Engine Rebuild - any advice?

Hey everyone. Miss me? Work has picked up around the holidays so I haven't done much since last writing. After a closer (and cleaner) inspection of the trouble cylinder and the piston I think that I am going to be able to use it! Which is pretty awesome. Obviously, still going to get it checked by a shop, but taking my time degreasing everything before I bring it in.



Other awesome news - $75 gift card to Sears for Christmas (thanks Mom!)

1. So, first thing's first - I want to take off the oil pan and all side covers (clutch, gearbox). Remember, Wiz, this is more an exploration for my own edification than a get-it-up-and-running project (although getting it up and running is certainly on the docket). Besides, I want to get it SUPER clean and nice looking.



I have taken all the bolts out of these covers, but can't seem to convince them to come off. TRIED: rubber mallet, wood block with hammer, a bit of kroil, propane torch. Won't even budge.

2. Robert's preceding post indicates that I should get the engine soda blasted as one piece. I was planning on bringing individual pieces in and getting them done (or doing them myself). That way, I can make sure to get inside the cylinders, etc. Thoughts?

3. As it gets colder, I am wondering about my garage. Should I worry about metal parts (like the pistons or the valve cover) getting that cold while out of the engine? Will they warp at all?

4. As a $$ saver, I'm thinking of making some of my own gaskets. I want to do valve cover, clutch, and gearbox. A friend of mine suggested that I hold the gasket paper up to the part and just tap around the edge so the machined edge of the metal will dig in. Anyone else have any tips?

 

With the drain pan, I've marked the oil level sender with a circle and '+'. You'll need to remove that first (it will leverage out, it has an o-ring so it will be tight).
Also I've indicated where you still have bolts (you may have already removed these, but just in case).

You may have to carefully leverage around the edges where appropriate to gently force the pan away from the crankcase.

1st time I've tried these attachments, hope they worked.

And the gasket Idea sounds good to me. use a round holepunch when making the holes for the fasteners to pass through the gasket so you don't rip it.

 

Sorry, here are those images.

 

Don't worry about your metal parts in the cold, private parts are a different matter. :lol:
Don't be blasting inside the bores.

 

Champ - thanks for the heads up. I have removed the sensor and all of those bolts. Still doesn't want to budge. I'm hesitant to push anything in there for fear of scoring the gasket edge. Your drain pan looks great.

Wiz - seriously. My privates are freezing.
Thanks for the tip on the bores. Is there anything I need to do to clean them up before honing? The one cylinder has rust on it and I thought I was supposed to soda blast to figure out if it's worth it to hone. That said, if I don't have to do that, I might be able to just clean it up with brake cleaner and not need to hone at all.

 

That #4 cylinder that had the water in it would be the one to really inspect. Once cleaned and lightly honed, Hopefully you don't have alot of corrosion/erosion in that one.

 

Bump. Any advice on getting this oil pan off?

 

I did it!



Probably not the BEST way to do it, but I ended up CAREFULLY grabbing a hold with some vice grips (I know, it's aluminum, I did a lot of cringing as well) and pulling it straight off.

Inside the engine:


Now I get to figure out what all of this stuff is. What are the cranks near the top of the picture and what is the name of the filter thing that looks like a flying saucer?

 

Near the top of the picture is you gears. the flying saucer thing is the filter for your oil pump.

 

Good job getting that pan away. If you put enough elbow into it, you should be able to remove the three bolts holding the back plate on so you can get in there and clean it up like new.

 

Thanks. That's next. Moving slow, though. Lots of work, and Chicago winters are making it unpleasant to spend too much time in the garage.

 

THAT'S an easy one: http://www.northerntool.com/webapp/wcs/ ... _200307957
Toasty! I wall-mounted mine and parked a propane bottle outside the garage, ran a line inside.

 

You mentioned the propane heater before. Someday I'll have some extra moola to afford one but right now I'm making due w a couple of electric heaters that I was given (I dont pay for the electricity in my garage).

 

Alright. It's warm out and I finally got the head over to Champion Cycle at Western and Addison. Paul took a look at the ring of rust around the cylinder and told me that it was shot. I'm pretty sure it would cost me more to get oversized pistons than to buy a new engine. Paul also tried to sell me an '83 Maxim.

So, a few questions:
1. What do I do with the old engine? Part it out? Sell the aluminum parts?
2. Do any of you know of a 650 or 750 engine near Illinois that I could get for cheap... REAL cheap?

 

Buy a replacement set of cylinder jugs...........might be the cheapest solution!

 

Help me out with a quick vocab lesson.

The part that is rusted on my bike is one of the four cylinders that the pistons travel in. The upper part of the head.

"cylinder jugs" - are you suggesting I purchase a new set of pistons, or do you know of a place where I can get a head?

 

From your description of the problem, it's not the cylinder head that needs replacing, it's the "jugs"....the actual cylinders that the pistons slide up-and-down within. The cylinders ("JUGS") and the cylinder HEAD are two separate parts.

And those JUGS are actually made up of two components, the cast aluminum, finned cylinder "shell", and four cast iron, replacable cylinder LINERS. It is actually those liners that wear, since it is the liners that the pistons and their rings actually ride up-and-down upon. Howeverm the cost and effort involved with replacing individual liners is usually not worth the effort.

The cylinder HEAD is where the valves and the camshafts live.

Depending on their condition, you may or may not need a new or used set of pistons (but probably will need/should replace the piston RINGS).


Of course, any used set of cylinders may need to be honed, or even bored out to an oversize to get the walls smooth. Minor rust on the ylinder walls can normally be cleaned up with a minor hone, which will not require new pistons. You can't really tell until you have them in your hands (or buy from a trusted seller) and measure the cylinder bores and their taper (besides the visual inspection for rust, scratches, etc.).

For your info, the cylinders for a 750 engine are:

65.00mm diameter, with a service limit of 65.10mm (before requiring an oversize bore).
Taper limit: 0.05mm
Ovality limit: 0.01mm
Piston-bore clearance: 0.030 - 0.050mm, with a service limit of 0.1mm


Further information on how to measure and determine wear parameters will require that you, or the machinist, have a factory Yamaha service manual or Haynes workshop manual for that engine.

However, if you take the above specs to your shop, and they get kind of a blank look in their eyes or try to blow off your desire to see that the measurements are done, then I would thank them for their time and take the work elsewhere.

 

For example...
This is not good
http://cgi.ebay.com/ebaymotors/1982-Yam ... ccessories

This is much prettier WITH pistons and rings.
http://cgi.ebay.com/ebaymotors/1982-Yam ... ccessories

Or get really spiffy. (they sure are pretty) but no pistons or rings
http://cgi.ebay.com/ebaymotors/1982-Yam ... ccessories

OH...wait, did you say it was a maxim or seca?

And then you'll need to buy a head gasket from Chacal!! ...hmm that reminds me.

 

Thanks, guys. It is the HEAD, not the JUGS. Sorry about the confusion.

Thanks for the ebay links, too, although I'll need it for a 650, not a 750. I probably led to that confusion. I was thinking that if I'm going to have to buy a whole new motor for the bike, it might as well be a 750 which fits into the same frame.

That said, it looks like I will not have to buy a whole new motor. Just the head. Anyone around Chicago have a 650 head?

 

Okay, but now that leads to another question, why would rust on the cylinder head disqualify it from further use (at worst, it would need a valve job and valve guides).............

But, if you do go head shopping, make sure it's off a 1980-81 650 engine, "non-YICS". The later 650 engines use a YICS head which won't be the same for your engine.

By the way, the 750 engines are not quite direct drop-in swaps for the 650's, so if you do decide to go that way, give us a shout so you can be prepared for what you'll run up against.

 

What he said >>

And if you have the head off, you probably should check the pistons and rings. You'd be bumming if you spend money on a head and have bad rings and she still wont run.

 

I think we still have a terminology disconnect here; the HEAD is made of alloy and cannot rust.

 

My bad, guys. THIS is the part that is rusted:



Not the PISTON inside (despite the appearance in this picture, all of that rust came off the top of it). The housing:



Bear with me. I'll get it.

 

So, the question is: Where can I get this cylinder block cheap?

 

Ebay is your friend!

There are a lot of them out there.
Shop carefully and make sure you get lots of good pics of the inside.
It would be nice to get a set of pistons and rings with it.

You should be able to get something for less than $75 but DON'T be a penny pincher if there is one that looks good for a couple bucks more.
You'll have a lot of time invested along with $ for gaskets to skimp on parts now.
Regardless you'll want to run a hone down the holes to clean them and true them as much as possible. You can get a cylinder hone at most autoparts stores