How To | KX250F Top End Re-Build

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How to rebuild a KX250F Top End. Most bike and ATVs have a similar installation process.
Not responsible for any damage that may occur during installation.
Only trained licensed mechanics should work on your bike.

[@bobert5785]

About 6 years late to this party but my son and I are doing research for his 2011 Kawasaki KX250f top end rebuild. I found this video very informative and well done. There were little tips included that will be very helpful. Enough so that we will be doing the work ourselves with some confidence.

[@marquiseanthony1668]

how did it go?

[@joeylucca]

@@marquiseanthony1668 I believe all the kx250fs have been pretty much the same since 2009

[@tyler238]

About 1 year late to your party… but how’d it turn out? She rip now?

[@Leeds535]

Me too 🇮🇪

[@bobert5785]

@@marquiseanthony1668 It went well. One mistake I made was not keeping the shims separated to each bucket so I could have the correct measurements. I did get some help getting new shims installed and when we got it all back together the bike ran like a champ. Again, without this video I wouldnt have had the confidence to attempt this; It was a good project I could do with my son as well.

[@jamesrossmotors]

Good on you for having a go. From a pro to a home mechanic. When using a tension wrench, you never should use extension bars. You can't get the correct tension on the bolts like that, the extention bars twist and don't transfer the tension to the bolt. Secondly, don't use assembly lube on the cylinder, use engine oil. You want the rings to bed in quickly when you run it in.

[@cableheadcrew3880]

I agree with the engine oil in the cylinder but it’s been proven that extensions don’t foul torque ratings if ya use them properly

[@jamesrossmotors]

@@cableheadcrew3880 I think that would come down to the make up of the extension bar and the material used in it. Do you trust your extention bar/s and where they are made?

[@SlammedBeretta]

For the cylinder head bolts you want to torque them down in 3 steps. If torque specs call for 60ft lbs, Tighten all bolts hand tight in a criss cross pattern taking your time and just snugging them down. Then first torque all bolts to 40 ft lbs, 2nd step torque them down to 50 ft lbs and 3rd step torque down to 60 ft lbs! You never want to torque bolts down in steps of less than 5 ft lbs as the torque will be reached before the bolt moves.

[@dlockel25]

Great video! just wish you did the disassembly in a part one. Next rebuild go all out. Thanks and keep em coming!

[@KG-yc6cl]

Great job man. Impressive to see someone go through this so efficiently and clearly.

[@lazyp3ngu1n66]

That's an awesome video for all of us who have this motor. Thanks again for taking the time and making the video.

[@woodywoodlstein9519]

Great video man. Guy admits he's not a pro. But he's definitely doing it. And commenters ain't.

[@AnDrEw122100]

Woody Woodlstein ya buddy

[@chrisgarcia4653]

I looked up specs and it says m6 bolts 104ft lbs and M10 bolts 36ft lbs. the service manual says the number 8 bolts the 4 long ones only 36ft lbs. that seems way to loose. Because i tightened mine to 60 something or whater he said and my gaskets leaked like crazy. Oil just spewing out. I literly had to hamd tighten them so it wouldnt leak. Please help

[@darkskies3075]

im really glad you made this video. been around motocross my entire life and im about to do my first rebuild ever with out help. you definitely answered my questions and was very instructive. good video.

[@joshuasmith5472]

found this video really helpful! just bought a brand new 2016 kx250f 6 days ago and at some point when it's time I'll have to rebuild the top end.

[@TripleWhopperWithCheese]

Don't hone the damn cylinder like this idiot says.

[@powerwagon3731]

Nice job. I m doing mine now, I would suggest using a micrometer and T gauges for piston to cylinder clearance , checking end gap on oil rails and compression ring. Oil expansion ring ends toward intake port and rails 20 degrees from expansion ring ends. Compression ring end toward exhaust port. Ends of piston circllip should not be in notch in piston wrist pin hole. Great overview.

[@TriplethreatindustriesRC]

Thanks man great job👏 just showed me how to save thousands of 💵 and not have to wait 3 months to get my shiz running . You make it look easy but this is a great video for people like me that want to build our own motors.

[@alexishermann7099]

The cam chain tensioner has a lock and you can use a skinny flat head to adjust the tension. I didn’t see this step in the video but overall good information. I will come back to it when it’s time to rebuild my bike.

[@scottnothintodowithya979]

Awsome mate, ive learned more from your vids than what i did when i paid an old "friend" to teach me. Nearly have my sons kx top and bottom rebuilt now 🍻

[@Thomasc1444]

👍 i like to manually turn the motor a few revolutions to check that everything functions smoothly before finishing completely.. also add oil and turn it over by hand to get oil pumping before ever starting

[@kayperez7797]

Great information here. Straight up clean top end rebuild. Nice job with the video!

[@stephencrisson3595]

Told him we need to get the tool to compress the valves down to take them out and install so now just waiting on him to get that your footage is very amazing

[@mazalaza92290]

Super vidéo. Ça m’a beaucoup aidé pour mon moteur. Thanx from France

[@goblinmxrendon1597]

estoy precisamente empezando a armar un kx250f muy buena guía....gracias

[@spoolsociety_nv1159]

Yo! Great job! I'm currently going thru a motor rebuild night mare! I wish I would have come across you before I sent it to the shop but hey I will be coming to your vids from now on if I need to which hopefully not lol but again man awesome awesome awesome! Thanks for taking the time to show us these great videos ! Danny m reno,nv, usa

[@jonathonewing6400]

Very good descriptive video, like the high quality video and explanation on everything.

[@judsonl8990]

nice! Great video man. Your work looks plenty professional to me. Subscribed!

[@stephencrisson3595]

Awsome job man on this video im replaceing the valves on my friend frend 2009 kxf250 and its giving me a good idea on were to start and end very helpful100%!!!!

[@sr2Xvet]

How did you get that exhaust valve into spec with that huge ring on the bucket. I would of got new buckets and re shimmed it.. great video just you should of known you need to inspect and replace. When in doubt the the part out

[@vinnyvinson]

Thank you. This is helpful. Hope I can get mine going soon. Appreciate this content immensely.

[@CJmontage101]

hey man! great video! I need to do my top end also (07 kx250f) very informative. only thing I can say I didn't like was that music on loop for 30 mins. good song but not for half hour just a tip for next time!

[@bugsysiegals]

I replaced the valve oil seals and put some assembly lube on the inside to make installation easier but now I'm wondering if they'll slide off the valve guide ... before I go putting things back together, should I remove them and wipe them down with contact cleaner to remove the lube or should they be fine?

[@mellows1970]

Great vid mate. Cheers from Perth western Australia 💯

[@BladeBarn]

excellent vid. just got the new 20 kx250f with finger follower design. wonder how much different it is going to be when its ready to come apart. no vids out on it yet.

[@hiredexpectations9037]

Pro Tip: factory torque spec on cam caps is 8ft lbs. that's unnecessarily tight and we have found that 6ft lbs works much better and helps free up some of the rotational friction.

[@hiredexpectations9037]

This pertains strictly to the kx250f 2013 and newer

[@stratigos11]

+Hired Expectations ya mines an 07, good tip tho!

[@slight_bikelife]

My torque wrench only goes down to 10

[@igortbp]

Hello, could get me some questions? I have questions regarding the size of the piston to put in place of the other, I would have to remove it and measure the cylinder diameter? after I know the size of that in the next exchange will be 0:01 mm bigger? Thank you!

[@Fadder90]

Hey, I bough an 06 KX250F with the top end already removed. Long story short, I'm missing 2 cylinder dowel pins... I'm worried they fell into the bottom end when cylinder was removed. What the best way to check for these pins??

[@danieldelossantos2443]

Very informative. Only thing, not too clear on piston rings position, but instructions might clarify.But excellent video!

[@dough3208]

Good job, nice to see what needs to be done for the rebuild. thanks for the vid.

[@zacrudek6297]

This helped me out a lot thanks

[@andrinaallan196]

is the scoring an issue on the larger cam journals. im doing mine now and have the exact same scoring, i was gonna hit mine with some 1500 to 2000 grit

[@bugsysiegals]

Why does the flywheel nut tighten clockwise but they have you rotate the crank counter-clockwise for timing chain adjustment?

[@justinv433]

thanks bro. about to tackle this

[@jamesc6137]

how many hours can you get on a fresh rebuild like that if youre just woods riding?…..and keeping the oil and air filter changed every couple rides. Thx

[@NRP1991]

Nice job man great video!!! 👍

[@skipperay]

Hi, what do you call that little hole with a rubber seal on top of the exhaust port? I have a 2008 model and it's leaking. What could be the problem?

[@tropicanadian]

Arnt those circular lines on the buckets mean that they need replacement?

[@chrisgarcia4653]

The head bolts are way to loose. I torqued mine to what you said and my gaskets leaked oil out realy good. What are exact torques

[@dirtbikesfordinner3706]

Mines only have 1 cam chain guide is it supposed to have 2 like this one?? Mines is 2016

[@henripuustinen4642]

One thing. Be careful with how much liquid gasket you apply to the valve cover sealing surface. The amount in this video is way too much and parts of it can fall in to the engine during assembly or when running the engine later on and might clog up the mesh filter or other oil channels. It just needs to be a thin layer and towards the outer edge as the valve cover will crush it and spread it evenly over the sealing surface. Otherwise a very nice video. Easy to follow.

[@oliklaas2924]

Horse with no name is awesome

[@fredflintstone2077]

Great video up until you used the silicon on the rocker cover. The last person to rebuild my 250 used silicon. You wipe the excess from the outside but what about the excess on the inside? My pick u0p strainers were full of silicon where the guy had used it on every surface and the excess on the inside had washed off with the oil, clogged the strainers and starved the engine of oil. Not only did the engine not last long but it needed a huge amount of work.. The manual suggests using a small dab of gasket bond just on the corners of the two semi circles. Excess gasket bond dissolves in the oil so doesn't cause any harm.

[@holdenman77]

Good Video Mate Big thumbs up

[@rockwilkinson8224]

Better then what I can do

[@baileycarr4009]

What are the head bolt torque specs? For the 07 kx250f?

[@brandonbecoat7362]

Great video.. Very explanitory

[@jamesgreen9848]

I was told you shouldn't hone the cylinder? Is this correct

[@bikedoctorauto1709]

Great look bro enjoy ur video

[@TEGT3ddyQL]

Great video! The only "bad thing" is your microphone, but it will do! Really great video!

[@k.b.24]

Great work. 👍

[@jamieneal3536]

Thanks. Great video

[@gustavodiaz1106]

what bolt size does that piston have? isn't it 17mm?

[@tm-ktmmx8945]

with how much strength Sphinx (newton) 15:50???

[@hammodysmix]

can i follow these steps for kx250f 2005 model ?

[@scottmorgan6099]

Nice work,....👍

[@jstevo92]

Good video, ignore the negative coments.

[@XxhockeybladerxX]

And is that homer possibly from harbor freight??

[@user-hi5vn4rp3d]

Красава, полезный видос.

[@calebmartin2457]

Yo how much was the piston and rings

[@100cockroach]

I accidently dropped the small head bolt by the timing chain down in the case. I could hear it bouncing off of a number of things before it stopped. I tried fishing it out with a magnet and then flipped the bike upside down and I wasn't able to get it out. Do you have any ideas on where it went and how to get it out. is there one side cover I could remove to find it. I really don't want to pull the engine out and rip it all apart. Any help would be greatly appreciated

[@stratigos11]

100cockroach you can lay the bike on the side by leaning it against the stand if you have a stand or a bucket will work. Take off the ignition cover and you should see it somewhere down there. You may have to take the flywheel off. That's where I would start.

[@100cockroach]

Thanks a lot for your help buddy. It turns out it was lodged under the stator wire. That may of happened when I was tipping the bike upside down.

[@garrettadams2526]

100cockroach

[@MrOmgSkittlez]

Is there a video on just putting the rings on? I have the same year kawi 07, not to sure about the rings. So I plan on doing my first ever 4 stroke rebuild

[@stratigos11]

No I don't have a video for just that, but make sure the letter is facing up on the top ring and the bottom three rings are the oil rings. First put the spacer (the one that is stretchy) on the bottom slot, then put in one side rail on the bottom of the spacer and then another side rail on top of the spacer. The ring gap should be about 20mm (0.8in) or more for maximum oil flow. Next is the top ring you should only have one and it should have a letter on it. Make sure like I said before that the letter on the top ring is facing up and put that in the top slot.

[@MrOmgSkittlez]

okay, thanks so much

[@fernandofernandez5719]

Why 59 dislikes this vid is for free if you want something profecional just go to school and pay for it. Good vid bro

[@iscooter247]

what year is this bike? i have a 2014 kx250f that locked up. gonna do the work myself any thoughts? lol my first four stroke rebulid

[@stratigos11]

It's an 07 and take your time and make sure you clean all the parts and cases really good. I'm guessing you'll have to split that cases and put in a new crank.

[@iscooter247]

I was hoping for just a top end rebuild but I doubt it will be that easy:/

[@tictocpops1_276]

I have a 2005 RMZ250 I rebuilt the top end and my question is my piston moves left and right on the wrist pin a pretty good bit but it does not move up and down before putting the head on is this normal to have that much play

[@stratigos11]

Bobo mcrae you need a service manual to see what the clearance should be on each side. Also check for any marks on the inside of the piston. You may need to replace. You can probably find one on google if your search for your bile model and year and out service manual after it.

[@stratigos11]

Bobo mcrae you need a service manual to see what the clearance should be on each side. Also check for any marks on the inside of the piston. You may need to replace. You can probably find one on google if your search for your bile model and year and out service manual after it.

[@Twisted.tv12]

What year is this

[@TCON42499]

hey man where can i find the valve clearances for my bike it’s a 2015 kx250f, i fucked it up before bc i accidentally used specs from an older kx250f

[@stratigos11]

I would google "2015 kx250f valve clearance" or "2015 Service manual" Thats how I find all my service manuals. Or you could always call a local dealership. If they are cool they should give you the valve clearances.

[@tanishpatel9508]

at 28:28 couldn't you use gasket maker?

[@10141957]

nice job kid

[@xXChaz9849Xx]

I thought you're not supposed to hone the cylinder of a KX250F because of the nitrate plating or whatever?

[@XxhockeybladerxX]

My stock 08' kx250f has a 77mm bore, how do you know how much material you took by honing it yourself?

[@marcuslee2177]

A micrometer

[@TripleWhopperWithCheese]

You're going to use a micrometer to measure the inside of a cylinder? LOL Can you post a video of you doing that?

[@4fiddy_J]

THANKS BROTHER

[@mke7876]

Good video

[@lolot9169]

Ωραιος ρε μαστορα!! δουλευεις σε καποιο συνεργειο αθηνα ?

[@marco20838]

When do i know when to rebuild the engine? How often should i do it?

[@marco20838]

+Travis Jansen thx for the aswer, how much it cost?

[@wolf360090]

the only time a plated cylinder is touched is at the machine shop,, u dont hone them out like a sleeve u will ruin the plating on it if u do

[@dantsy6397]

12:00 what about the valve spring retainers?

[@stratigos11]

They were already installed, I didn't take the valves out in this video.

[@williamv.z9706]

Goood workings

[@hiredexpectations9037]

Also, a ball hone is safer to use on the nikasil bores. The coating is extremely hard but if you don't use caution you can wear through it. A ball hone with three passes or so should do just fine. If you can see some cross hatch use a scotch bright pad and some soapy warm water and make circular motions up and down as you rotate the cylinder in your other hand to deglaze. Otherwise man your doing fine I'm sure you engine runs great so don't listen to the idiots on here.

[@marcelloroos766]

With the blok on the bench it's way easier to install the piston with the cilinder together. I mean putting the piston into the cilinder first

[@danillopradovalentim8914]

Qual a marca do pistão ?

[@rodrigopaiva6103]

kx 250f King bike

[@markeljohnson7023]

Could you list all the parts for an top end rebuild for an 09 kx250f

[@levimartinez6312]

Look on Motosport... they have complete kits

[@swedish_sadhguru3854]

how often do you have to change top end on kx250f? I am thinking about buying one.

[@stratigos11]

You would want to check your compression, once your compression is low you would want to change your rings and check you cylinder. Also a good time to adjust your valves if needed.

[@swedish_sadhguru3854]

@@stratigos11 Thank you! I guess the manual says how to check all these things right? Looking forward to learn this stuff, thanks!

[@swedish_sadhguru3854]

@@stratigos11 Thank you man!

[@melissagross3180]

2005 kx250f head bolts 36 ft. lb torque as per service manual Gor head bolts

[@Lukedormer]

Would have a debate on putting anti-seize on the head bolts. Great video tho 👍

[@brianstone5668]

Overall good video. Jim, brother, you tend to mumble when speaking. Makes it hard to understand what you are saying at times. Please speak with confidence, it's obvious you know what you are doing. Keep it up!

[@jasons44]

for a first timer, what advice would you give?

[@stratigos11]

Jason Spears good luck, lol

[@sr2Xvet]

Take your time. Keep your work place clean. Video your disassembly for questions when you reassemble. Label and bag your parts. Inspect your parts upon reassembly, that being said I go by this saying when rebuilding when in doubt the the part out. Go buy lock tight and assembly lube, anti seize. Anywhere it's need it would be a good idea to use. Last thing never cut corners if you need something it's a good idea to do it the right way or not at all. Hope this is what you were looking for.

[@mxracer158]

Good video minus a few things.Way too tight on the torque specs, Mention setting TDC BEFORE you tear it downMeasure the wear on your cylinder if you can

[@livinitup9656]

what year is that engine your working on

[@stratigos11]

Montell Martin 2007. But I'm pretty sure 07-09 are the same.

[@turboford4353]

Great video but one thing, you never put anti seize on a bolt that is torqued as it makes the bolt slip easier and strip the holes out.

[@stratigos11]

Thanks for the comment, but I have been rebuilding my engines for about 2 years now while applying a very thin layer of Anti-Seize and I have never had a problem with the head bolts slipping or stripping out. It's really just a personal preference and what you are comfortable doing to your machine. You can use Anti-Seize, a thin layer of oil, some "Thread lube" or just clean out the threads with a brush and install dry. But at the end of the day its just really what you feel more comfortable with. I use Anti-Seize because it makes the bolt easier to remove after install, keeps it from seizing up and it creates an extra sealing layer when it dries. You might have heard that Anti-Seize might not let you torque the bolt accurately, but a very thin layer of Anti-Seize or oil will not affect the torque that dramatically to make it will fall out. Thanks again for the comment, hope you see where I'm coming from.

[@jeremysummers2324]

+Gregory Maibach /stratigos11 Putting anti-seize or oil on a bolt that is torqued is not right or wrong. It's simply understanding that a dry bolt will reach a torque value in less turns than a bolt with lubricant of some type. They make charts (Zuess charts) that have dry vs. wet equivalent torque values. The issue is that if you torque a lubricated bolt to the same value as a dry bolt you are actually putting more strain on the threads of the fastener and hole. It may be minimal and you may never see an issue, but on softer materials like steel bolts into aluminum, you need to be very careful.

[@bikerbros6667]

Nice video man, how did it run?

[@stratigos11]

ran good, sold the bike a few years ago and haven't heard any complaints

[@kidzcannon]

Do any one know how high temperatur the silicone should withstand?

[@stratigos11]

kidzcannon just get blue RTV silicone instant gasket and you'll be fine.

[@kidzcannon]

dont think i can get that stuff in denmark, but i found some other kinda of high temp silicone, just not as sexy at that blue tho :P

[@igortbp]

Hello, I am in doubt which brand of 250F will buy, what do you think is the best? which has a higher durability in your engine? Yamaha Suzuki Honda Kawasaki?

[@stratigos11]

I would go with the Kawi if I was you. All around great bike and great engine.

[@igortbp]

They say that the 2004-2006 version the engine is pretty bad, has some year it is perfect? thanks

[@stratigos11]

Igor Vinicius go with the fuel injected models.

[@igortbp]

Thank you, grateful!

[@tanyamaddock600]

Can you re build my engin for me

[@melissagross3180]

good video but those torque specs will definetally snap some cam cap bolts so listen to him and look up your own torque specs !!

[@roxannaosorio6120]

Helpful video except when it comes to the cam Tension