A wonderful video filled with great tips. Very interesting how there seems to be quite a few cracked cases for this year with later years beefed up. You covered a lot in the video. Great camera angles and explanation of your failure analysis.
Thank you, Pete, turns out this was a common issue on the early models, the case was reinforced in the countershaft bushing hole area in late 74. I was able to find a good used set with the reinforcement. Think we are all set.
when the bearing goes out then it eats the seal out, bearing trouble first, on your fly-wheel puller you can just hold the nut with your big wrench instead of the spanner wrench, im not trying 2 correct you, if i lived to be 200 years old i wouldn't be half the mechanic that you are so im not trying to teach you any thing, boat motor flywheels come off the same way, when i was 27 years old i could rebuild a mercury v-6 blindfolded and now at the age of 65 i don't even remember what the timing was supposed to be set at, when you don't work on them all the time your memory slips on you... your the best iv ever seen ol buddy, just keep on jammin...
Yes, I think it all started by the oil injector tank being run dry, took out the bearing, then melted the seal. Your right on the puller James, what was I thinking.
Good morning to my dear friend and brother Dale. I want to thank everyone who supports this outstanding channel and my dear friend brother Dale as he provides excellence with his shop videos teaching so many with his excellent knowledge in motorcycle mechanical repairs and amazing restorations. Thank you my dear friend and brother for the good Lord blessed you so much and through your videos we all have so much goodness that is so admirable.!! Ricardo
These videos are very inspiring to me. I’m on my 2nd project now. Both of them are stuck cos I couldn’t open the darn flywheel. I come here and see how easy it it 😭😭😭😭
Maybe the cracked case and melted/displaced seals caused by gear shafts not being stable in their case bearings. That instability would transfer damaging torque pressure into the case making it buckle and crack. Would also cause the gear bundle and crank shaft to twist and overheat. Would be interesting to see if there is run-out on shafts in the lathe. That engine was 1 minute away from zero hour!
After looking on Ebay at some cases I found several listed on there have the same crack in the same place. Then the ones that are listed as 74 up have a redesigned bushing boss and no more cracks. Looks like it was an early problem for 73 and maybe mid 74.
Hey Dale, great job with the screw extraction. I think the case was damaged by someone hammering the cases back together in the past, causing misalignment of the shaft bushing and the tight spot. The crank is very much like a Bantam crank, where the rod munches through the crankshaft half. I'm working on a repair scheme to fit commercial thrust washers, it takes a little bit of machining to achieve it. The melted seals suggest they ran it without oil, possibly cooked the top end too, hence the rebore. Best wishes, Dean.
Thanks, buddy, the case cracks seem to be common on 73 and 74 models. I did some looking on Ebay and many of the early models had the same crack in the same spot. After what I think is late 74 the case was resigned with a beefer bushing boss with radial supports emitting out from the shaft center. The owner is looking for one of those, I did a quick look and found the shaft to be the same. So, I believe all will work. Yes, the crank, after 77 they started using thrust washers, the crankshaft part number after 77 is the same as the 73 model, so I think I will spot face the worn crank half and reassemble with thrust washers for the 77 up, after checking the case dimensions to insure it will fit in there with the 2mm wider crank. I totally agree with you about running without oil. There were many indications of lots of heat. I did not know the bantam's didn't run thrust washers. I will be watching to see how you handle that. Actually, while I am thinking about it. It might be the right thing to spot face 1mm from each side and put the washers in, at least that way I know the crank fits, unless that makes the space where the rod comes through too small for the rod to fit. Lots of things to look at. Thanks Dean.
Good video, thanks. Cracked case; my money's on the k/start travel restrictor - rides up on that rounded section of case - applies massive pressure ( see Vintage2 kicking!) and something has to give. Looking forward to next instalment.
Thanks man, it well may be, after some research I find this is a common issue with the 73 and 74 models. They beefed up the countershaft bushing area with some extra webbing in late 74. But I'm with you.....still leaning toward the kick starter. I know watching Joe, kick and kick and kick just wears me out. I figure if I have to kick more than 5 or 6 times there is something wrong and I need to go looking for the problem. Got another case coming, hoping for the best.
Great video as ever. Good to watch your analysis and thinking through how to resolve the problems. Take care. PS - we got a lot of rain but nowhere near what your friends in the South East got. There will be a few water damaged engines down there!
You can buy an early yz80 gear set, shift forks and shift drum pretty cheap and it will drop right in as the cases were the same for several years. The first 4 gears will be the same with the benefit of.961 “ over drive”. I’ve done it to 2 of my GT80 bikes. The engine is 4.9 hp and has plenty of power to pull the extra gear.
Thanks for all the great info, I passed it on to the owner, but he is only interested in it being returned to running, reliable condition. 4.9 hp, wow the 90cc twin that I'm working on is the same hp rating.
With regards to the cracked case you have nothing to lose by grinding out the crank and either welding it up with aluminium or trying those low temp ali braising rods. I've managed to fix a few things with those rods. The crack will need flushing out with acetone. Of course it might all end up distorted but is worth a try, especially if the engine numbers are stamped on that case half. The other thing which I believe is a 'no-no' is mixing case halves up anyway. (it might be a myth and it is fact OK to do this). You then need to sort out the binding but with your mill and stuff that might be possible. It would make for an interesting video!
It turns out the crack was common on the 73 and 74. New beefer cases in 75, we are looking for a new case. Yes, no problem on mixing and matching case halves. The manufacture offered each case separate. I have swapped cases on other bikes like this with no issues. Not sure that applies to all bikes or not, I can only attest to these older enduro type machines.
I wonder if the later crank halves were spot faced approximately 1mm deep to allow for the big end thrust washers in which case you might be able to spot face the halves either in a mill or by using a four jaw chuck in a lathe. If that crank and rod setup is used on a YZ then you should have no issues on your engine as I bet the YZ makes twice the BHP of your engine! Another interesting project Dale, it will (and already has) resulted in interesting video content.
With a bit of research, I found the crank for the 73 and the 77 and later are the same part number, but we know they changed it by putting thrust washers in 1977. So, the crank will fit either model. I was thinking the same. I will spot face the side that was worn and put the washers in after checking the case dimensions to make sure it will still fit. I was also thinking about what you suggested to spot face both sides 1mm and go with the washers that way you know it fits, but also have to check the slot where the rod goes between the two halves to make sure there is still good clearance for the rod. We have time to think about it while the owner is looking for a 75 and up case with the new improved countershaft boss. Thanks for the discourse, it's always good to hear what others are thinking.
Dale ,thanks again for another extremely informative and well executed video. Your knowledge is extensive and you have a great presentation. In my opinion you are definitely a master technician. I too have a passion for these vintage machines and just about anything with an engine (and clutch)! Do you take on any customer bikes? Also curious what state you live in,if I may ask?
Thank you, Michael, I do really enjoy these old machines and like you I share the passion of just about anything mechanical. I do take on many customers projects during the year. I generally do not work customer projects in the summer months that is more for my stuff, and local walk-in projects. I am slow and take my time for I am retired and don't wish to still punch the clock or feel like I am or have to. I am located in Great Falls Montana.
Never know what you're going to find during teardown, I guess. I see that you found the early cases to be prone to that damage. Since it shows the YZ crank to be the same, I wonder if the cases were already redesigned when the YZ came out in '74? There would definitely be more stress on an all-out dirt bike.
Hey Doug, it sure could have been a known problem. It seems the retrofit on the beefed-up bearing boss was implemented by midyear 74. I just found a set of late 74 cases and they are on the way.
Dale, was that a report of some sort you ran about interchange? Often a guy can find the part that works if you dig, but the digging can take time. Very curious. Thanks!! Great video!!
OK found something else Later years have a spot for a tachometer cable In the casing So you can only use the earlier years casing. I don't know if later year would match up?
So apparently in 1977 and up There was an option to put a tachometer on these bikes. I checked the part number for the case and They didn't change part in 1977 they still use the same part number 🤷♂️ So Will it match up to the left side Questionable.
Hey Marcel, I think the change in part number may be because of the painted black cases. Not sure though. I found a set for probably a late 1974 model. They have the reinforced countershaft bushing hole. So, I think we are all set. Thanks for all your insight.
Thanks for the heads up. After looking on Ebay at some cases I found several listed on there have the same crack in the same place. Then the ones that are listed as 74 up have a redesigned bushing boss and no more cracks. Looks like it was an early problem for 73 and maybe mid 74.
After looking on Ebay at some cases I found several listed on there have the same crack in the same place. Then the ones that are listed as 74 up have a redesigned bushing boss and no more cracks. Looks like it was an early problem for 73 and maybe mid 74.
A wonderful video filled with great tips. Very interesting how there seems to be quite a few cracked cases for this year with later years beefed up. You covered a lot in the video. Great camera angles and explanation of your failure analysis.
Thanks Jim, turns out this was an issue on the 73 and early 74 cases, later on they beefed up the countershaft bushing hole with some radial webbing.
Great detective work! You will get to the cause of the crack and have the fix done in no time.
Thank you, Pete, turns out this was a common issue on the early models, the case was reinforced in the countershaft bushing hole area in late 74. I was able to find a good used set with the reinforcement. Think we are all set.
when the bearing goes out then it eats the seal out, bearing trouble first, on your fly-wheel puller you can just hold the nut with your big wrench instead of the spanner wrench, im not trying 2 correct you, if i lived to be 200 years old i wouldn't be half the mechanic that you are so im not trying to teach you any thing, boat motor flywheels come off the same way, when i was 27 years old i could rebuild a mercury v-6 blindfolded and now at the age of 65 i don't even remember what the timing was supposed to be set at, when you don't work on them all the time your memory slips on you... your the best iv ever seen ol buddy, just keep on jammin...
Yes, I think it all started by the oil injector tank being run dry, took out the bearing, then melted the seal. Your right on the puller James, what was I thinking.
Good morning Dale, I'm looking forward to it.
Nice to see your ready for the ride Larry.
Good morning to my dear friend and brother Dale. I want to thank everyone who supports this outstanding channel and my dear friend brother Dale as he provides excellence with his shop videos teaching so many with his excellent knowledge in motorcycle mechanical repairs and amazing restorations. Thank you my dear friend and brother for the good Lord blessed you so much and through your videos we all have so much goodness that is so admirable.!! Ricardo
You are too kind Ricardo, thank you so much, the good Lord has indeed blessed me, I thank him every day.
These videos are very inspiring to me.
I’m on my 2nd project now. Both of them are stuck cos I couldn’t open the darn flywheel. I come here and see how easy it it 😭😭😭😭
Thank you very much, that means a lot to me. Always glad to be able to help and I like to hear of other folks' success stories.
Maybe the cracked case and melted/displaced seals caused by gear shafts not being stable in their case bearings. That instability would transfer damaging torque pressure into the case making it buckle and crack. Would also cause the gear bundle and crank shaft to twist and overheat. Would be interesting to see if there is run-out on shafts in the lathe. That engine was 1 minute away from zero hour!
After looking on Ebay at some cases I found several listed on there have the same crack in the same place. Then the ones that are listed as 74 up have a redesigned bushing boss and no more cracks. Looks like it was an early problem for 73 and maybe mid 74.
Hey Dale, great job with the screw extraction. I think the case was damaged by someone hammering the cases back together in the past, causing misalignment of the shaft bushing and the tight spot.
The crank is very much like a Bantam crank, where the rod munches through the crankshaft half. I'm working on a repair scheme to fit commercial thrust washers, it takes a little bit of machining to achieve it. The melted seals suggest they ran it without oil, possibly cooked the top end too, hence the rebore.
Best wishes, Dean.
Thanks, buddy, the case cracks seem to be common on 73 and 74 models. I did some looking on Ebay and many of the early models had the same crack in the same spot. After what I think is late 74 the case was resigned with a beefer bushing boss with radial supports emitting out from the shaft center. The owner is looking for one of those, I did a quick look and found the shaft to be the same. So, I believe all will work. Yes, the crank, after 77 they started using thrust washers, the crankshaft part number after 77 is the same as the 73 model, so I think I will spot face the worn crank half and reassemble with thrust washers for the 77 up, after checking the case dimensions to insure it will fit in there with the 2mm wider crank. I totally agree with you about running without oil. There were many indications of lots of heat. I did not know the bantam's didn't run thrust washers. I will be watching to see how you handle that. Actually, while I am thinking about it. It might be the right thing to spot face 1mm from each side and put the washers in, at least that way I know the crank fits, unless that makes the space where the rod comes through too small for the rod to fit. Lots of things to look at. Thanks Dean.
Such a cute little bike holding some nasty traps for the unwary. Good meticulous work as usual Dale.
It happens Darren, just got to adjust and move on.
Great progress Dale, albeit with some surprises. Such a pity about the case.
Cheers, Peter.
Nothing but a thing, as they say. You just have to roll with the punches.
Good video, thanks. Cracked case; my money's on the k/start travel restrictor - rides up on that rounded section of case - applies massive pressure ( see Vintage2 kicking!) and something has to give. Looking forward to next instalment.
Thanks man, it well may be, after some research I find this is a common issue with the 73 and 74 models. They beefed up the countershaft bushing area with some extra webbing in late 74. But I'm with you.....still leaning toward the kick starter. I know watching Joe, kick and kick and kick just wears me out. I figure if I have to kick more than 5 or 6 times there is something wrong and I need to go looking for the problem. Got another case coming, hoping for the best.
Great video as ever. Good to watch your analysis and thinking through how to resolve the problems.
Take care.
PS - we got a lot of rain but nowhere near what your friends in the South East got. There will be a few water damaged engines down there!
Thank you, yes, the southeast is getting hammered. I'm in the northwest.....no rain in sight here. Our next moisture will more than likely be snow.
@@montana2strokeracer the most predictable thing about British weather is it's unpredictability. 3 seasons in one day.
Take care
@@montana2strokeracer there is a saying in Northumberland. If you canny see the Cheviots (hills) it's raining, if you can see them it's gonna rain.
Impressive as always
I appreciate that
It will be intersting to see your measurement process for the runout on the main and counter shaft.
Chucked between centers on the lathe.
@@montana2strokeracer I would believe that, however I was really more interested in knowing if one of them is bent.
Did you see the washer pop off when you were splitting the case and taped on the detent. It shot over to the coffee cans.
I did Cain, I found it in the top of the nut can. Good eye my friend.
Another great video
Thanks Carl, sure appreciate you going along on the ride.
Here!
great job dale looks like its never been down as the gearbox bearing got a lot of play could have caused the damage sure ul sort it next video please
Thanks Mark, yep going to look it over good and see what needs help.
You can buy an early yz80 gear set, shift forks and shift drum pretty cheap and it will drop right in as the cases were the same for several years. The first 4 gears will be the same with the benefit of.961 “ over drive”. I’ve done it to 2 of my GT80 bikes. The engine is 4.9 hp and has plenty of power to pull the extra gear.
Thanks for all the great info, I passed it on to the owner, but he is only interested in it being returned to running, reliable condition. 4.9 hp, wow the 90cc twin that I'm working on is the same hp rating.
With regards to the cracked case you have nothing to lose by grinding out the crank and either welding it up with aluminium or trying those low temp ali braising rods. I've managed to fix a few things with those rods. The crack will need flushing out with acetone. Of course it might all end up distorted but is worth a try, especially if the engine numbers are stamped on that case half. The other thing which I believe is a 'no-no' is mixing case halves up anyway. (it might be a myth and it is fact OK to do this). You then need to sort out the binding but with your mill and stuff that might be possible. It would make for an interesting video!
It turns out the crack was common on the 73 and 74. New beefer cases in 75, we are looking for a new case. Yes, no problem on mixing and matching case halves. The manufacture offered each case separate. I have swapped cases on other bikes like this with no issues. Not sure that applies to all bikes or not, I can only attest to these older enduro type machines.
Hey Dale make sure the bearing didn't spin in case and cause of play. I've ran into that problem with these
So far these have been tight, got another case coming will make sure to check them.
I wonder if the later crank halves were spot faced approximately 1mm deep to allow for the big end thrust washers in which case you might be able to spot face the halves either in a mill or by using a four jaw chuck in a lathe. If that crank and rod setup is used on a YZ then you should have no issues on your engine as I bet the YZ makes twice the BHP of your engine! Another interesting project Dale, it will (and already has) resulted in interesting video content.
With a bit of research, I found the crank for the 73 and the 77 and later are the same part number, but we know they changed it by putting thrust washers in 1977. So, the crank will fit either model. I was thinking the same. I will spot face the side that was worn and put the washers in after checking the case dimensions to make sure it will still fit. I was also thinking about what you suggested to spot face both sides 1mm and go with the washers that way you know it fits, but also have to check the slot where the rod goes between the two halves to make sure there is still good clearance for the rod. We have time to think about it while the owner is looking for a 75 and up case with the new improved countershaft boss. Thanks for the discourse, it's always good to hear what others are thinking.
Dale ,thanks again for another extremely informative and well executed video. Your knowledge is extensive and you have a great presentation. In my opinion you are definitely a master technician. I too have a passion for these vintage machines and just about anything with an engine (and clutch)! Do you take on any customer bikes? Also curious what state you live in,if I may ask?
Thank you, Michael, I do really enjoy these old machines and like you I share the passion of just about anything mechanical. I do take on many customers projects during the year. I generally do not work customer projects in the summer months that is more for my stuff, and local walk-in projects. I am slow and take my time for I am retired and don't wish to still punch the clock or feel like I am or have to. I am located in Great Falls Montana.
made it, Saturday morning! hi, Ya,All!
Nice to see Frank ready for the ride.
Never know what you're going to find during teardown, I guess. I see that you found the early cases to be prone to that damage. Since it shows the YZ crank to be the same, I wonder if the cases were already redesigned when the YZ came out in '74? There would definitely be more stress on an all-out dirt bike.
Hey Doug, it sure could have been a known problem. It seems the retrofit on the beefed-up bearing boss was implemented by midyear 74. I just found a set of late 74 cases and they are on the way.
Dale, was that a report of some sort you ran about interchange? Often a guy can find the part that works if you dig, but the digging can take time. Very curious. Thanks!! Great video!!
Hey Nick, yes, I have the Zedder program it is indeed a parts interchange. Zedder.com
works pretty well and is available for all the big 4 Jap bikes.
OK found something else Later years have a spot for a tachometer cable In the casing So you can only use the earlier years casing. I don't know if later year would match up?
So apparently in 1977 and up There was an option to put a tachometer on these bikes. I checked the part number for the case and They didn't change part in 1977 they still use the same part number 🤷♂️ So Will it match up to the left side Questionable.
Hey Marcel, I think the change in part number may be because of the painted black cases. Not sure though. I found a set for probably a late 1974 model. They have the reinforced countershaft bushing hole. So, I think we are all set. Thanks for all your insight.
Breaking out the popcorn
Awesome.
plenty of cases on ebay at a decent price looks like they beefed up the crack area with reinforcements in later cases,
Thanks for the heads up.
After looking on Ebay at some cases I found several listed on there have the same crack in the same place. Then the ones that are listed as 74 up have a redesigned bushing boss and no more cracks. Looks like it was an early problem for 73 and maybe mid 74.
Could have been caused by too tight of chain tension and jumping that little tike with a heavy adult...😮
After looking on Ebay at some cases I found several listed on there have the same crack in the same place. Then the ones that are listed as 74 up have a redesigned bushing boss and no more cracks. Looks like it was an early problem for 73 and maybe mid 74.
Dale, does that case side have the serial numbers?
No, they are on the left case.
Well I hate that for the owner.
He seemed to take it pretty good, he is a guy that rolls with the punches pretty good.