Hi Joe love your videos just a word of advice from a old biker mechanic with 2 replacement knees get yourself a roller starter or make one, then you can just spin them over and save your knees.
I'm just in the beginning, but for what you paid for that absolute blast from my own personal past, even if it need an entire top end rebuilt, piston, ring - maybe not to have to split the case, but even still - totally worth the price of entry on that one Joe. I don't know how you keep finding these sweet bikes man, all these old 90s bikes were what my friends and I all had back then.. man what memories!!
You should contact Weisco and tell them what happened. They might want to examine the defective part to determine how it failed and give you a replacement crank for your troubles. I think it's worth a try. Another great video!!!
More than likely the crank was damaged when installed, maybe when they trued up the 2 crank halves which is done by beating on it with a lead hammer. Maybe they used a sledge hammer...
@@lionblue3449I've never seen such cornball maintenance. Kicking 50 time's obviously something else wrong. And when he said new plug could be faulty??? 😂😂 This dude. But the walk around was. Pretty Sweet dorky Dirk
I'd definitely message dude one last time and tell him thank you that you cleaned the carb, changed the gas and pissed on the front fender and it runs great!
Agreed, 1) the focus is not on him but on the project 2) plain-spoken, talks you through steps/thought process, 3) laughing as I listen while glancing away only to look up and see dancing orange hands (gloves) across the screen.
Never have I had a wiseco crank or rod fail.the problem came from the installation,they probably used a vertical press and probably very poorly at that.i have literally installed hundreds of wiseco products over the years.
@@2vintageso that's the 3rd yz250 that you've bought that same model 96-01? I've seen 2 different ones in your other videos, are you keeping them all?
Your videos are great. Learn a lot from just watching. It’s impressive to see the shenanigans that people do in motorcycles just for it to run instead of doing things right… Cheers from the other side of the world!
A project most of us would have RUN from. Your patience and knowledge will be tested. Keep up the hard work, sub up, view up. 2Vinny is suspicious of how much this will cost us in Alpo money. Either that or the seller had a dog
@@RandomDudeOnUA-cam 🤷🏽♂Don't know what is worse, buying something running and it fails, or something not running you know needs a rebuild - guess not running = cheaper
@@thebigguy8306 i mean, its okay, it didnt fail so far, but Overall its just had better days... But yeah i guess buying non running for under a grand is definitely the way to go, especially if it's in this condition and you can do all yourself
My guess would be that those bearings were damaged during the rebuild and the crank nose was cracked during the bearing installation. This lead to the crank failure after the rebuild. The bike probably didn't run after the crank failure, saving the rod bearing, but the seller probably was feeling done with it after the rebuild and didn't want to mess with it. Since he didn't replace the piston/ring, he figured that was the issue since he replaced everything else.
That is a very very common thing with Wiseco cranks they have been known to fail like that and I recommend to all my customers to absolutely not use them a lot of people say hot rods are bad cranks but I've never had a failure of a hot rods crank but have seen multiple Wiseco cranks fail in a very similar way
Love the video. All those kicks make my stomach twist around , I've never seen anybody kick a bike that many times. Don't the racers use electric wheel spinners.
Wow. Like you said, the gunk in the carb was probably because he tried running straight ethanol. That might have screwed up the crank bearing (got no or little oil in the mix), and thats what snapped the new crank. Anyway a fantastic channel love watching you work on these bikes 👍👍👍
I was thinking the same thing - gasoline. For an engine not meant to run on 10-20% ethanol (standard gas in Minnesota), it can be crappy for an engine. My rule of thumb for most older or small engines (snowmobile, snowblower, lawnmower) is non-oxygenated non-ethanol gas.
Whomever rebuilt that crank used a hydraulic press with very little mechanical sympathy or common sense. And it was a budget rebuild: they didn't even bother to replace the seals for the shifter shaft, countershaft sprocket shaft, or kick starter. Real backyard stuff.
Plugs are really a one use only, the seal beds in like a copper washer. You can get an airleak from the sparkplug too. Also you have been doing this long enough to get a ring spanner or correct socket for the sparkplug, a shifter is bad practice
I have a 2003 Harley Davidson V -rod that I broke the shift shaft laying it down to miss the rear end of a Camry … and I’ve let it sit for 2 years almost . Just because of rumors of how tedious of a repair it “Could “ be . You’ve inspired me to take a crack at it . I haven’t found a channel I like so much in quite a while . I like your style and simple approach. I appreciate that man . I subbed and hit your bell . Thank you 🙏
I'm wondering if the gear tooth failed first, got momentarily jammed in something, and that was enough to cause shockload through the crank? Great video. I applaud you keeping a sense of humor during the strip down. mine would have been R rated!
The broken tooth came from a gear that is not in the crank case. The crank case has no openings leading to the clutch/transmission and nothing from the clutch or transmission can find it's way into a bearing inside the crank case. The kickstarter mechanism is also outside of the crank case (gear tooth)
The 1976 RM125 sheared off the flywheel end of the crank after a couple months. All my friends raced those bikes and within 2 weeks they had all done it ! Suzuki warranted the cranks but not the labor to install them. Not a good deal and waited months for the new cranks.
Considering what broke, the associated carnage is really not that bad. It could of been so much worse if you think about it. Just the fact your flywheel and mag electronics are okay is a blessing. I think I’d be looking for another set of bare cases though too.
@@Sam-ob4of I know the right way but I don’t like how the contraction word looks on paper (could’ve), so I write could of, but I say it like the contraction. Consider it Jersey slang.
I'd never put those reeds back in that bike like that , my buisness and my reputation is top notch where I live never send half ass work out the door, or sell that way .
Well, Vinny was all over that engine. And when asked about it he barked. Normally, if the bike is generally okay he will look at it and quickly lose interest. But this one he kept sniffing around the engine & was cranky. He knew! He’s obviously a mechanic savant! Joe, you need to start taking Vinny with you when you buy, so that he’s in on the price negotiation. He could save you a lot of money & heartache.
Kick starting is kick starting. It almost doesn’t matter what position the engine is at unless it’s right after the compression hits because compression and spark come together in a two stroke I believe.
When you was kicking it over with no plug even through the phone you can hear the crankshaft bearing I was surprised you didn't hear it straight away, but great video love to watch these Exploratory strip downs👍
😮😮 I’m sure glad you got this one now we have something to talk about to our friends. 😊😊When you opened it up you were in disbelief how could this happen without more damage. Can’t wait to see the conclusion. 😮😊😊😊😊
I've learned from the way you approach each bike, visually, then a system by system check until you find the problem. Having experience in working on a certain type or model is a big plus, but it's not the main thing.
That would be awesome, if you could train Vinnie to alert you to the problem.. like those dogs that can smell tumors or sense a seizure coming on. I think he could do it. One bark for dirty carbs, two barks for stuck piston rings, growl for broken crank, etc.
-Seems like a decent deal that thing is super clean!- that case bottom is such a heartbreaker. I got my KDX with “just needs a top end” and it was way more than that lol I have a Wiseco piston and it’s been great but all the stuff about the cranks I’ve seen has been very negative
As always awseome vid's, the only question i have, which is driving me crazy, in you last couple of videos you have a super anoying beeping sound in your workshop :D
Another UA-camr I watch who is very good at diagnosing engine start problems, with the results you have and before pulling the carb, squirts a bit of fuel/oil mix directly thru the plug hole, reinstalls the plug, turns the engine over. Often the engines will start at that point sort of confirming the carb as the problem. FYI.
The same thing used to happen to the crank of the 1725 cc Holbay engine of the British Sunbeam Alpine in the 1960s until they rounded out the sharp cut between the crank and the flywheel hub. It started the science of crack starting fatigue.
Airbox looks very similar to the 02 CR125/250 so check for an airbox mod kit. Stock ones are terrible and leak dirt around the mount flange from the boot to the airbox. The boot can bunch up (get wavy) and bulge out in places, allowing dirt inside.
Basically the same bike I’m rebuilding right now mines a 2000 biggest thing is that it needed a top end rebuild, clutch plates, and crank seals. Love the yz bikes their great to work on
Well at least the piston ring was ok! I've never seen a crank broken like that before thankfully! It makes you wonder what kind of abuse it was subject to. Great video, thanks! .
I had an 85 YZ 125 back in the day. I used to ride it a lot, nearly every day. One day,I rode it inside the garage and parked it.The next day,it refused to start. I couldn't figure it out, so I brought the engine down to my old high-school,small gas engines & metal shop class. My shop teacher found the problem in about 15 minutes. The flywheel cracked around the rivets. So my mom lent me some money to get a new one and a new piston, rings base & head gasket. It was running good as new after that. I still have an old bike, 1990 KLR 250,still runs good. Btw I've heard of those aftermarket crankshafts are sometimes out of balance straight out of the box. And I've heard of them breaking also. If it was mine, I'd probably try to find a good used Yamaha crank,and have it rebuilt. Idk if you can get a brand new factory crankshaft for that bike anymore, because of its age? Maybe some shop has one squirreled away? Good luck.
10:42 That is a perfect plug color for a carb. But it does look close to the edge. It looks like perfect jetting set by a pro tuner for that day of racing at that track. He probably dropped the needle one groove.
The reason is rebuilt cranks are not balanced properly like they do at the factories. Rebuilt cranks shake motors apart or themselves in this case. It was a perfectly good part and bad assembly that caused this. Only factories have the accurate equipment needed to ballance a crank properly.
@@andrewsock1608 I use a crank trueing stand and duel micrometers to fully balance and true a crank within .001 factory specs are .003 to .005. It does take time but once finely trued up it will be closer tolerance than factory. There are many videos out there that show the technique. There is 4 axial points that need to be trued.
@@andrewsock1608 vibrations known to be from the crank are cuased by the crank not being true. For $650 you can purchase a trueing stand complete with duel micrometers . And by reading the mic and rod pin alignment you can tell if the crank webs are spaced in or out ( angled in or out) and web lineup in relation to rod pin and crank output shafts. Just by dropping a crank from several inches can untrue if it lands on one part of either web. The trueing stand is valuable and easy to learn. There are some great vids on crank trueing. I believe one of them is "2 stroke stuffing"
Good-Great Buy - time will tell. Looked in good condition, but as I recall these can be Very Good bikes, lots of Zoom Zoom, 70mph from a 35hp engine. But engines often have to be rebuilt (top end) every 20-30 hours. Good luck, and keep up the hard work Vinny.
I saw this once before on a Honda 4 wheeler. I argued there couldnt be any thing wrong with the crank. It was...was twisted, not completely snaped yet. I think it may have been after a rebuild too. Fragile little things!
I doubt that the seller was trying to get over on him, most likely did not know what the issue was. You heard him say that he was just riding it around his grandparents property. One of his friends probably told him that it has bad rings.
foreign object destruction FOD. that hunk of gear stopped that crank on a dime, and the piston with 150 psi torqued it off. i hit a fire hydrant flange bolt head with my honda mower the AK47 of lawn care ,and it broke the crank and cracked the case, oil leaving the engine.
Crank not assembled and checked for runout correctly. This causes misalignment and vibration which probably caused the failure. Always clock and measure crank runout before assembly. Damaged bearing seats also causes misalignments too.
"Seller said" lol when I got my atc the seller said everything worked when parked, after seeing no brake shoes on the rear I determined that was a lie lol
Literally in the middle of an 02 yz125 build. Guy said just needed a top end. Well the whole bike is being rebuilt now 😂😂 crank had mini seized when the bike overheated so I’m going through everything and re doing it all to spec. It’s never what they say it is and now I know why people low ball or walk. Got mine for $950 as well 🤘🏼
And the coolant And the oil And the sump plug And the air filter And the spark (take your own spare plug) All easily done on site before you decide to buy or walk away
very nice video. I enjoyed the way you tackle the concerns. On my own ,i have got the same crankshaft broken concern on an Husqvarna chain saw but on the output pinion.
"Set of rings" boy, that guy should run for public office! This is one of the more roached wonkfests you've been scammed on in a while. Love the optimism in the beginning though =)
I used to back bikes off my truck like that until I slipped off and dropped one. When I bought my SxS I purchased a aluminum trailer and have never used the back of my truck for anything big again. Best investment ever was that trailer. Much safer also.
I also had the same problem with my CRS 125 cc ICC kart engine, but on the other side. The crankshaft had just been replaced with an original one, but it simply broke off for no apparent reason.
I think some one put straight gas in that bike which led to the first failure. Rebuilt it and didn't replace the bearings when those bearings get hot due to lack of lubricant they distort and excess wear. Which caused the new crankshaft to fail. Pull the bearing off and look at the face of the crankshaft where it was on the bearing and see if there is any discoloration and if there is that says there was a lot of heat in that crankshaft. I did some more research that they had problems with a supplier of materials 5 years ago and the metals where not within specifications and caused a lot of issues
Hi Joe love your videos just a word of advice from a old biker mechanic with 2 replacement knees get yourself a roller starter or make one, then you can just spin them over and save your knees.
I'm just in the beginning, but for what you paid for that absolute blast from my own personal past, even if it need an entire top end rebuilt, piston, ring - maybe not to have to split the case, but even still - totally worth the price of entry on that one Joe. I don't know how you keep finding these sweet bikes man, all these old 90s bikes were what my friends and I all had back then.. man what memories!!
Hardest working man on UA-cam love every single video that you do mate keep it up ❤
You should contact Weisco and tell them what happened. They might want to examine the defective part to determine how it failed and give you a replacement crank for your troubles. I think it's worth a try. Another great video!!!
its a 2 stroke motocross bike thats high rung and easy to abuse...i doubt theyd even respond, especially after 30+ hrs and the wrecked cases
it's 950.00 you got what you paid for change cases new crank zoom zoom
Painful watching him Kick-start it
More than likely the crank was damaged when installed, maybe when they trued up the 2 crank halves which is done by beating on it with a lead hammer. Maybe they used a sledge hammer...
@@lionblue3449I've never seen such cornball maintenance. Kicking 50 time's obviously something else wrong. And when he said new plug could be faulty??? 😂😂 This dude. But the walk around was. Pretty Sweet dorky Dirk
I'd definitely message dude one last time and tell him thank you that you cleaned the carb, changed the gas and pissed on the front fender and it runs great!
This is a hidden gem of a channel! Definitely one of my favorites.
Agreed, 1) the focus is not on him but on the project 2) plain-spoken, talks you through steps/thought process, 3) laughing as I listen while glancing away only to look up and see dancing orange hands (gloves) across the screen.
Thanks Joe for the great content! You have encouraged me to resurrect my old fleet of trail bikes from the 80's. Good therapy for an old guy.
I was waiting for the Kickstart lever to break off
Never have I had a wiseco crank or rod fail.the problem came from the installation,they probably used a vertical press and probably very poorly at that.i have literally installed hundreds of wiseco products over the years.
Now THAT is crazy! No wonder Vinnie couldn’t figure it out.
Yeah he was stumped on this one
@@2vintageso that's the 3rd yz250 that you've bought that same model 96-01? I've seen 2 different ones in your other videos, are you keeping them all?
Vinnie thought it was the piston rings too, also the stuff in bowl looked like it turned back into corn
🐕He thought the engine ran ruff ruff
@@snowyowl7042 vinnie knows something is quite not ok with this..lol
@@snowyowl7042snap
After 4 kicks is good to say something ain’t right 🤣
He kicked it 47 times, i counted. 😂
Lol
Your videos are great. Learn a lot from just watching. It’s impressive to see the shenanigans that people do in motorcycles just for it to run instead of doing things right…
Cheers from the other side of the world!
I love his videos too, he really loves this stuff, takes his time going through everything, no better videos out there!
Tbh I didn't learn a thing, his skill level is so far above mine I just sat back and enjoyed his work 😂
I would had checked the plug first thing
Made popcorn when u were kicking good snack
Seller really means....This bike just needs a new engine....frame ,wheels and everything else...!!
A project most of us would have RUN from. Your patience and knowledge will be tested. Keep up the hard work, sub up, view up.
2Vinny is suspicious of how much this will cost us in Alpo money. Either that or the seller had a dog
I bought a running 04 yz 450 but it looks worse than this one 💀 Maaaaan i got shafted 😂
@@RandomDudeOnUA-cam 🤷🏽♂Don't know what is worse, buying something running and it fails, or something not running you know needs a rebuild - guess not running = cheaper
@@thebigguy8306 i mean, its okay, it didnt fail so far, but Overall its just had better days...
But yeah i guess buying non running for under a grand is definitely the way to go, especially if it's in this condition and you can do all yourself
Sorry it turned out bad, but it was a very interesting episode. I have never seen a complete teardown. Now, I'm looking forward to the rebuild.
My guess would be that those bearings were damaged during the rebuild and the crank nose was cracked during the bearing installation. This lead to the crank failure after the rebuild. The bike probably didn't run after the crank failure, saving the rod bearing, but the seller probably was feeling done with it after the rebuild and didn't want to mess with it. Since he didn't replace the piston/ring, he figured that was the issue since he replaced everything else.
You are correct.The bike would have stopped running the instant the crank sheared; as there would be no timing for the spark.
That is a very very common thing with Wiseco cranks they have been known to fail like that and I recommend to all my customers to absolutely not use them a lot of people say hot rods are bad cranks but I've never had a failure of a hot rods crank but have seen multiple Wiseco cranks fail in a very similar way
what cranks do you recommend? 😢
Love the video. All those kicks make my stomach twist around , I've never seen anybody kick a bike that many times. Don't the racers use electric wheel spinners.
Wow. Like you said, the gunk in the carb was probably because he tried running straight ethanol. That might have screwed up the crank bearing (got no or little oil in the mix), and thats what snapped the new crank.
Anyway a fantastic channel love watching you work on these bikes 👍👍👍
I was thinking the same thing - gasoline. For an engine not meant to run on 10-20% ethanol (standard gas in Minnesota), it can be crappy for an engine. My rule of thumb for most older or small engines (snowmobile, snowblower, lawnmower) is non-oxygenated non-ethanol gas.
@@greathornedowl3644 If only you could get that in California.
Whomever rebuilt that crank used a hydraulic press with very little mechanical sympathy or common sense. And it was a budget rebuild: they didn't even bother to replace the seals for the shifter shaft, countershaft sprocket shaft, or kick starter. Real backyard stuff.
Rebuilt the crank? Is it not just a cheapy Wiseco crank?
Yeah and Cranks for these are only $125-$150 on ebay. very very cheap
I cannot imagine what happened to snap that crank at the thickest spot???
Cheap aftermarket crankshaft most likely, would of been better off putting a cheap rod kit in a factory crank
You have know clue what your talking about 😂😂.
Plugs are really a one use only, the seal beds in like a copper washer. You can get an airleak from the sparkplug too. Also you have been doing this long enough to get a ring spanner or correct socket for the sparkplug, a shifter is bad practice
I have a 2003 Harley Davidson V -rod that I broke the shift shaft laying it down to miss the rear end of a Camry … and I’ve let it sit for 2 years almost . Just because of rumors of how tedious of a repair it “Could “ be . You’ve inspired me to take a crack at it . I haven’t found a channel I like so much in quite a while . I like your style and simple approach. I appreciate that man . I subbed and hit your bell . Thank you 🙏
Usually all they need is a carburetor clean and good to go! Then you get them home and they're good to go alright!
I was thinking crank seal. Did not expect the Bluetooth stator. Wiseco cranks are hot garbage.
I'm wondering if the gear tooth failed first, got momentarily jammed in something, and that was enough to cause shockload through the crank? Great video. I applaud you keeping a sense of humor during the strip down. mine would have been R rated!
The broken tooth came from a gear that is not in the crank case. The crank case has no openings leading to the clutch/transmission and nothing from the clutch or transmission can find it's way into a bearing inside the crank case. The kickstarter mechanism is also outside of the crank case (gear tooth)
Keep up the vids! You already helped me a bit with your videos on my old 450 i bought... thanks man 😅
The 1976 RM125 sheared off the flywheel end of the crank after a couple months. All my friends raced those bikes and within 2 weeks they had all done it ! Suzuki warranted the cranks but not the labor to install them. Not a good deal and waited months for the new cranks.
Considering what broke, the associated carnage is really not that bad. It could of been so much worse if you think about it. Just the fact your flywheel and mag electronics are okay is a blessing. I think I’d be looking for another set of bare cases though too.
*could HAVE
@@Sam-ob4of I know the right way but I don’t like how the contraction word looks on paper (could’ve), so I write could of, but I say it like the contraction. Consider it Jersey slang.
@GNX157 I agree on all levels... Could of been much worse.
@@Sam-ob4ofGeez! Grammar patrol gets everywhere!!
@@kencannuck We do! But I restrained myself here.
I'd never put those reeds back in that bike like that , my buisness and my reputation is top notch where I live never send half ass work out the door, or sell that way .
Excellent content Joe as always. Maybe just maybe you might cleanup the engine/outer casings dirty bits?
I have asked about this many times. Makes no sense to not clean the bike a little before tearing into them
Your comment will fall on deaf ears. This same comment has been suggested 100s of times to no avail.
We will see haha
@@2vintage🤣
Vinnie sniffin out the VIN numbers!
What’s up with all the dog comments
Ran fine the last time we rode it....... Good teardown looking forward to the rebuild!
Well, Vinny was all over that engine. And when asked about it he barked. Normally, if the bike is generally okay he will look at it and quickly lose interest. But this one he kept sniffing around the engine & was cranky. He knew! He’s obviously a mechanic savant! Joe, you need to start taking Vinny with you when you buy, so that he’s in on the price negotiation. He could save you a lot of money & heartache.
Alot of your starting issues is your kick starting techniques
I MEAN...STOMPED THE YARD!! LMAO
Kick starting is kick starting. It almost doesn’t matter what position the engine is at unless it’s right after the compression hits because compression and spark come together in a two stroke I believe.
When you was kicking it over with no plug even through the phone you can hear the crankshaft bearing I was surprised you didn't hear it straight away, but great video love to watch these Exploratory strip downs👍
😮😮 I’m sure glad you got this one now we have something to talk about to our friends. 😊😊When you opened it up you were in disbelief how could this happen without more damage. Can’t wait to see the conclusion. 😮😊😊😊😊
I think they might have stressed the crank when they replaced the rod.
I've learned from the way you approach each bike, visually, then a system by system check until you find the problem. Having experience in working on a certain type or model is a big plus, but it's not the main thing.
man i move these videos. he brings us with him every step of the way. learning a lot
That would be awesome, if you could train Vinnie to alert you to the problem.. like those dogs that can smell tumors or sense a seizure coming on. I think he could do it. One bark for dirty carbs, two barks for stuck piston rings, growl for broken crank, etc.
He already does this lol
Vinny!!!! 🎉😊
Never seen a crank do that before in my 45 years experience
-Seems like a decent deal that thing is super clean!- that case bottom is such a heartbreaker. I got my KDX with “just needs a top end” and it was way more than that lol
I have a Wiseco piston and it’s been great but all the stuff about the cranks I’ve seen has been very negative
nice honest videos,, i have a duke 390 but its good to see a lot of these videos recently and see the workings of head problems.
As always awseome vid's, the only question i have, which is driving me crazy, in you last couple of videos you have a super anoying beeping sound in your workshop :D
We had a year old Suzuki RM125 that broke the stock crank at the same location
Another UA-camr I watch who is very good at diagnosing engine start problems, with the results you have and before pulling the carb, squirts a bit of fuel/oil mix directly thru the plug hole, reinstalls the plug, turns the engine over. Often the engines will start at that point sort of confirming the carb as the problem. FYI.
The same thing used to happen to the crank of the 1725 cc Holbay engine of the British Sunbeam Alpine in the 1960s until they rounded out the sharp cut between the crank and the flywheel hub. It started the science of crack starting fatigue.
Airbox looks very similar to the 02 CR125/250 so check for an airbox mod kit. Stock ones are terrible and leak dirt around the mount flange from the boot to the airbox. The boot can bunch up (get wavy) and bulge out in places, allowing dirt inside.
Basically the same bike I’m rebuilding right now mines a 2000 biggest thing is that it needed a top end rebuild, clutch plates, and crank seals. Love the yz bikes their great to work on
Love your videos , waiting for a part 2 on this bike .
Broken crank is crazy! Would have never suspected that, good troubleshooting.
Keep them coming, I enjoy your content.
Well at least the piston ring was ok! I've never seen a crank broken like that before thankfully! It makes you wonder what kind of abuse it was subject to. Great video, thanks! .
I had an 85 YZ 125 back in the day. I used to ride it a lot, nearly every day. One day,I rode it inside the garage and parked it.The next day,it refused to start. I couldn't figure it out, so I brought the engine down to my old high-school,small gas engines & metal shop class. My shop teacher found the problem in about 15 minutes. The flywheel cracked around the rivets. So my mom lent me some money to get a new one and a new piston, rings base & head gasket. It was running good as new after that. I still have an old bike, 1990 KLR 250,still runs good. Btw I've heard of those aftermarket crankshafts are sometimes out of balance straight out of the box. And I've heard of them breaking also. If it was mine, I'd probably try to find a good used Yamaha crank,and have it rebuilt. Idk if you can get a brand new factory crankshaft for that bike anymore, because of its age? Maybe some shop has one squirreled away? Good luck.
10:42 That is a perfect plug color for a carb. But it does look close to the edge. It looks like perfect jetting set by a pro tuner for that day of racing at that track.
He probably dropped the needle one groove.
Send a pic of that crank to Wiseco. No reason for a failure like that
The reason is rebuilt cranks are not balanced properly like they do at the factories. Rebuilt cranks shake motors apart or themselves in this case. It was a perfectly good part and bad assembly that caused this. Only factories have the accurate equipment needed to ballance a crank properly.
@@andrewsock1608 I use a crank trueing stand and duel micrometers to fully balance and true a crank within .001 factory specs are .003 to .005. It does take time but once finely trued up it will be closer tolerance than factory.
There are many videos out there that show the technique. There is 4 axial points that need to be trued.
@@bradley7723 vibrations will tell if your lying or mistaken.
@@andrewsock1608 vibrations known to be from the crank are cuased by the crank not being true. For $650 you can purchase a trueing stand complete with duel micrometers . And by reading the mic and rod pin alignment you can tell if the crank webs are spaced in or out ( angled in or out) and web lineup in relation to rod pin and crank output shafts. Just by dropping a crank from several inches can untrue if it lands on one part of either web. The trueing stand is valuable and easy to learn. There are some great vids on crank trueing. I believe one of them is "2 stroke stuffing"
My friend who has had 2 strokes his whole life told me that if the crank isn't balanced or trued, it'll vibrate until it snaps.
Yikes, what a mess. Always a learning moment. 😢No riding today.
Using your videos during cardio just pure relaxing man love it
I didnt make it throu yet but you said 33hrs, look at the paint and the rad. Way more hours on that bike.
Who else knew what it was as soon as he spun the crank freely?
Good-Great Buy - time will tell. Looked in good condition, but as I recall these can be Very Good bikes, lots of Zoom Zoom, 70mph from a 35hp engine. But engines often have to be rebuilt (top end) every 20-30 hours. Good luck, and keep up the hard work Vinny.
How it managed to have spark definitely surprised me
I see that happen on snowmobiles quite often.
I saw this once before on a Honda 4 wheeler. I argued there couldnt be any thing wrong with the crank. It was...was twisted, not completely snaped yet. I think it may have been after a rebuild too. Fragile little things!
Maybe Joe you could invest in a used motorcycle paddock roller starter, to save yourself kicking over.
1 000 000%
Great video. I've only ever seen a snowmobile engine crank before, but never a bike engine. Very weird
Can't blame Vinny on this one...lol he knew it wasn't just right tho..
I'm always happier when you have a seller that tells the truth. Too bad most are like this guy...
I doubt that the seller was trying to get over on him, most likely did not know what the issue was. You heard him say that he was just riding it around his grandparents property. One of his friends probably told him that it has bad rings.
But the ring needed changing... :)
foreign object destruction FOD. that hunk of gear stopped that crank on a dime, and the piston with 150 psi torqued it off. i hit a fire hydrant flange bolt head with my honda mower the AK47 of lawn care ,and it broke the crank and cracked the case, oil leaving the engine.
This video just made me appreciate rebuilds and the people who do a good job with them sooo much more. Love the vid, Subbed and All the Best!!
So cool watching this, he’s working on the same bike that I own. Just 25 years older 😌 I love seeing this.
love the vids bro, Long time watcher here. But the crescent wrench to take off the plug is KILLING me 😂
Crank not assembled and checked for runout correctly. This causes misalignment and vibration which probably caused the failure. Always clock and measure crank runout before assembly. Damaged bearing seats also causes misalignments too.
I like ace mechanic Vinny. He knows his stuff.
Vin figured it out right away on first sniff, but loves to see you struggle.
Yeah he loves to see me struggle lol
"Seller said" lol when I got my atc the seller said everything worked when parked, after seeing no brake shoes on the rear I determined that was a lie lol
Just now found you and as a mechanic I'll be watching more of your stuff!
Anytime a seller says "All it needs it a (insert cheap part)" You know its a total basket case
Not true at all.
@@jerrywilcox9890 I would say it's true more often than not
Agreed, if it doesn't run when you buy it, prepare for the worst
Wow, sheared off crank that's wack. Even crazier is that it had a spark. Love watching your videos. Sad that so many sellers are not honest.
new video🎉 second vid i watch from you today:D
The mystery of the fail always makes me come back to your channel which also learns us a lot of course.
Literally in the middle of an 02 yz125 build. Guy said just needed a top end. Well the whole bike is being rebuilt now 😂😂 crank had mini seized when the bike overheated so I’m going through everything and re doing it all to spec. It’s never what they say it is and now I know why people low ball or walk. Got mine for $950 as well 🤘🏼
Never thought I would see that, broken crank?? Crazy
25 year old broke bike for 900 dollars. Is not a great deal. And it's only a 125cc.
Excited for the next video. I love those old YZ 125's.
If I've learned one thing from watching your video's, it's inspect the the bottom of the crank case before buying.
And the coolant
And the oil
And the sump plug
And the air filter
And the spark (take your own spare plug)
All easily done on site before you decide to buy or walk away
@@HUSKY7-1 All those are easy fixes. But a busted crank case with the plug JB welded in,.. not so much
Wow, I never seen anything like that before. I seen the shaft spin all together, I was like what
very nice video. I enjoyed the way you tackle the concerns. On my own ,i have got the same crankshaft broken concern on an Husqvarna chain saw but on the output pinion.
"Set of rings" boy, that guy should run for public office! This is one of the more roached wonkfests you've been scammed on in a while. Love the optimism in the beginning though =)
I used to back bikes off my truck like that until I slipped off and dropped one. When I bought my SxS I purchased a aluminum trailer and have never used the back of my truck for anything big again. Best investment ever was that trailer. Much safer also.
I'm the guy who bought his "death trike" I'm happy to see he's getting a bunch of views wow!
I also had the same problem with my CRS 125 cc ICC kart engine, but on the other side. The crankshaft had just been replaced with an original one, but it simply broke off for no apparent reason.
I’ve owned & fixed my own & a few friend’s dirt bikes for nearly 40 years and have never seen a crank break like that!
Nice house you got there vintage. Fixing old cheap motorcycles must make good money.
i always remove the exhaust as well as i once rebuilt an engine just to find out it was a blocked end can hahaha
Slightly misrepresented
I think some one put straight gas in that bike which led to the first failure. Rebuilt it and didn't replace the bearings when those bearings get hot due to lack of lubricant they distort and excess wear. Which caused the new crankshaft to fail. Pull the bearing off and look at the face of the crankshaft where it was on the bearing and see if there is any discoloration and if there is that says there was a lot of heat in that crankshaft. I did some more research that they had problems with a supplier of materials 5 years ago and the metals where not within specifications and caused a lot of issues
A bad crank, who would have thunk it. Great job sticking with it.
Vinny is like, DAD JUST GIVE ME THE WRENCH AN QUIT TALKING, I GOT SHIT TO DO