Yamaha XZ550 rebuild

[r97]

Ok, so before I put my newly acquired engine in a buggy frame I want to get it in good condition first.... rebuild time! Here is the basic plan:

-Remove from motorcycle (check!)
-Disassemble engine
-Clean ALL parts
-Strip and re-paint engine cases
-Rebuild starter motor
-Replace all gaskets
-Reassemble engine

I'm hoping to avoid getting new clutch plates, or piston rings as those are pretty expensive. The stupid gasket set is already $125, and that's not even including the $99 twin carb and fuel pump kit! Piston rings will run me $130... I already need to buy paint, and lots of pipes.

Anyhow, I'm going to try and save as many gaskets as I can, and not touch the carb until I know as a fact that they do not work.

Here's some pics! Engine is a 552cc V-twin, liquid cooled, four stroke, DOHC, 4 valve, electric start, 5 speed manual, shaft drive, twin downdraft carb, 83' Yamaha!

And of course the most important tool.....

I'm noticing now that I have acquired a lot of parts! Most are from the motorcycle, and my go kart (disassembled), but not all. ATV tries and rims were scored almost new for $100!

Also some upgrades to the shop! I cleaned it up nicely, and was given a big tool chest for Christmas (how did I live without it!?). I threw in a picture of my welding cart too, just need to make the gas cylinder mounts and a welding table so I can start my build!

 

[sideways]

That should make your kart fly!

I've got to ask (sorry if you've posted elsewhere, as you can probably tell I don't frequent the forum much anymore), why are you taking it apart, it seems quite an expense for something that doesn't seem necessary?

Did you try and get it to run before you took it apart?

As for preserving gaskets, if you have a new, full gasket kit already, use the new gaskets! It'd suck to have to have to replace several other gaskets to get to the old one that has failed!

 

[r97]

HAHAHAHAHA, yeah.... little more power than the 250 I was planning for my buggy. IIRC 64hp and 30-40ft/lbs @ 9000RPM!

I'm tearing it down for a few reasons:
1. Need to re-paint it, and I don't want to glue the thing together.
2. Few oil leaks here and there that need to be fixed
3. Kinda curious
4. Would like to give it a good once over before I go and build a frame around it.

I did try to get it to run before taking it apart, but It is just so difficult to work on it in the frame/covered in dirt and oil. Maybe i'll check the compression now that its out of the frame, but I'm taking it apart anyway...

I don't have any new gaskets, and I'm probably going to replace all of them (Why is it so expensive!?).

See the camshaft sprocket retaining bolts on the very left in that picture? Those won't come out, and ideas/tips? I tried tapping the socket with a hammer, both CW and CCW, extra leverage, and probably something I can't remember.

Should I just try removing the camshaft with the sprocket still attached? I thought about heating it up, but I don't want to warp anything. I'm thinking either there is red lock-tite in there, or some one used an impact gun , there was a bunch of blue gasket maker crap too.

 

[r97]

Ant tips? Are there any special pins I should be looking to remove first? Should I find somewhere else to ask my question?

 

[Rustydog2010]

See the camshaft sprocket retaining bolts on the very left in that picture? Those won't come out, and ideas/tips? I tried tapping the socket with a hammer, both CW and CCW, extra leverage, and probably something I can't remember.

Should I just try removing the camshaft with the sprocket still attached? I thought about heating it up, but I don't want to warp anything. I'm thinking either there is red lock-tite in there, or some one used an impact gun , there was a bunch of blue gasket maker crap too.

Please don't heat it! If it was me I would just remove the cam chain. Then just pull the cams out with the sprockets still
attached. I really see no need to remove the sprockets?

Just rotate the engine until you find the master link in the cam chain, get it out. Remove the cam chain. Out with the cam shafts. Check the bearings. Remove the head... etc.

Have fun! Looks like a great project.

Edit: Would the service manual not tell you how to remove the cams?

 

[DustinWolfe]

Please don't heat it! If it was me I would just remove the cam chain. Then just pull the cams out with the sprockets still
attached. I really see no need to remove the sprockets?

Just rotate the engine until you find the master link in the cam chain, get it out. Remove the cam chain. Out with the cam shafts. Check the bearings. Remove the head... etc.

Have fun! Looks like a great project.

Edit: Would the service manual not tell you how to remove the cams?

theres not gonna be a master link in a cam chain

 

[r97]

I wouldn't have thought there would be a master link. I guess I'm leaning towards just taking the cams out, but it's going to be kinda close. The service manual does tell you how to remove the cams, step one of that process is to remove the cam chain sprockets...

 

[r97]

Ok, well after a bit of work I got the cams out without removing the sprockets, I was happy for a good minute or so..... It appears the last guy who worked on this has done the same thing to the cylinder head bolts (and I'm going to assume the WHOLE engine....) as he did to the cams. How badly do I really want to take this thing apart? Only thing is those oil leaks, the terrible paint, and a LOT of carbon buildup.

 

[sideways]

Ok, well after a bit of work I got the cams out without removing the sprockets, I was happy for a good minute or so..... It appears the last guy who worked on this has done the same thing to the cylinder head bolts (and I'm going to assume the WHOLE engine....) as he did to the cams. How badly do I really want to take this thing apart? Only thing is those oil leaks, the terrible paint, and a LOT of carbon buildup.

I'd say don't bother. Where are the oil leaks? If it's the cylinder base gaskets, replace them. There'd be pressurized oil galleries in them and one day the gasket will let go and you'l lose you oil pressure then bang. If it's just random side covers then they're easy to do. Heck, if you clean it up really nice (drain all the oil out, de-grease it ect) and use a thicker paint it'd probably seal them up.

Anyone who's worked on old, alloy motorbike engine will be able to tell you all the bolts are going to be like that. You pretty much need an impact driver or a breaker bar for everything. :/

How are you getting around the shaft drive? Quad diff? Turn the engine sideways? Or maybe a RAGB?

 

[Bluethunder3320]

quad diff! thats a great idea. maybe even a small car rear end like a VW. (engines in vw bugs make like 60hp)

good luck with the rebuild... may i suggest a good degreaser like POR15 marine clean?


you might have more to work than you think right now. i dropped a nut (accidentally) down into the opening where the timing chain goes on a Xr100r, TWICE. first time got it with a magnet. second... it disappeared. so i had to take the stator cover off... tranny cover... oil pump.. eventually took the whole thing out of the bike and flipped it upside down to get the nut out. bottom line is it was a PITA to work on that engine, and its only 100cc, about 9hp @7000rpm, free air cooled.

i really never want to take that engine apart again lol. even though some how i got it all back together and it runs to this day. to find out what way those nuts loosen off, find out what way the engine rotates and then you know it is the opposite way to losen that nut.


i suggest you stick with a top end rebuild and just replace the crank case gaskets IF needed. it doesnt seem like a big deal to take it all the way apart like you would a small engine, but it really is harder than you think. lots of parts in the crank case you would be like WTF is this. as soon as i took that case off the XR100r i knew that i would NOT be touching anything inside there, at all. i also highly suggest you mark the tooth/chain allighnment because when i had to re-time that little honda motor, i couldnt figure out if i was a link off or not. it cost me a $80(IIRC) exhaust valve because it hit the piston and bent. oops. valves for that motor are probably way more expensive. and since its overhead cam.... (someone correct me on this) the only way to adjust the valve lash is to grind the valve stem.


if the internals still work, even though they may be a little dirty, my opinion is LEAVE IT BE! you will be thankful. you can assemble the engine minus carb and exhaust to clean and paint.

 

[r97]

I'd say don't bother. Where are the oil leaks? If it's the cylinder base gaskets, replace them. There'd be pressurized oil galleries in them and one day the gasket will let go and you'l lose you oil pressure then bang. If it's just random side covers then they're easy to do. Heck, if you clean it up really nice (drain all the oil out, de-grease it ect) and use a thicker paint it'd probably seal them up.

Anyone who's worked on old, alloy motorbike engine will be able to tell you all the bolts are going to be like that. You pretty much need an impact driver or a breaker bar for everything. :/

How are you getting around the shaft drive? Quad diff? Turn the engine sideways? Or maybe a RAGB?

Not exactly sure where all the leaks are, but there is oil EVERYWHERE it could just be the starter motor seal, or the case gasket has gone... Maybe someone spilled oil on it, I can't be sure.

I would really like to avoid gluing it together with paint, and if I can tear it down and inspect/replace/clean all the parts I would be more than happy to. I want this thing looking and running in mint condition.

Are you saying if I were to barrow an impact driver I would have this thing apart easily? I was just offered the use of my neighbors the other day. I'm going to pick up some penetrating oil tomorrow and let the bolts soak a while (I know the bolts have been soaked in oil for near 30 years, but its worth a shot no?)

Engine will be turned sideways, and a sprocket w/ support bearing with be attached to the PTO. Should look pretty sweet from behind. Dual exhausts on either side, and twin carbs in the middle! Should be able to lower the wheelbase a bit that way too.

quad diff! thats a great idea. maybe even a small car rear end like a VW. (engines in vw bugs make like 60hp)

good luck with the rebuild... may i suggest a good degreaser like POR15 marine clean?


you might have more to work than you think right now. i dropped a nut (accidentally) down into the opening where the timing chain goes on a Xr100r, TWICE. first time got it with a magnet. second... it disappeared. so i had to take the stator cover off... tranny cover... oil pump.. eventually took the whole thing out of the bike and flipped it upside down to get the nut out. bottom line is it was a PITA to work on that engine, and its only 100cc, about 9hp @7000rpm, free air cooled.

i really never want to take that engine apart again lol. even though some how i got it all back together and it runs to this day. to find out what way those nuts loosen off, find out what way the engine rotates and then you know it is the opposite way to losen that nut.


i suggest you stick with a top end rebuild and just replace the crank case gaskets IF needed. it doesnt seem like a big deal to take it all the way apart like you would a small engine, but it really is harder than you think. lots of parts in the crank case you would be like WTF is this. as soon as i took that case off the XR100r i knew that i would NOT be touching anything inside there, at all. i also highly suggest you mark the tooth/chain allighnment because when i had to re-time that little honda motor, i couldnt figure out if i was a link off or not. it cost me a $80(IIRC) exhaust valve because it hit the piston and bent. oops. valves for that motor are probably way more expensive. and since its overhead cam.... (someone correct me on this) the only way to adjust the valve lash is to grind the valve stem.


if the internals still work, even though they may be a little dirty, my opinion is LEAVE IT BE! you will be thankful. you can assemble the engine minus carb and exhaust to clean and paint.

Like I said above, I will be running a chain. That chain will be going to a homemade reverse chain-case (Gears are expensive and complicated). Hopefully I should be able to make the chain-case strong enough; it will be similar to wim's, but in an oil bath w/ reverse. Finally some shortened type IV CV axles (needs to fit through ATV trails, so unfortunately the track width needs to stay within 48"...).

I think I have some marine clean, although not nearly enough for this engine. Will probably just use mineral spirits.

I know this is no small engine, trust me after reading up about it, and working on it a bit, those lawnmower engines are now so simple! LOL. I am going to do my very best to keep all the parts in order, I have plenty of clean, stable spaces prepared to layout parts on in the order they came off. I'm also keeping a watchful eye on and pins, dowels and seals.

Even though it seems a bit silly and pointless to take the whole thing apart, I want to make sure there are no hidden quick-fixes or severely worn parts. I also want to make it easy to work on, and look (and work) tip-top! On top of all of that I would really like the experience so I could be more confident working on similar engines, maybe even making some money repairing my friends dirt bikes. If I can't get these bolts out without going to a machine shop then I suppose I will just hand in the towel, but not yet.

 

[Benjo]

Engine will be turned sideways, and a sprocket w/ support bearing with be attached to the PTO. Should look pretty sweet from behind. Dual exhausts on either side, and twin carbs in the middle! Should be able to lower the wheelbase a bit that way too.

i have the motor from this bikes little brother, the XZ400.
Im putting it into a chopper.

i dont think you will need a support bearing.

I have already converted mine to chain drive,
I machined the spline out of the uni join and tig'd it into a sprocket, then turned the sprocket to fit into the oil seal.

I also had to skim the front of the bearing housing so that the chain had clearance.

Im planning to countersink those three holes and get some taperd head blots.

*Pics added*

 

[r97]

Ok cool. I don't have a lathe or TIG welder, so if I wanted to go hat route I would need to outsource it. I'm hoping I can just modify the U joint fork to either have a sprocket welded to it, or a keyed shaft. Not really sure yet, but I bet I'll probably need to send that part to a machine shop for some reason.

 

[Bluethunder3320]

i dont wanna put an idea down, but a home made chain box that can withstand that engine's power would be pretty impressive.

 

[r97]

Yeah, will be overbuilt a bit. Kind of an experimental thing too, but reverse would be really nice! Either all aluminum or a steel tube frame with an aluminum shell. If I can find it cheap I will run double wide #50 chain too, maybe even spline or hexagonal shafting if I can afford it.

As you might have guessed by now I'm going to go all out on this build, going to be slow though, spending time to get money for good parts and taking time to do it perfectly will be time consuming, but worth it. Maybe by some miracle I will have a driving machine by summer.

I want people to ask me if this thing is Yamaha's new model, not ask me to get off the trails before it explodes, LOL.

 

[Rustydog2010]

theres not gonna be a master link in a cam chain

Okay then. Why have many 4 stroke MB engines I have played with had a master links?

I have seen endless cam chains, riveted and clipped, master links. Not to sure on this engine, but it always pay to check.

 

[r97]

valves for that motor are probably way more expensive. and since its overhead cam.... (someone correct me on this) the only way to adjust the valve lash is to grind the valve stem.

Forgot to mention this, but on this engine the cams run directly over shims which push on the valve stems. You can buy different thickness shims to adjust the lash. I need to get a good leaf gauge to do that though. I'm really disappointed with that craftsman one.

EDIT: Do you guys think soaking in liquid wrench or PB blaster will help at all? Impact driver? Thanks.

 

[Bluethunder3320]

siese the engine and use a breaker bar, that should do.. but remember you should make it just as tight as it was when you took it apart when you re assemble.

the shims... never thought of that. you might not need to do anything to the valves though, im too concerned with details there


if the chain is loose enough and the cam bearings are taken out you may be able to just lift each cam out.

 

[r97]

Already took the cams out, the chain tensioner pushed the chain a lot more than I anticipated and it wasn't that bad, but I still haven't gotten too far... LOL

Not at all too concerned about details, I spend lots of time sorting out the most obscure parts of my projects, seems silly but once you get to that part you just build it, no more decisions required!

Bolts will probably not be going back on as tight as the were, they will be torqued to spec. . Cam bearings? This thing is just metal on metal! Of course there are 2 1/2" pressurized oil passages running through each cam!


Benjo, That is exactly what I was thinking to do!

 

[KieranM]

Gaskets and parts for bike engines are sh!t expensive, I was going to redo the head on my 600, but a new gasket set was over 150, and I had to buy a starter, second hand for 50! very expensive.

Cam bearings? This thing is just metal on metal! Of course there are 2 1/2" pressurized oil passages running through each cam!

There Must be bearings, plain bearings, you wont notice them, just thin pieces of high grade steel.