YZ250 2-Stroke Engine Assembly

In this video I assemble a 2004 Yamaha YZ250 2-stroke engine from the ground up. Let's get the bike dialed in!

[@wanted_450r]

i’m young and trying to learn these mechanics and i stumbled across your videos i just binge watch these to learn all about motors and engines thanks for uploading these videos and don’t ever feel discouraged please keep them coming 💪🏼

[@nastysoda9212]

Awesome rebuild! Your mechanical knowledge and skills are crazy for your age. Super impressive.

[@knolysjohnson7244]

Nice work man like how you are cleaning up replacing all worn parts, The little details make a big difference!

[@himotox2788]

Turned out great bro🤙 keep it up

[@motoxjim929]

Awesome build!!

[@charliesbuyandsell3486]

Love your vids man

[@robertwoods2505]

Very good job and thank you for sharing it.

[@Tatted_gunna]

Beautiful job buddy 🤙🏼

[@surronstuntz3146]

i love rebuild videos

[@leelafarlett3535]

I piut my thrust washer on, then the primary drive gear, then the second gear, and the second gear didnt make it all the way to the end of the shaft, making it impossible to get them tight. Also the primary drive gear dosent line up with the driven gear on the basket. It meshes about half way, actually less. And one more thing, there is a huge air leak through the splines on the crank, Anyone making sense out of all this? I even checked to make sure my year modle was a 2001. I did notice the repair manual that someone gave me was for a 2019 yz250. Was told they were the same . Cant find one for a 2001

[@sethverzinski7202]

At 22:47, that washer in the idler gear is supposed to go between the gear and the curclip, not behind the gear. Reference via service manual

[@travisk5589]

This is correct. 11:55 He put it in wrong

[@braxtonduden4474]

How much to rebuild my yz125

[@AbcAbc-ox6pg]

Do you have long-term experience with the hot rods crankshafts? I've read about connecting rod tears many times.

[@oprghost7227]

Hi I’m rebuilding a yz250, I replaced the bearings along with the bearing cap/seals and the crank as well. When I went to put the casing back together, it didn’t want to fully seet down. I ended up getting it about a quarter inch away from being fully flush but it won’t go the rest of the way down. When i tried putting a few screws in the block and lightly torquing them down to see if it would help, it caused the crank to freeze up and also made no difference in the gap in the block. Any ideas?

[@jzsquad6866]

I didn’t know you could press the bearings into place like that I thought they had to be frozen

[@CammedRacingCo]

Thats the correct way heat and cold it’s a machined fit bore if you do it room temp and with a press you risk messing up that interference of the bore

[@padilahpadil745]

Yamaha semakin didepan

[@skylerlaw24]

Is the rear rim bent on that 250

[@poojr1828]

how do you know where to put the bearings

[@kurtdavidson9808]

How’s it going? This was a great video. Thinking about doing anything to the bottom end of a motor has always scared me to death. Because of this video it’s a little less scary.(thank you) just wondering you seem to be very knowledgeable when it comes to the re builds or bikes in general. Have you had any formal education or are you self taught? The reason I ask is that myself and my three sons all have bikes and I just can afford to pay a shop to do all the maintenance that comes with owning dirt bikes. Please keep doing the videos and if you could not skip any aspects of the builds that would be greatly appreciated. That bike sounds as good as my 21 yz125. Thanks

[@akmoto_]

I can't show every step of the process, that'd make the videos many hours long. Everything always looks much easier in a video, but takes much longer off camera.

[@theaustralianconundrum]

@@akmoto_ Use a seal installer to fit new seal in place. Don’t hammer directly on the seal, and never use a punch or drift to install the seal. Denting of the seal’s shell by the punch can distort the lip and cause the seal to leak. All seals are pressed into place in the factory. I have done several factory tours in Japan and the Yamaha assemblers do NOT belt them in as you are doing here. FAIL!

[@alexisbenetatos1611]

Great job rebuilding that motor but why wouldn’t install a new clutch? Those clutch plates you installed looked really burnt up

[@samgrandberry9866]

You need to be trying to contact some top amateurs in the Texas area, they would easily hire you!!

[@pars9455]

Hi. I have a question,I have 96/98 two yz 250 2 stroke. Can you please help me find out what type of engine I have?And what is engine B type or another types ? How do we know what type we have ? And how can we find good quality (like what brand ) parts for engine too and bottoms for rebuild ? Thank you.

[@akmoto_]

I get all my parts from RMATVMC

[@Thepianobird]

im just wondering why you would not put OEM bearings in and would put chinese stuff?

[@kosailin8665]

👍👍

[@salvatorebuda5182]

every minute 12:48 there is an assembly error, the gear ( Primary Drive Yz250 1n1ss-100e1)must be assembled upside down

[@redrum7790]

Wish we could seen the last pet put on the bike

[@ericrivera219]

Where is your torque wrench??

[@eschrader]

Where are you engine rebuild videos?

[@josephineknutson9259]

hard working young child,.

[@mrmotocross6819]

Look up the torque spec of the crank case bolts and torque them to spec.

[@mrmotocross6819]

Bro i like the fact your building your own engines. But torque specs are made for a reason use them. Torque all case bolts and cylinder bolts to spec, or one day they may just rattle out. Use the torque specs bro .

[@akmoto_]

If torquing each and every single fastener makes you feel better then go right ahead. I always make sure to torque anything important (clutch hub nut, primary drive gear bolt, cylinder head bolts, etc) but for case bolts you could also just go by feel. I’ve done a few engines this way and don’t see anything wrong with it, as long as they are all snug and equally torqued. Spec is 10 lb/ft, which isn’t much at all. Low spec because these bolts are threading into aluminum.

[@redtobertshateshandles]

@@akmoto_ I started my motorcycle mechanic apprenticeship in 1979. We never torqued those small screws or bolts. Head bolts were about the only thing we torqued.