Motorcycle Bottom End Rebuild | Part 2 of 3: Crank & Bearings
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- Опубліковано 16 жов 2024
- Motorcycle Bottom End Rebuild Parts & Tools:
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How-to disassemble and rebuild the crank and transmission on a modern 2-stroke motocross motorcycle or ATV. By using a Crank Puller/Installer tool and a crankcase splitter. We demonstrate how to remove your crank bearings and seals. We show a couple tips on what to do to help this process go smoother by freezing your crank bearings and heating up your cases. This is called sweating the bearings.
Watch Next:
Motorcycle Bottom End Rebuild | Part 1: Engine Teardown
• Motorcycle Bottom End ...
Motorcycle Top End Rebuild | Part 3: Final Assembly
• Motorcycle Bottom End ...
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I don't know about "better", but If you have lots of money and lack the confidence in doing it yourself, that philosophy is right on.
@loop1612 - it depends if the others are bad or not. i don't like tearing down engines, so I replace anything I think could cause a problem down the road.
Some manufacturers sell the case halves together and some sell them individually. Suzuki sells them together and when I had to change the left half for the same reason I had the same question. I measured the new half and comared it to the old -- no difference. so I ran only the new left. It worked fine. no problems. Just double check by measuring.
28 thumbs down? this video is probably one of the better videos out there. Great video :D much help to me!
@@Arteken dummy
That is correct, you can do a rebuild without the help of the Tusk Tools but they sure do make the job a whole lot easier!!!
Most KX models need a slightly diferent procedure. I do it by heating the right case in an oven (torch will ruin seal) to 200 degrees. Freeze the crank and drop it into the right case half. Assemble the trany into the right case half. Then use the crank puller to pull the left case half onto the crank. In other words, the tool will only work on the left side. heating the case and freezing the crank is the way to do the right.
You're doing a excellent job... Thanks for the helpful video.
- your YFZ doesn't have a gasket between the case halves. you must use yamabond. Usually the rod bearing wears out before the main bearings (not always). I would consider changing it as well since you will have it split.
It could be a couple things. i would pull the right side case cover and make sure the shift cam mechanism is working right. If it is, you most likely have either wore out gears or bent shift forks (or both). You will need to split the cases the get to them. Refer to your manual.
- It isn't actually cracked. It is a "mark" from the casting process. it is on the surface only and was there when they pulled it from the mold. It is not a problem.
Water boils at about 212 degrees at sea level, which is where the water drops start to sizzle (they are boiling). You don't need to heat it to 400 degrees. In the hundreds of crank bearings I have put in over the years, I have never seen any kind of problem come from it. Don't forget, the engine can get 3 times hotter just from normal use.
Don't lose sleep over it. Greasing any seal helps it go in easier and helps it come out easier years down the road. It certainly won't hurt anything.
I like to use a bearing driver set but if you don't have access to one a socket that sits on the outer race works just fine. Just watch and make sure the bearing goes in straight.
I am not sure who the other guy is promoting, but I don't think anyone can beat Rocky Mountain on the Tool prices. Shop around for the cheapest option. Call a local shop and see what they charge to press in a new rod. That may help you with your decision. Gook Luck.
@jmicm13 - you could put a little premix on the bearings if you wanted. No grease. The bearing is lubricated with the premix in your gas.
i suppose you could warp it if you applied a lot of heat. You are only heating the case to around 200 degrees Fahrenheit (to water boiling point). This isn't near hot enough to damage the aluminum or cause it to warp. However, the oven heating method works good too, but be prepared for your wife to be angry at the smell in the kitchen!
Its help like this that make RockyMountain a quality company!!
- great question. Very common on kawasaki's. yes you can still heat the case, but don't use a flame. heat the case in your cooking oven. Just set the temperature to about boiling temperature. This will not hurt the seal. Your wife may be mad about the oily smell in her oven though (of course we like the smell)!!
Regarding the gasket - a 1997 kx250 does not have a center case gasket, so don't use one - use the liquid gasket. the one in the kit is most likely for another year the kit also fits.
It sounds like your lower rod bearing is toast. Make sure to change the main bearings and seals while you are there. You can buy just a rod rebuild (rod, bearing, pin, thrust washers) for the bottom end. You will need to have a shop press the old one apart and put the new one in ($50-$100 for their time). We don't sell a complete crank for a 1990 RM250. Any dealer can special order these parts for you.
@RockyMountainATVMC
ive done it all now, cheers guys. yeah it took about 10 minutes of fiddling around with it but its all done. your vids are excellent. keep up the great work guys, Regards Carl.
The bearings and crank will get to a point where it's not going to let you pull it together anymore. You'll feel it when it stops and you won't be able to go anymore. Obviously you don't want to crank on it super hard but also as you put your other case half on it will put the crank where it needs to be
The Tusk Crank Puller, what parts come with it to adapt it to the end of the crank? If it can go on my crank nut I guess it could work looks like you bolted something into the crank but if that bolt hole doesnt exist or is worn out you cant do that. Just checking I was thinking of maybe using it on an older bike if it would work before rigging up my own.
Absolute top class video, just redone by transmission while watching this video. KX125 rebuild as i got the bike in a right state from the previous owner. Little winter project :)
Really appreciate your videos, gave me the confidence to do the rebuild myself ;)
Sorry but unfortunately we don't offer this service so you have a couple different options. If you were to follow this set of videos and have your service manual right there for reference i'm sure you would be fine doing the split but your service manual and the correct tools are key to a succesful job. If you don't feel comfortable doing the split one of your local dealers or local shops would be the next best option.
Usually i will put the bearings in the freezer overnight so they are good and cold and then pull them right before you and going to set them in. When heating up the case half i will go around it with a torch for a few minutes to the point where water will sizzle as shown in the video. Alot of times the bearing will drop right in with a little assembly grease but if it doesn't drop right in don't hit it directly on the bearing.
We were just using an aerosol contact cleaner but most times we'll clean each case half in a parts cleaner
great video sure this will come of great help to some of us newbies out here
this is a great vid and it also helps promote the tools you guys offer thanks alot rocky mountain
We don't show it because there isn't an oil pump on a YZ 250. I really don't know too much about the oil pump on an RXS100. It souunds like you have a bad seal or gasket somewhere if it is leaking into your transmission.
@loop1612 - I would check to see if you have any free-play in the bearing behind the flywheel (grab the flywheel and pull up and down). if you have any play, time for a rebuild!
This video will be very helpfull for my technical English classes. Thank you
You don't want any up and down play in the connecting rod so you have a couple options... depending on the bike you have some cranks are easier to rebuild than others but a lot of times you have to have a shop do it. You would need to buy a new connecting rod assembly if you go that route... If not you can just buy and entire crankshaft assembly which already comes balanced and assembled but it's up to you...
@woodydasotonman - if you stripped the head, it may be time for the drill and easy-out. i would try to make something fit the head first though (vise grips or cut a screwdriver slot in the head).
DRY ICE AND BUTANE TORCH???!!! Amazing! I just learned a new way for bearing intraction. Thank you very much. Excellent execution of lesson and great storyline. Please make more videos. FIVE FU@@ING STARS. ***** RESPECT= RH DSD
Thanks! That is the Bel-Ray Waterproof Grease, We carry it in a 14 oz. Tube (1043410001) and also the 16 oz. Tub (1043410002).
correct. Clymer service manuals will show this procedure.
You could do this for the 1 side but it's critical that the crank goes in straight to avoid causing any damage.
@xNCKxKrusty - not unless you can come up with soming to pull the crank into the case. What ever you do, don't "push" or squeeze the crank in. you will ruin the lower rod bearing.
congratulations on your video from Colombia
I do not speak English, you only need to see a video to learn more
thank you very much I wish had had a teacher like ud to teach me a lot more.
very immaculate your workplace
esto lo hice por medio del traductor google
We lightly used Bel-Ray Bearing grease on the seal and inner race of the bearing, but oil can be used. The goal is to make sure the seal slides over the crank smoothly, and that the crank rotates smoothly once installed.
@RockyMountainATVMC cheers mate, ended up borrowing a puller from moto joint, not easy to get your hands on if you dont know the right people, and the case splitter are sold most auto and tool shops, but the thing is, no one knew what it was or what its for haha
- It is easy on a dirt bike!
Great help. Thanks Rocky Mountain.
@OffroadBeaver - the crank shouldn't be moving at all. The rod will have some side to side play. Refer to the manual for those specs. Each machine is different.
Most dirt bike cranks don't require shimming; rather, the crank needs to be pressed together with its width in spec with the tollerences in the service manual (Some KTMs do need shimming). In most cases, the crank will always be pulled to the right side (primary gear, bolt and spacer are all tight). Regarding your cylinder, I am not sure what you have going on. side to side or front to back? Typically, there is enough side to side play in the rod to put any side pressure on the piston.
I'm actually kind of amazed at how big all this stuff is. I'm used to seeing Maico parts, which are rather on the small side by comparison, I suppose. The compact size of the cases can really be something to behold.
Oh, hello there Toby, what a coincidence. :-)
Thank you for making this video 👍
Anytime *RideArizona.* Thanks for watching our tutorials.
You lucky bastards and your shop and all your tools and whatnot:D i have had to bring whole twin street bike engines into my apartment and all i had was a socket set, some allen keys, and 1 flat and philips head screw drivers. This was a great informational video and i subscribed to you guys.
@breno6511 - you will need to look at a parts diagram to see where the water chanels run. It has been a while since I tore apart a CR250r engine. if the oil runs through the right case cover into the center case, it is a possibility there as well.
It certainly sounds like a fried clutch.
The only way to get these bearings off and not jack up your crank is to use a bearing puller. We sell a Tusk Crank Bearing and Gear Puller Set for $59.99 a piece. The part # is 1195970001. You don't want to hit and pound on your crank at all so a bearing puller is by far the best and easiest route to go.
@lamborev69 - you should be able to pull the seal out from the outside (you will ruin it) and put a new one in. That is what I would suggest.
I neant for the actual bottom of the connecting rod, but i talked with one of your customer service people and got my answer.
If you are refering to a KTM, they sell thin spacers (thrust washer) for the crank (between crank and main bearing). They sell them in different thicknesses to adjust the play. Check the OE parts diagrams on our site to see the spacer options.
Correct-No grease. On a two-stroke you can put a little premix on the bearings or motor-oil on a 4-stroke, but you do not want to use grease.
The plastic pieces on the crank are used to fill a void of steel that was removed on the crank to keep it balanced. These pieces can not be purchased separately. You will need to buy a new crank assembly. Chances are that your rod or main bearings are shot if the plastic came out. We sell a Hot-Rod brand complete crank for your bike for $183.99. You will want to get a main bearing and seal kit as well. We have that for $38.99. Good luck!
@bar4rodski - The crank on a two stroke is lubricated by the premix oil you put in the gas. The Air/fuel mixture is drawn into the crank, then pushed up to the combustion chamber.
@littleenjoiskater - side to side is OK, straight up and down is not OK.
@wardy1231980 - that bike is tricky because you have to put the two gear shafts, shift forks, shift cam intogether at the same time. It is best to refer to the manual to see how they all fit together. It is tricky getting them into the case half at the same time.
excellent video , Thanks !!
You don't want to pack the bearings with grease inside the motor. They are lubricated buy the premix (main bearings on a 2-stroke) and by the transmission oil in the transmission.
Ok thanks, I already got them out. The case was cracked so I was putting everything into a new one and I had to cut the old case because she shift drum wouldn't break free from the bearing
- It helps to do both.
Refer to our website for piston pricing - We don't have cylinders for that machine. Tear it down before you buy parts. You may not need a new cylinder.
as far as the kfx goes, did the bearing spin in the case (outer race) or on the crank (inner race). That will determine whether you need a new case half or a new crank.
You Bet! Thanks for watching!
When re-installing the crank how do you know when it has been seated properly into the crank bearing? How much force do you apply without over torquing it into the crank bearing?
When u put the cases together they seat them self's just torque it to spec and it's done
Nope it doesn't matter, you can install them into either side. I will usually start with the right side and work from their but it's basically up to you to start with whatever side you think is gonna be easier. On some bikes if your crank puller only fits on one side of the crank it may be easier to heat the bearing and freeze the crank and install that side first and then use the puller tool to pull both cases together. Other than that it's totally up to you
Oh and another thing. Dont bother spending nearly £100 on the tusk crankcase splitter. Just buy a harmonic balance puller for approx £10 on Ebay. It will do the same job. When reassembling the crankshaft. You wont need a Tusk crankshaft puller either. Put the crank in the freezer for an hour and put the case half in the oven 150 degress for 15 minutes.Crank will slip in without problems.Fit the oil seals after the Crank is installed. Use the case half bolts to pull the 2 Crankcase halves back together. Cheap as chips to do your own engine rebuild. Dont bother buying gasket kits either.Too expensive. Buy A4 gasket sheets for a couple of quid and cut your own.Plenty of vids to show how to make your own gaskets for a fraction of the price.
***** I do crank rebuilds with a 30 year old adapted bench vice. You would be surprised how easy it is. You dont need big expensive hydraulic presses. Just a bit of accurate measurements.
***** This video is about rebuilding the bottom end on a 2 stroke engine. There are no shells and no grinding is required. You are talking about a different type of Crank altogether.
This engine has a roller bearing and simple pin crank. There are only 5 parts that need to be replaced. Con Rod, Con Rod Bearing, Crank pin and 2 spacers. The 2 halves of the Crank assembly do not need to be replaced. It is a very simple process to push out the pin and re install it after new parts fitted and can easily be done with an old large bench vice. You have to grind a large slot in the vice jaws for the assembled Crank to slot into. Thats why i used a very old vice.
The only critical point is lining up the 2 crankcase halves. 2 "G" clamps and 2 straight pieces of metal are used to line them up. I was shown how to do it many years ago when rebuilding Lambretta engines. Its an old way of doing the job but works perfectly. 2 stroke engines have been around for far longer than modern machinery and hydraulic presses.
Funny i was thinking wait thats a harmonic balancer removal tool lol
when re-installing the crank you used bar stock across the case doesn't that mean the crank installer is pulling on the crank / inner race of the bearing only? it should be holding the inner race and pulling the crank into it. I love your videos but had to close my eyes for that part
@irishman922 - You can do it either way. They both have to come off. I don't understand what you are talking about "clutch side comes off ign. side". they are on opposite sides.
yes you can
@HandSanitiza - i assume you are talking about the magneto cover?? The gasket is most likely stuck. Try tapping it gently with a rubber mallet.
@171apples171 - I feel for you. I still have to use my tiny garage most the time when I work from home. Between the wife and kid's stuff, there isn't a lot of room for working on the bikes!
Not a problem!
Brilliant...Absolutely Brilliant. RH DSD
The new top end won't cause additional stress. if the bottom end is in good shape you will have no problems. Check your main bearings by grabbing the flywheel and try moving it up and down. it should have no up and down movement either.
We were using a Water Proof Grease from Bel-Ray which we carry in either a 14oz. Cartridge or a 16 oz. tub.
You need to find out what is wrong with the 125 before you start buying parts. Does it have spark? The 95 YZ was famous for having the crank bearings go bad and the stator frying. I would check that first.
$1100 for a KFX is a killer deal, but what bearing is "spun". Once again, you need to tear it down to see what damage you are really looking at.
@crazycow127 - you can split it from the flywheel side and keep the gears in place.
@jesserodriguez73 - when it gets loose, you will often hear a "knocking". If it fails...yes, it would most likely lock up and damage a lot of other parts in the process.
Hondabond 4 is similar. It should work fine.
@SeppLainer - That tool would work, but would take a lot longer on this application. These bearings fit tight!
@cordoprod - no it won't. This is how all the manufactures have designed it to be installed. The pressure is far from being strong enough to damage the bearing.
I had a watch band like that when I was a teenager
@breno6511 - It can only get in the transmission in a few places, so you will have to double check each one. Obviously one is not sealing. The base gasket or waterpump seal should be the only two places.
thank you your video was really helpful
Just follow these videos and your service manual very closely. You'll need a few different tools such as a flywheel puller, case splitter, crankshaft install/ puller tool and then also a clutch holding tool.
We are rebuilding an 06 kx 250. The crank seals come out to the inside. As a result heating the case to insert the bearing could be detrimental to the seal as it must be placed first. Got any ideas? By the way, THANK YOU for this vid. We rebuilt a 90 CR 500 successfully because of you!
+phdequipped If you have to seat the seal first and cannot heat the crank case, then you have to use the method of freezing the bearing and use a bearing seater where one end of the seater rest on the opposite end of the crankcase and the bearing seat on the outer race of the bearing and turning the screw of the bearing seater, will easily seat the bearing without impacting into the bearing. Another improvised method is to use the right diameter of sockets and washers and a screw of appropriate diameter and apply force by counter opposing two ends by tightening the nuts at both ends.
@RockyMountainATVMC Cheers done it in the end got some good quality tools and hammerd a hex in there a size larger took some strength but done it in the end! Cheap tools dont do anything just go's to show lol
Brake/contact cleaner. It removes the oil film quite well.
Great video! I am currently rebuilding a 2008 KX250f. I have the motor pulled out and piston removed and oil drained. Bottom end is on the bench. When I rotate the rod/crank by hand, there is a slight clunking sound. It rotates smoothly but there is still a noise. Is this the main crank bearing? There is no free play up and down but a little from side to side of the rod. The clearance free play from side to side is 0.35mm (between connecting rod and crank), standard clearance is 0.25mm-0.35mm and service limit is 0.55mm. This is my first bottom end job so I'm not sure if the rod/crank should rotate with no noise at all. Also, my service manual states that you should not use a torch on the case as it will cause warping. Is it still okay to sweat bearings in as long as you don't heat it up too much (above 200F)?
If your connecting rod bearing is all good, then i would say it would be the main crankshaft bearings. Have you tried applying any motor oil with your finger onto the main crankshaft bearings to see if it goes away with a little lubrication? Your side to side free play seems to be within spec. If it was me, I would replace it all. Does it still have the stock crankshaft in it? As far as sweating the bearings in goes, that is a well practiced method for installing crankshafts and bearings. Also other methods would be heat transfer and using a crankshaft puller installer tool. We sell that tool as well: www.rockymountainatvmc.com/p/989/17166/Tusk-Crank-Puller-Installer-Tool
Let us know how it goes and if you run into any other questions! Vinny
The bike used in the video is a Yamaha (Japan).
tusk this tusk that...this job is simple wo the special tusk tools...
You can always just bang on the parts with a metal hammer like all the other kids do.
@SoobaaSteve - sounds like you need to pull it apart and repalce the ruined and worn parts.
@lamborev69 - on some bikes it could block the lubrication port to the main bearing.
@ddanj13 - it sounds like you need to reinspect the piston and rings to see what is going on. if you lost compression again, you need to figure out why.
@sirjeffreyhcc - You need to determine where the noise is coming from and what is causing it. Then you can address the problem.
It depends on the machine and the parts you are replacing. You can research the parts specific to your machine on our website.