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My XT 550 project. Engine rebuild and maybe something more.

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Hello. I have a xt 550, which was running ok, but recently started to produce smoke and eat oil. What could've caused it? I suspect piston rings, but compression didn't seem bad. Anything else? Valve seals? Something? What other stuff should i change on such an old bike? I took the engine out of the bike, but didn't start to dismantle it, as i've never took a 4 stroke apart before, i don't want to mess anything up, i love that bike and i want it to run again.

Excuse my bad English, i'm not a native speaker.

Edited by BananaPowered

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Your English is fine . :bonk:

IF the compression is within service limits , I would have to say the valve stem seals need replacing . When you have the head off , it would be a real good time to clean and lap the valves , insuring a better seal between the valve face and the seat . If you can , Viton valve stem seals are the best option . They handle the heat better than their predecessors , so they last longer .

Here is a free downloadable service manual for a 1982 XT550J :

http://megaupload.com/?d=XGH4OVO0

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Thanks. However, i noticed, that crakshaft bearings require changing. I guess i will have something to do during those long winter evenings.

When looking at service manual, rebuilding the engine doesn't look very difficult, just requires some special tools and basic knowledge. I've already removed the headcover, head and cylinder goes down tommorrow. I'll be working slowly and gathering knowledge during the process. I take photos, write notes and put small parts into plastic containers with labels. Hopefully i'll be able to put it back together again after that :bonk:

Edited by BananaPowered

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That's an excellent approach . You shouldn't have any problems getting it back together . If so , we're here for you . :bonk:

Maybe you could post pics and explain what you are doing while tearing down and rebuilding . That helps you to concentrate and us to learn from your experience . :smirk:

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I'll post pictures, when i'll have something to show. All I can show now are these three photos, one of how my bike looked when i bought it, one pseudo-artistic shot, and one of how the bike looks like at the moment.

clicky - http://imgur.com/a/iFBKn

Exterior has been modded by previous owner, a bit bad quality work. Original parts are difficult to find and very expensive, so i'll try to make it look at least tidy and maybe put on some kind of round headlight. I love that vintage look :bonk: . But this is going to be done later - engine is first.

Changed the thread title, as I don't really care about that smoke anymore.

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From : "I don't want to mess anything up." To : Nothing but a bare rolling frame . :bonk:

I do like your enthusiasm . :smirk:

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Well, i have some knowledge, i just don't have experience, that's why i'm afraid to do anything. All i have performed before was just oil, brake pad and light bulb changes. I also have changed clutches on several cars and that's pretty much it.

Anyway, I've done some more dissasembling today. I've removed head, cylinder and piston. Piston and cylinder are in good condition, looks like they've been changed not so long ago, as i've found some markings done on head and headcover (probably done by repair shop workers). Camshaft and rocker arms are also good. Didn't check the condition of cam drive chain and sprocket, but visually they look OK. Piston rings are worn, they'll be replaced. So far everything's going well.

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Pretty simple stuff . Like a 3 dimensional puzzle . Nothing to it but to do it . :bonk:

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Hello, i just write here to say, that the project isn't dead. I'm slowly taking the engine apart and gathering knowledge. Well, i'm young, and it's really difficult to stay focused to one thing. I have plenty of free time, but there's so much interesting stuff to do, i don't even know where to start!

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Hello

I am parting out a xt 550 engine, 2800 mile (very low miles)

If interested in engine parts. contant me

Mark

mark.frandsen@yahoo.com

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Hello! Nothing to show yet, but i'm still slowly moving forward. Does anyone have experience, and can tell, how many of 550's parts are interchangeable with old XT600? I've found one stripped for parts close to my town, and at least from pictures, engines look almost identical. What kind of ignition system does it have? before i took my 550 apart, it was acting strange, probably shot CDI, maybe 600 has better ignition? Also carb, 550s carbs ar not the best, are 600s ones any better? I would also like to install front forks, wheel and disc brake from it, but i'm not yet 100% sure if i'll do that. Oh, and that Yamaha has a huge fuel tank!

Edited by BananaPowered

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We have to know what year your bike is as well as the 600 .

You should find that information on the steering neck .

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According to the parts fiche , the carbs look to be very close . No doubt the jetting is different . And the electrical also looks very similar but have different part #s .

You can easily see this all for yourself : http://www.partspits...s?aribrand=HOM# Or many of the other online parts houses .

I can't say they will be an exact replacement , but I would think that the 550 and 600 are the same with a few changes ( improvements ) like bore size , etc .

If you want to see which bikes a given part fits , copy the part # into the Quick Part Search: and then click on Select Model in the next window .

Hope this helps . :bonk:

Edited by pd350

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Most of the 550-600 parts that interchange are a whole. If you want the electrical, you need to do the whole electrical, stator, cdi, lighting, etc. You want the 600 cylinder on the 550 bottom, cylinder, piston (obviously), and I'm pretty sure head and cam. From what I recall, the carbs are pretty much identical. I'm pretty sure I read the 600 bottom will drop into the 550 frame. To be honest, I would buy the 600 parts bike and see what fits visually, then try it physically.

BTW, your English is better than half the people I talk to which I find to be more and more likely the more locals I meet as well as the more foreigners I speak to.

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Most of the 550-600 parts that interchange are a whole. If you want the electrical, you need to do the whole electrical, stator, cdi, lighting, etc. You want the 600 cylinder on the 550 bottom, cylinder, piston (obviously), and I'm pretty sure head and cam. From what I recall, the carbs are pretty much identical. I'm pretty sure I read the 600 bottom will drop into the 550 frame. To be honest, I would buy the 600 parts bike and see what fits visually, then try it physically.

BTW, your English is better than half the people I talk to which I find to be more and more likely the more locals I meet as well as the more foreigners I speak to.

I've forgotten the bike for some time, as I have plenty of other stuff to do. However the bike doesn't go out of my head. I noticed the connecting rod has plenty of free play and I think complete used crankshaft might be cheaper. Does the 600 crankshaft fit? Is stroke the same length?

Or maybe I shouldn't bother with small stuff like that? I like your suggestion of 600 for parts. I'm not going to make a completely authentic 550 out of it anyway, so who cares what engine is in it?

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