1982 GS 550 MZ engine rebuild from zero

[Guest]

Hi all!

I haven't got time to update my project thread, but I managed to tear down my '82 550 MZ engine. Only thing left is to separate the cases. In my country there is no way I can find a better engine to swap, and it is needed some paper work and etc, so a complete rebuild comes. It has almost 100 000 kms in it, and had a hard life. The lower engine never opened up, so it is still intact from PO's , I think the only real fault is the transmission, I suspect the little metal flakes comes from there ( I found lot of it in the oil pan, and there was a strange noise in 5th gear). I have a donor engine, I hope the tranny is OK, and i can swap them. I will measure everything as the manuals sad.

I have some question.

First:
Because the hard story and the high kms of the engine, what should I change for sure? I mean should I change all the bearings, cam chain etc??? (Don't forget european motorcycles are in worst shape than those in the USA) Or if the bearings are seems fine I can reuse them? I can't find any information about what should be changed 4example at a given kms.

Sure I will have more questions.

Thank you.

[Sci85]

I'm fixing to start this same rebuild myself soon. Currently selling some stuff to get the funds. I plan on doing the 650 head swap for more oomph. With that said, it's my opinion that if you go through the trouble of splitting the cases, you replace all wear related items. That means all seals, bearings, rings, etc. It's not worth the hassle and usually costs more if you have to open it up more than once.

Good luck!

[gabos666]

Yeah, I think that too Sci85, but I just want to ask if there is anything what is should be changed beyond bearings and seals. Man, this should be very interesting and $$$ project, for sure. I am happy about your project, because we can help each other I will update my project thread if I can split the cases, and measure everything. I hope my crankshaft and tranny are OK. I think the engine is the most important to be done, so my suspension upgrade have to wait unitl it is done. I am planning an oil cooler, and maybe 650 upgrade, but nothing is sure now.

[gabos666]

I checked some price, and I am confused now. Should I change the crankshaft bearings and so ? High prices! 5 bearings for just the crankshaft are 5 x 97$ ... ouchh plus shipping of course...
Is there a chance IF I can buy these from SKF?? Or another supplier?

[dark7068]

the motor in my katana was all in pieces,, the previous owner was in the middle of a 650 head swap and then gave up on it and I acquired the bike and parts.. I will be going thru the parts and hopefully finish the motor this winter once I orgainize the parts he thru in boxes..

[gabos666]

That's interesting.. I hope once I can do the swap, but I am not so lucky than you, because in this side of the world, is not easy to find a proper 650 head, jusg and pistons. I am frustrated on these bearings. If they are bad, I think the game is over. around $500 for just these.... the interesting thing is in Europe the parts prices the same as in the USA, 100 for the bearing, just in Euros! 1 Euro = 300 hungarien forints, 1 USA dollar = 220 forints. Insane!! USA prices are way better, but here comes the shipping... so a full rebuild is way over my reach financially. And the other things, gaskets, o-rings, etc.,etc,... pfff. Hard choices fro sure.

[dark7068]

wow, might be time to find a different motor. I have an 85 550EF motor in mine, but the cams were bad. I have replacement cams on the way then can run it I hope.

[Nessism]

My suggestion is to tear down both engines and pick the best parts for your runner. The crank bearings are not easy to replace and likely not necessary anyway. Inspect both cranks and pick the one with the least wear.

Parts that are mandatory to replace are piston rings, gaskets and seals (only use OEM Suzuki), and maybe the cam chain.

With the transmission, look for rounded off engagement dogs, worn shift forks, and any other obvious wear.

Honestly, it's hard to say what needs to be replaced until you get inside the engines. GS engines are amazingly tough, so most parts are likely just fine.

Good luck

[gabos666]

Thank you all!

We will see. I am a bit concerned about bearings, but I hope the little metal flakes, and overheating engine didn't destroyed them (luck in the drama is the PO didn't rode it much, and me neither until now). I will keep you updated, I hope next week I can write more infos about the situation.

[Sci85]

HOly 24k gold! 94 bucks for a roller bearing? That is nuts! I've replaced many of these on top of the line competiton dirtbike engines and have never paid more than 20-25 bucks for a main bearing. That's just crazy and I agree, if all of those needed replacing, I would probably junk the engine. Maybe there is a more reasonable aftermarket source for these? Hopefully yours will all be in good shape!

[Nessism]

With a roller bearing crank like many GS bikes use, before you can replace one of the main crank or rod bearings, the crank needs to be pressed apart. This is not a do it yourself type job. There are only a few people in the US that you can truly trust to do this kind of work, and I have no clue about in Europe. Needless to say, this kind of work costs a lot of money. It's far far cheaper to just purchase a good used crank. Fortunately, in this case a parts engine is available so you shouldn't have to resort to this type of work (hopefully).

[gabos666]

Hi all!

Finally I had time to open up the halves. The journey to the center of an GS 550 engine just started. I could inspect them just with the old mk1 eyeball, measurements with caliper is the future.

So:
+my tranny looks intact, the metal flakes doesn't came from here all gears are good, everything is in good order, there are not much round off or anything bad
-except the bearing wich is pressed in to the crankcase, it gives terrible metallic scratch sound



-there should be another faulty item in the trany, becaus the bearing should give sound not just in 5th gear

+my crankshaft looks OK, all the bearings turns nice, and easy
-BUT my bearing yournals looks a bit sad

[gabos666]

[gabos666]

I can't sense anything with my fingers, just where the interesting "pittings" are. Very small punches, but where these comes from? And how bad are they? The yournals looks terrible, but the surface is nice, and very flat. The bearings outter races are almost intact, but a very few "pitting" in some of them.


And the BIGGEST MINUS ..... I discovered that the engine was opened before, look the disgusting silicone "sealer!!!! aaaaaaaaaaaarrrrrrrrrrggggggghhhhhhhh

The big question is, what I should do with the bearing yournals?

[ashdricky]

I have been through a 550/650 conversion and had alot of help from dansofield 550, nerobro, suzuki don and nessim, I am more than happy to help, also I make an oil cooler adapter plate and lines which is cut special to fit the larger fins of the 650 top end. I have no issues shipping to the EU.