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Need Any and All Tips for Replacing Seal
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Author:  mitchie [ Thu Apr 12, 2007 7:18 am ]
Post subject:  Need Any and All Tips for Replacing Seal
Finally giving up and admitting I didn't get my clutch-side main seal seated correctly last winter. No matter how I jet, still wayy too much smoke, poor idling and foul plug about every 5 miles on a trail. So I got a new seal.
My Shop Manual, of course, tells me nothing about replacing this. I think I just guessed which direction to turn it last time. This is the big seal that is smooth on one side and has several raised spots, about 3/8" long on the opposite side. Which direction is it supposed to be installed???
I remember the crank has a step down between the seal and the bearing and I was just hoping I got the seal to go over the right part of the crank when I assembled the crankcase.
Last time, I put the seals and bearings in the crankcase halfs, placed the crankshaft and gears in the right side case, stuck the other case on and tightened bolts until cases were tight.
I'm thinking this time about not putting the right side bearing in until the cases are together and I can stick my finger in around the edge of the seal to see whatever. Need any advise I can get because I really hate splitting the cases more than I have to. Thanks.
Author:  mdlafferty [ Thu Apr 12, 2007 11:09 pm ]
Post subject: 
What bike is it?
Author:  mitchie [ Fri Apr 13, 2007 6:18 am ]
Post subject: 
Good question. This is an MR250, which I guess is the same seal arrangement as the MT and CR of the same year ('76).
Author:  mdlafferty [ Sat Apr 14, 2007 5:37 pm ]
Post subject: 
Refer to the manual on this website on the "manuals" tab. It has the CR250 manual. I've done a few 125s but never a 250.
Here's what I do with my 125. Lay the right case on the bench with the painted side down.
Install the new bearing into the right case. Tap on the outer race only, round and round. Make sure it goes in squarely. Put the bearing the freezer for 10 minutes first. When the bearing hits the plate on the other side it is in far enough.
Install the new right hand crank seal. The sealing lips face the oil in the transmission. The flat side of the seal faces the crank cheek. Lube with grease so it slides in easier. Tap it in with a socket from a socket set of the appropriate size. When the seal lightly hits the outer race of the bearing it is in far enough.
Install the right end of the crank into the seal and bearing. Lube the crank and seal first with lots of grease. No hammering on the crank. Use the nut on the right end of the crank and jury-rig spacers and washers to pull the crank through the bearing until it bottoms out on the bearing.
The next steps are to install all the transmission parts, install the gasket and dowels. Install the new bearing and new seal in the left crankcase and then install the left crankcase over the left end of the crankshaft and bolt it together. On the left side, the seal lips face the crank cheek and the flat side faces the ignition. Again this is for my 125!!
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