

Interesting stuff, why the piston ring pin location for port work may I ask? 🤔

I changed my piston 30 hours ago and it had 0,5mm of piston ring clearance. Manual states that it should be 0,4mm on one ring piston but I put in dual ring piston. Is it normal? The bike is 2021 ktm 125 sx and its working great as of now

What do you do if you have a ring gap that is too large? Are there different size rings like pistons? (A/B/C/D)

Where do I BUY that CASE SAVER for a yz460?

Really appreciate the video! Thoroughly gone through and learned a few new things!!!

Have you done anything with the beta 300rx? Would love to see what’s possible, seems like there is a lot left on the table with it. I have a 22 and would love to hear your thoughts

@HPRaceDevelopment

3 ай бұрын

I have not

@ottokirk2325

3 ай бұрын

Look into the new STIC Super X carb. It will make substantial gains across the entire powerband. My 200SX feels like a ported 25cc big-bore. Makes a stronger and wider peak HP plateau. Derek is a dealer, BTW.

Can you explain the electric pump and fan set up more please? I want to do this in my Beta 300rx...speaking of that, have you done any work on one yet? Great video btw.. excellent content.

@HPRaceDevelopment

2 ай бұрын

Have not, It's the same combo all teams run on 250 race bikes. Bosch pump, we plug and remove impellar

Wish u showed or mentioned the porting and base gasket thickness, compression ratio, if gears were undercut on dogs, and other modications you made to the engine other than just the ceramic bearinngs, piston , head and clutch. What type of pipe , carb , fuel , oil ratio. Things that help make power and / or reliability. I usually shave .. ten to 20 thousandths off the head ( stock ) advance timing slightyly and match / polish the intake exhaust and transfers, powervalve mods? Spring tension ? Deck height? I enjoyed your video but was,hoping for a little more. Crank runout , welded crank? Corked ( more plastic on crank ends / higher primary compression? Things deeper that work. Good stuff!

@HPRaceDevelopment

3 ай бұрын

Undercut gears dont shift well under load - undesirable in our experience. We dont publish our specs - its how I make a living -

On your pistons do you run thicker domes?are those the crank stuffers stock ?i noticed they are recessed slightly would that not disrupt flow and hurt crankcase volume?

@HPRaceDevelopment

3 ай бұрын

whats recessed?

@denniswilder3014

3 ай бұрын

@@HPRaceDevelopment the plastic round reed stuffer on the crank webs.i built a few yzs back in the day and the plastic never fit flush. I always skimmed them with devcon then machined them flush. Its only a few thou but yes im that picky

@HPRaceDevelopment

3 ай бұрын

@@denniswilder3014 While I appreciate the attention to detail it doesnt translate to power for me. The expression of step over a dollar to pick up a penny comes to mind. The yz is arguably too low on crankcase volume - If i waved my magic wand I would add some volume - but i prefer that volume in the transfer tunnels and just below them - removing stuffers all together wouldnt put the space where we want it If we werent so busy on all various projects - I think we could find another 2-3 hp on the yz from where we are with an additional month of r&d but past that - it would be slow coming. Our current package outruns a solid ktm250sx and current 300 sx. its not far off what we have dyno the current yz450 at - so vs stock its a long ways improved The piston crown is shaped in a manner to more properly dissipate heat. we (his current carb) have been far too lean when it was first tested - and no crown issues - its still a tad lean in areas and been punished in deep sand and mud and all solid. You will detonate or hurt something else before crown issues - at least so far

Are you guys running OEM crank? I need to rebuild my bike and the hot rods rebuild kit is a lot more budget friendly, any thoughts on those?

@HPRaceDevelopment

3 ай бұрын

Oem, we have snapped rods on non oem

Thanks for another great video 🙏, Did you try using gapless rings ? Will appreciate your insight.

@HPRaceDevelopment

2 ай бұрын

No - not worth the cost or effort on race build - in running operation a properly gapped ring is at basically zero gap.

@bbmoti

2 ай бұрын

@HPRaceDevelopment thanks for the fast response, was considering it not on a race bike, more for my daily ktm 690.

@HPRaceDevelopment

2 ай бұрын

@@bbmoti if you can source a set...you can try it.

@bbmoti

2 ай бұрын

@@HPRaceDevelopment 😁😊

If this is sx build, is it for max midrange and response or is it linear all the way to the top? Well made vid👍

@HPRaceDevelopment

3 ай бұрын

Maximum power possible with motocross fitable pipe. We have made tweaks to the pipe to pick up a little midrange - but one "flaw" of all thes pros is they rev too much. Jared routinely revs past 13000 - we'd like to see never past 11500 for parts :)

My engine builder always says if you crack a piston you have to replace the rod. But I’m a pro rider also and budget is extremely tight and I ended up cracking a piston (tune is perfect) replaced piston and I’ve got 15hrs on it rn and it’s still running good. I was very concerned because the top of the rod had alittle blueing to it but full engine rebuild is pricey

Might be an silly question but do you ever hone the cylinder between rebuilds or is it replated before it gets to that point?

@HPRaceDevelopment

3 ай бұрын

I never hone and I dont suggest it 90 percent of the time

@ChickenKing55

3 ай бұрын

@@HPRaceDevelopment Thanks for the reply. Good to know. I watched a few more of your videos after this and understand now.

Any noticable gains with the electric pump on the 250 twostrokes?

@Recedinghairline180

3 ай бұрын

He said the jury was still out on that one..

@winterfriction

3 ай бұрын

@@Recedinghairline180 Yup but I mean power not cooling.

Does Wiseco make a 412 Piston for Husqvarna 300’s ? I have a new Te 300 and it’s only been Started once and i want to swap Oem out with Either a Wossner or Wiseco and torn on which one . Love the Channel appreciate the content.

@HPRaceDevelopment

3 ай бұрын

Not a leshar special - but they do make a 300 piston you can run as seen in our previous video

@mrmoparrr

3 ай бұрын

@@HPRaceDevelopment ahh yes, was wondering if that Wiseco has shorter skirt than Oem . Appreciate the reply!

Buy the SKF for you main bearing better than the stock oem bearing last longer.

I don't know if you have worked on yz 125s before but im having issues with how too find the correct piston size. The owners manual didnt help at all but the one piston we bought from yamaha was the exact size as the oem piston and the bike ran perfectly fine while breaking in the new piston. Then raced it and 2 laps in, it heat seized the bike has 130 hours and id hate for the oem piston too grenade. Any help would deeply be appreciated.

@HPRaceDevelopment

3 ай бұрын

if the clearance was correct and it was oem piston its more likely you didnt mix enough premix, were far too lean, or a combo of both

@kylebeach2316

3 ай бұрын

​@@HPRaceDevelopment we always mix 40:1 or 50: 1 with the elevation we're at and never had an issue with that mixture before unless we got bad pump gas "ethanol free" which is highly likely. But what you said could also be possible since we have the lectron carb on it and it did self adjust itself to a lean mixture before. I just hate the fact that yamaha has numbered or color coded their piston sizes.

@HPRaceDevelopment

3 ай бұрын

Kyle your manual says 32:1 and its for a really good reason. I highly suggest you run that if you want your parts to last as long as possible. OEM piston sizing is nearly irrevelant - the differences are very small and each size will work in any size cylinder - although we as a shop always recommend the A size pistons, which are the smallest of all of them. It sounds to me like you need to take some of the free info we have put out there - and use it to your advantage - measuring your piston to bore clearance, ring gap clearance, and from my reply here - 32:1 would do you a lot of good.@@kylebeach2316

How many hows would you expect are on that motor before it came in?

@HPRaceDevelopment

2 ай бұрын

Not sure - we generally have something break before 40. Main bearings in the past 2 times, this engine got hot at daytona - nothing really looked bad but was smart to freshen it up - at the pro level it's not worth the risk to push it. His other one grenaded the output bearing on the trans - it likely had 30 i'd have to get notes off the mechanic.

Those barrel studs could of been cleaned before final assembly , @ 12.02 gunge in the threads (especially the long stud) will affect final torque for sure, great vid however

@HPRaceDevelopment

Ай бұрын

below the portion of the nut thats engaged - but these studs should be replaced frequently and these are far past due. These had been vapor blasted and brushed - still look terrible, the cycling stress applied to them combined with corrosion will lead to broken studs

I am a 60 year old man, and after about 20 years off I picked up a slightly used 2019 YZ250 2-stroke, and totally hated the modern tall bike set up. I am just riding trails, but I love more bottom end power than the YZ had. I have been porting/stroking little 2-stroke gas engines for a living, and have a great name out there, (even a water brake dyno), but I just did some stuff to the engine to lower the curve and will not be able to jet it and ride it until weather and I get a bit better. If you would be willing to offer your opinion, I would love to tell you what I did, and you give me your expert opinion of what I should expect. 1) FMF Gnarley pipe and silencer 2) V-force reeds. No stock aluminum spacer plate. I found the stock reed upper stop plate blocks off the rear reed transfer port tunnel maybe 50%. 3) Lowered the cylinder .024" (removed the base gasket, sealed it well. Not sure if i want permanent yet.), .048-.049" squish left with the stock head. Running 100 octane gas. The lowered cylinder exhaust port timing should, in theory, match the lower rpm target of the FMF pipe. I like a lot of bottom end and mid range power (like my old 97 KX250), so I hope I get there with those mods, but I am sure I can lose up to maybe 1000 top rpm. I prefer a "short shifter". :) Thanks for your time. Great little company, I can tell. Doug in Michigan Earth Surfer Performance.

Ceramic bearings are available in every ball bearing application. What company did you get them from? Actually they do make power and also let the engine rev quicker.

@HPRaceDevelopment

3 ай бұрын

You want to bet money on this? My dyno LOVES to test claims.

@HPRaceDevelopment

3 ай бұрын

@davewho3080 If we cared about that we wouldnt run a flywheel weight

I was able to get that output shaft bearing from SKF.

@HPRaceDevelopment

3 ай бұрын

They arent stronger in our experience than a Japanese bearing. The reason ktm uses a roller rather than a ball is much higher load carrying ability - with modern tracks and power levels - we think its a smart way to go. Ill have a video with it when installed in our motor - we shall see how it goes long term

@danwilliams1132

3 ай бұрын

@@HPRaceDevelopment deffinetly interested. My bearing failed there and I replaced it with a SKF. Next crank swap I’d definitely be interested in the KTM style.

I can’t tell if I’m seeing correctly how that bore gage works. Is it using three points of contact or two?

@HPRaceDevelopment

3 ай бұрын

of course it works

@dylancrow7919

3 ай бұрын

I didn’t mean hope. I meant to ask how.

@HPRaceDevelopment

3 ай бұрын

@@dylancrow7919 That gauge is 2 points of contact at measurement point - but has a guide “wheel” that is its own 2 points of contact - making 4 points of contact. In a future video ill zoom in on how it works

@dylancrow7919

3 ай бұрын

Ok thanks. I’m about to subscribe.

Can you run that piston in a bike stock cylinder

@HPRaceDevelopment

3 ай бұрын

Yep

Interesting watching. Will have to contact you about some gear for a rm250 2000 model

So Derek, no STIC/Keihin this year? Someone said Jared has Lectron sponsor this year. I have a 125X buddy that did this move, bc he said the STIC was too much instant power down low(C+ rider on trails). Another dude told me he pulled the block, too much YAT for his CR125 at tracks. I run the yet stronger new STIC Super X on my 200SX. I run the slowest turn G2 cam, as to get more control, as it returns a normal spread of power again. Not stupid all within an 1/8 turn.

@HPRaceDevelopment

3 ай бұрын

As I understand they are a title sponsor now.

Any updates on the ceramic bearings please?

@HPRaceDevelopment

2 ай бұрын

regarding what

@ValentineFarm

2 ай бұрын

@@HPRaceDevelopment how they are going and if there is a difference in power etc please. 😊

@HPRaceDevelopment

2 ай бұрын

No power difference as I mentioned in the video. Currently 2 hours on them - so we shall see@@ValentineFarm

@ValentineFarm

2 ай бұрын

@@HPRaceDevelopment thank you for answering, looking forward to seeing how they go. 😊

Your videos are extremely interesting so I have three questions to ask. There’s been so much talk about a straight 250 vs 250 class. From what you’ve seen and tested, what is the most peak HP you can extract from a 250 2T vs a 250F and do you think it would be fair? Also I’ve been comparing the 300SX vs the 350s as I’m considering it for a next bike. In terms of peak HP what do they make on your dyno?

@HPRaceDevelopment

4 күн бұрын

Would be a good video. A pro 250f will kill all 250 2t, power is similar and 250f has much wider power window. Thats why 4 strokes are so good, they are able to put down more average power - as we cant keep any engine at just one rpm the whole time. 350 makes more power than 300, but on those 2 the 300 will feel lighter and at times more nimble, more exciting. I think for some people the 2t is still great option but at pro - it would get smoked on equal riders

@da5863

4 күн бұрын

@@HPRaceDevelopment thanks for the response, I’m not sure if you are familiar with Nicholas Lapucci but he was able to win the EMX250 class on a Fantic(YZ250). Do you see any inherent 2 strokes advantages that could explain why he dominated that class against a sea of 250Fs?

@HPRaceDevelopment

4 күн бұрын

@@da5863 Again it comes down to rider - a 250 2t is capable of competing against a 250f but its not an advantage. Its not what people want to hear so they dont believe me - but its the truth. If the rider can shift on time, manage the power perfectly, and do evrry detail right they are on par with a slight peak hp advantage but for only about a 1000 rpm window. a good 250 f makes within 1-2 hp, but makes that power for a 5000-6000 rpm window.

@da5863

3 күн бұрын

@@HPRaceDevelopment I see what you’re saying, but don’t 2 strokes have a massive torque advantage? On a deep loamy track how would the torque difference not be a massive advantage between a 250 2T and 250F? Comparing stock bikes the typical 250 2T will make at least 8-9 lb ft more than a 250F. If 2 strokes are more powerful per CC why is it that pro 250 2T are only 1-2 hp stronger at peak than pro 250Fs?

@HPRaceDevelopment

3 күн бұрын

@@da5863 Understanding the difference between torque and horsepower is challenging for most people. Engine Torque is a meaningless number without rpm at said torque - and if you put the effort into learning why this fundamental truth is why power is all that matters - a lot of things in racing become more obvious. Power is define by your ability to do a set amount of work in a set amount of time. Time is what matters in racing….

you don't ditch the plastic crank stuffers?

@HPRaceDevelopment

3 ай бұрын

Nope - I think that entire concept is dumb. They only “melt” if you loose a rod bearing - they are never the cause of failures.

@minibikemadman

3 ай бұрын

@@HPRaceDevelopment I've seen em go on the smaller 65s and 85 ktms..didn't know if the yamahas had the same issue. I know they make billet ones.

@HPRaceDevelopment

3 ай бұрын

@@minibikemadman they dont “go” in our experience the rod goes and melts the stuffer or the bolts come out and werent properly loctited - a common ktm issue on all sorts of bolts

@minibikemadman

3 ай бұрын

@HPRaceDevelopment ya the bolts I've heard are a issue..im always intrigued by that kinda stuff..I've got a 380cc cpi lynx cylinder on some billet cases for my trx 250r...im a hard core 2 stroke guy.

So no modifications on the crack case ?

@HPRaceDevelopment

3 ай бұрын

Nope - what mods do you think would make additional power

@freddyvenerini

3 ай бұрын

Maybe the side where cylinder and case joint, smooth them and make sure they are line up perfectly

@troylambert5140

2 ай бұрын

This guy is awesome spectacular work sir do you have a price list and list of services for both two strokes and four strokes?

Whaaat? A pro rider uses a flywheel weight? I thought that was only for enduro guys 😂. Are you running the gytr flywheel or a stealthy?

@HPRaceDevelopment

3 ай бұрын

I think he he has both actually

@Shaw413

3 ай бұрын

We run the GYTR YZ250X flywheel weight, so its +8.04oz. Helps with the small chatter out of the corner in SX/AX and helps a ton for getting the rear wheel to roll over the whoops, without it, each whoop seemed to stop the wheel, so this helps it drive across them.

For a "PRO" mechanic it amazes me that you don't have a engine stand/holder and a crank puller/extractor tool. Iam waiting for the outcome of Ceramic bearings Cheers from Sweden

@HPRaceDevelopment

3 ай бұрын

HUH? Without a doubt the wooden boxes are the best assembly stand on the planet. We have multiple engine stands - and top dollar ones at that - and all they are good for is looking nice for social media or basic top end work. I have multiple "crank pullers" and "installers". That said sweating in the crank via hot and cold is BY FAR a superior assembly method. In tear down - of course we use a crank "pusher" "case puller".

@zacharyhickman8382

3 ай бұрын

These comments usually come from a guy who believes it's a requirement to use a torque wrench on the oil drain plug..

@Motoinc

3 ай бұрын

@@zacharyhickman8382 haha that was a good one👍 It was a ....written with blink in the eye...like a "joke" .....any funny in you 2 guys bodies?.....nah

@HPRaceDevelopment

3 ай бұрын

I guess im just not a pro mechanic...that's my real problem @@Motoinc

@Motoinc

3 ай бұрын

@@HPRaceDevelopment 🤣🤣👍

Thanks for the awesome insight but you didn't even spell his name correctly in the description ... wtf? It's Jared Lesher

@HPRaceDevelopment

3 ай бұрын

Ooops. Maybe you can forgive us...or maybe I wanted an extra comment for the algorithm...

@11GalleryATV

3 ай бұрын

@@HPRaceDevelopment ha! no worries, I just thought you would like to know since google won't pick it up if someone searches, the way you spelled it ... rock on, and thanks for motor insight!

Being fast is expensive

@HPRaceDevelopment

3 ай бұрын

sometimes….these are very cheap vs our supercross four strokes…

Not to take away from the content or your view count, but have you or anyone reading this heard of a you tube channel called '2 Stroke Stuffing'? Dude has been building and developing a supercharged, rotary valve, 50cc 2T engine from scratch in his garage hoping to get 50hp on his home made dyno. it's like a fail video in super slo-mo. 😮

@HPRaceDevelopment

3 ай бұрын

i do watch him, its a struggle at times as he has visions of granduer but thus far he has missed the boat. If i were him - id start with the best 50 that exists already - approx 20 crankshaft hp - and add the power adders to it. He tried too many new things at once and it has hurt him

@DougTunnler

3 ай бұрын

@@HPRaceDevelopment i think you're right. worked on paper and looked good with nice cameras. 😂

@HPRaceDevelopment

3 ай бұрын

I'd love to hire him - he is very good problem solver on mechanical things. And his skills at film and production are top notch - totally under rated@@DougTunnler

Why did you spend all that time to put a motor together with a fried clutch.

@HPRaceDevelopment

2 ай бұрын

His mechanic is more than capable of swapping clutch plates…answered in the video why did you take the time to ask the question….

@likeaboss860

2 ай бұрын

@@HPRaceDevelopment I don't understand putting worn parts in dude

@HPRaceDevelopment

2 ай бұрын

@@likeaboss860 Don't understand what???? He didn't ship the parts to me to replace - we turned this engine around in under a week - and it wasn't planned. He owns multiple replacement clutches - and is more than capable of installing them. I ship it complete so it's safer than trying to package loose parts in a cooler.... Not that complicated. But guess you don't understand.

Great build. But not a fan that he says there are no "secrets here" and then points out the head and says he won't show us that......

@HPRaceDevelopment

3 ай бұрын

You have a pause button….

Why not leave all the coating intact? rather than remove some for signatures, name brands, "#412" etc. I get it, promote what you've proved to be a great product. I'd rather see the magic port work.

@HPRaceDevelopment

3 ай бұрын

You gotta pay to see that… The pistons only “rub” where this one is worn off at - lower third of skirts. So those are the critical areas to coat - the other areas are just for bling mostly but included for the same price so why not make it look cool.

I can tell you know what you are doing. IMO, you should leave the shops phone number. Some contact, but I like the phone because we are suppose to do business with each other. Business is personal. :)