Why 2 Stroke Crankshafts Fail

Hey guys, I thought I’d bring y’all a quick video giving a quick glance at some of the common issues that causes 2 stroke crankshafts to fail. Thanks for watching!

[@kurtdavidson9808]

Good morning Just checked out your latest and greatest video. Great information! Every morning 4:30am I always look to see if you’ve posted a good video on bike care and maintenance. This one was great. I’m sure there are a lot of people like myself who love to ride there two strokes but don’t have the money or time to take there bike to a mechanic every time it needs maintenance or some kind of service. I really have come to rely on you and a few others that produce really informative high quality videos on how to take care of our bikes. So please don’t skip on any steps when your demonstrating these how to videos. I know that there are many points that should be greased on these bikes.wanted to see if the next time you take the time to go through and grease all these points on one of your bikes if you could to a detailed video on it. You do awesome videos and out of the hundreds that I look at on this topic your how to videos are in the top few. I like the fact that you do these videos as if your talking to someone who has little to know experience with bike maintenance. Because you are. Once again please don’t stop and I will definitely be looking for more. Thanks for doing what you do.

[@dbrunetti6770]

Bought a 65 that sat for years... its been a guessing game finding out what happened. I started putting together the pieces over the past several days as I'm getting the bike ready for the season (fixing it). I found out it was the crank shaft. Tore down the entire lower, split case, and I can see 100% exactly what you explained. The needle bearing /big side bearing pieces are so flat that they all worn down making a powder glitter throughout the lower /oil. From there they loosened out of place, found their way into other areas, froze up... From your explanation I have all 100 pieces of my puzzle figured out on what happened, how, why.... LOVE !!!! THANK YOU

[@jameselias9399]

Awesome info, keep up the great videos

[@conner_iversen]

This is so dope that your at 3.8k I’ve been subbed since like 200

[@user-xu1tk6zx7r]

So cool, alot of info. in one video! Thanks for sharing this video👍

[@thomasyoung4943]

Thanks for the video man!! Very helpful

[@josephineknutson9259]

amazing video Anthony

[@archie3252]

Thanks for your help keep up the good work.

[@Sulley1562]

Great info thanks for sharing 👍🏼

[@akmoto_]

Thanks for watching!

[@keeganfoster1792]

And something that u should mentioned is with big bore kits, is quite alot more compression too thus more pressure on the conrod

[@aarondeslatte786]

The crank that you spin at the end of the video, I have a older yz250 and I’m at a loss on how to properly seal the clutch side of the crank. The bike clearly had a bad past when I got it and I’m not sure if it even has the right crank in it/collars etc and the seals I get for it don’t seem to fit. That style crank where the clutch side is only a straight shaft with splines, what does the seal seal around? Is there a collar I’m missing? Any info would be GREATLY appreciated thanks.

[@chiradip24]

Hi, Nice video!! could you please help me understand, when changing connecting rod kit, should we go for over size pin or same size pin? Thanks

[@justsomedude5591]

Yo, it would be awesome if you made a KZbin short of just the sound of the engine with a bad connecting rod. I didn’t come across a video that sounded like my issue and thought it was a top end issue until I opened the engine up. A video showing this as the issue would help a lot of newbies out with diagnosing!

[@iandavin9224]

i saw you at creekside one time love the vids

[@donalddonaldson7211]

Great video really explained a lot to me Unfortunately I think I need to rebuild my 2016 TC 250 because I lost compression yesterday while riding When I bought the bike it had a k&n air filter on it and i switched to a twin air but never realized I didn’t have the air filter cage that keeps it secure. Dirt got in there once when I changed the filter months ago but I got a cage and have been running it. But my lucks run out and now I’m hoping I don’t have any up and down play but only one way to find out

[@donalddonaldson7211]

Also am watching your yz125 rebuild videos as I am rebuilding my 05 and I have to finish that up before I tear into my husky. Thanks for your videos. It helps a lot

[@PEPILLONINO]

I allready replace 3 piston 3 cilynder head, on eton txl50cc it keeps runing like shit scoring my piston. Next thing ill check is the crank shaft.

[@chillycheeze2207]

Do you rebuild them yourself? Or do you take them to a place? Or do you ship them? Im looking for someone to do mine on my rmx

[@tannermartin7263]

I have a 66 cc bike kit I got from Amazon (goes on your pedal bike) any way was coming back from a long run and tire went flat and wrapped around the hub and sprocket and the chain wrapped around the sprocket as the tensioner came off but it basically stopped the motor dead stop 🛑 and can’t get the motor to turn over it’s basically locked up . I’m assuming I shattered the connecting rod pin on the crank would that do it?

[@paahtopro3950]

I had my bike running lean and the big bearing went bad. The area around it was white on the connecting rod

[@luismelendez935]

Great video! Do you know where I can find a próx crankshaft for a kx 250

[@jimciancio9005]

Slotted on the big end or non Slotted is the question 🤔 I've come across the 2 different types in rod design and there's a bit of theory behind the slots in in big end or not..... One non Slotted helps retain the trapped oil vapor in the bearing or on the other hand Slotted allows fresher oil in and older oil and possible debris out as centrifugal force whips it around the case. I have one on the bench right now I'm not sure if I will slot this or not. It's a old yamaha 175cc engine and the aftermarket company Vesrah Co. Gave me a little different designed Con rod from the original yamaha rod. When it's fully assembled there's nothing but the little indentations on the sides of the thrust bearing surface to supply the oil to the rod bearing. To me that seems a little bit lacking in the lube department. I don't want to have to rebuild this thing twice when this could be prevented. I know their case hardened and cutting the slots need to be done in a water bath to prevent any over heating or changes to the metal hardness. Just wondering what other opinions are on this matter and if anyone's noticed any differences in lifespans between the 2 types of big ends?

[@PEPILLONINO]

Hey ak moto question after market cilynder head and piston from amazon are they anygood. What you think. I allready replace 3 times my cilynder head and pistons and keep scoring iballready play with oil jetting no matter what ido keep scoring, is an eton txl 50cc.

[@Sulley1562]

About how many MX hours do you get before the bearings on the crank go out? Just curious, I’ve done several top end rebuilds but have had to dive into the bottom end yet for anything. Thanks again for sharing

[@akmoto_]

I got around 130 hours of my crank, but you can essentially run them till they go out. Once they do go out, it happens fast. A lot of the time there will be little to no indication, so I just run them till they go out, but I check for play every top end or whenever I have the motor open.

[@CrashOutTiming718]

Switched premix a few times within a year can this cause the rod bearing to go sooner then later?

[@morley3810]

@@CrashOutTiming718 Unlikely. As long as you're always using a good oil with a good ratio your engine doesn't really care if you switch out.

[@CrashOutTiming718]

At first thought the oil was the issue soon to find sand in my bottom

[@TheL046Kid]

Any advice on what the best replacement non OE crankshaft is for most brands? Inquiring minds....you know.

[@zoomous4424]

Thank you for your videos. How you got all your knowledge this young?

[@akmoto_]

Mostly just from building motors in my garage, and just hands-on learning in general. The internet is also a very helpful resource, but I try to primarily speak based on my own experiences.

[@manux1508]

Im re building my yz 125 from 2005 and i cant wait to finish it

[@connornobbs3487]

I gotta rebuild a 95 but I can’t find a crankshaft anywhere 😔

[@manux1508]

@@connornobbs3487 yz 125 crankshaft?

[@sethmacgillivary1281]

Are the needle’s supposed to just fall out of the bearing?

[@mattgoupil2224]

I have a big bore kit on my stock (OEM) honda cr 500 crankshaft,ive never had a problem and i kick the shit out of it.its all in a good break in!

[@minecrafthacker9582]

Question; do you think whacking a crank with a rubber mallet during disassembly could throw the crank off balance and cause failure later down the road?

[@bigrich7026]

They never stay where you set them so we would emery cloth the journals to slip fit brand new crank bearings. Let your motor warm up and the crank centering is set by the natural alignment of the piston in the bore. This works up to high performance applications.

[@Miniorpernik]

​@@bigrich7026Good to know...I was worried that I may have inadvertantly thrown a few off balance during installation ,tho I Neva hammered them inand the engines still work smoothly but that thought was at the back of my mind:-)

[@danb37]

I just finished rebuilding my cr80. Stock bike. 20 over wieseco piston. Wieseco crank kit. Im getting engine vibration at wide open throttle in neutral. Someone said i needed to check the crank for true before install. Any idea how long she will last?

[@user-wd1ey3qz5p]

Check your engine mount

[@Blocanbentlyyahu]

My crank is rusted cause the guy before me radiators we’re leaking so water and antifreeze was getting in the bottom end. But I think it’s still good

[@rumpoh8039]

WHEN A 2 STROKE BIG END IS LOOSE WORN.. WHICH PART WEARS MOST???? PIN, NEEDLES OR ROD OFTEN A 3 PART KIT IS NOT AVAILABLE

[@worldclasspawn]

Have you ever seen a melted crank stuffer? What would cause this?

[@aaroncrain2343]

Do you use OEM cranks in your 125 or do you run aftermarket ones? Like hotrods or wisco?

[@akmoto_]

I prefer OEM or OEM rebuilt with quality parts, but Hotrods is a good aftermarket alternative. I have heard bad things about Wiseco so I avoid their cranks.

[@aaroncrain2343]

@@akmoto_ thanks, definitely gonna stick to OEM to be on the safe side.

[@jonathanquamme1397]

Me old snowmobile crank went out by carotion it was siting for 20 years and started it and zsounded great then 2 hours later and now it's very knoky

[@gediminascxz625]

Hey, my kx85 crankshaft bearings went bad and the big end bearing is bad. The connecting rod has play up, and down and has diagonal play. Do i need to replace the whole crank or just the bearings with the connecting rod?

[@floridaunreleseent631]

I have the same problem with my rm 85

[@gediminascxz625]

Ended up replacing the bearings and connecting rod

[@danielwhiteley5941]

Twisted webs dude is more common than Conrad’s snapping

[@intaniik5743]

Have a 98 yz125, i started it up and i heard what i thought was a grinding sound around my clutch, so i killed it, and went to start it again and my kickstarter was locked up. I took the plug out, ignition cover off, and top end off, i can turn it over by the flywheel but it is crunchy and rough like 1 out every 30 times i turn it over???? Any ideas????

[@intaniik5743]

My crank does not have any up and down play, and is still in spec side to side play

[@blazed5058]

Ever find out? My 1997 cr125 is like that and I haven’t rode it 3 hours

[@intaniik5743]

@@blazed5058 nope, been at a hault since then as no one seems to know, thinking only thing i can do is start tearing apart the bottom end sadly

[@danielallen-xf7yu]

What about twist play like a screw driver?

[@dineshtamil2849]

Hello bro my Kawasaki kh 100 connecting rod has some side play this is a problm ?

[@akmoto_]

Side to side play is ok

[@yassineyt2388]

Hey i want to ask you about the 125yz im 5’6 and im 5’7 with my shoes i want to buy a 125 yz but i dont know if im that tall thanks and btw how tall are you nice vid 👍

[@akmoto_]

Maybe just a tad short but you’d be fine 👍🏼

[@sethmacgillivary1281]

Do u think woods riding u can get 300?

[@uranium3111]

6:07 Subbed for this!

[@dantrezbeadshaw6949]

What if you pour oil inside

[@deepinurmom8159]

Is it crazy to bike a new dirt bike and never ride it? Always wanted to have it in the garage just to look at it sometimes

[@akmoto_]

I ride every weekend lol

[@morley3810]

Sounds like a depressing life

[@Itdontmatter69]

Ya well I’m tired of fixing the junk 2 strokes

[@RideWithTheWolf]

You forgot worn bearings and seals causing leaks and a lean mixture ...

[@hobbeekid]

Why do you call them crank webs? It’s always been countershafts to me. Have I been using the wrong terminology all these years???

[@Miniorpernik]

I guess if u managed to imbalance it during installation....it won't last very long either:-)...I don't know how easy that is tho ...U proly need to hammer it in to cause that:-)

[@hadrobinson4443]

Great intro video. Could be shortened about 40-50%.

[@eaglemx45]

Just don’t use hot rods, junk.

[@yxngbrisk4541]

First

[@cinogilo6362]

Use tungsten big end bearing set and also the big pin