Engine Rebuild - any advice?

Here is the situation:
I have a non-working (doesn't start - I can't even get the engine to turn when I open the ignition cover and try with a wrench), 1981 XJ650 maxim that I bought as a parts bike. It has a title, though, so I want to play around with it a bit.

I am pulling the engine out this week. I would like to take it apart and check out the innards. So, as long as I am taking it apart and putting it back together (hopefully) can anyone offer me some tips or advice or suggestions? What should I focus on? How much should I expect to spend? Any how-to threads on a full engine rebuild that I could check out?

 

Don't pull the engine from the frame until you have exhausted ALL possibilities to get it to turn over. It needs to be held down solidly if you're going to get it to turn over.

Search the forum for the word "seized" and you should get some hints on how to break it free.

Good luck!

 

http://www.xjbikes.com/Forums/viewtopic/t=8962.html

There's alot of info in this ^ thread.
Hope that leads you to some answers.

 

Thanks, guys.

Is there a consensus on making your own gaskets? I have heard people go both ways on this ("It's fine!" "It's a bad idea!"). It seems like an enormous cost-saver. Anyone want to chime in?

 

I made my own gaskets for carb-boots-to-head and for oil pan on my XJ, and they've been fine. In both cases, though, I did them as time savers rather than money savers.

I would never try to make a head gasket. And, since head gaskets by themselves are nearly as expensive as complete gasket kits, I would say to go with a Vesrah or similar complete gasket kit and be done with it. That's what I did for the GPz, and the $100 for the complete kit was well worth it.

 

SQL -
Fair enough and I'll take your word for it. Just out of curiosity, though - Why would you never try to make a head gasket?

 

Very different materials (metallized or composite), with metal elements often involved as well. They're also designed somewhat to fuse to the head and cylinder block once the reassembled engine is run.

 

I have made my own gaskets to save money with great success. However, as I get older and wiser (and my time becomes more valuable to me) I have stopped doing this except for late night, gotta-get-it-running moments. It is just easier and better economy to buy the complete gasket kit. You can reasonably count on them fitting correctly and sealing as required. The other side to that is the kit will supply you with beautiful templates to copy as much as you like (if you are in to that sort of thing)!
As for the rebuild, I'd be sure to take your time and educate yourself as to what you are diving into BEFORE you break into the engine. I highly recommend obtaining the manual for the bike and reading the rebuild section several times before you create a miserable experience for yourself. Ask questions and take pictures, LOTS of pictures. Draw diagrams for anything you can't find pictures of. Label everything, ziplock baggies are invaluable. A sheet of cardboard to poke your removed bolts into is invaluable. Just draw a silhouette of the engine case and poke holes in the appropriate places, you'll know right where the correct bolt goes every time. And change out the starter drive chain tensioner block!
Best of luck Duck!

 

Try putting some penatrating oil in each cylinder, most likly the rings are stuck from sitting for a long time. Let it sit for a few hours then try turning with a wrench. Work it back and fourth until you can get it to turn. If the engine is really stuck and has major dammage, look on Ebay. You can pick one up for less that the cost of a rebuild. I have seen them go for around 200$ for a running engine. Exhaust all your possibilites before condemming your engine.

 

Alright folks -
I tried a lot of your ideas, but couldn't get the engine to top dead center. The engine is out of the frame now:



Is this going to be a serious problem? Is there an easier way for me to set it to TDC now?

 

Well, at this point, since you're stripping it down for rebuild anyway, it's not too important to get it to TDC now. TDC mainly gives you a known alignment of parts when installing cams so that you don't damage any valves.

Since your engine is already in synch, you should be safe pulling the cams as-is. The one thing I would do would be to try to loosen and remove the cams at pretty much the same time, going back and forth between them, to minimize any risk of chain tension pulling one cam forward or back when the other is removed.

Once the cams are out, everything else is safe to disassemble without worrying about crank position.

Cheers,
Paul

 

Awesome. That is what I was hoping for... now I just need to figure out how to get the cam chain sprockets out without being able to turn them.

I will continue to post my progress on this site. I'm going to try to do it with as many pictures as possible.

All of this stuff (rebuilding an engine) is new to me. In fact, I'm mainly doing it on this engine because it was so cheap I won't feel awful if/when I screw something up. If anyone has ANY advice/ANY suggestions please feel free to throw them my way.

If anyone wants particular pictures of any spot along the way, let me know and I'll do my best.

 

You don't have to turn them. You just need to loosen up and remove all the cam bearing caps. Once the caps are off, you can pull the intake cam forward and that will release enough tension from the chain that you can pull the chain off the sprocket and pull the cam out. From there, getting the exhaust cam out will be easy.

 

Thanks, SQL; will try that today. Anyone have any suggestions for getting the engine off the floor? Some of you have fancy engine mounts from Harbor Freight but my budget calls for something a bit more... improvised. Just a box? Perhaps some of you have constructed something?

 

Somebody made an ugly, solid stand out of 2X4 and 1X4's that looked a little like a stool, and used the engine's lower mounting points.

 

Once you get going on the project ... Engine Parts are going to start piling-up, ... fast!
I use storage bins that fit inside of each other and Lunch and Sandwich Bags with Masking Tape and a Sharpie to inventory and label everything.

 

Haynes Manual suggests something similar. Just a basic box frame made from 2x4.

 

Excellent. I have started with the sandwich bags and masking tape and sharpie. I am putting everything in red, cardboard boxes - the kind you get at Staples for files. Everything is pretty well labeled - I hope. I am also keeping a notebook with embarrassingly primitive sketches of where everything goes along with other little notes (shim sizes, etc).

Today, I pulled the cam chain tensioner and guides out:



The red string is holding the cam chain.

Since this picture was taken, I have pulled out the cylinder head bolts (all 14, including the ones in the front and back that travel UP). According to the Service Manual, I should be able to "remove the cylinder head." I can certainly wiggle the head up a bit, but it doesn't seem to want to come off. Any ideas/suggestions? Am I forgetting something? Do I have to pull the valve shim lifters out?

 

Oh, and I think that just having the engine on a piece of card board on the floor is doing the trick for now... thanks for all of the stand suggestions.

 

Do yourself a favor and get a parts bike motor that runs to keep you rolling while you fix the original one.

 

Haynes recommends tapping around the joint with a rubber mallet.

Usually the head will have a couple of pry points where, using the widest pry bar you can fit, you can apply moderate force to break the seal between the head and the block. The fins are very delicate, so make sure you only pry where the fins have vertical support ridges.

For the GPz head I had to pry a bit at the front corners.

 

Don't start prying and slugging until you have looked-around the whole Head for any fastener not yet undone.

You have to break the Head loose from the Gasket.
A 6-Inch length of 2X4 comes-in handy.
Use the 2X4 to protect the Head.
Apply IMPACT to the 2X4 to get the Head to break loose.
Once you get it loose ... use a Safety Wrapped Pry Bar to free it.

 

Wesley - This IS my parts-bike motor. I have a running bike as well - same make, model, and year.

SQL and Rick - I have already broken the seal between the head and the gasket. The problem isn't that the thing won't budge, it's that it won't pull off for some reason. It feels almost as if something on the inside is holding it on.

 

The only remaining things I can think of that would hold them together a bit would locating dowels (oil channels) and their O-rings. They shouldn't hold much, though. There is nothing else that holds them together or could hang up. Unless you've missed a bolt or a nut, there should be nothing that could be damaged by all the lifting force you can manage with your bare hands... unless it comes off suddenly and you drop it.

 

One of the things that can make head and barrel removal difficult on these old motors is rust around the main studs. Shine a light down the stud channels and make sure there is no rust down there . If they have not been stored particilarly well water does work it,s way down there causing all sorts of havoc. If it is gunged up,a good soaking with penetrating oil over a few days should help.

Cheers, Murray

 

Murray - Unfortunately, I'm inclined to believe it is rust. When I pulled the head bolts, there was quite a bit rust on them.

 

Many a guy has gotten to where its tome to yank the Head, ... only to find something he forgot to undo.

For the really TOUGH ones.
Sacrifice a 1-Inch Chisel.
Grind the end to a sharp edge with a gentle, gradual slope.
Use it to split the Head from the Block by firmly tapping it between the Mating Surfaces.
Once you have the Head lifted-off the Block enough; Insert a Ratchet Handle to keep the one side lifted-up and work the opposite side..

 

this may be a silly question but.........
does the ambient air temp matter, or rather the head/block temp?

i guess what i'm asking is whether the head is more likly to crack
if the metal is cold,as in 40F or below?

and would a bit of bearing grease on the end of the chisel
be any help?

 

If the Head ws off before and the PO used a Gasket Varnish, like INDIAN HEAD, or PERMATEX Spray-a-Gasket, ... you are going to need a Pry Bar.

Get the Head raised-up enough for some Purchase and use a Pry Bar that has the End Taped.
Slip a Putty Knife below the Bar to prevent a Tool Mark on the Aluminum.

 

is the front can chain guide clear?
if it moves, all the bolts must be out so just wiggle and jiggle
eat your Wheaties and go show it who's boss

 

Alright, after a lot of prying and pulling and cursing I did it! Although I'm not sure I'm ready for exclamation points quite yet.

Here is what was under the head:


And a close-up of that charming cylinder (though a bit blurry):


Here is the underside of the head:


So, what's the story? Do I have to give up? Is this something a machine shop could handle?

 

Looks like a job for soda blasting.

See my results in this thread: http://www.xjbikes.com/Forums/viewtopic ... rt=15.html

Depending on what you already have for a compressor and stuff, I'd either get a soda blasting setup and clean the parts with it, or bring the head, jugs, and pistons somewhere to have them blasted... then see how things look (and measure).

 

I will certainly give this a try. Notice, however, the scoring on the inside of the cylinder? Will this have to be ground down?

 

I can't really see the scoring in the pictures, but, depending on how bad it is...

really nothing: just clean up
light scoring: hone out the cylinders
deep scoring: hone and new rings
beyond wear limits: bore and new rings and pistons (almost definitely not worth it)

 

You need a Manual to take you through HONING the Cylinders.
Then you need an "Inside Micrometer" to Measure the I.D.

You can use a New Compression Ring and a Cleaned Piston to push the Ring down into the Hole and Measure the Ring Gap.

If the 4-Hole Measures-out for STD or 1st OVERSIZED Rings the Block will be good to go.
Clean the Pistons.
Use a Broken Ring to Clean the Ring Grooves.
Make sure the Oil Control Passages are sparkling.

From the looks of that 4-Hole Exhaust Valve; I'd send the Head "Out" for the Machine Shop to refurbish.
Valve Job, Oil Seals, Knurl Guides, Remove any broken or seized Studs or Screws.

Maybe its just "Cruddy Looking"
Soda Blast or Wire Brush Clean
Put a set of Plugs in it.
Set the Head >> LEVEL << and fill Combustion Chambers with
Isopropyl Alcohol.
Look for Bubbles around the Valve Seats.
Leaks mean you need Valve Job.

 

I wouldn't send the head out until a decision has been reached on that cylinder.

You'll need to pull the cylinders, clean that disaster out, and see what you have. It may be nothing more than rust and debris if the bike sat for a long time with the valve open on that pot.

Decide on the fate of that cylinder before doing any more expensive work.

 

Obviously that rusted piston to the cylinder is why you couldn't get it to TDC.

I just had a similar problem with an 81XS11 I'm having to rebuild. I let it soak for 2 weeks and tried to rotate it daily. Could only get a quarter turn on it before I decided to take the head off. Pistons 1 & 4 were rusted bad. Even with all the soaking and bumping around I couldnt get them to move. Pistons 2 & 3 came right out as they were on the bottom of the stroke. I still had the engine in the frame so I used a ratchet strap to pull the cylinders up and beat the two pistons out little by little. Turned out 1,3&4 cylinders were etched bad enough from sitting with water in them since 1988 they would require a re-bore. Fortunately Andreas had a set of XS11 STD cylinders/pistons/rods sitting on the shelf and made me a deal on them and I have a new set of STD rings for it.

 

Unfortunately, that's the 'rub.' If that one cylinder is so bad it can't just be honed, then you can either look for a deal like Richard got or get on eBay.

It's generally not "fiscally responsible" to actually rebuild one of these motors. If you can find a decent low-mileage set of original jugs and pistons, then you might be able to get away with rings and honing on those.

Until you get it apart and see, it's all speculation.

 

I plan on pulling it apart this weekend (might take a bit longer) and taking a look at what's inside. I will post pictures and take suggestions. I'm also up for borrowing a friend's compressor, getting a soda blasting rig and making a pass at it (I'm sure I'll need to soda blast other things as well).

This project, ultimately, is more about learning than finding the EASIEST fix. That said, I'm on an extremely tight budget and WOULD like to have a running bike at the end of it all. So, we'll see. If you guys think it's hone-able, I'll give it a go, otherwise, I'll look in to other options.

Some questions (bear with me):
1. What kind of manual should I be looking for to explain "Honing?" I want to read up a bit on all of this stuff. Any other literature suggestions while I'm at it?

2. Rick - you mentioned an "inside micrometer" to measure the inside of the cylinder. Will my manual caliper that I got at Ace Hardware for $6 work?

3. Some of the engine part - names that you guys used in your previous posts sound foreign to me (remember, I'm doing all of this for the first time). What's a compression ring? Where is the oil control passage? What is a "valve job?"

 

1. Public library. Basic automobile machine shop techniques. Honing is actually quite simple: the hone is a tool with abrasive stones mounted on a scissors-like mandrel that expands as rotation speeds up, like the old "speed-ball governors" on steam engines. You use your electric drill, and with the drill running, make even vertical passes up and down the cylinder, thus polishing, cleaning and preparing the surface for the new rings to bed in. The trick is in the even-ness and speed of the honing passes, the end result is a cylinder with nicely cross-hatched "scratch marks" from the honing process. Not difficult, just takes practice. This is a good place for you to learn.

2. No, it won't. You need an actual micrometer; an inside bore micrometer is a specialized version of that. Take it to a REAL auto parts store or actual machine shop and they can mic the bore for you. There is a technique to that too, and it is explained in most service manuals (I believe my Clymer 550 and Haynes 650/750 books both explain it.)

3: Compression rings are one of the types of rings on a piston; generally there are two compression rings and a 3-piece oil control ring.

The oil control passages are passages machined into the piston, behind the oil ring, that allow the "controlled oil" to pass through.

Generally speaking it means: Everything comes apart and gets thoroughly cleaned, of course.
The valves are removed from the head and inspected. The springs are checked for length and replaced if "sagged."
If either the valve or seat is excessively worn, then the valve gets replaced and the seat gets "cut" (with a valve seat cutter) to create a fresh seat.
Valve guides, usually pressed into the head, are inspected and replaced if excessively worn.
Upon reassembly the valves are "lapped" into their seats using valve grinding compound until the proper degree of seating between the head and valve are achieved.
Then everything is cleaned up again, reassembled with new valve stem seals, and it's good to go.

It IS possible to do the entire process, or most of it, yourself. A few special tools need to be bought (valve spring compressor, lapping "stick" etc.) Or you can send it out and let a pro do it; I've done both over the years depending on the motor, the degree of wear and my financial vs. energy levels at the time.

 

This is advice for low end, hobby rebuilds:
You can compare the bore between the good cylinders with the bad one by sliding in a compression ring and measuring the gap between the ring ends with a feeler gage. Set the ring at different depths of the cylinders and compare.
You can hone that bad cylinder with a rented hone and measure it again before you decide to buy new rings. But I think it's going to be too badly scored to use as is, however you can have it re-bored.
Because this is your bike and hobby, low end is OK.
By the same token, feel free to be impractical and spend a little money, claim it on your income tax as education and retraining.
Bill

 

I with BigFitz, he says it all.
Proto has darn good advice too, though you might want to check with your tax agent before you claim that tax deduction unless you can show you are pursuing a career as a mechanic.
Good luck on that motor.

 

Alright, I'm soaking that cylinder in kroil (There really isn't much that I can hurt at this point doing that, right?) and I will pull off the bottom half of the head in the next couple of days assuming I can find a larger space heater.

Looks like I have some reading ahead of me. One more question before I start trying to figure all of this out from some books. If I re-bore, what other changes will I have to make? Will I have to re-jet the carbs? Adjust the exhaust? Get a radiator? Change the timing?

I'm pretty gung-ho about all of this (I'm paying for this garage every month, I want to get as much out of it as possible) but I am trying to figure out how much it will cost and how many favors I will have to call in.

 

First off: RE: Space heater: I heat my garage with an indoor-safe, wall-mounted propane heater running off a standard bottle like a bar-b-que. (It doesn't have to be mounted it could stand up too.)
TOASTY. It's 14*F outside, and I'm in the garage right now on the laptop and its toasty, and the heats only been on an hour or so.

Re-boring won't cause you to have to re-jet or do any of those other things; the carbs will need to be re-ADJUSTED when you put it back together, re-bore or not.

Cost will depend on what you find. If that cylinder is destroyed, actually reboring would mean finding oversize pistons and now you're talking big money. If honing won't clean it up, I'd be on eBay looking for a parted out cylinder bank with pistons that honing WOULD clean up, and you could just buy rings.

The problem with these old bikes is that the law of diminishing returns kicks in REAL quick. You can EASILY spend $300, $400, $600 OR MORE completely rebuilding one of these motors, if you can even FIND the parts. You'd have to drop a good $500 or so for a set of aftermarket 10-over pistons, since the real thing is most likely unobtanium. At some point it makes more sense to go find a low-mileage motor with decent compression for $200 or less, unless you're fanatic about the frame and engine numbers matching as in a full on resto.

Let's get that cylinder cleaned up (after you pull the jugs) first.

 

Would a SECA engine fit on my Maxim frame?
http://cgi.ebay.com/ebaymotors/Yamaha-1 ... ccessories

 

There was a guy on the forum who picked up SECA engine off CL for $20 (i saw it but didn't jump on it) listed at $50 in MA. Search "aluminum boat anchor" on the forum (it was a steal because it had more pieces). Engines can be hard to get rid of because they cost so much to ship, so you kinda lucked out that this is in your area. Also, if you search on CL, keep in mind that an engine may not have the words SECA or MAXIM or XJ attached, because the bike/frame may be long gone. The one I mentioned was just listed as "Yamaha 750cc" and was supposed to be for a go cart project. I called the guy and asked about the YICS.

Starter motor is still on there, so at the very least bring a battery and compression test that thing (someone may have advice on how to do that off the bike), maybe you could make sale dependend on compression test and talk him down a bit.

 

A 750 isn't a PURE bolt-on to the 650 frame, there is a difference in the shifter linkage and a couple other minor fabs you need to do. Do a forum search, that one comes up all the time. Search on 750 in a 650 and see what you get.

I wouldn't even CONSIDER buying that motor without a compression test; you don't want another example of what you have already.

$200 is a bit steep considering the "lack of pedigree."

 

Update:I have gotten the bottom half of the top of the engine (what is the right terminology for this part?) off.


I have also taken the pistons off:


Sooo, the inside of the cylinder doesn't look as bad as I originally thought. From what I have read, I think that it can be honed without being re-bored (will get some better pictures up here soon and will get some more opinions).

As usual, I have some questions and - per usual - I have numbered them:
1. There was a significant amount of rust (and road grime, and sandy-looking stuff) trapped in crevices of all of these parts. Now, all of that sandy grossness is stuck to the sides of cylinders, pistons, and perhaps a bit has dropped in to the lower part (again, help me with some terminology here). What is the best way to clean this? If I wipe it with a rag, I am nervous it will scratch... unless this is OK. Compressed air? Is there some chemical I could/should dip these parts in?

2. The studs that the parts of the engine fit on and slide down are sticking straight up. I would like to turn the engine over in order to get the oil pan off (also, to try to shake out any dirt that fell in there). How do I get these studs out?

3. Do I need to buy a new cylinder? The only part of the cylinder that looks bad is the top. The sides are still pretty.

4. What is my next step? Should I focus on the head/cylinder (it will be at least a month until I have enough cash to get the cylinders honed)? Ultimately, I would like to take apart everything that I possibly can, clean it all up, and put it back together... should I start taking off side panels and sanding them?

5. Lastly, but still in the vein of cleaning, a friend told me about a service where they will dip an entire engine into a vat of some sort of chemical and then flush it all out and it will clean everything. Is this something that anyone here has experience with?

OI! A lot, I know. I can't thank you all enough, though. Your help with all of this stuff has been invaluable.

 

Flush out the motor with cheap engine oil.
You shouldn't need to drop the pan.
Have the cylinders & head soda blasted.
You have to test the bores for size & roundness, you can do this by putting a piston ring (on top of a piston to keep it square) & measure the gap between the ends of the ring. but if you are not sure, have this done by a pro', you can then tell if it needs reboring or honing or throwing.
Keep up the good work.

 

1. I would blow all the crud off with compressed air (compressors are worth every penny spent IMHO). Shoot everything in sight with brake/carb cleaner. I would drop the pan as a matter of course given the condition of the upper end. You need to ensure it isn't rusted up down south as well.
2. Throw the cylinders and head back in place to flip the engine if you can't make matching holes in a 2X6 plank.
3. Don't know. I'd need to see better pictures of the cylinder before I could even hazard a guess.
4. You should have the engine parts soda blasted. Money well spent.
5. Hot tanking aluminum is not a good idea. You are best served disassembling the motor and having it all soda blasted after you clean it out and reassemble it. Best bet is using a selection of bore brushes and hot soapy water (liquid dish detergent works) followed by WD40 to prevent rust.
Good luck.