In those cases (83 maico I believe is like you describe) you can't, if you can do the seal seperate (like here) then you can use the oven. Press is prolly fastest, easiest way to go but requires you buy a press (I recently bought a small 12 ton press).
I've done all 3 options between the maico and honda I rebuilt.
It is not a myth, metal expands under heat. To replace bearings you have 3 basic options:
1. Oven
2. Low Heat Torch (propane, not welding)
3. Press (requires you buy a press)
Maico's documentation reccomends a propane torch to replace bearings. Honda reccomends to use the oven and NOT a torch (because you can warp the cases).
Ya, I don't know how the factory does it, probably press them on. They could do it hot, once the casings come out of the mold still hot they could drop the bearings on, assembly lines for some products do use heat like that.
Large ovens exist though for powder coating your frame :) I heard that even the factory doesn't actually powder coat your frame but when you want to paint you either spray paint it and it chips off or you put it in a big oven :)
I replaced the inner casing bearing using a small hand held propane torch and I am going to use that to do my CR500 crank and casing bearings. Check out 1982 Maico 490 6303 C3 Bearing video.
I don't have welding torches but I don't see why they wouldn't work when used at the right temperature/setting, as long as you're not using them as cutting torches.
That depends, if they charge just "shop time" which is like $75 an hour typically, they'd probably charge you that or double to do both bearings. If they have to take the motor apart they may charge you a flat rate or up to $150 or even $300. Depends on who you would take it to and how much they have to do.
Are you replacing the connecting rod and bearings? I took only my crank and new parts to motosport and they charged $80; I am taking my CR500 to rb-designs,com he charges like 40.
Do NOT use welding torches, use either the Oven or the little Propane tourch like I used in my videos. Using a welding torch it has a much higher heat output and can warp the case or even melt the alumnimum. You must be very careful when heating this.
ya, if the bearing heats up at the same rate of the casing they don't come out. You actually don't need to heat the casings at all to get the bearings out just to put them in. The left casing I just hit all the bearings real hard and they just fell right out.
put some videos up on how to take those bearings out a crankshaft man when ya do yours i have a 81 cb750f i have to take them out of........ what i am doing is useing the motor for a harley type bike man i am makeing there is something called a bearing puller ya can get it for about 80 or a il more on e bay but tusk has one for 80
150° Celsius, then you can tap the casing on a piece of oak (or hard wood) and all the bearings come out immediately and after cleaning the bearing seatings with brake cleaner you can put in the new bearings very easily (they just fall in) because the temperature is still high enough and they are seated perfectly.
oh btw on cases and heating them
the old ones sometimes had the oil seal go in from the inside,so heating the case would warp the new oil seal,better off with a press
musiclovr2 3 years ago
In those cases (83 maico I believe is like you describe) you can't, if you can do the seal seperate (like here) then you can use the oven. Press is prolly fastest, easiest way to go but requires you buy a press (I recently bought a small 12 ton press).
I've done all 3 options between the maico and honda I rebuilt.
tobyeo 3 years ago
hey you guys think the factories use ovens ,and freezers?lol
i think its a myth but works?, maybe someone got a bearing that was a lil too big,and use this?,or pressed a bearing in a cold case,and broke it?
so they came up with this as a safe way??
i know they dont need it , actually some cases the bearings are pressed on the cranks
musiclovr2 3 years ago
It is not a myth, metal expands under heat. To replace bearings you have 3 basic options:
1. Oven
2. Low Heat Torch (propane, not welding)
3. Press (requires you buy a press)
Maico's documentation reccomends a propane torch to replace bearings. Honda reccomends to use the oven and NOT a torch (because you can warp the cases).
tobyeo 3 years ago
i was meaning the factories using ovens,and freezers as the myth-lol
i know the process works i have done it also they need to have the drops of water sizzle as you drop it on the metal
my point was the factories assembling with out the ovens
musiclovr2 3 years ago
Ya, I don't know how the factory does it, probably press them on. They could do it hot, once the casings come out of the mold still hot they could drop the bearings on, assembly lines for some products do use heat like that.
Large ovens exist though for powder coating your frame :) I heard that even the factory doesn't actually powder coat your frame but when you want to paint you either spray paint it and it chips off or you put it in a big oven :)
tobyeo 3 years ago
won "t welding torches work heat the bearings up i am takeing the ones out of my crankshaft and replaceing them 60 dollars worth of bearings man
buckwheat39 3 years ago
I replaced the inner casing bearing using a small hand held propane torch and I am going to use that to do my CR500 crank and casing bearings. Check out 1982 Maico 490 6303 C3 Bearing video.
I don't have welding torches but I don't see why they wouldn't work when used at the right temperature/setting, as long as you're not using them as cutting torches.
tobyeo 3 years ago
thanks that' what i figured about those crankshaft bearings those propane torches ork good man not like the welding ones,
buckwheat39 3 years ago
Should be faster you can get the torches hotter. It can take like 20 minutes or so with the propane torch.
tobyeo 3 years ago
what would someone charge to just take the bearings out a crankshaft and put new ones in but i know how to do it now i got the crankshaft out....
buckwheat39 3 years ago
That depends, if they charge just "shop time" which is like $75 an hour typically, they'd probably charge you that or double to do both bearings. If they have to take the motor apart they may charge you a flat rate or up to $150 or even $300. Depends on who you would take it to and how much they have to do.
Are you replacing the connecting rod and bearings? I took only my crank and new parts to motosport and they charged $80; I am taking my CR500 to rb-designs,com he charges like 40.
tobyeo 3 years ago
Do NOT use welding torches, use either the Oven or the little Propane tourch like I used in my videos. Using a welding torch it has a much higher heat output and can warp the case or even melt the alumnimum. You must be very careful when heating this.
tobyeo 3 years ago
you needed a (blind side bearing remover)
but i have had to do the same
and NO IM SORRY HEATING THE CASES DOESNT ALWAYS LET THEM SLIDE OUT
thats the shift drum needle bearing
and needs pressed in propperly
jasonb32 3 years ago
ya, if the bearing heats up at the same rate of the casing they don't come out. You actually don't need to heat the casings at all to get the bearings out just to put them in. The left casing I just hit all the bearings real hard and they just fell right out.
tobyeo 3 years ago
put some videos up on how to take those bearings out a crankshaft man when ya do yours i have a 81 cb750f i have to take them out of........ what i am doing is useing the motor for a harley type bike man i am makeing there is something called a bearing puller ya can get it for about 80 or a il more on e bay but tusk has one for 80
buckwheat39 3 years ago
is that the 4 cyl 750? the cases should be bolted together top to bottom, no pressing bearing, unless its a 2 cyl
musiclovr2 3 years ago
SORRY TO SOUND LIKE A SMART ASS GUYS
musiclovr2 3 years ago
Engine casings have to be heated up until
150° Celsius, then you can tap the casing on a piece of oak (or hard wood) and all the bearings come out immediately and after cleaning the bearing seatings with brake cleaner you can put in the new bearings very easily (they just fall in) because the temperature is still high enough and they are seated perfectly.
Guus46 3 years ago