Another bottom end rebuild question or two

[hellbertos]

I know these pop up from time to time, but I couldn't find any answers w/ a search so...

I just did my first case split on a dead bottom end and have a couple quick questions for any of you experienced guys...

A) The main bearings were seized to the crank and came out w/ it. In a normal, or functional motor, is it difficult to remove the main bearings. I want to replace them in my "real" motor and am curious.

B) When re-assembling the cases, I wondered if there is a "best practice" for which gear the bike should be in. Just wondered.

C) Anyone know where to get slugs to drop in the main bearing holes to heat indirectly (like the Eric Gorr book shows; seems like a great way to keep direct heat off the case... obv. if EG does it that way).

D) When putting the "real" cases back together I plan to Yamabond them, or similar. Any tips on the application AND do you guys use that stuff w/ a gasket or w/o.

I may have more questions coming, but thanks in advance for any info you can pass along.

 

[bwood]

A) The main bearing usually come out with the crank. It doesn't mean they are seized, they are just holding on better. I you plan to reuse the old crank you will nee to use a bearing seperator of some other sort of puller to get them off. I had to buy one to rebuild a Honda 50cc scooter a long time ago because the crank was discontued. I would recommend a new Hot Rods crank for the piece of mind.

There is an example of a bearing seperator below. Most autoparts stores can get this for you, mine was a larger unit so I could use it on large and small bearings. @ Carquest Auto Parts it was $34. I think it will work up to 3 1/2".

B) Neutral

C) Clymer manuals show to set each case in the oven on a old cookie sheet and heat it up. Place the bearings in a ziplock bag and submerge them in some ice water. Let both stay in the oven or ice the same amount of time. The case will expand slightly and the bearings will shrink slightly. Work fast. I would recommend a Clymer as they show how to get around using specialty tools.


D) I have always used a gasket on the Honda motors I have rebuilt. I recommend putting it back just like it came apart. If it didn't have a gasket, then don't use one.

Good Luck

 

[Rich Rohrich]

C) Anyone know where to get slugs to drop in the main bearing holes to heat indirectly (like the Eric Gorr book shows; seems like a great way to keep direct heat off the case... obv. if EG does it that way).

http://www.onlinemetals.com/merchant.cfm?id=195&step=2&top_cat=60

 

[hellbertos]

thanks for the input guys.

Bwood- I appreciate the input on the main bearings and the pic of the tool as well as tip to pick it up at Carquest. Nice to not have to buy the moto specialty tools where possible.

Rich- thanks for the link. I'll sort out what size I need and order up!


More questions to come. Thanks so far!

 

[2strokerfun]

I would absolutely not put bearings in ziploc bag and dip in icy water. Few ziploc bags I've ever used were actually water tight. I put them in ziploc and put in freezer overnight. Less chance of getting rusty bearings that way.
If your case mating surfaces are pristine, just put light coat of grease on gaskets and use. The grease helps start the swelling process that seals the gaskets and holds them nicely in place. No leaks and easy to remove next rebuild. If you have scarred up your mating surfaces, just put very very light coat of yamabond (3bond is what I have) on surfaces. You still use your gasket. Only time you don't use gasket is when engine is designed to not be used with gasket.