GS550 Rebuild Engine questions

[jakeolsen]

So, My frame is going to be gone until I am back in two weeks to get it powder coated. I am off work so next week, so I decided to start tearing into a couple things.

The big thing is the engine. This bike has 36k, and it seems there has been no work done in this time.

The first pic is where I have the engine tore down to at this point. You can see in that picture that the pistons look pretty ugly. The second pic shows the valves, and they are pretty nasty, but I don't see any cracks. I have a junk engine from another 550 with 16k on it, and I plan to use its top end.

So, for the questions:

1. Where do I get a new set of head bolts?

2. Gaskets.. I know for sure I need four at this point.. is there a kit that i can buy that will include everything?

3. Pistons.. the rings around them seem wore.. they are loose and springy (maybe I will steal pistons from other engine)

4. Do you think tearing into the crank case is necessary at this point? I was hoping to avoid it because I figured it would mean big $$ but I want to do this project right

[ShortyzKustomz]

With the exception of your ring concerns to motor doesnt looks horrible, a few good seafoam treatments or something of that sort would clean that carbon up..... But I am subscribing to this thread, Cause 550 info seems to be scarce and I am considering finding another motor and building it up for mine in the future as well

[Steve]

So, for the questions:
And then the answers:

1. Where do I get a new set of head bolts?
Why do you need new head bolts? What's wrong with the ones you have?

2. Gaskets.. I know for sure I need four at this point.. is there a kit that i can buy that will include everything?
Buy what is known as a "top end kit", it will have everything you need.

3. Pistons.. the rings around them seem wore.. they are loose and springy (maybe I will steal pistons from other engine)
Uh, ... rings are supposed to be loose and springy. Put them in the cylinder bore, make them level, measure the gap.
That's how you know if they need to be replaced.

4. Do you think tearing into the crank case is necessary at this point? I was hoping to avoid it because I figured it would mean big $$ but I want to do this project right
Personally, I don't think you needed to take it as far apart as you have it now, unless there were oil leaks you didn't mention.
With only 36K on the clock it should have been in pretty decent shape.

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[Nessism]

You can't judge things like the pistons/cylinders and head/valves by just looking at them, you need to measure the parts and compare them to the factory standard listed in the service manual.

You can take the valves out of the head by stuffing a rag in the combustion chamber, flipping the head over onto a sturdy surface, placing a socket over the valve spring (after removing the bucket) and giving the socket a good wack with a hammer. The keepers will spring out and you will be able to remove the valve and spring. You want to put the valve back in without the spring in the way, open the valve about a 1/4" and then wobble it to see how much clearance there is between the valve and guide. If the valve wobbles more than a slight amount, the valve stem and guide are worn.

To check the cylinders and pistons, you can stick the piston into the cylinder up side down after you remove the rings. Move the piston around to both the very bottom and the very top and try to slide a feeler gauge between the piston and the cylinder. This the the area that the piston will not normally run so there shouldn't be any cylinder wear in this area. Get a feel for the clearance and then check the same way with the piston in the normal sweep area of the piston in use - about 1" down from the top is the point of max wear. If there is cylinder wear the difference will show - you can also check the service manual spec. This is not the best way to check for cylinder and piston wear, but it will do for a budget rebuild.

Hope this helps and good luck.

Edit: check partsnmore.com for good prices on gasket kits.

[chef1366]

Just looks like a motor that's been ran.
What was wrong with it?

[GavinJuice]

looks like rings in cyl 3 didn't seal well lotsa blowby, prolly others too...

[jakeolsen]

Why do you need new head bolts? What's wrong with the ones you have?
I'm not sure that I DO need them. As you can see in the picture there are a few that are missing. They came out when I was trying ot loosen the nuts on the inner bolts of three of them. Since the tops were rusty, I figured it might be a good idea to just replace them. since I am taking the top end from another motor, perhaps I will just steal its studs since they don't appear to be as rusty.

Buy what is known as a "top end kit", it will have everything you need.
Thanks will do.

Uh, ... rings are supposed to be loose and springy. Put them in the cylinder bore, make them level, measure the gap.
That's how you know if they need to be replaced.
Yeah I have not dealt with that before. I just thought it looked a little out off that a few of the rings were so loose that I could see the outer and inner edge of the ring clearly. Will check the gap.

Personally, I don't think you needed to take it as far apart as you have it now, unless there were oil leaks you didn't mention.
With only 36K on the clock it should have been in pretty decent shape.
I should have mentioned that when I bought this motor two exhaust bolts had rusted to the point of being gone, and two more broke when I was removing them. The head of the top end of the other came off without breaking any bolts(lots of PB blaster and a little patience). So I figure that it had to be tore down this far at the least, but I am hoping not to go farther.

Nessism, I will do the piston and ring and valve checks that you mentioned.

chef, I'm not saying anything Is wrong with it, I am just asking questions. I am pretty new to motorcycle engines, so I am erring on the side of caution.

Gavin, thanks I will pay special attention to the rings. How bad would it hit the wallet to just replace the rings? I don't want to spend extra money that I don't have to, but if it wasn't too much $$ I might as well replace while I have it apart.

[gearhead13]

I looked at bike bandit, each set of rings are $29 x4 cylinders. It would be a shame to put it back together without new rings imho. There are other sites to get parts from, but you can go to bikebandit.com and price out the different things you will need, like valve stem seals, head and base gasket, rings, and other misc parts. A pre teardown compression test would have given you an idea of the condition of the top end.

[jakeolsen]

gearhead, this set at partsnmore.com seems like it would do the trick, and all for a little bit more than the two gaskets on bikebandit. Thanks for the pricing on the rings. I will keep looking around because that is just a little more than I was hoping to spend on them if I buy them.

[Steve]

I looked at bike bandit, each set of rings are $29 x4 cylinders.

I just looked at Cycle Parts Nation and found them for $21.81.

Just remember, Bike Bandit is OK, but they are the second most expensive supplier, right after Alpha Sports. (Rings are $31.75 there.)

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[jakeolsen]

I just looked at Cycle Parts Nation and found them for $21.81.

Just remember, Bike Bandit is OK, but they are the second most expensive supplier, right after Alpha Sports. (Rings are $31.75 there.)

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That make sa big enough difference to pay for those superbike handlebars!

[Suzuki_Don]

I just looked at Cycle Parts Nation and found them for $21.81.

Just remember, Bike Bandit is OK, but they are the second most expensive supplier, right after Alpha Sports. (Rings are $31.75 there.)

.

You guys are so lucky. I've just snapped a ring putting the cylinders back on my motor (not an easy job by yourself) and a new set is $77 from Suzuki in Melbourne. I would gladly pay $21.81. We need an arrangement where you guys will buy the rings for us and then send them over to us (just joking).

[mike_of_bbg]

If you measure your end gap, free end gap, and groove clearance on the rings and they're within spec, then there's really no reason to replace the rings at all. Remember that, if you do replace the rings, you should freshly hone the cylinders to ensure they break in properly. The observation that the rings are loose is probably a good sign that the free end gap is good (i.e., the rings have plenty of "spring" left in 'em).

I went with the Athena gasket set from Parts-n-more. For the most part they seem like quality gaskets. However, my head gasket is weeping after just a few hundred miles. Some have had better luck than me though. Might just be me and the way I installed it or the surfaces. In a month or two I'll invest in an OEM gasket and see if that does any better. A friend of mine who's done a lot of bike work is also not a fan of the Athena valve stem seals, claiming they start to leak after just a couple of years. Of course he's working on Hondas mostly.

[Nessism]

If you measure your end gap, free end gap, and groove clearance on the rings and they're within spec, then there's really no reason to replace the rings at all. Remember that, if you do replace the rings, you should freshly hone the cylinders to ensure they break in properly. The observation that the rings are loose is probably a good sign that the free end gap is good (i.e., the rings have plenty of "spring" left in 'em).

I went with the Athena gasket set from Parts-n-more. For the most part they seem like quality gaskets. However, my head gasket is weeping after just a few hundred miles. Some have had better luck than me though. Might just be me and the way I installed it or the surfaces. In a month or two I'll invest in an OEM gasket and see if that does any better. A friend of mine who's done a lot of bike work is also not a fan of the Athena valve stem seals, claiming they start to leak after just a couple of years. Of course he's working on Hondas mostly.

Did you retorque the head after the first few heat cycles? I think this is critical. My Athena head gasket loosened up a fair bit and definitely required retorquing. Factory gaskets are reputed to be better in this regard but for the money I still think Athena is worth the extra effort.

[jakeolsen]

I will definitely try checking the piston rings when I get back from outta town. It would be awesome if I don't need to change them, as the money saved would almost pay for a new set of progressive springs for the front. I just see a lot of brown marks below the springs on all of the pistons, and I am wondering if that is a sign that things are getting past the springs.