Yamaha YZ250F Top End Rebuild | Part 2

Top End Rebuild Parts and Tools:
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If you need to rebuild the top end on a Yamaha four stroke motor, but you are not sure what to do, you are at the right place. Our detailed instructional video will walk you through how to rebuild the top end on a modern day YZ250F motor. The steps shown in this video will be the same as they are on a YZ250F and the WR450F and YZ450F. Get all your bike rebuild needs at rockymountaina... !
Watch Next:
Yamaha YZ250F Top End Rebuild | Part 1
• Yamaha YZ250F Top End ...
Yamaha YZ250F Top End Rebuild | Part 2
• Yamaha YZ250F Top End ...
4-Stroke Motorcycle Cylinder Head Rebuild
• 4-Stroke Motorcycle Cy...
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[@wrathofrighteousness4801]

"If you don't have any friends, ask your mom." Classic. Great video. Thanks for putting it together.

[@lyricderbin1169]

Caught me so off guard😂

[@johnbrass8910]

After you torque the head, wait an hour or so, and check the torque again, you will notice that they loosened up, because the head is compressing the new head gasket. Also lower the spark plug with a magnet, so that the gap does not get smashed if you just drop it in.

[@rmatvmc]

Good tip! Thanks for checking out the video.

[@samkeeley2871]

Just follow you guys step by step now waiting for coolant to arrive to hopefully have a running bike for the first time in 4 months

[@jameo1095]

The engineering behind piston rings is pretty interesting.

[@renostubbs8504]

Brilliant job Steve, you are an amazing bike mechanic,wish you were our neighbor... Awesome video bro

[@damberson4698]

Valves clearance should be checked before finishing this job

[@keptoutsideproductions]

damberson4698 I 2nd this! Lol

[@user-ms8ri3fb5j]

YES

[@KOSIARA666]

I just working on my yamaha yz250f 2016 very helpful

[@hreindustries]

Great video, so relaxing and informative.

[@232Stangpwr]

"Ask your mom." 😂😂😂😂

[@raptormx9502]

Lol if you don’t have any friends ask your mom

[@MerroEnduro]

hahahah

[@AdrenalineRushMX]

my mom would help me for sure lol

[@yzf450]

this was one thing what I understand :D :D

[@fla8502]

Hardest part of the build is inserting the cer clip. He makes it look so easy

[@Sir_Wilo]

“If you dont have any friends, ask your mom” 😂😂😂😂

[@johnbrass8910]

I made the mistake of installing the head and cylinder, after that, the front plastic chain guide would not slip into the top of the cylinder slot. I had to remove head, and place it into slot. (service manual does not show steps) Good video.

[@johnbrass8910]

I made that mistake as well, the service manual doesn't say anything about it

[@NCCreationz]

I have to rebuild the top in on my YZ 250 F I know how to do the labor, but there are a few things I have questions about to make sure they are correct! Thank you

[@mike_paschos]

Awesome video!

[@stevenmcilwrath5371]

Can you tell me what grit of ball hone should be used please?

[@motomatt6752]

Man great video I really wish I lived closer to you would still want some professional help with this we need a fresh top end in my sons 2019 yz250f

[@Tommy-lu3my]

1:53 wanna lightly put it and move it back and forth lightly

[@pc-dc4gm]

To clarify, do NOT let it idle for 30 minutes. He means stay under half throttle when riding it

[@connersnow298]

Awesome vid and edits and filming and bike

[@plbyrne]

That was awesome - thanks

[@TaxationIsTheft439]

Do you still have to torque to a spec then remove and re torque to different spec even when your reusing the cam bolts

[@jake300win]

Thanks for the video! will be ordering the rebuild parts from y'all soon. Already buy my gear from you

[@ABCsuspention]

Hello sir...I have a 2013 Yamaha yz250f...while there is a slight scratch on the piston...the piston size I use is 76.98 vertex D.is there a bigger piston?

[@KOSIARA666]

Great video

[@gavinjack9321]

What size ball hone!!???

[@chuckfinley3152]

Fun fact, I rebuilt my 2 stroke top end in the time of this video

[@mochacraft6865]

Chuck Finley i see a lot people say they claim to do this in 20-30 minutes but I imagine it runs like shit, and if you want, make a video and prove me wrong.

[@chuckfinley3152]

Mochacraft have you ever heard of sarcasm dumb ass?

[@Aabbcczzxxcc]

Chuck Finley but this video about dirt bikes, not about chainsaw))

[@jakewaggoner4196]

@@mochacraft6865 I saw a video of a kid doing his top end at Glen Helen between moto since he blew is motor up. It takes me about 8 hours total but I like to take everything off for room so I take the radiators off, tank, sub frame, carb, ect. After watching these motors I'm really surprised how easy the 4t's are!

[@100868ful]

I like 4 strokes a lot but heck I’d rather do a top end or bottom end rebuilt on a two stroke any day. Less is more. Long live the 2 Stroke!

[@dirtbikerplay11]

This useful

[@05redser]

If you don't have any friends, ask your mom 😂😂😂😂

[@rmatvmc]

🤣

[@richardcayer2937]

Hey just curious at 7:28 in the video. When you are putting the head on the cylinder why does it seem like you have 3 gaskets for it?

[@rmatvmc]

The stock head gasket has 3 layers riveted together.

[@vistkri]

Good video

[@TheMadMonkey3]

Is the process the same for a 2018 wr250f?

[@TubolMotoadventures]

Hi I didn't know that there is A B C size vertex piston.. I bought the A size on my first rebuild and after the rebuild a very light puff of blue smoke coming out when reving the engine on high RPM.. Was it because I'm using A sized piston instead of B sized?

[@NCCreationz]

It’s funny, it’s pacifically says in the instruction sheet persons Pro X do not use a ball hone but seems to work fine. Anybody have any opinions on this?

[@haydenbaha]

Would recommend someone new to working on bikes to do this or should I pay someone to do it?

[@stuckcamping]

If you have the tools go for it, it's super easy.

[@bertamusprime618]

Just like M. Kasner said if you got the tools then go for it. My only suggestion is stay super organized. Clear out a big spot where you can work. If you don't have a garage or a shed ask to use a friend's. I was super nervous when I did my first top end on a 04 WR450 but I stayed super organized and it turned out great.

[@rmatvmc]

If you take your time and follow these steps and have the tools, like mentioned below, you can get er' done!

[@hreindustries]

probably pay someone, I would try this first on an old bike or like a pit bike.

[@haydenbaha]

I really appreciate the feedback. This video is very helpful because there is little to none on information on working on these bikes. I had just bought a 17 YZ250F and found it has a 100 hours on it. I got a screwed and this is my first bike. Didn’t know better. I have been wanting to do a top end as a preventive measurement.

[@ItsJohnFkinLyons]

Forgot the coolant o ring on the base

[@muhammadkhan3557]

is this the same engine as 2005 yzf250

[@Kyle-pl6rl]

I have a 450fx and it's a pain to work on. Great bike but so much has to come off to do a top end.

[@volkusa5808]

Get a 2 stroke..

[@axelayerdi8524]

The new piston its the same size that the old pistón?

[@blinxkyanalyst5053]

Sooo I followed all the steps and my kickstart is stuck 🤷🏽‍♂️ , I don’t know what might have happened??

[@slickstrings]

It means something is bound up or hitting something. If you didn't align the timing marks properly, the piston might be hitting the valves for example. DONT force it, take it apart and re check everything

[@braedenwalton1480]

@@slickstrings timing is probably off. had the same issue. do not kick it if its stuck. you can bend valves

[@karenmler5632]

I have the same issue😦

[@karenmler5632]

I followed every step in the video but i cant turn the engine over

[@kcind3371]

You’re not supposed to hone a coated cylinder unless you have a diamond hone

[@hydrogenlion1852]

Coooooooool

[@gaylynnevans4025]

Wiseco piston part 40111M09700 for a 2017 YZ450F - the top of the piston doesn't have an arrow but has FWD. It seems that normally the arrow points towards the exhaust but on the YZ450f the exhaust in the rear. so I am assuming that FWD is towards the front of the bike which would be the intake? Also, the instructions tell me to put an oil rail above and below the oil ring expander - yet my package only came with 1 oil ring expander, 1 oil rail and a top ring - am i missing one? thanks

[@daddywood-88]

When is the timing chain to streched out. & What is the measurement from link to link. 2005 xt 225 Yamaha.

[@jameswilson4780]

Palykidrock

[@lemontebrown566]

Did the bike ever start tho

[@eviloracle]

now i know why its still sitting with the valve cover and head off for the last 10 years. time to knock out some projects and tear this thing apart.

[@benshort7740]

What size cylinder hone did you use I got a 14 yz250f and it’s burning oil

[@rmatvmc]

If you enter your bike on our website it will tell you the correct size. Should be the 77-83mm.

[@ethansexton2725]

@@rmatvmci have a 2022yz250f i have a 83mm ball hone will it fit?

[@gamercoboy6787]

Yea guys I have a question what bike should I get a yz250f or a kx250f I’m 6’1’ 125 pounds and I’m 14

[@skidoo31]

Yz is a more reliable bike however both are good. cant go wrong with either

[@mochacraft6865]

Gamercoboy 678 it’s literally just preference, sit on both and see which one fits better

[@gamercoboy6787]

Mochacraft well I have a old 2008 kx250f and I like it and at this dealership in my city they sell a yz250f which I sat on and test rode and I like both yet I wanna get the new 2018 kx250f which I really like yet I heard both the yz and kx are both good bikes so idk which one I like more

[@thatguyrides7072]

How do you check timing if you don't have a kickstarter?

[@HazrdHazrd]

Move the fly wheel

[@gavinjack9321]

What size ball hone???

[@stevenmcilwrath5371]

77-83mm

[@billnyetheapplianceguyju5080]

Hello

[@gavinjack9321]

I can’t figure witch way to position piston ring ends even after I look at manual

[@DaCodesMan]

Did you get it working? Is your bike running now?

[@peteh8077]

Don't trust anyone that doesn't know the difference between level and square.

[@justinsavs]

"If you don't have any friends, Ask your mom" Wow. Why do you have to be so right?

[@2759sausage]

If you don't have any friends, ask your mum... Story of my life.

[@stevenmcilwrath5371]

What size ball hone and what exactly is that he sprays on the ball hone to lubricate it?

[@rmatvmc]

The ball hone for this bike was the 77-83mm and the lubricant we used was Maxima MPPL. Flex-Hone: www.rockymountainatvmc.com/parts/flex-hone-cylinder-ball-hone-p Maxima MPPL Lube: www.rockymountainatvmc.com/parts/maxima-mppl-lube-p

[@stevenmcilwrath5371]

@@rmatvmc thanks for replying. Will the same size hone do for a 2019 yz250f?

[@TubolMotoadventures]

Hi I did not hone my cylinder because I do not have the tool and just put new piston kit on it. Replaced all the valve seals also. Noticed a thin blue smoke when I rev high the bike after rebuild and after spending 2 hours on it. Im thinking that is because the cylinder was not honed.. Can I still hone the cylider and put it back togher even I've already riden the motor after few hours?

[@illhaveanother4365]

No, you now have to take bike to salvage yard

[@TubolMotoadventures]

@@illhaveanother4365 it's been 2 years and still using the same piston. :P

[@haloreach107able]

Anyone ever have the bucket not able to come out even with a magnet? If so I need some tips on how to.

[@bosu1855]

how often do you rebuild top ends?

[@countryboymtb1042]

i heard that you want to do it about every 50 hours just the bike running in tip top shape.

[@F80__Los]

No lubes when installing the piston into the cylinder? On the rimgs?

[@rmatvmc]

You can see him putting assembly lube on the piston skirt at 6:19 when installing the piston. If you want to lube the rings when installing them, it's up to you!

[@F80__Los]

@@rmatvmc oh I thought you were supposed to run it dry for proper break in

[@rmatvmc]

You will want to have assembly lube on any internal moving part when putting an engine back together.

[@F80__Los]

@@rmatvmc oh okay thanks for the info!

[@austinrosser9522]

I have a 2014 yz250f. My intake cam does not point upward when the cam marks are level with the head. Exhaust cam points upward like yours. Could my intake have a spun cam?

[@rmatvmc]

Did you have a serious failure before you took the engine apart, or did it run and just need a fresh top end? If it ran before, it's probably not spun. Is the single dot to the left and the two dots facing up?

[@austinrosser9522]

@@rmatvmc yes the bike previously dropped a valve

[@austinrosser9522]

@@rmatvmc yes, I followed manual Instructions, 27 pins in between, single dots setting horizontal with the valve cover gasket surface, flywheel mark aligned, and fresh valve adjustment. Getting great spark with fuel. But no boom

[@rmatvmc]

@@austinrosser9522 Ok, with that happening and if your intake cam lobes aren't in the same location as ours compared to the dots on the cam chain sprocket, it sounds like you found the problem. I'd give it one more look just to verify, and if it doesn't match, then I'd replace it. Let us know how it turns out! -Charles

[@david-yj4qw]

which yamabond did you use 4 or 5?

[@rmatvmc]

I believe we used Hondabond 4 in this video which is similar for Yamabond 4.

[@seanmiller2849]

I'm putting my cams back in, but can't seem to get the intake one back in. Feels like the cam chain is to tight to fit them back on... Help... Anyone else had this problem???

[@Alex-hl8hs]

Had this problem on a wr400f You need to put the exhaust cam first at the marks and chain on it. Then you want to put your intake cam in place and positioned at the marks too. The chain is in front of the sprocket now and you need to not force it, just leave it slightly loose to put the next cam. Now to put the chain on, you need to get 1 or 2 teeth from the top, slowly lifting the cam from his back (opposite of where the chain is) and swinging it inward a bit. Then when you have 1 or 2 teeth in at the top of the sprocket, you have to push the chain from the bottom with your other hand to help it get a little loose (down where the chain goes). Gently moving the cam back-end upward and pushing the chain to fit the rest of the sprocket and it should work... Sorry if it's not clear..let me know, it's hard to write it down and there are no videos that shows the process on yt suprisingly

[@Max-wg2vz]

6:22 What does he lubricate in the cylinder?

[@jakegardiner6366]

Assembly lube.. it is just lubricant that mechanics or anyone who is rebuilding an engine uses in order to properly lubricate the engine when it is first started after a rebuild or refresh. This is done because the possibility of not having the engine oil reach certain places in the first few seconds of start up.

[@jonoj7666]

Jake Gardiner why not just used engine oil?

[@daryld1325]

@@jonoj7666 you could. the oil would create boundry lubrication for initial startup.

[@haydenbaha]

What is the benefit of using a hi compression piston

[@p4fstaaar]

Hayden Bahadoorsingh little bit more power, but also shorter interval off changing

[@haydenbaha]

MX57 I really want more mid to top power. Would a hi comp piston help?

[@p4fstaaar]

Hayden Bahadoorsingh yess but also depands on your motorsettings

[@larryfly3615]

Wouldn't recommend one. Your bike will overheat like nothing

[@haydenbaha]

LarryFly what would you recommend for getting more mid to top power

[@Edgarq-jw6cu]

Second

[@DR-br5gb]

You forgot something

[@ATL37]

Wrong cylinder head torq!!!

[@dayday187]

G

[@bleachinuri]

That cylinder is wipped, after breaking the glaze you can still see scoring, time for a new one

[@mochacraft6865]

bleachinuri no, he honed it and recreated the crosshatching dumbass

[@Ri731]

Cahooolant

[@lintonrichards4620]

rrbike