Opening the crankcase for the first time

[vdavidoff]

I'm going to be opening the crankcase on my '74 GT550 to replace the crank seals. I have never been this deep into a motor before and have some first-timer type questions. I feel like a bit of a spaz for having so many questions but here goes.

1. I don't plan on touching the transmission, but I figure anything that comes out of the crank area should probably get cleaned up. Is it okay to drop things like pistons, rings, etc, into carb cleaner? Or should I just put things back as I found them?

2. While the case is apart, I want to clean up at least the head, cylinders, and top half of the case. I was just going to use simple green and a non-abrasive scrubbing pad (the blue ones). Is it okay to wash all surfaces of these parts in that way?

3. Once parts have been washed with simple green or carb cleaner, I planned on washing the cleaner off with water then immediately drying with towels and compressed air. Will that be okay, or should I not be using water/water based cleaners on some of the parts? Once the parts are dry, what should I use on them to deter rusting before reinstallation?

4. I plan on doing this work on a table-top bench. I have a little wooden frame I made for the motor to so on, so that it doesn't rest wonky on the neutral detent bolt. I see from the service manual that most of the crankcase bolts are on the bottom of the case. Does the case need to be upright when removing and installing those bolts, or can I tilt it up on its side without issue? Or, is a table top not the right place do be doing this?

5. When it's all going back together I figure I should apply a thin later of injection oil to all moving parts - cylinder walls, piston rings, bearings, etc, so they're already lubricated for the first start after reassembly. Is that the right idea?

6. Aside from gaskets and the seals themselves, is there anything else I should be replacing, and not simply reinstalling as it came out? Parts that are not meant to be reused once removed, that is?

Anything else critical that I haven't asked about?

Thanks for any help you can provide!

Andy

[vdavidoff]

I got the case apart and the crank out today. Found a few other problems, glad I opened it up. One of the piston pin bearings fell apart in my hand. A piston circlip was twisted oddly and installed improperly. The clutch has some cracked friction plates. A rubber split washer looking thing on the end of the crank gear was sort of half out of its seat. Other than that, to me, the insides look super clean less a little bit of gook in the crank bearing seats.

Looking at the seals on the crank, I don't see anything that's to me obvious damage, but I don't know what they should look like. Should they spin freely independent of the bearings? Because they do. Also, I am having trouble getting the nut off that holds on the crank gear. I hit it with my impact wrench but it didn't budge. Could be my small compressor. Just want to see if there are any tricks or dangers before I perhaps get whoever presses the crank to pop that off for me.

Still really curious about water based cleaners and how to deter rusting after cleaning, if anyone has any advice.

Thanks.
Andy

[vdavidoff]

Thanks Pedro.

For the sake of giving this thread some closure, in the chance it might help others, I have the bike back together now and my less than idea work station worked out fine.

I ended up not trying to clean up the pistons and rings because I didn't want to possibly complicate my project further. I did clean a bunch of case parts with simple green and non-abrasive pads. After drying them I used compressed air to clean passages, nooks, and crannies, and gave parts I was afraid might rust a quick light coating of WD-40 like Perdo suggested. I developed no rust even over the course of a few weeks of having the case apart.

The little wooden stand I made so the case could sit flat without wobbling worked fine, but a word of caution - you will get transmission fluid on your work space even if you drain the case before starting work (which I did). Things got slippery and I ended up smashing my finger pretty good under the case when it slipped off the stand I made while I was swiveling it around, due to parts and the stand being coated in transmission fluid.

I put a thin coat of injection oil on the small end bearings, piston rings, and cylinder walls before putting the cylinders back on. This seems to have worked fine to ensure things were lubed up well on the first start.

I had some trouble getting the top half of the case back on without pinching things up with the kick starter (exactly how, I am not sure) so that with the case bolts torqued down, it wouldn't return even though the spring was set properly and preloaded. I strongly recommend dry fitting the top, even though it's kind of a hassle, until you have a feel for how it should all slip back together. Taking the case apart over and over is a bit annoying, but not nearly as annoying as having to clean up the mating surfaces where you've put case sealant each time.

Anyway, maybe this'll be helpful to someone. I know it's very basic but we've all got to learn.

Andy

[jabcb]

Starter clutch upgrade is worth doing now if it hasn't previously been done.
See service bulletin #26: http://www.ozebook.com/compendium/techb ... 022-26.pdf