Author Topic: Crank Seal replacement for a 79 CR250 Honda - Any tips?  (Read 1511 times)

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Offline Kenneth S (222)

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Crank Seal replacement for a 79 CR250 Honda - Any tips?
« on: May 25, 2012, 05:43:10 am »
Hi Guys, at the last race meeting my 79 CR250 was running on like crazy. I have been told it is probably the crank seals gone. Even though I think it helped with my corner speed, I think I should bite the bullet and fix it before it gets ugly. This is a fix I haven't had to do before, any tips would be much appreciated.

Is it possible to do without splitting the cases?
Kenneth S
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Heaven VMX Club - Racing No 222 - 79 CR250RZ - 84 CR250RE (Steam Train) - 89 CR250RK

Race Bike History
76 RM125A, 77 RM125B, 78 RM125C, RM400C, 79 CR250RZ, 80 YZ250G, 81 RM465X, 82-83 RM490 Frank Pons Special(Beetle's 81 Race Bike)

Offline smed

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Re: Crank Seal replacement for a 79 CR250 Honda - Any tips?
« Reply #1 on: May 25, 2012, 03:20:04 pm »
Yeah you can change the main seals without splitting the cases but check that the bearings have no play or you may as well do the whole job properly.

If the bearings are O.K. prise the seal out with a small scribe or similar tool,You do not want to damage the case,the crank or the bearing so be bloody carefull :'(,If you are lucky the seal may come out easy as it may allready be half popped out causing the problem of running on,if the seal looks O.K. i would be looking elswhere for an air leak before you tear into the job :)

Offline Graham

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Re: Crank Seal replacement for a 79 CR250 Honda - Any tips?
« Reply #2 on: May 26, 2012, 06:59:54 pm »
If having a problem getting the seal out drill a small pilot hole in the side of the seal get a wood screw blunt the end and then screw into the seal it will bottom out on the bearing and start to push to seal out :D
Gosh its a shame a slow 4 stroke trail bike can go so Fast !!

Offline Kenneth S (222)

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Re: Crank Seal replacement for a 79 CR250 Honda - Any tips?
« Reply #3 on: May 29, 2012, 06:30:54 am »
Thanks for the tips guys. Good call Smed. It was the base gasket. It had been sucked in on the side. Good and bad news really. Easy to fix but a bit of crap was sucked in and has marked the cylinder. :-\
Kenneth S
Go For It

Heaven VMX Club - Racing No 222 - 79 CR250RZ - 84 CR250RE (Steam Train) - 89 CR250RK

Race Bike History
76 RM125A, 77 RM125B, 78 RM125C, RM400C, 79 CR250RZ, 80 YZ250G, 81 RM465X, 82-83 RM490 Frank Pons Special(Beetle's 81 Race Bike)