How-to do a KTM 250/300 Top End Rebuild

[@ZSharkPH]

As someone who's never attempted a rebuild on a two stroke. This was very informative and makes me want to try it.

[@carlograssetti513]

Hey jeff i wanted to really thank you for this video ! Ive been riding bikes all my life but never touched an engine. Last night i looked at your video and i rebuilt my top end in 2 hours!!! Im so happy without your video i would of paid someone! Your the best kee up the good videos

[@hamish2202]

It's nice to know that it's not only me using the slavens torque setting on the base gasket

[@backyardboosters9128]

Mr. Slavens your videos are an invaluable service to many like me just getting into the two stroke game. Appreciate it.

[@gordyc]

I ordered my rebuild kit from Jeff and I got it in 3 days(I live in Houston). Thank you for the detailed video! I felt confident rebuilding my top end for my first time with no surprises and no problems. Thank you for your detailed videos and shipping quickly.

[@waynemodesitt3445]

Excellent video. I've done a few top ends on my KTM 250 XC, with great success, but still learned a few tips here. Slavens "easy clips" are fantastic, so much easier to install than stock clips. Thanks Jeff for all your videos!

[@DerricTubbs0x00]

Thanks for all you do for the community Jeff.

[@loganburns385]

Hey Jeff, I just ordered a top end kit and a few other goodies from you and I've watched this video about 6 times already and still have a few more to go bc I don't want to miss anything when it's time for me to do it myself. Excellent videos! It's great to get info and tips from someone that actually knows what they're talking about. Thank you

[@johnathanyinger]

Get his circlips!

[@parv100]

Awesome video Jeff. Has given me the confidence to do a rebuild myself. Instead of taking to a bike mechanic. Many Thanks !!!

[@devinkokenge8801]

So cool how the C clips have the ends folded in so you can grab the clip with a pair of pliers and place it exactly where it needs to go. Makes that step so much easier compared to the YZ's. Good job KTM.

[@KushRTX420]

Those are actually Slavens easy clips he sells. slavensracing.com/shop/ez-clip-ktm-husaberg-250300-slavens/

[@devinkokenge8801]

Kushbump oh no way, had to watch this with no sound cause I was at work so I must’ve missed that part. Very cool!

[@MrKane101111]

Doef! Doef! Doef! "It would help if I take the bolts out" -> Video thumbs up.

[@blacklight4460]

A lessor man would have edited it out.

Jeff is Gods gift to us do it at homers, Thank you Jeff

[@slaverace1]

Thank you

[@26jessyjames]

Hello jeff, you helped me with this video! My 300 xcw 2014 ad 145 hours and still in good shape, those are really strong engines!!

[@slaverace1]

We'd appreciate your business. We have the largest selection of KTM parts on the planet at fair prices.

[@lunchtimelunkers6566]

Awesome video as usual so helpful for all of us DIY guys, be sure to buy your stuff from these guys and support. I definitely do thanks!

[@KrinklingPlasticBits]

Super helpful and refer to this vid when I do my top ends; 6 so far. I had the bottom end done at 524 hrs, probably could have gone more.

[@PotatoPilots]

Thanks for the video going to do it my first time one of these weeks on my 2009 300 exc.

[@chucspe]

Thank You Jeff! Your videos have been a lifesaver more than once.

[@empirecycleman355]

I always enjoy watching your videos. Have known about you since I was stationed at the USAFA in 1973. Best wishes. Don in Empire Colorado.

[@petrielo9487]

Nice video but couple of comments. First of all it would have been nice to hear your tips & tricks regarding piston sizing, when you should go up for next size? You talked about the thickness of bottom gasket but not mentioned anything about measuring the piston height (in relation to cylinder top surface) - why is that? You think that in real life it does not make any sense to do it? Another interesting thing would have been to hear your thoughts about aftermarket pistons (ProX, Ahtena etc.).

[@200xcBruce]

Very good video only thing that a newbie may need to know is the direction a piston goes on the rod ie. arrow on top as a reference. Thanks for these I share with friends who are frightened to do these tasks.

[@lenhoward4305]

+Bruce Kennedy Yes, I thought this was important to know too. It's supposed to point toward the exhaust port if I'm not mistaken. Please confirm. Nice job on the video. I've got to get some of those clips!

[@bfrykman]

Such a great video, its like checking out a library book. Every time I need to do a top end, I watch this vid as a refresher and reference guide to jog the memory. All 5 top ends (on different blue and orange KTMs) done the slavens way have been without issue! Thanks a million,

[@slaverace1]

You're welcome.

[@johnnyreb86]

Good trick I learned is heat the side of the piston where the wrist pin is coming out with a propane torch for about 10 seconds around the pin and it will slide right out with no effort

[@tylerm3371]

Finally found a helpful video, good job cutting out all the BS work too. Thanks for making this.

[@rywaz1234]

AWESOME VIDEO! I was able to rebuild my 04 250sx by following this video step by step. The only thing that was trouble is the small clips in the piston. BUY THE EASY CLIPS FROM THIS VIDEO. I know I will be buying them in the future. Thank you for your help.

[@LikeAPetrol]

Hey Jeff, thanks for video. It would be great to see a hydraulic clutch bleeding procedure performing by you. You are always make good tech videos.

[@shaneshuttleworth2979]

thanks for the video, time to tackle my first top end rebuild !

[@danielsaffioti1570]

Thanks great video i just put new piston & rings on my 2016 300exc with some help of my brother will be testing the bike tomorrow after work .bike was at 100hrs

[@grahamsampson769]

Excellent mechanic - does not suffer fools lightly.

[@sensojistyle1836]

Great video thank you sir , 2013 KTM 250SX checking in 🫡📳

[@slaverace1]

Thank you.

[@rickydoherty1147]

thank you for this video. i want to upgrade a 2017 ktm 250R Freeride. I bought the 250 but I wish I bought the 350 now. Do you have any advice how i could best increase the 250's power without wrecking its reliability? Thank you again.

[@1bad335ii]

rick doherty big bore kit google It

[@rajkirannatarajan9276]

I don’t think there’s big bore kits for that bike. Better reeds and lectron carb will probably give you what you want for the bike. Nowhere near the 4t 350 territory but these two add ons usually do a great deal to improve power

[@lukeyallop7165]

hello jeff awesome video. Do you have to size up the bore every time? Mine's done about 50/60 hours since last rebuild wonder what size piston i should use and how to find out!

[@FrankB064-q6k]

killer video, im about to do my first top end on my beta and this really helped.

[@joeymorris4863]

Love the modesty. I get ahead of myself all the time. Now I know there’s no need to remove the handlebars to change a tire. 😌

[@rolf737]

This video helped me a ton when I did my '17 KTM 300 top end. I have a 19 TPI and I see the kit is the same (got one from you sitting right here). Any different tips or tricks with the TPI? Probably going to tackle it today. Thanks!

[@slaverace1]

No tips or tricks. Dive in.

[@marblespaw]

Very informative video! Rebuild on 2016 ktm 250sx was successful

[@fredysegura4093]

Hey man thanks for the information , I was little confused with the gaskets I have 110 hours on my bike is time for new piston

[@slaverace1]

Hello: If the head on your bike is stock (not machined) you should use just one .4mm base gasket. If your head is machined or if you have an aftermarket head, you should use the stock gasket configuration (.4 & .2 stacked).

[@fredysegura4093]

@@slaverace1 i’m going to use the 4 mm ,The bike is all original , thanks 🙏

[@idunno1684]

no lube on the piston before inserting into the jug ? shes going in dry!!

[@goinhot9133]

Tighten until you hear the casting crack , then back it off a 1/4 turn 😂

[@zannnewman3147]

I want to say thank you for sharing your expertise and knowledge. I found this to be very informative. I think you did a great job explaining but I could do without the negative pessimistic comments. I know it's none of my business but keep it upbeat and positive. Thank you sir

[@21AirDrop]

Very informative. Thanks.

[@j-moto1215]

Hey Jeff tech question for you. I rebuilt the top end on my XCW TPI and replaced the base gasket with the same size that came stock .6mm (.2+.4mm) and when I went to measure the X dimension and it was .2mm at TDC. That’s too big, so I went with a .4mm gasket and the X dimension reads 0mm. I watched your video and you said to only run a .4mm gasket above 6000’. If I’m running around 1000m what effect will this have on my bike?

[@slaverace1]

Hello: The thinner gasket will raise the compression slightly and give a mild boost to the low-end grunt.

[@TheEggSample]

Those radiator braces are pretty gnarly! What kind are they? Thanks in advance! Great video by the way...

[@fredmitchel1236]

I like the way you work...and the starter needed a good beating...

[@emofilipof3150]

hi Jeff. i changed the rings of my ktm 2 strokes 380. first day it was ok, but next day noise i hear as if the piston kick something inside and the power is dying. what could be that noise? thank you for the video.

[@theenduropest]

Cheers for the great Info Jeff, Bloody legend!

[@slaverace1]

You're welcome.

[@Big.Ron1]

2 questions. I haven't worked on a modern water cooled 2 stroke. All pre 1990 aircooled. I went in HD direction but now coming back to trail bikes. Now for the questions. Was there still plenty cross hatch to seat the rings or did you ball hone for the finish? Second, no front or rear to the piston?

[@bloomerb4162]

I'm about to put a new top end in a husky tc 250 with 300 kit. I will be using one off your kits that comes with everything. The tc 250 was converted at around 90 hrs to the 300. Then the previous owner used a piston and ez circlip from you but did not record the hrs when installed. I'm guessing he did this at around 120 hrs bc he was racing woods and previous recorded top end rebuilds when it was still a 250, showed every 20 hrs they were replaced. So now the bike is at 150 hrs and I just checked compression, it was around 140 psi. So this will be the third piston including the original that came with kit. Should I go with size B or A?

[@slaverace1]

B

[@christomlin268]

Thanks Jeff for video. I have heard about measuring ring end gap. Is that applicable when installing new piston and rings. 2012 300xc

[@slaverace1]

It is usually a waste of time but if you want to check it, .012-.014".

[@deanmathews1926]

Love at 8:30 he makes the mistake of not taking out the bolts, but then doesn't try to cover it up. Like, oops I screwed up, but not I'm on the right track, here's what happened.. Love this mentality.

[@garywoodman9304]

ok ty Jeff slaven your videos are awsome I haven't torn mine down yet but I will soon I have 1 more question my 2010 ktm 250 sx has had the piston replaced once before and right now I'm at 180 psi for compression what should the compression be ? and at what compression should I replace the piston and rings ?

[@mattpowell8890]

Check your service manual for the baseline if it drops more than 20% def throw in a new piston. U could also just take off the cylinder and see if the piston has any blow by from the rings

[@dirtrider88]

+Gary Woodman in addition to what matt said it varies by elevation. Also like he hinted at, theres no definite psi for a given bike at a given elevation that tells you when your top end needs to be changed. it all depends on what your compression is with the same gauge when the top end is new with all the proper tolerances and measurements.

[@jonjelen9755]

Jeff, I'm doing a top end on a 200, and am wondering if I have to get assembly lube for reassembly of the powervalve, or is it okay if I just use 2 stroke oil? Thanks! :)

[@slaverace1]

+Jon Jelen Any oil is fine.

[@The199racing]

Have you measured the tolerance of cylinder? did you mesured the cilinder whether it is necessary to measure the cylinder at each change of the piston. Or is measured only at a greater number of hours (eg, 250h )

[@jonjelen9755]

+Tine N Probably not a bad idea to measure it, since it takes so little time

[@chaoscrewmx]

Hey mate currently rebuilding my 250 this video is super helpful, would you be able to give me the ideal piston to cylinder wall clearance ??

[@slaverace1]

.0026" to .00346" is the factory spec. Beyond .004" needs a new piston or the bore replated and a new piston.

[@billmalec]

Thank you for the videos and moreso the common sense stuff. My further thank you is buying parts from you.

[@slaverace1]

Bill Malec Thank you

[@ctk166x2]

I like your style Jeff. To the point and no Bull

[@slaverace1]

Thank you.

[@user-ju3ns2cz1u]

Great video! Got my top end apart with no drama. Only one question that my service Manuel and local ktm dealer/internet couldn't answer. What is the min ring gap clearance? ktm service only show a max clearance. (12ktm 300 xc) Thanks for the great videos

[@slaverace1]

.012"

[@user-ju3ns2cz1u]

awesome . Thank you

[@izmeorbin9602]

Hi Jeff, please increase the sound volume of your vids? Thanks in advance!

[@finnroby9233]

Give maxima castor oil a go, I run it 40:1 in my 125 and the piston came out looking brand new and shiny on the top after 26 hours with no carbon build up at all.

[@philgraves7814]

I recently bought a 1996 ktm 250 the vin says it’s a DX however I can’t find parts for a DX I’m wondering if you or anyone else knows if SX parts will work?

[@scrambled1213]

Thank you for the videos. So with a stock engine with stock head at near sea level; is ok to use at .4 base gasket? Does the slight change in port timing change engine power characteristics in anyway (besides the effect of added compression)?

[@slaverace1]

yes

[@ianmickelsen5853]

jeff, i am currently finishing up a top end rebuild and aside from having to take the whole pv apart it went smoothly until i went to reconnect the rod the the pv linkage.. the rod connects to the ball but the pin/clip will not slide back through any suggestions?

[@byadRiYT]

When a rebuilt of a Ktm 125/200?

[@duckodb_4389]

I have a 2016 Husqvarna TC 250, if I want to convert it to a 300 is that the TE or TX cylinder? I wonder too could you just buy the cylinder and piston and put the head and power valve from the 250 on it?

[@slaverace1]

TE and TX cylinders are identical. The 250 head and PV parts will not work. Cylinders by themselves cost more than the complete kit.

[@runnerfxabc8160]

Any tips for installing the stock vertex circlips? they are a pain in the ass😠

[@enduro-parts-aus]

very good video, will defiantly help me when the time comes to rebuild my 300, all i was shocked about is the fact you run it at 80:1 or 100:1 it worrys me to run 50:1 with motorex haha

[@dirtrider88]

+Micheal Rex that's for the oil he uses (saber) and you should rejet for that ratio.

[@jimineutron259]

I have my top end apart on my 2018 ktm 250 xc-w because a Reed pedal broke off. I pull the pedal out on one piece and am now doing a Wiseco piston kit at 70 hrs. Do you think I really need to rebuild the power valve or just clean it up?

[@slaverace1]

The PV should always be serviced when the top-end is off and I wouldn't put a Wiseco in my lawnmower let alone my KTM.

[@jimineutron259]

@@slaverace1 thanks for the reply. I put a Wiseco in my 200 xc-w and ran it hard for 100 + hours, you should see it next to the vertex that was in it for the first 100 hrs. I value your opinion and appreciate you taking the time out to respond to all of us.

[@dmorgan3244]

Hi Jeff - I'm looking at the Vertex replica piston kits available on your site. Do you recommend them over OEM? They seem like a different shape than the OEM as I see in your video.

[@slaverace1]

The Vertex we sell are the same as KTM OEM, NOT a different shape.

[@dmorgan3244]

@@slaverace1 Got it thanks.

[@donpablo007franko6]

Thank you for the video

[@tjtharp2432]

Great video!

[@sethsc77]

Great vid. Thanks for sharing!

[@slaverace1]

You're welcome.

[@HubbellMotorsports]

My 2 questions. Do the rings need gapped? And am i mistaken or do the ring gaps need to be almost 180 from each other?

[@slaverace1]

Hello: The ring end gap should always be checked. 2 strokes have ring location pins and they are NOT 180 degrees apart.

[@kennethluke446]

Hi great video! Do you know which two gaskets together make the stock setup for a 2010 B KTM 300 ? The thickest and the thinnest? Make the .6 mm, if that is the correct thickness? Thanks anyone

[@slaverace1]

If you want the stock thickness, stack a .2 and .4.

[@SerhiyTemchenko]

Hi there! Is it necessary to remove the cilinder head when replacing the piston? Let's say I just want to replace the piston. What is the purpose of that, other then cleaning carbon deposit? Thank you

[@slaverace1]

Yes it should be removed to replace the head o-rings.

[@matthieudangerous]

Great video

[@garywoodman9304]

I have a question do u have to hone the cylinder bore ? I know it has nikilsil in the cylinder but shouldn't you still lightly hone it so the rings seat well ? I'm about to do my 2010 ktm 250sx so a little help would be greatly appreciated

[@slaverace1]

+Gary Woodman No, No, No. Watch my cylinder care video.

[@eadccomponents8897]

Hi Jeff- wanna do a 2 or part series no a ktm 200 (2012) top and bottom end rebuild ;)

[@slaverace1]

+Eadc Components No thanks. I prefer to spend my time riding.

[@pekka9041]

Hi! I might have droped my power valve rod pinclip in the clutch case while rebuilding on my ktm exc 250 2019 what damage it can cause?

[@slaverace1]

Probably won't do any damage but might get hung up in the shift linkage and your bike would stop shifting.

[@pekka9041]

@@slaverace1 okey,Thanks:)

[@Sruikyl]

What kind of fuel do you use? Concerned about E10 gas around here locally and was wondering if there's any alternative to race gas.

[@gravediggmn]

A lot of stations where i live generally sell their premium gas ethanol free. keep a look out on the 92 octane pumps next time you go for a fill up, you might luck out.

[@Sruikyl]

Unfortunately I live in austin where E10 is mandatory, I've heard bad things about it and 2 strokes. I did find somewhere on KTMs website saying all their bikes can tolerate E10, would still rather do without it lol.

[@gravediggmn]

I hear you, spent enough money replating my cr250 cylinder, would like to keep the fuel as pure as possible. Theres a website called pure-gas.org that list stations who sell ethanol free gas, they list 118 in texas. Find the one closest to you, make a trip and stock up.lol

[@andrewevergreen9103]

What did you use to clean out the power valve and other parts?

[@tylerm3371]

Would it be a good idea to put loctite on the cylinder and head bolts if so red or blue?

[@slaverace1]

+Tyler M Never use Loctite on those bolts.

[@rceric1]

Very good video! Thank you!

[@treadway47025]

Where did you get hour meter mount? That is slick

[@slaverace1]

It's not an hour meter. That is a Trailtech digital fan.

[@ant88z]

Hi mate could you please do a video on a 250f ktm exc 2011. Top end rebuild. Cheers if u can

[@slaverace1]

anthony williams Sorry, I don’t have a bike to rebuild.

[@ant88z]

Jeff Slavens ok thanks anyway mate

[@griffithracingteam2412]

Good morning mr. Slavens, I'm looking for information about a 2006 250XC to 300 conversion and if they make one. I was told you the man to talk to and if you don't want to answer on here if you could send me an email link I will email you so I can get more information about this. the only thing I can find on it is 08 and up and just wondering what I could do to make mine a 300 and what I need to buy thank you very much have a nice day!!!

[@slaverace1]

Sorry, no 300 kits available to upgrade an '06. Time to move to a newer model bike.

[@griffithracingteam2412]

I already did brother. I went ahead and just got a 300 this time. I got a decent deal in one. Be ordering some parts from you soon. Thank you for the reply brother.

[@denelvo]

I don't douse the piston either, but bone dry, really? I use the Slavens bolt torque system as well ;-)

[@spencergoldstein3744]

Do we need new gaskets for the power valve?

[@crazybcenduro7536]

This helped a lot thank you!

[@mudpro200]

Should the ring gaps be staggered on a 2 stroke or is there a place on the piston for them to line up?

[@slaverace1]

2 strokes have ring locating pins so they can't rotate.

[@mudpro200]

Thanks so much!

[@singletrack_king7700]

I got about 500 hours on my KX,I think 2 strokes crank in general are tough for just trail riding lol

[@rajkirannatarajan9276]

FAQ: 1. What piston brand? -Vertex 2. Why not lube the needle bearing and piston? -Because he’s been doing it for decades and it’s never caused an issue.

[@slaverace1]

Rajkiran Natarajan We always use Vertex, which is the stock brand. Lube whatever makes you feel good.

[@Fontainebleauify]

Is there any difference between a 250 with 300 kit versus a stock 300?

[@slaverace1]

Yes, more low-end and mid-range torque.

[@mtpkts7431]

Where can you get that driver handle with the 1/4 socket in the handle?

[@slaverace1]

+Michael Mahoney Sears, Mac Tools, Snap-on.

[@r6chrisk]

+Michael Mahoney halfords.

[@RIPPERTON]

The starter cable is NOT "hot" as you say. There is a solenoid contactor probably in the air box. The cable you are talking about is only live when the starter is engaged

[@slaverace1]

You are correct BUT accidents do happen and the button is easily touched and then you have a problem.

[@rajkirannatarajan9276]

If I understand correctly, the starter motor cable is connected to the 12V bus. The starter turns over when the starter is connected to ground which happens when the starter button is pushed. It is hot. A multimeter on the starter terminal vs battery negative would show battery voltage 12V

[@jdhart111]

thank you jeff!!

[@natebennett2873]

Thank you!

[@julianwilson5174]

I just got a top end kit for my KTM 200, and i came with about 5 of the same gaskets all with different thicknesses. How the hell do i know what one to put on

[@slaverace1]

As stated in the service manual, adjust the base gasket thickness to achieve a zero X dimension.

[@haloreach107able]

What is a zero x dimension

[@minutemanoutdoors7730]

you might hafto take a pill to get over it hahah thats clasic! lol

[@johnathanhimka]

Did you get the piston bored to the piston or is that not needed

[@slaverace1]

Nikasil coated cylinders are not boreable.

[@michaelsteven1090]

What is "blow by?"

[@jakeapple3129]

what kind of foot Pegs are those?