1:11

2021 YZ250F Yamaha top end rebuild. New piston, checking valves and a good checkup on the bottom end while in there.
Donate Race Fuel link... www.paypal.com...
Thanks for watching!
[e-mail]

[@Somebaldeagles]

I never comment on KZbin videos, but this most informative moto video I’ve seen. I just finished replacing the top end on my 2020 yz250f and this video made it so easy to do. Thank you!!!

[@UpAllNight91]

Oh man thats great news! Thanks for sharing. My wife has a female friend who is about to do the same job and will be following this video. Hearing you say it got you though it surely gives me the confidence it will walk her through it well. Happy New Years!

[@damnbikerw5043]

Thanks for taking the time to do this video. Very informative and thorough explanations as you were completing each step. Hopefully you’ll keep doing these types of videos.

[@UpAllNight91]

Thanks! Appreciate it. Yes I do plan to keep doing these as different jobs come around

[@kaydendelgado6]

man you are FKIN AWESOME for this video. this is my first time doing a top end and long story short it’s been a nightmare until i found your video. your video helped me walk through step by step to finish up my bike and get it ready and i can’t say thank you enough!

[@UpAllNight91]

Dude thats awesome news! Thanks for letting me know and glad it to hear it helped!

[@lawrencecorbo6586]

Spider nice track

[@UpAllNight91]

For sure. Miss that track!

[@mattbishell6759]

I plan on using this vid for when I do my top end , great vids man and very informative

[@UpAllNight91]

Right on! Glad it will be of help!

[@athinastudios5899]

Amazing video, thank a lot dude, just a tip, you could film even the idiotic parts like filling with oil and coolant, some times it matters... Anyay thanks a lot

[@UpAllNight91]

Hello. Thanks and thanks for the tip. I think your right. I probably should include even that little stuff. Thanks!

[@Fefell_fe]

Such a great video I appreciate the detail and explanation on the steps. Do you know why we have to grease the cylinder mount bolts?

[@UpAllNight91]

Thanks! Oiling the cylinder head bolts reduces the friction when bolting them down. This is done so the torque wrench can torque the bolt down to the correct specs without additional friction getting in the way.

[@Fefell_fe]

@@UpAllNight91 oh cool thank you for explaining

[@UpAllNight91]

@@Fefell_fe Yes Mahm!

[@bobileksen3496]

You Are the best man 👏🏻

[@UpAllNight91]

Thanks!😊

[@joelatkinson2080]

Another great video!!!

[@UpAllNight91]

Glad you enjoyed it!

[@jshab001]

Just finished the rebuild on my 2015 YZ250F. It started right up but now I am getting a backfire and it’s hard to get started again. Any advice would be so appreciated? These videos are absolutely awesome. Thank you.

[@UpAllNight91]

I would start by double checking anything that you unplugged during the job, The intake air temp sensor, TPS, and all. Something might have came undone.

[@evergiordano]

Did you forget to install one of the cam chain plastic guides back on?

[@UpAllNight91]

Hello. No if you check the 50:30 mark that where I slide in the second guide.

[@UpAllNight91]

Awesome!

[@lawrencecorbo6586]

One question for the group when to change / the timing chain tensioner / is that holding clip available !!

[@UpAllNight91]

I dont know if anyone sells them. I acquired mine from purchasing new timing chain tensioners, some makes and models include the tool with the purchase. But I imagine it wouldnt be hard to make with some tin and tin snips if needed.

[@UpAllNight91]

Like this one on this link here www.ebay.com/itm/355062523809?hash=item52ab6027a1:g:1HEAAOSwRLxlE~nT&amdata=enc%3AAQAIAAAA8KuWImzIyufrC9jXiWnbV7SRvU%2FJxHMgR2QoGaN5ZbG%2FAxSC4hY%2FHS3PkCMd%2FuC4%2BTcLCpPFSR0RYKUVAR7IEYLZCpJRAMg9mrwfhGG1XMh34m5ERpCl1JqP%2Bl8la%2BAKT%2FbO61%2BF0m9UNCIpNsR8dRrc9N%2BsagadYBVn4rQlEH%2BZzkYJm3DX0UVsOkYXjKcLpGhd9%2FUeTi%2FLrcs6N%2Frzck9YusrFTUjSsIjR7mya4c1vLHtq4E1duFHOFfZC7hdXlJJa6QT6lJyrHpVD7K53vLyh%2F2b7ylNw0uMCVHP39OeOyoAdQNSPhrJZmBk3CuwWnA%3D%3D%7Ctkp%3ABFBMyuLE_qpj

[@lawrencecorbo6586]

Thanks for getting back to me

[@barbenfischen]

Great video, but I was wondering why you didn`t exchanged the timing chain like in the YZ450F video? I realized that the 250 possess the same flywheel and I have to order one. Problem: Ebay says M30x1, but I measured the diameter ~24mm. Can you tell me the specs of this tool. P.S.: How can I screw the nut with the right torque, when I don`t have experience with my impact drill please? Thanks in advance

[@UpAllNight91]

Thanks. The puller needed for the YZ250f is a 24mm x 1.5mm thread. I didnt do the chain because the owner didnt want a new chain, only a piston. But a new chain is always a good idea for sure. After making the video someone pointed out that there is a place on the flywheel just below the thread that the puller threads onto that allows you to hold the flywheel with a wrench as you tighten the flywheel nut. It is also shown being done this way in the manual. I just never noticed that before. So you should be able to tighten it up that way if not using a impact. Hope this helps.

[@barbenfischen]

@@UpAllNight91 thanks for your support. What di you think about the size of the replacement piston (serial diameter or B-size +0,01mm). Thanks

[@UpAllNight91]

@@barbenfischen I really dont think its needed. I would just replace with the stock size as long as the cylinder still looks good. Its a sure safe bet that way. I have a video on cylinders that may help you whewn it comes to inspecting your cylinder, here is a link kzbin.info/www/bejne/d6C0ZZKXprudqtE

[@barbenfischen]

@@UpAllNight91 thanks for the nice video of the cyclinder stuff. The surface in the front and rear don`t look as new in my case, I will check with a engine expert if he can just fine hone it. I don`t know how many this will change the diameter and if the original piston size anymore.

[@UpAllNight91]

@@barbenfischen Right on

[@user-fj4ds5vq9l]

Nice edkt job right when u started the bike back up lol...just no way it would start that quick after ripping the engine apart...plus u could tell it was edited ..only question is ..wjy??

[@UpAllNight91]

Hello. Been so long since I did this video I honestly wouldn't remember if I did or why I did. Sorry

[@kyleallen146]

Thanks so much for the video! Planning on doing my 2019 yz250F in the next week. First time doing it and tackling it myself😎 mechanically inclined so not too worried. Anything I should be careful of? Replacing everything with OEM parts🙏🏻 and what grease do I use on the bolts? Motor oil or bearing grease?

[@UpAllNight91]

Hello. Hmm, if your doing the timing chain too, a viewer pointed out that the flywheel can be held with a wrench while installing and removing (instead of a impact or if you don't have one). Its mentioned and shown in the manual. I just completed overlooked that. You can download the manual for free. It does have lots of useful information. Otherwise its all pretty straightforward and you should be good!

[@UpAllNight91]

I like to just use motor oil on the bolt. If I remember correctly thats all the manual mentions to use as well

[@kyleallen146]

Perfect thanks so much! Will check the manual about the fly wheel🙏🏻 keep up the awesome videos man!

[@UpAllNight91]

Right on and thanks!

[@kyleallen146]

Me again man! Did the top end successfully😎 now checked valve clearance and the left intake went from 0.14 to 0.23🤔 is that normal? Last reading was 16/09/23 Everything turns super smooth when turning it over on the crank/flywheel. I also put a new timing chain on. Timing is aligned etc

[@lawrencecorbo6586]

How many hours on timing chain

[@UpAllNight91]

I honestly don't remember how many hours where on this bike during this job.

[@hud2713]

Hey man, I hope you see this because I’m stuck in a sticky situation, at 845 ish in the video you’re taking off the fuel line from the tank to the throttle body, I’ve squeezed the buttons and wiggled and have tried everything and it won’t come off, any ideas or suggestions would be very helpful!

[@UpAllNight91]

Yes. Try pressing the hoses together as if you where reconnecting, while pressing together also press the two little buttons in deep and then slide them apart

[@UpAllNight91]

Any luck?

[@hud2713]

@@UpAllNight91 ok I’ll give it a try when I get home, thanks

[@hud2713]

@@UpAllNight91working on it right now we’ll see

[@hud2713]

@@UpAllNight91it worked, something was just stuck inside of there, but I pushed it back on and it clicked and then was super easy to get off!

[@lawrencecorbo6586]

How is it so clean ( personally I have start over and remove what I missed during cleaning

[@UpAllNight91]

Sorry, whats clean?

[@lawrencecorbo6586]

@@UpAllNight91 no clumps of mud my motorcycle is from New York originally and I thought I washed it good !! Not the case

[@UpAllNight91]

@@lawrencecorbo6586 Ahh got ya! LoL.

[@andrew.cardone]

Great vid! Question tho…I’m in the process of doing the same and I was going to hone out the cylinder but have no idea what material the cylinder is made of to know exactly what hone to get. Would you happen to know this or does the steel wool work?

[@UpAllNight91]

Thanks. Its a nickel plated cylinder. Honing is usually not required if its still in good shape. Just a good cleaning with steal wool will do as long as its still in good shape. I did a video on cylinders that may help, here is a link kzbin.info/www/bejne/d6C0ZZKXprudqtE

[@mattbishell6759]

Was that piston and rings standard size or where they oversize

[@UpAllNight91]

Standard size.

[@LoganPiper-du6hg]

Hey thinking about doing a top end on my 2021 yz250f with 165 hours on it where did you get the parts for the top end In the video. If possible send a link. Thanks

[@UpAllNight91]

Hello. I ordered the parts on rockymountain . I dont have a direct link to the parts but I do have a video that will walk you though ordering OEM parts from these sites, hope it helps, here is a link to it kzbin.info/www/bejne/qZ2yl3qFgramntU

[@LoganPiper-du6hg]

Thanks so much very helpful

[@UpAllNight91]

@@LoganPiper-du6hg Your welcome!

[@Dan_416]

Did you measure the cylinder bore off camera or did you not measure? If you did not, is it uncommon to need to replace or replate the cylinder?

[@UpAllNight91]

Hello. No I didnt measure it. It still showed all its honing which indicates to me there is no real measurable wear on the cylinder. and all thats needed is a new piston to freshen her up. These nickle plated cylinders last a long time and can be reused many times before they start wearing thin (under good maintenance). I did a video on cylinders some time back if you are interested here is a link kzbin.info/www/bejne/d6C0ZZKXprudqtEsi=VaCbHf4odYNQk0O4 Thanks for watching!

[@Dan_416]

@@UpAllNight91 Thanks for the reply. I'll watch your other video as well. I've got a top end to do this winter, so I'm just doing a little research.

[@UpAllNight91]

Right on, research is good!

[@oneeyehunter8248]

Did you reuse the head bolts or are they new?

[@UpAllNight91]

I reused them. I'm ok reusing head bolts on these bikes one time. On the next top end it will get a new set of head bolts. Some say using them 3 times is ok but I only reuse them once

[@oneeyehunter8248]

@@UpAllNight91 thank you. I'm getting ready for the first top end and was wondering about the blots.

[@UpAllNight91]

@@oneeyehunter8248Right on!

[@LuckyNikitaBoba]

At 43:15, I noticed the black cam chain guide. Is that removable? It doesn’t look like it.

[@UpAllNight91]

It is, but it is bolted down, down under the stator cover behind the flywheel. There is a bolt holding it down.

[@clouse526]

My crank had a green dot on it. i lined it up to the arrow and had perfect cams lined up after top end and re shimmed valves and it starts rough and backfires when tryiong to start now. any thoughts?

[@UpAllNight91]

I would start by rechecked the cam timing and valve clearance again. If all that's well then double check all connections like the air intake sensor, throttle position sensor and such.

[@traxxasrc1]

Use the machined marking it’s not the green dot

[@sethmacgillivary1281]

How long will the crank in this last?

[@UpAllNight91]

It really depends on the rider, usage, and maintenance. It can last 200 hours if the bike is treated right. At 200 hours its suggested to replace the crank no matter how well it checks out (mainly for track use, big jumps and stuff) but if its just trail riding you can take it past 200 hours if your ok with it.

[@sethmacgillivary1281]

@@UpAllNight91 oh ok how many do yz 125 cranks last u?

[@UpAllNight91]

​@sethmacgillivary1281 it depends really. If a good amount of premix is run. And everything stays good the yz125 crank can last a very long time. Longer than even the yz250 crank. I currently have about 85 hours on mine and the cranks lower rod bearing is not showing any real wear yet. My wife's yz125 (which she rides rather easy) is about to hit 300 hours (and I'm not even kidding). Very durable cranks as long as enough premix is used and jetting is close enough.

[@UpAllNight91]

I would say in good care the crank bearings usually show wear sooner on the yz125 than the cranks lower rod bearing does.

[@sethmacgillivary1281]

@@UpAllNight91 how tf do they last longer then 250???