2015 KTM 250 EXC-F Engine Top End Rebuild (Four Stroke)
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- เผยแพร่เมื่อ 29 ม.ค. 2025
- This video shows how we rebuilt the top end of a 2015 KTM 250 EXC-F four stroke. The bike had done 190H and we replaced the piston and rings.
KTM Piston Kit: 777300071001
Wiseco 78mm Ring Compressor: RCS07800
KTC Ceramic Scraper: KZ4-12 - ยานยนต์และพาหนะ
Just finished my first top end rebuild by working alongside your video. I really appreciate your help, guys. Take care.
This has got to be one of the best Mechanical videos on TH-cam
Just for the record here, I was able to remove the head off my '15 250 SXF without removing the entire engine from the frame. I did have to loosen the top 2 subframe bolts to make more clearance from the throttle body. A little shimmying and it came out the clutch side.
Thanks for the detail in this video. I wouldn't have had the confidence to do this job without your guidance.
Thanks!
Good to know. Maybe there is more clearance with the 2015 SXF frame allowing the head to be removed.
Thank you! Just did my top end at 182h in my Husqvarna FE250 -2015 after watching this superb video. You really gave me confidence to do it myself. I had to adjust one intake valve, in my bike all schims were 2.16mm so changed one to 2.12mm.
Nice work again! 4 stroke engine rebuild is much more complicated. I can feel the cheer sound in the end of the video is from the bottom of his heart! LOL
An Absolutely fantastic video! goes into detail about everything even down to the torque bits without too many cuts in the video.. great stuff! All you tubers cut out a lot of stuff, play loud ass background music so you can’t hear what they’re saying and overall not give much info about it so this video is the best video I’ve seen by far! Great stuff guys. Thanks a lot! ❤️
For anyone doing this repair on their 250 - 350 with these year models, if you take out the bottom and front engine mounts and just loosen the swing bolt the engine will tip about 5mm which is just enough to get the cylinder head out!
Cheers! 👍
@JonathanBourbonnais it should work on your bike, It will be tight but it should work! 👍 did the job myself aswell and almost got furious when i realized i couldnt get the cylinder out 🙈 so after doing some thinking I thought it was worth a try and to my surprise is worked! 😂
Great video, meticulous as always. I'm sure glad I made a switch from a 12 RMZ450 to a 17 TE300 :). 2 strokes are so much easier and quicker to work on!
Ohh amazing bike, enduro monster
Great work! Wish I had this level of professionalism available where I live. I need to open my entire EXC-R 530 2008 motor to change some parts and to do a preemptive maintenance. Almost making a pact with the devel to find someone I can trust to do that for me.
Very nicely explained. Excellent video, but what a nightmare compared to a 2t overhaul. That old piston didn’t look all that worn out. If the compression reading was down a bit, just putting a new set of rings would achieve the same result I think. Unless the cost of the piston is not much, and once you are that far down into the engine, then I can see the logic in replacing the piston as well.
Yes I was surprised at how little wear the piston had after 190H. But considering the amount of time I think it's worth replacing the piston with the rings. For many people this would be once every 2, or 3 years...
I had been debating whether to get a two or four stroke, this vid has helped make my mind up!
crpm73 so it will be a two stroke right? :D
Ádám Szabó Yup, I’m definitely not a masochist!
A 2 stroke cylinder with 190hrs will never look like this, it won't get there.
Don’t get a tpi lollllll
Thank you so much for doing this, it's helped me tremendously on my '15 Husky FC 350. Knowing going in that I needed to remove the engine made it seem less daunting. Getting the rest of the parts in today and tomorrow, it's been fun wrenching and doing it myself. Local dealer / mechanics couldn't work on the bike for months.
Colton - I am just getting ready to do my 2015 FC 350 as well. Did you have to pull the engine per the video? Any other advise?
@@ericwarnat52 Yes sir, engine has to come out. I was able to get the job done by myself but an extra set of hands would have been nice. I used a ratchet strap to keep the engine still on my table. Keep patient and follow the manual. Chain tensioner was a headache for me.
I have on mine 2017 almost 400 hours, engine never opened runs great.
Still running good?
@@KyTaundry still runs great, I rebuilt the forks though.
@@robsonenduro3316 awesome man, I'm collecting a 2007 model this weekend, so alot older than yours but a perfect bike for me to enter the KTM realm having rode Suzuki RM125's 😎.
@@KyTaundry welcome to orange :)
@@KyTaundry 500 hours now, still run good.
Excellent. Felt like I was right there watching. Production values we good too for a garage setting. Maybe a bigger light box for seeing into frame areas where work is being shown? Still, really good! Thank you for slowing down the process to capture the video.
Thanks for the feedback and pleased you enjoyed the video. I do have a light box, but didn’t use it during the rebuild filming. Wanting to keep things as simple and quick as possible as it adds quite a bit of time and we needed to finish the overhaul in one day...
Tokyo Offroad really well done!
Underrated video. Very well done and thanks for sharing
Glad you enjoyed it!
Thank you! You are an inspiration. Thanks to you I encouraged to disassemble the engine and perform the change of piston and valves. I am a faithful fan of yours. From Argentina I send you a big hug !!!!
cristian bosio - Thanks for the kind words and pleased that you found the video helpful.
lol I love all the expert advice from keyboard legends! I thought you did well & a great video to teach the uninitiated, there's always areas to speed things up especially if you don't do these jobs every other day however your video overall was well done.
Watching this makes me happy to have a 2 stroke 😁 great video as usual
Crazy how short that stroke is ... it really amazes me sometimes with what they do
Very nicely explained video! Thank you for taking time to film, edit and post this video. Liked and subscribed.
Fantastic video. I know guys say 2t is so much easier but after building Harley tc motors a 4t seems so great to work on
Been trying to decide whether to do the top end on my YZ250FX before putting it up for sale. Nice to see a good run through.
Wooooo!!! Yeehaww!! That was exciting, watching you crank on them head bolts!! It's 50 degrees past the 30nm!! Not 50nm.... holy cow!! That was fun, very entertaining!!
Page 187 of the 2015 250 EXCF Repair Manual details the head stud tightening torque sequence. Stage 1=10Nm, Stage 2=30Nm, Stage 3=50Nm. It does not specify a degree amount.
Where did you get the 50 degrees past 30Nm information from? My 2013 KTM 500 also had the same three stage torque sequence stated in the repair manual Stage 1=10Nm, Stage 2=30Nm, Stage 3=50Nm
@@TokyoOffroad good ol interwebs. I have a repair shop so I just use online programs that have info for all bikes. In this case 50 degree and 50nm turn out to be almost identical, close enough that considering human error it's good enough. I was mostly just poking fun at how people get silly with how precise one must be when torquing. As if there machine will be flying astronauts to Mars.
@@nwfadv7086 - Oh, I thought you were poking fun at me because you thought I'd screwed up the tightening torque. If you regularly work on KTMs I highly recommend that you get the KTM repair manuals. They are clear and easy to understand and typically contain all the required information to repair/overhaul anything on the bike.
Thanks for the vid! Really interesting!
I have always installed the piston to the con-rod first and then dropped the cylinder over the piston (Honda). Honda has a beveled edge at the bottom of the cylinder to help compress the rings. The KTM cylinder edge looked quite square on the bottom in this video. Do you suppose the Honda method would work on the KTM? I simply use my fingers to squeeze the rings together as they enter the bottom of the cylinder.
Your cylinder looks amazing for 180 hours! Gentle rider?
Fantastic video. I really love the way you enjoy riding AND maintenance.
Great in-depth video. I've done quite a few 2T and 4T full engine rebuilds and just top ends. Two things I would have done at 190 hours. I would measure the cylinder for runout. Even if it looks good it may be at service limits. Second, I would have replaced the timing chain. You had the engine on the bench. a timing chain replacement would have taken another hour at most.
Thanks. Yes both good suggestions. The overhaul in the video was a friends bike and we were very constrained for time as he lives a long distance away and we need to do everything quickly. It's always good to measure the cylinder even if it looks good. I did make a 2-stroke cylinder bore measurement video which may be of interest: th-cam.com/video/VnVosSuFY-E/w-d-xo.html
In general though, the KTM late model cylinders tend to wear very little and last a long time if good cold start procedure is used and the air filter kept clean. If you don't have the ability to measure the cylinder bore then carefully inspect it. If no significant damage and the crosshatching is still clearly visible it is usually OK to continue to use.
So satisfying to watch. Great work.
This is why the Honda Unicam engine with a wide aluminum frame is great, so easy to work on!
Moto ReLeif - The KTM 450 and 500 engines (SOHC) are also very easy to work on. The top end can be overhauled with the engine in the frame.
Great video! I will be doing mine soon.
Wouldn’t it have been good to do the cam chain at the same time as the engine is out the bike?
Certainly if the bike had been ridden hard and raced it would be a good idea to replace the timing chain. The bike in the video was used for trail riding, with all the hours low stress. It ran well with no strange noises. But it is a good idea when the engine is apart to check the timing chain for wear and replace if necessary. If I make a new 4-stroke engine overhaul video I'll be sure to include that...
All that to do a top end on a 4T?! Thank you for making this video as a reminder why I'll never own one again. Congrats on banging that out like it was nothing!
Some of the steps, especially removing and installing the engine in the frame, would be difficult to do single handed, so recommend having a helper available. I personally wouldn’t base my motorcycle purchase choice purely on how easy it is to work on, but it should definitely by a factor to consider, especially if you intend to maintain your own bike and ride it for a high number of hours. Yes, 2T are a lot easier :-)
Tokyo Offroad How long did that take from first bolt out to starting it back up?
Jake T those guys are always trying to justify why they prefer high maintenance over low maintenance.
Cool Video chaps but a few pointers, maybe re-move the studs from the crankcases to allow you to remove the head without removing the engine.... if they are tight remove them when the engine is out and clean the threads so that it can be serviced this way the next time you remove the head..... never put matched metals together ...do not use the old piston to push the new one in, use the wooden handle end of your mallet and tap it through the piston ring compressor until the skirt is protruding or push it through with your thumbs... then locate the skirt in the barrel and tap it through with the handle of the mallet......do your valve clearances on the bench whilst the head is off... no need for paint on the cam chain you have cam marks... if the chain jumps on the crank sprocket you will get confused.... always double torque your head bolts go around 2 or 3 times until they are all settled at 10n/m or 30 n/m or what ever because if you are using stretch bolts you end up all over the place, just good practice.....All the best
Great job oh, very good instructor video. Just to let you know next time you don't have to pull the engine out if you take everything apart on the right side, cylinder head and lower assembly comes out from the left side.
You can just retitle this vid "2 stroke appreciation"
LOL. Yes, it’s a lot more work than a 2 stroke. KTM single overhead cam engines (450&500) are much easier to work on and do not require the engine to be removed to do a top end overhaul.
Roflmao. Yeah sohc are a lot easier for everything like valve adjustments, etc
I have also a 350 exc but with 550h on it. Done nothing, even not checked the valves. Runs good tho
@@TokyoOffroad 400 hours on my 500exc and I'm thinking about replacing the piston and rings. It doesn't burn any oil, runs better than a 2019 I test rode last summer but it seems like good preventative maintenance.
CdnX690 - Yes, I’d recommend changing the piston and rings even if it’s running fine. I know some guys are getting crazy long hours on 500 top ends, but I think to keep the engine running fresh and minimize cylinder wear I think it’s important to to overhaul the top end regularly.
Very helpful and we'll explained, lucky for me (having an older 250 exc) I had plenty of room to do it in the frame
honestly if you are going to do a piston change just take the swing arm, subframe and the shock off, its so easy and makes it so much easier to take the engine off.
Very instructive. I have a Husqy FE 250 2016, pretty much the same engine I think. Learned a lot on your video. Thank you very much.
Thanks for the video, I've been looking to buy a KTM 350 XCf, I have my eye on a 2015, totally bummer the motor has to come out to do a piston swap.
Now to research if the same is true for the 2017 and up models(that's if the 350s need the motor to come out too). OR keep saving a while longer and buy a 2020 300XC!!!!!!!!!
Have had a 2011 exc 250f, briljant bike! Miss it :s
Brilliant video very detailed and well explained. Would love to see a bottom end rebuild done by yourself 👍👍
Thanks. Yes, one day I'll do a bottom end rebuild video. It probably won't be for a while though as they do last a long time.
Tokyo Offroad how long is a long time? Thanks in advance 🙏🙂 edit: seen your comment stating 500 hrs 👍
Outstanding video. Thanks for posting.
Great how to! But I wonder if you could answer how to choose the right size of the piston A, B or C ?
Great video, been debating on doing my top end rebuild my self or bringing it to a shop. And now I know I'm just going to take it to a shop lmao. I don't have the right work space at home to do all that
Getting the engine out would not be an easy task on your own. But if you have the time, motivation, basic skills and tools it is something that can be done. But don't blame me if you screw it up ;-)
Tokyo Offroad yeah see i dont really have all the right tools, like torque wrench for example. And i have no bench space or a clean garage to comfortably work on it
Very Nice as Always!
5:44 i like that ktc wrench.
When would you do the 1st top end? Mines at 50hrs of practice days and racing at sportsman level? (No green lane riding)
Hi there is this channel ur personal channel and do u have more videos like this
I like the way u explain each part and the name of the part is awesome
I've been looking for this exact videos thank you
Pleased that you like the video. Tokyo Offroad is a TH-cam channel and Webshop (off-road bike tools and performance parts) run by myself, Mark. I’ve made lots of bike maintenance videos so please browse through the channel video list to see if there are any others which interest you.
Just to let you know, that you may consider using shorter extenders, or no extenders if you can when torquing down bolts, as the extenders affect the torquing.
So long as the torque wrench drive is held directly over the fastener there will be no change in torque if an extension, or long socket is used. But yes, it becomes more difficult to effectively do this if a very long extension is used as there will always be some slop. Certainly something to be aware of while using a torque wrench.
Great video! I have this exact bike. Super.
Pls Tell Me parts Number Cylinder Liner?
The cylinders on these bikes do not have a liner. If the cylinder bore is worn you'll either need to buy a new cylinder, or have it replated (nikasil plating)
always run a ball hone to de-glaze the cyl and make fresh cross hatching so the rings will seat properly ....if you dont i bet dollars to donuts your leak down will be high....old cross-hatching is worn smooth and wont bite the fresh ring enough to seat them well during break in .....they actually wont break in leaving you with high leakdown %
Great tutorial 👏 I have an 2018 model +100h by now, I will check the clearences specs before changing piston+rings , maybe I will just replace the rings, is it recommended?
I just did this based on the movie and 1. You do not have to drain oil and take left cover off - there is a plug to simply disconnect the rotor. 2. Head nuts torque is 10Nm, 30Nm and then 50 degrees NOT 50Nm... I did based on movie 50Nm and after that read the manual... I hope that it won’t brake my engine.
The 2015 KTM repair manual states: “Tightening sequence: Tighten diagonally. 1st stage 10 Nm (7.4 lbf ft) 2nd tightening stage 30 Nm (22.1 lbf ft) 3rd tightening stage 50 Nm (36.9 lbf ft)”
Tokyo Offroad Ok It seams that they have changed it in 2015 because in my manual in 2014 is 50deegrees 😀
Beautiful video great work helped me out a lot!!!!
Great stuff, thanks for sharing.
Hi. Question. To replace the oil seal behind the generator, do you need to split the motor or can it be done by removing the generator only from the side. Oil is leaking into the generator housing and effecting recharging.
There's actually a flat spot on the cam shaft, that lines up with two dots on the bridge...
That's TDC people...
No need to paint dots. That can still lead to failure.....
Great vid tho 👍🏼
This is a great video, thank you! The only comment I have is that the valve bridge bolts are torqued to 14nm and I went by what I THOUGHT you said, which was "40nm" and stripped one of the bolts. Shame on me for not verifying or realizing that was way too much torque for those little things.
I'm pleased that you enjoyed the viceo. I just rewatched the video. I did actually say 14Nm (not 40Nm) for the bridge screw torque value.
th-cam.com/video/P0BuBy2GsKw/w-d-xo.html
Really sorry if you misunderstood what I said. Yes, it's always a good idea to double check torque values in the service manual when working on your bike.
@@TokyoOffroad Yeah, emphasis on "what I THOUGHT you said". I had re-watched it after the fact with my ear closer to the speaker. All on me.
@@TokyoOffroad I really want to say thank you again for this video. I'm not someone who would dig into such a job without a great, detailed video like this as a guide. Between saving labor rates on this and the repair of my refrigerator in the past week, that leaves me with a lot of money to spend on upgrades... is how I'm going to justify it to my wife.
I think they meant 120 degrees per ring so the oil rings will be 120 apart and finally the compression ring so all your rings are spaced evenly over 360 degrees. It doesn't really matter as long as your compression and top oil ring are on almost opposite sides as so compression and oil cant leak thru
Another great vid Mark, thanks.
I was actually a bit surprised that you were using engine oil on the threads of the higher torque bolts like the cylinder base and the head, etc. I though that would affect the torque settings?
Was that a requirement in the KTM manual or an old trick you use for some reason?
Thanks! Pleased you enjoyed it...
Brilliant video, thanks
Did you know the reference of the circlip tool please ?
Nice clean work. Great video.
Any tips on cleaning the gasket surface when refreshing the top end?
Was this bike fuel injected or carbureted?
Great video !
Excellent VID as always... But don't you also have to check ring end gap?
Thanks
For KTM OEM piston kits, KTM only specifies maximum ring end gaps in the service manual. If you're using an OEM cylinder (not replated) and OEM piston kit I don't think it's necessary as KTM control the tolerances tightly. However, if you're using a replated cylinder, or aftermarket piston kit you should absolutely check the piston ring gap. I recently made a video about 2-stroke ring end gap, details are different from 4-strokes but still may be of interest: th-cam.com/video/aC-K9r_-lIc/w-d-xo.html
Just curious as to why you didn't replace the cam chain? I've usually done that when you hit the 100hr mark or even sooner since they can wear.
i've done over 360hrs on my 450 and its fine.
Hi based on What did you choose to use the piston size 1 ? Thanks
Is there no small end bearing on the con rod? In the video it seems you just install the pin. @ 22:31.
Yes, the four strokes don’t use roller bearings in the small end. It’s a plain bearing (piston pin is installed directly into the conrod).
Always safety glass on when you remove/install a spring....
Wow, insane how short the stroke is
Excellent video!
when installing the jug rotate an revolution just to be sure
How did you know which poston size to order before stripping the engine? Really great videos though 👌
How many pound does the screw has to be tight
I wish I had the money to buy all those special tools. 👍
THIS PISTON AND CYLINDER WAS LIKE NEW?
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?
you or sombody else needs to do a video like this with a crf150r
what is the number and ratio of primary and secondary gears in the primary reduction
From the 2015 KTM 250 EXCF owners manual: Primary transmission 24:73
Ok.. Thanks for information
Great video, please tell me how do you decide on the piston size, before disasembling the top end? I need to do the top end on my KTM 300 EXC 2016, done 140h, it will be a 1st piston change, and the problem is that the dealer is 5 minutes away, whereas the bike is 1000 miles, and I would like to buy the parts now and then get to the bike, not go there, disassemble it and come back for the parts. Thanks
I would go with the same size piston as original. If you want to be certain you'd need to measure the cylinder bore and compare the measurements to the specs in the manual. I made a cylinder bore measurement video here (for my 250 2-stroke), which may be of interest: th-cam.com/video/VnVosSuFY-E/w-d-xo.html
Great video. Really appreciate the detail of your information. Excellent. Wondering if you did a compression test and or a leak down prior?
Thanks for the positive feedback. No, we didn’t do a test. The bike was running fine before the rebuild so I doubt there is much difference in compression...
@@TokyoOffroad Then why bother doing a top end rebuild so early?
What's the reason you installed the piston in to the cylinder before installing the piston to the crank?
j0rss - 4-stroke piston rings are difficult to compress by hand. As such it’s easier to use a ring compressor tool and do it as I showed in the video. For 2-strokes I install the piston on the rod first and then install the piston into the cylinder by hand.
@@TokyoOffroad Thank you! I figured that was the case. Just haven't seen it done this way alot, but it makes perfect sense. Excellent video.
Great instructional video, thanks!
What, a video on top end rebuild and you don't show how to adjust valves if they're out of spec?! Also, would be nice to show how the KTM circlip installer works, and the chain tensioner. Thanks for the video, it's a lot of work, I know!
Yes, the video was rather rushed as it was a friend’s bike and we need to get everything done in one day. The next time I have the opportunity to work on a 4-stroke I’ll be sure to make some more videos…
Very good video 👍
Great video! Thank you!
13:43 why is there a similar rectangle on the side of the piston? Is it an indicator?
If you are referring to the little square right next to the piston ring.. it's got a little piece that stick in there to hold the ring in the right spot, stops the rings from rotating within the cylinder bore
Did you need to replace the sealing for the generator cover as well?
awesome instruction video. well made gents....
I have ktm 250 sfx its hard to start and blow up when I Get Get kick start what is the problem ?
Thanks for the video. Now I know I am not buying a KTM any time soon! Some rather strange technical solutions there. The only thing I like are the double headed bolts. Like if you strip the hex you’ve got a torx. That could be useful some day, but the rest... I am not ready for it.
The KTM SOHC engines (450 & 500) are a lot easier to work on and it is not necessary to remove them from the frame to overhaul the top end. Yes, the bolt head design (hex socket and torx compatible) is a great idea.
It is a great video. But i have a cuestion. When you changed the piston with those 190 hours, did the bike have the original connecting rod??? I have the same bike with 100 hours still. Thanks guys.
Yes, the bottom end (including the conrod) was original. Typically the bottom end will last 500+ on these bikes.
@@TokyoOffroad wow!!! Those data are amazing. Thank you very much, friend. 👍👍👍🇨🇴🛵
maybe u wanna try mount the piston in the other way just covering the rings and then have the skirts visible for easier alignment into bore.. just a tip perhaps. also turn the motor over before everythings done and put back on the bike.. u'd probably be frustrated if u haven't and it wouldn't later..
So you eventually have to take the whole engine of, Isnt it easier then to take of the timing chain and stuf after you took it off?
We wanted to see if it’s possible to take the cylinder off with the engine in the frame. We found out it is not possible. The same is true for a 350. As such if doing this again we’d take the engine out and do the work on the bench. Note that if you have a 450, or 500 it is possible to overhaul the top end without removing the engine. Yes, we knew that the service manual shows the engine being removed from the engine, but it says to do that for 450 and 500 also. I like to try and see if things are possible for myself. In this case it didn’t work out, but we did learn...
How many hours for a complete rebuild ? (Enduro amateur use, fe350 2018)
Thanks
You did nice job 💪
When you do a top end on a 2 or 4 stroke, do you have to get the cylinder wall honed?
For nikasil plated cylinders honing is only a requirement after replating and is performed by the replating company. At home I would not recommend honing a cylinder during a top end rebuild. Certainly if the cylinder is in good condition and cross hatching still clearly visible all that is required is to carefully clean the cylinder and reassemble. If one spot has some light damage you can carefully use some scotchbrite in a cross hatch pattern to clean up the damage and then clean thoroughly. I always aim to try to not use abrasive materials this leaving the cylinder bore size as close to original as possible. If on the other hand the cylinder bore is excessively worn (no cross hatching visible) I would recommend sending it out for replating. If this wear happened over a short operation time it may indicate an issue (leaking air box, dirt air filter, poor warm-up method, pre-mix issue)...
@@TokyoOffroad thank you for the excellent explanation. Great videos, very well done.
What brand of silicone sealant did you use on the valve cover gasket? What brand of liquid gasket did you use at the crank case seams on the base of the cylinder?
I used ThreeBond 1215 Liquid Gasket Gray on the engine case joints and ShinEtsu 1 Component RTV Silicone (clear) on the valve head cover gasket
Great job. Brazil.
Really if you have the head off the engine it is not much more trouble to pull each valve out of the head and check the seats. Valves can get carbon building up on the back face of them which messes up the flow, you can spin each valve in a drill and using something hard to 'machine' off the carbon. You can then polish up the back of the valves to help stop new carbon sticking to them.
Measuring the valve clearances when rebuilding the engine is not the best idea, you should measure the clearances before you take the head off, that way if you need to re-shim the valves you can do it whilst the cams are out, then as you re-assemble the engine you should do one more check off the clearances, hopefully if your maths is right the clearances will now be right! I know that the shims are not 'under buckets' but it still makes sense to sort the shims out whilst the cams are out. Anyway, nice vid!
Sidecarbod - I’ve overhauled 4-stroke heads before, so know it’s not that much work. I previously owned a KTM 500 and overhauled the engine twice. This 250 was not my bike and the owner just wanted to change the piston and rings. We needed to complete all the work in less than a day, so time was pretty tight. Certainly for the next overhaul I will recommend to him that he checks the head...
@@TokyoOffroad Fair enough!