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  • Also dont forget to purchase a Clymer or manufacturers manual.

  • After watching this video and purchasing all of the Tusk tools in it, I rebuilt the top and bottom end in a 1990 Suzuki RM250 with no issues. Since then I have rebuilt a 1988 Honda CR125 and a 2002 Yamaha YZ125, saving me lots of money instead of paying for labor at a shop or dealership. Thanks RockyMounainATVMC!

  • Wow, you guys made that look super easy, but it doesn't look like it.

  • forgot to put the crankcase dowels back in

  • @breedam ohh you clever dog

  • @noahlyden17 - trust me, we got them in.

  • have a question i have a 1997 kx 80 big wheel real fast but i seem to b aving a problem with te clutch ... the bike starts first kick but the clutch is not grabbing inside the wire moves and everything but not inside i have to power shift to ride any input will b appreciated thanks.. meaning the bike turns on i just have leave in nuetral wen its on give it a little push and pop into second and everything is else is fine.. popstart with the bike already on

  • @jonrod48 - you need to pull the cover off and see why it isn't disengaging.

  • when you split the cases there is a seal on the front of the engine i need one, do you have them on your site and if you do can you give me the part # so i can buy it its for a 1999 yamaha yz 250

  • @Yamahayz2502t - sorry so late. Yes we have the O-ring that goes between the cases on that bike. part # 1241700001.

  • @RockyMountainATVMC its ok I will order it thanks for the reply 

  • How long did this process take?

  • @1stchoicepc - longer than normal since we had to film it! With the motor out of the bike and top end off, you can do it is an hour or two.

  • Thanks man your videos helped me a lot :)

  • hey i did exactly everything you did in the video to my yz250 but once i kick to start it its so hard to kick it i dont know if sumthing is stuck or wat once i kick it the kick lever stays exactly where i kick it to and doesnt come back up im in need of help im so close to putting this beast together but thats my only problem

  • @dmbnorthphilly - Did the crank spin smoothly when you got the cases together? I hope you used a crank puller. Retrace your steps and see what is rubbing or hitting. It could just be something with the kick start mechanism.

  • Quick Q' if i may!.... You changed the crank bearings and all is good but is it neccesary to change the other bearings in the crankcase for transmission at the same time or do you not need to change them as often? and also if you do need to whats the best way to go about that as i know you don't have access to the rear of them to hit them out like you do with the crank bearings??

  • @jaydaintith - it isn't a bad idea to change them, but they may be just fine. inspect thm for free play or signs of wear. Refer to our "motorcycle wheel bearing replacement, engine bearings removal - ATV " video for removal instructions.

  • hey i just rebuilt my yz250 and whe i kicked it ovr it tured on but when its on nuetral the tire keeps spinning like if its in gear. what do u think i did wrong

  • @paintballer2X5 - i assume it is on a stand with the tire off the ground??? This is most likely normal. There is still drag in the transmission that will move the wheels some when off the ground. It it wants to drive off on you, you may have a problem.

  • hi there my CR250's tranny is tweaked out. 1st slips into neutral and only 1st and 2nd were working 3,4,5 were not going in. now i tore it apart i see why 1st was slipping out into N. but the little spring loaded thing that holds the star into place show that 1st goes in halfway then slips back into N. but when its in N the bike is still in gear. now i can see the shit drum and i only find N in between 2nd and 3rd according to the Star. but all the gear are shifting thrue. Any ideas PLEASE HELP!

  • @Sandeep9201 - you most likely have a bad shift fork and a couple gears.  you will have to split it to inspect. i am not sure about the cam mechanism you are talking about without looking it.

  • My cylinder is measuring 66.85mm STD is 66.4mm i am sending it to Millennium technologies in the states to have it bored and re-plated to suit a 67mm.

    those tools are not essential but make the job alot easier and less chance on damaging your motor. so buy them! well worth the $250 i spent. and well built so i can see them lasting forever.

    Thanks again

  • Good Thing this video. My Cylinder is stuff though, any advice on whether i should re-sleeve or re-plate. Personal preference?

    Thx

  • @KyleMrK - "My Cylinder is stuff though". I am not sure what you mean. I have had good luck with new sleeves from LA Sleeve though.

  • I just blew a crank bearing and I'm wondering if all those fancy tools are necessary for replacing it?

    Please answer

  • @9lives22 - it depends on the machine. refer to your manual. In most cases you need the tools to do it right and with a lot less frustration.

  • i got a yamaha yz 250 and it just got new bearings and new crank and new piston

    and its harder to start is it normal y is it harder to start plz reaply fast !!!!!

  • @Yamahayz2502t replace the spark plug be for you do any thing then do a compression test and spark test and clean the carb if it still doesnt start then check your stator plate timing marks

  • hey man, great vid. Im changing my 1st gear cog and shift fork on my yz250 2000 model. this vid is such a great help, thanks.

  • @wardy1231980 - glad you found it helpful! thanks

  • is this pretty much the same configuration on a 1993 suzuki rm125? I am in the middle of rebuilding my engine and need to get it all apart, will I need a puller and engine splitter or are there other ways of doing it?

  • Since I am probably going to put in shift forks and maybe drum or something else, do you have a video of how the transmission and drum/shift levers engage?

  • @mrjata - i don't. when you split the engine, just pay close attention to how it is working.

  • Thanks for this video, will be a huge help. I have shifting issues, not wanting to shift easily or at all. Did you use a main center case gasket ot just RTV?

  • @mrjata - It depends on the machine. Some bikes (most hondas) use a gasket. Some only use a sealant (most Yamahas) like yamabond 5. If the manufacture calls for a gasket, you have to use a gasket for spacing reasons.

  • Yes I wanted to know how much does your crank puller/installer cost I'm actually rebuilding my crankshaft assembly and one main bearing is a pain to get out on the left case also wat should I do? Your videos are super handy wit my project 01yz250 thanks !!

  • @dmbnorthphilly - check out our website for tool and part pricing. If the main bearing is stuck in the case, you either need to press it out or carefully pound it out.

  • Hey,

    I have a yz125 and the second gear is stuffed - to work on the transmission only would I need to remove the clutch / drive gear and all the stuff on that side of the case, or could I skip that and just split the case on the other side and remove the transmission?

  • @sx512 - you can split the case from the other side, but if you want to remove the transmission from the case you need to take out the stuff on the right side.

  • @RockyMountainATVMC thanks for the reply!!! I'm going to buy some of those tusk tools from your website now and go ahead with taking a look myself.

    Also, on the 01 yz125 are you aware of anyway to swap out the 6th gear to something that will give me more top speed? I know you can can do this on the 02-05 yz250s, swapping 3-5 gears with the wr 3-5 gears....?

  • @sx512 - sorry, I don't know of any other gear you can put in there.

  • @sx512 Easiest way to change that would be to swap a sprocket out

  • ok so i have a 2005 honda crf 250r. the engine was seized but i got it loose. i drained the oils and have alot of brass filings in it. what and where would that come from? and how much work am i looking at here?

  • @contreeboie - You need to split the cases and inspect the crank and tranny closely.

  • @contreeboie brass colored is probably from lower connecting rod bearing. You will need to probably get a new crank or at least rebuild it

  • Stick some string on that washer, trust me it sucks when you drop it in the case! :)

  • hi i have a cr250 (91) what is the torque settings for the clutch baskit plz?

  • @sirdaveomac - without a manual i don't know either. sorry!

  • how tight do i put the clutch bolt thing that have the springs?

    

  • @pmkfrtscvo - refer to your owner's manual for torque settings. If you are refering to the 6mm bolts on the clustch springs, it is usually 7.2 foot pounds.

  • i put my left case on and screwed the cases together but the gears arnt spinning what did i do wrong?

  • As a machinists and hydraulic pump/motor/gearbox repair tech

    You really shouldn't load bearings like this, Why doesn't your puller slip into the case and support against the inner race? That's how I made mine.

    Of course on a POS kawie the seals are alfeady in and you can't support there.

    Trying to figure that one out right now

  • @ rockymountianatvmc I have a yz80. I've had this problem for a little while, the bike starts in neutral I can put it in gear but it won't go but it's in first gear but it revs instead of pulling. I put a new clutch in what do you thank the problem can be

  • I have a 82 yamaha xj750 seca that I am going to rebuild the transmission in. Is your vid pretty much the same as the rebuild that i am about to do?

  • hi i have a question, when re-installing the crank on a KX 250, that only has threads on one side, is there a specialty tool to do this, I see you use the crank puller for this application, but how would you go about it on the KX, since the drive side is a spline drive, not a threaded piece?

  • @KX817 - Great question. If you have a KX with the c-clip that holds the primary gear on, I now have an adaptor that works with our crank puller. It should be in stock this week!

  • Good video and good tecnic.

  • question, how much torque do i apply to the clutch hub nut?

  • @gekopacific - Every bike is different. Refer to the manual for your specs.

  • even on the right side crank seals of 2-stroke engines with wet clutch? can an excessive quantity of grease in such a seal make it leak and let the engine suck in the gearbox oil? experienced anything like this?

  • @22kurgan - it is similar.

  • hey im doing this rebuild to my cr125 but i want to glassbead each cast do i need to do to get the other bearings out

  • @UE211 - yes unless you want glass beads in the bearing.

  • hi,guys! i have a question - do you use any lubricant on inner surfaces of crank oil seals? thanks

  • @22kurgan - Yes. I always put a litle grease on them.

  • hi there.i have a question.i have a 2001 2 stroke cr 250.and im trying to ship my engine together with the cage to texas.will the engine starts leaking if they put the box upside down because i didnt drain the oil?thanks.

  • @nicorolden - yes, it will drain out the breather. Why don't you drain the oil the best you can and then plug the breather. then put it in a heavey plastic bag as a safety measure!

  • Great Video!

    Just a question though. The video doesn't show the torquing of the crank screws / bolts to the factory settings or the installation of the other gaskets is that because it's not important?

    Thanks,

    Chris

  • @chrisnorman83 - it is important, but every bike is different. make sure you refer to your manual. Also, some guys that do this enough have a pretty good feel for the torque they are putting on a bolt and therefore don't use a torque wrench all the time.

  • @RockyMountainATVMC Thanks, I have just replaced my bottom end bearings and I'm in the middle of putting my yz crank halves together and wanted to make sure also do the guys use lock tite on the crank bolts themselves?

  • @chrisnorman83 - wanted to make sure what? Unless the manual calls for the locktight, I wouldn't use it on the case bolts.

  • @RockyMountainATVMC Sorry for the bad sentence! Yeah you answered my question. Cheers again for the video!

  • wow, jeez man, ur like the bike gods.... i love workin on things, an i have a 89 kx80, and im putting on a new gasket bc the oils leakin....... but i was gonna take out my engine, an i got all the way down 2 pullin out the engine, an the kill switch was there.... i took the kill switch bolt off the handle bar, an im stuck on how i undo the wiring 4 the kill switch , on the main wiring system? where all the wires go, 2 the little system thing..... bc without me undo that , i cant takeitout help

  • @paintballing03 - thanks. your kx 80 kill switch should just plug into the wiring harness. I doubt it is hard wired in. I am confused why you need to pull that to get the engine out though. Pull your stator and spark plug wire and your engine is no longer connected to the electrical.

  • i dont understand what a bottom end rebuild is if u just take it apart and put it back together

    it was helpful explaining what to do but why should i do this what should i replace just the barrings ??

  • i dont understand what a bottom end rebuild is if u just take it apart and put it back together

  • excellent video i just ordered my crank installer tool from rocky mountain today when it gets here in the uk i will be following your videos to complete the teardown.

  • cheers for the video breakdown.

    Pretty helpful knowing what I'm getting into if I buy an RGV250

  • Excellent videos! Well done.Thanks for sharing this!

  • Wow man, just wanted to say thanks for taking the time to show everyone how to do that. I have built several top ends but never dreamed I would attempt the crank and berrings until I watched you 20 times. I ordered all the tusk tools you mentioned, a service manual, berrings, and a Hot Rods complete crank like you said. Very nice tools and crank by the way. Now, if I only had a bike to work on....

    Just kidding. The tear-down is almost complete. Thank you for your videos.

  • @Kjames9951 - thanks a lot! I am glad it helped out.

  • Comment removed

  • can i use termo silicone instead of liquid gasket???

  • @BAKARDAN1 - probably, but if I have gone to the trouble of splitting the case, I will spend the money on the liquid gasket the manufacturer recommends.

  • I have a 99 YZ 125 and just need the power valve assembly diagram, and the setting points in the case! Could you help me out on this? Thanks

  • @wicked1k - you can get the parts diagram on yamaha's website.

  • i watched the whole procedure, so could i follow this procedure to do work on the yz 125 im getting? also im really new to rideing and dont know how to work on bikes so would you suggest i learn and do it?? or get someone too?? whats best for me and my bike? thanks and nice vid by the way. :)

  • @FratusDillon - you should learn. get a service manual and take your time to learn how to work on your own bike. most likely you will learn to do it better and save a lot of money.

  • @RockyMountainATVMC okay man, thanks a lot

  • good

    

  • good......................

  • best instructional video on this subject on the web.

  • nice vids makes everything look easy (with the right tools of course) and congrats to you for explaining everything

  • Muy bueno...saludos desde Argentina.

  • hey nice videos, very good info, i hav a question

    My buddy has a 02 CR 125 that he crashed, landed on left side, bent the bars, subframe, left rad, etc. and soon after he was trying to get it started (no spark issue) and the engine locked up. He brought it over and we split the cases to find nothing visibly wrong with the engine/tranny at all. we should have done more diagnosing before splitting it. Do you think it is just a shift fork jumped out of the drum? or something like that? thanks

  • @79stingman - Yeah, I would have done more to diagnose the problem before. Do you know it was a problem in the transmission? Could the cylinder or crank have been full of gas from being laid down, locking the piston? I have never seen a shift fork jump out of the drum. if it did, you would see some seriously bent forks and most likely some ground gears (a wreck won't do it though). I am not sure what to tell you without knowing the problem. good luck!

  • @RockyMountainATVMC yes it is definently a tranny problem, couldnt shift through the gears and the bike wouldnt roll. One shift fork might be very slightly bent but i dont think it would affect anything. I think we are going to get new gaskets and a few other little things and reassemble piece by piece, seeing if it locks up after each one, and we will either find the problem or find nothing and hopefully it will work! thanks for replying.

  • @79stingman - Good luck. It is always a lot more difficult when the problem can't be pin-pointed.

  • hello very helpful video

    just wondering when installing a new crank does it have to be balanced?

    thanks

  • @gihidohe - a new crank assembly should come ballanced.  yes, being ballanced is important.

  • @RockyMountainATVMC so does this mean if i buy a complete crank i can just install it

    thanks

  • @gihidohe - correct

  • Hey I have a 03 yz 250 pretty much the same bike as in the video, and I was wondering how much crank oil should I put into it in order to fill it up to the proper level? It's completle empty right now. Thanx a lot

  • @Jr91D lol. none its a 2 stroke

  • @hill2t i used the wrong word i ment oil for the tranny wise ass

  • hellow im rebildind a yamaha 2 stroke motor on the halfs of the cases what other sealler can i use like whate kind of rtv or form a gasket

  • @stutest2 - i am not sure. I would use what the manual recomends. In this case it was yamabond 5.

  • where can i get a flywheel holder ,, the clutch hub holding tool wont work,, i need a "flywheel holder", please

  • @TheRoy34 Rocky Mountain carries flywheel pullers for around $15.

  • what sort of assembly lube did you use

  • is this fairly similar to a 06 crf250r

  • @TheRoy34 - It is fair to say that it is "fairly similar".

  • Thanks for taking the time to put this together. I have a question: which is safer? Sweatin' in the crank (heating up the bearings and freezing the crankshaft) or using the puller tool? I have purchased the puller tool but I'm hesitant about using it since the pulling pressure would bear on the inner racing of the bearing. Should I be worried?

  • @plomarine - Both methods work and are safe if done right. The OE books will tell you to use a puller (They are pulled in the factory when the bikes are manufactured).

  • Comment removed

  • @tlbohanon - The last thing you want to do is press it in. it has to be pulled in.  On a KX250 you need to heat the case half in an oven (flame eill damage internal seal) and freeze the crank. It will drop right into place.

  • you make it look easy

  • great videos, they helped me alot

  • you know what your talking about, which is more then i can say about my local dealer, where are you located, and how much would it cost to replace a yz250 crank, bearings and just check everything in the bottom end?

  • @mxjunkie28 - Thanks. We are located in Utah. We are a mail order/internet company for all your apparel, parts, and accessory needs. However, we don't have a service shop - just discount retail.

  • im bout to do the bottom end rebuild on my 2003 kx 250 are they similar to some extent i have alot of tools and stuff just have to by the splittter the crank puller/installer and clutch hub tool and also is it a good idea since its gonna be apart ne ways to replace the bearings as well as the crank or if they are good should i leave them on there

  • @durginKX - They are very similar.

  • I am thinking about buying a piece of garbage, old, 125cc two stroke from craigslist so i can try to rebuild it to get some practice because i cant afford to mess up on my YZ125. Also would you recomend OEM or Wiseco pistons for a top end rebuild? Thanks, Great Vids!

  • @ghat13 - it doesn't get much easier than a yz125. you won't mess it up. Just refer to the manual. OEm and Wiseco are good.

  • Great Videos!! I am in the process of rebuilding the bottom end on my '00 YZ250 and have a question for you guys. How do you get the main transmission shaft bearing out of the left crankcase half (stator half)? The back of the bearing is covered by the case and there is no way to pound it out like the other bearings. It feels a bit rough so I'd like to replace it while I have it apart but can't seem to come up with a solution for getting it out. Any advice would be appreciated.

  • @Levytate - it is easy if you have the right tool. Watch our "motorcycle wheel bearing replacement" video. We actually do a transmission bearing as well.

  • hey u guys are awesome i'm soon going to be doing a top end rebuild for my 2007 crf150r this is ny first top end on a four stroke. I've watched your four stroke top end rebuild which was totally sweet and this 3 part series on the bottom end and i was wondering if you guys still make videos and if you do could you probaly do a top end rebuild vid of the crf150r if you can that would be awesome:)

  • @noodler11 - Thanks! your CRF150r will be much easier than the KTM we did in our other video. I doubt I will be doing a 150r video any time soon. Just invest in a service manual and it will be a breeze.

  • This was by far the best video I've seen in my life, thank you and keep them coming ;)

    ps how about a vid about fuel system, carburator and timing

  • hi could you please help me, i have just bought a complete crank it is off a 94 model cr 250 will it fit my cr 250 98 model cheers, dean

  • @juliethomas01 - Pro-x lists them all the same from 1992-2001.

  • i have a yz 125cc my spring in it came off hoe do i fix it

  • @TheMotocrossboys - I don't understand the question.

  • A good tip for reassembly is to use a zip tie on the aluminum washer that is about 6" long. You can't forget the washer as the case will not close with the zip tie end sticking out. I use orange ones. Easy to see. ={D

  • @gaijin1200 Good idea. I never thought of that.

  • I watched this video about 6 months ago when I bought a bike with a blown bottom end. Decided to give it a try and my bike is still running strong. I even bought the fancy tools you got to. I now do work on my friends bikes as well. Thanks!

  • what would you need to split a horizontal crankcase?

  • @priaprism717 - most horizontals are not pressed. It should take anything special unless your manual says otherwise.

  • what are the torque specs on the hub and primary gear??

  • @alliballillama - depends on the machine. Refer to your service manual.

  • this was a great video. I was on the fence about getting a bike, i had really wanted one and I found a really good deal. the only issue with it is everytime it is put into second gear it pops out. The bike i'm looking at has another transmission included in the purchase price that is brand new. I was iffy and uncertain before, because i felt like it would be an overwhelming task. after watching your video, I am going to buy this bike and do this job myself. Thank- you so much for posting this.

  • @priaprism717 - glad I could help.  Good luck

  • Does the tusk flywheel puller fit the ltz 400? I cant find one for it on rockymountain

  • @chino185 - No. it takes a special one from Motion Pro. We sell it on our site. Part # 1177270013.

  • do you absolutely have to buy these special tools in order to complete the bottom end rebuild? How long does this take you?

  • @crf250rider6 - if you want to do it right - YES. it takes a few hours with practice.

  • What do you recommend regarding the bolts? It looked as if you oiled them up a bit prior to installation.

    Am i right?

  • @RatRaper - a shot of wd-40 never hurts.

  • this is a very specific and clear video thanks a lot

  • How much would you normally charge for this procedure? Thanks

  • @collinw420 - Me personally? i don't know. Depends on several things. Call a shop in your area for a better idea of what it would cost you. i can tell you it is worth doing yourself.

  • I put my crank in the freezer, it dropped in the bearings like butter :)

    No need for force.

  • What exactly is the power valve and what is it's function

  • I mean Honda engines BTW.

  • @guitarfreak2105 - pretty much. no powervalve on the 500.

  • Is the 250 motor basically just a smaller version of the 500 motor?

    Kinda like Fords 4.6L and 5.4L engines?

  • do u know anything about the namura pistons?

  • @metalmillica - not much. I can't say I have ever used one.

  • when u install the trans. and the shift drum is there any certain way u have to put them in? kinda like a timing or do u just drop it all in and it should shift through the gears?

  • @metalmillica - As long as the shift forks are lined up in the right grooves on the shift drum, you should be fine. Just make sure it rotates through the gears. you have to spin the gears so they can move into place as you are testing.

  • @RockyMountainATVMC well u where right about the shift cam. i wasnt too sure if thats what you where talking about at first but thats what was wrong with it and the shift pawls

  • have you ever had the inner race on the ingnition side become tight when using this method? i have seen them get pushed outwards slighlty making the bearing diffcult to spin becuase it has resited the pressing action and put side load on the ball bearings. is there any harm in using heat on the bearing to help it slip onto the crank to avoide this . also is this neccessary when the ignition side has a roller bearing ?

    thanks

    good video good products

  • @WATTSWANNABE - No I have not. This is the method all the OE manuals will recommend.

  • what you think, any tips would really help, iv bought 100 in tools from you guys...and im going to buy more so help me out!...

  • hey , iv bought case splitter from you guys,awesome tool really sturdy, maybe i shouldnt say this but

    on my crank (kx125 97) , the crank installer will only work on one side, other side doesnt have threads, how do you think i should get the other case half on, the hot cold method? iv never done it, but i will try...maybe i should take it in for this half of motor...

  • Thanks alot. I just watched the bearing removal video, and I'll be ordering a Tusk Bearing Removal kit this week from RMATV. On another note, keep up the great work with all of your videos. I enjoy watching them all.

  • @topstar3 - Thanks!

  • Just curious how much do you guys generally charge to have a complete rebuild?

  • @cawille6694 - we are a internet/mail order company. We actually don't offer the service. instead, we show you how.

  • Alright, thanks for the video

  • If the main bearings remain on the crankshaft once you split the cases, whats the best way to remove them without a hydraulic press? Do you sell a tool that will accomplish that?