When to rebuild an engine?

I have just revived my 81 XJ650 Maxim after 4 years of no riding. I got the bug and decided I wanted to do a solo tour through Eastern Europe on my bike. I have always referred to the XJ line up of bikes as the "Armageddon Bikes". Meaning that when the world is inhabited by cockroaches and mutants these bikes will still get you where you need to go. Over the years I have owned a few and although they have broken on me they have never stranded me anywhere. Even on 2 cylinders I still managed to drive the 1000kms needed to get myself home.

So I managed to get her running without doing much of anything besides putting in a fresh battery and changing the oil. She has some pep in her but I did a dry compression check last night and I got readings of 100-95-100-110 across the board. I then checked 'Wet' and the readings jumped to 140-150.

Now I understand that with 57K kms on her I should expect lower compression but to me that says new rings. Am I correct?

My questions are as follows:

If I do the rings should I rebuild the top end at the same time?
If I rebuild the top end should I rebuild the bottom and replace bearings as well.

I have a spare 650 engine and a 750 Seca project bike I can steal from.

What do I need as far as parts go to do a rebuild? Gaskets? Rings? Shims?
How much of this is in DIY territory? I mean honing and changing piston rings couldn't be too hard especially if I take the engine right off the frame. But I've never shimmed or lapped a valve in my life. Is it tough?

Am I being a little premature on a rebuild? Should I try using that Marvel Oil in the cylinders and give her an Italian tune-up (get on the highway and drive the hell out of her) up and keep checking my compression. I haven't put any miles on since I got her going. Have you ever heard of rings self healing after a long sit. Keep in mind I didn't store her properly (the gas was gelled really bad).

I'm flying this bike over to Europe on August 2nd so my time is running out. I'm going to do a complete strip down and cosmetic on her so if I do a rebuild the time is approaching quickly. Anyone have some advice?




Eastern European Bike Tour

 

Mmmm! Worn rings, AT LEAST.

Yes.

Yes.

Yes, yes, and more......

It's not "tough", but it requires a level of experience and tools that are not normally available to the average mechanic. All that being said, I wouldn't want to "practice" on my own bike if I needed it for reliable transportation.

Mmmm!

No, never. Not ever. Only on TV in those "rebuild your engines in a can of goop" commercials!!

 

ha.. chacal... needed a laugh

 

Rent a BMW with anti-lock brakes for the trip----rebuild your 750 when you get home, store 650 indefinitely. . .

Anyway, you'd need new tires also for the trip + shipping there and back.

 

If your bike has been sitting for 4 years it's quite possible that the rings are "gummed up" in the ring grooves and may not be worn out.

I'd ride it regularly and see if it improves.

And anyways, if it's running OK and not blowing smoke, who cares about what your compression figures are??

 

I would pull the plugs and dump a couple tablespoons of dexron (auto trans oil) in each cylinder. Put the plugs back in, and crank it over with the kill switch in "off" so it doesn't fire up. (yes you will foul the plugs) but that will throw the oil up onto the valve stems and might help free them up too.
let it sit and soak for a while. The dexron seems to have good detergents that break down the goop making the rings stick.
When you are ready to fire it up, pull the plugs and clean them off (with something like carb cleaner spray)...screw them in and give it a shot. Run it for a couple days and then do a compression check again. Yes it will smoke like no-body's business at first.
No guarantees, but it's worth the $5 of oil to find out....an engine rebuild is not a 4 hour job, and the parts alone will cost almost as much as the bike is worth.
If it is just stuck rings, it is important to get them freed up ASAP or you will do even more damage quickly.

 

Winter.

 

To rent a BMW in August is 1000 Euro per week I have checked a few places in Germany and that is about the going rate. As for shipping, it's gonna cost about $750 and the bike isn't coming back. I'm leaving it at our house on the Adriatic and I will return yearly to tour about Europe with it.

Now, if it's necessary, I've braced myself to the rebuild. I think that is a decision I need to make. Will the ATF in the cylinder be of any benefit? Has anyone tried this?

Now for the rebuild. How complicated, and expensive, are we thinking? I mean these XJ's are great bikes and I'm only into it for my purchase price of $400 so far. As for the bottom end. Would I just use plastigages to check the bearings before I arbitrarily change them or do we just do it as a matter of course?

Lets put a menu together of procedures and prices. Are we talking $300? $500? $1000? I've seen a few postings on the subject but no definitive answer. Lets try and answer this question

 

Hey, im rebuilding my xj650 maxim for a NYC to seatlle ride. Only the top end, but ended up spending-

40 for complete piston ring set
110 for complete gasket kit (top and bottom)\
30 for valve spring compressor
7 for valve lapping tool (tough not nessesary, can use pliers on valve stem)
and some valve grinding compound and rtv (15?)

This is my first engine project on my first bike; besides brakes axels and water pump on my car this is my first big mechanical undertaking and it has gone quite well (besides breaking a ring while putting the cylinder back on and breaking part of the timing disk and a gasket while angrily taking it back off. Be patient and two weeks of a couple hours a day and youll get it done. Good luck

 

This is fantastic information. If you're making your trip out to Seattle before August I'll ride down for a Mariners game and road test. I'm going to need to get used to couple hour stints on the back of a bike.

I'm reading and re-reading my Haynes manual and it honestly doesn't sound that tough. The only real pain looks like if I need to change the five bearings. But even that couldn't be too tough.

So you basically have the entire top end rebuilt for less than $200. That sounds lie a great investment.

 

You only replaced one set of rings, not all 4? Add another $25 in for a cylinder hone, otherwise you will toast those new rings prematurely. I am assuming with the valve spring compressor that you bought you re-ground the valves and put new stem seals in, so the seals came with the gasket kit (some kits have them, some don't).

 

I am going to be going into my 750 engine next winter so lets assume the best case scenario to get some rough prices and a parts list started.

$140….Piston rings.. $35 x 4 (assume cylinders and pistons spec. ok, crank/rods are ok)
$110…. Gasket kit (assume includes steam seals)
$60……Cam chain
$90…… Cam chain guides (with 57,000 KM they will be worn)
$75….. Clutch fibers and springs
$14….. spark plugs… $3.50 x 4
$45…. Starter clutch rebuild kit (weak point of these engines, might as well replace now)
$10….. Oil pump chain
$5…… Oil filter
$15….. shifter return springs (good time to replace)
$25 …. Cylinder hone tool (attaches to your drill)

Right now we are at about $600, best case and I am sure I forgot something. As you can see, rebuilding these is not cheap, it is something that you should do if you want to keep the bike for a while. Then add in the other items you will be replacing for the trip, brakes, tires, battery, fork seals?, better shocks? Replacement cables (get OEM Yamaha cables, motion pro are good but it sucks snapping a clutch cable in the middle of Montana, I don’t want to think about doing it in Europe).

As you can see it will be expensive to get your bike back into full touring shape, granted once it is done it will be ready for years and years of service.



As for difficulty, I can’t say. I rebuild single cylinder ATV engines often, I have done a top end on a CB1100, and I have disassembled an XJ engine, I have enough experience that I am not worried about it. Paint wise, it took me about 3 weeks to disassemble, sandblast, and repaint/polish my bike last year and that was just working on weekends and after work.... but I didn’t go into my engine.

 

Lessee Yr gonna err.. Rebuild your Old Bike (with no prev expeience or knowledge.. Then have it shipped to E Europe. ??

Errr WHY?
last time I looked there were Lotsa Bikes already there.
Some quite interesting machinery..for V good prices too.
Not an overly well thought out Plan..Kid.

 

It's true I've never rebuilt a Yamaha 650 Maxim engine before but having a millwright/machinist/hydraulic/pneumatic/electrical/welding background gives me the confidence that I'm up to the task.

As for buying a bike there the thought had crossed my mind but there are a couple of things that weighed out that option:

First, I only get a finite amount of vacation time and I don't want to waste it looking for a bike.

Second, since I plan on leaving the bike there and coming back year after year the process of insuring my bike is a pain in the ass in Croatia. Safety inspections take a whole day and they are thorough. Plus if I leave Croatia I need to get different insurance depending on which country I plan on traveling to.

Third, I plan on leaving my BC plates on it and just getting tags for when I travel plus a little additional insurance as needed. Done here, before I travel there so I don't have to waste my time standing in some lineup where I hope the person can speak a bit of broken English.

Fourth, having owned a few early 80's XJ's in my lifetime I'm comfortable with these bikes and have faith in them.

Fifth, I have more parts than God for these bikes so why wouldn't I work with what I have? In my line of work I see so much waste in the name of economics. Do you remember when it was worthwhile to fix machines? Now everybody throws perfectly repairable equipment away because it's cheaper to buy new (Chinese Junk) than to pay the skilled labour to fix something of quality. It's wasteful and I personally find it offensive (though understandable).

Sixth, life is an adventure. Have fun and do stupid things.

Now listen Danilo, I don't mean to go off on you. I have read many of your posts and I know you contribute a lot of useful information to these forums. I was honestly hoping when I saw your name beside the post that your post would have read more like... "Hey! sounds like a great project. I see you're in Vancouver too. Maybe I could come over and help sometime or at the very least, go for a ride"

I typically keep a lot of very cold beer at my place so if you do wanna come over sometime I would be happy to have you. I would love to see your bike and pick your brain about stuff.

 

Amen, Brother G!

 

My first reaction is that you are getting WAY ahead of yourself.

After sitting that long it is likely that a number of things can cause the low compression. Most common are stuck piston rings. It needs a few good high speed runs to re-seat the rings before you declare it dead.

It is leaking? Is it burning oil (smoking)? Does it have a miss? Are there any knocks or clatters?

At 57k km the motor is less than half way through its useful life if the maintenance has been mediocre. I know of one Canadian Turbo with 130k km on the clock and still going strong.

Since you have some time it would be prudent to check it out before dismantiling it.

 

[/quote]

My first reaction is that you are getting WAY ahead of yourself.

After sitting that long it is likely that a number of things can cause the low compression. Most common are stuck piston rings. It needs a few good high speed runs to re-seat the rings before you declare it dead.

It is leaking? Is it burning oil (smoking)? Does it have a miss? Are there any knocks or clatters?

At 57k km the motor is less than half way through its useful life if the maintenance has been mediocre. I know of one Canadian Turbo with 130k km on the clock and still going strong.

Since you have some time it would be prudent to check it out before dismantiling it.[/quote]

I was hoping you/someone might say that. I was told to put a couple of tablespoons of ATF in each cylinder and half a liter in with the oil and just crank it over a couple of times per day for a week to let the detergents do some magic. Put in a set of sacrificial plugs at the end of the week and fire her up and watch the smoke show for a bit.

Then change the oil again and take her out for a high speed run and then recheck.

I am doing this. The funny thing is after some of the offhand comments... I almost want to rebuild the engine now. But I'm not one to do things that are completely unnecessary.

 

There are a couple of problems with the engine sitting for a long time. Usually the rings with stick to the piston lands. The other is the absence of heat cycling (expansion/contraction) of the engine components. Heat cycling helps keep the rings loose, seals wet, guides lubed, etc.

No need to run it hard but a number of brisk, sustained accelerations will tell the tale. Usually highway on-ramps are a good place or a long uphill grade.

After you do the run-up find a place to pull off and stop while the engine is still very hot. I know this sounds backward. Stop the engine and let it soak in the heat for 10-15 minutes. Have a soda, a coffee, whatever. Then fire it up and ride home.

After a few such runs check your compression again to see if it improves. The gas pressure exerts outward force on the rings. If they are stuck it will break them loose. If there is a bit of glazing in the cylinder it is likely to clean it.

If this doesn't help then you may need new rings.

For an XJ top-end you should only need to change the timing chain, lap the valves, new valve guide seals, new head and base gaskets. Oh and a cam cover gasket. Rings are cheap and you cna change them out while in there. No way to tell if the pistons are worn until they can be measured.

Much less expansive than a full rebuild (that you probably don't need).

And still get it together in time for run-in prior to shipment.

With everything lined up, a good shop manual and tools you can do the top-end in 12-16 hours of labor.

 

ATF is one way. I prefer SeaFoam or Marvel Mystery Oil.

The first oil change should be to a high ZDDP oil with detergent. Then high ZDDP levels (1200 ppm) after that. Many of the current low ZDDP oils will cause rapid cam and lifter wear in flat tappet engines like the XJ.

 

Marvel and Seafoam?

I'm assuming Marvel in the cylinders. Where and how much Seafoam should I use?

 

Hey, just checking back on the post, wanted to just say that the ring set was for all four pistons and it was 40 dollars and the gasket kit included the valve stem seals, and yes youd need the 25 dollar honing tool as well. I say go for it. At least the new rings and cleaning up the valves.

 

Testify Brother G!!!
(Danilo, sounds like a right nice invitation, I'd be headed over there if I was you)

 

It would be best if you headed over the day I need to take the engine out because according to the book it's a two man job.

 

For me it was two men and a forklift

 

If you are doing a repaint at the same time then it is a two person job to install the engine, but one fairly strong person can remove it by their self. When I pulled mine, I strattled the bike and lifted the engine out, placing it on a cycle jack that was even with the frame on side of the bike. Although it was much easier to put it back in with 2 people.

 

I guess I'm spooled.
Hung it from the crane

I did muscle it around from one bench to the other during the rebuild and painting process.

 

Or lay the bike on it's side and lift the frame off the motor. It's a 1 person job then....

 

You Aussies always have a work around don't you!

Necessity breeds invention. I can picture the first Australian sitting there scratching his head wondering how to remove the engine without putting down his can of beer.

 

So I've done the Seafoam thing and I'm going to take her out this weekend for an Italian Tune-up.

One question: When I check my compression I do it with the throttle wide open and I get readings of 100psi across the board. Should I take the carbs out and test again. Could there be something creating a restriction that causes the compression to test out low?

I only ask because my readings are even across all 4 cylinders.

 

So I took her out for her Maiden Voyage or is that her Iron Maiden Voyage and the verdict is out. I'm going to have to do a complete overhaul. I've started purchasing the items I'm going to need and so far the costs are quite minimal. You really have to love eBay. So far I've picked up new rings, head gasket, piston seals, and valve stem seals. Still need the journal bearings for the crank and the seals for the bottom end.

All in all this should go pretty smooth. The bike is running fine right now. Has quite a bit of pep so I'm going to retake my Motorcycle license tomorrow and then begin the tear down on the weekend. I'll post lots of pictures here and at my blog. Elvis on the Move

 

From the sounds of it, you did your compression test correctly. However, did you do a wet test following the dry test? That will give you an indicator of ring or valve stem seal wear without the road test.
It also sounds like your off to a good start on the overhaul. There have been a few threads written on what to do beforehand and what to look for once you are elbow deep in the machinery.
Don't forget, anything you can't track down easily you should give Chacal a hollar for. He usually has everything at reasonable prices.

 

That's good to know. I will give him a PM for the hard to track dowb stuff (ie. if I need a set of 1st oversize piston heads)

I did do a wet test and sure enough 145 to 155 psi.

What boggles my mind is how fast my bike is with poor compression. I can't imagine what it will be like after the overhaul.

 

I've been riding the bike alot lately and she seems to be pretty reliable. With the exception of a battery that won't hold a charge. Man I wish I had a kick start. I'm way too out of shape to be push starting this bike everywhere. That being said, I'm way too out of shape to be riding through Europe. I'm really going to have to start working my CORE big time if I plan to do 500 kms per day through Europe. Otherwise I'll be cripple after day 2.

Well This Sunday I'm going to begin tearing my bike down to the frame. I have a lot of work planned for her. Mostly cosmetic but a top end rebuild as well. I also plan to completely replace the electrical and a few other odds and ends... handlebars, tank, seat, lights, new luggage, brakes, controls. But asides from that, not too much work.

I'll take lots of pictures and make sure I post regularly. If anyone wants to come over and help I'll make sure the beers are cold.

 

Gwyndwr,

It has been a month now with no posts. What is the latest? Like you, I am a machinist / Certified welder / Aircraft Machinist and a list too long to mention. I have been a machinist for about 38 years now, built hundreds of race engines, close tolerance parts for F-4s, F-16s, C-141s and others.
One thing I have read on this post and many others is the part of cylinder honing. I totally disagree with this.
First of all, a real cylinder hone is much too expensive for the average back yard builder to purchase. They are terribly big and not portable at all. What most people are referring to is a tool called a glaze breaker. You will find these in a automotive parts supply packaged as a cylinder wall hone. Trust me, they are not. There is no possible way you can hone a cylinder wall and maintain your true cylinder bore. The glaze breakers when used as hones will actually wear the cylinder wall out of round because they don't have a supporting guide opposite the stones to hold them true.
Honing a cylinder wall with one of these is not a good idea. Seems like the first thing people will recommend is to "Hone" the cyliinders. If you are going to hone it, take it to an automotive machine shop and they will hone and true the walls. If you are not going to do this you would be much better off to not touch the walls for the following reasons:
(1). You are going to knock the walls out of round.
(2). You are taking material out of the cylinder wall that doesn't need to be removed.
(3). A piston ring doesn't seal well in an out-of-round cylinder.
(4) You can't reproduce a cross hatch with a glaze breaker.
(5) No way you can get the cylinder wall smoother than it already is unless it has rust in it. In that case you need to have it bored.
(6). You will have better oil control in a (used) cylinder that is not honed.
(7). It takes a good bit of running to seat the rings to the out-of-round bore and these are cast rings. By the time the rings seat to the cylinder walls they are already mostly worn out.

This has been tested and proven over the years by engine building professionals.

Now, about rings and the question whether to use oversize or standard. The standard for determining the ring gap is and always has been a MINIMUM of .004" per inch of bore. 2" bore = .008" ring gap. 4" bore = .016" ring gap.

An oversize ring should never be used in a standard bore cylinder wall. A standard ring covers standard to .019" overbore. There are exceptions to this but not on the applications on this forum. Keep in mind that if you use a .020 oversize ring that you have to file the ring gap ends so that you will have the desired .004" per inch of bore size. If not, you run the serious risk of the engine seizing when it gets hot and galling the cylinder walls. Then you have lost the total objective of re-ringing to begin with.
One other thing to keep in mind is that by going to an oversize ring, you are effectively putting more pressure on the cylinder walls as well as the rings causing more friction resulting in higher operating temperatures, thus risking seizing the engine and also causing premature wear on the cylinder walls and the rings as well. By doing this you have effectively nullified any reason that you wanted to rebuild the top end to begin with.

Take the smart way out and install a set of standard rings and forget the honing. You will be much happier with a much better oil control and a lot less hassles.
One other thing. UNDER NO CIRCUMSTANCES SHOULD YOU EVER RE-INSTALL A USED RING. If it comes out of the bore it needs to be replaced. The rind has already worn to fit the bore and when it is reinstalled it has to wear to re-seat again. The used ring doesn't have enough life in it to re-seat and will ALWAYS leak.

Ed

 

Lou627,

Where did you find a full set of rings for $40?

Ed

 

Ed,

Thanks for posting. I had almost given up on this thread. You are absolutely right about the equipment. I have 175 machines in my shop and I wouldn't hone or bore my own cylinders. The time it would take me to set up a machine would be ridiculous compared with your average head shop. They have the jigs and machines set up for the exact purpose. The money I pay them would be well spent.

As for oversized rings, I wouldn't attempt to fit them into a standard bore. If I decided (for the right reasons, not just because I felt like it) to bore my cylinders to one size over (+0.25mm damn metric system) I'm curious if I could use a standard set of pistons. I have heard that you can but until I tear down my engine and start miking everything I don't know. I'm hesitant to trust a lot of the information I get on these forums without seeing it for myself.

As for pictures I have taken a lot of pictures. I'm slowly starting to upload them to my gallery on this site. I haven't cracked the engine yet, but the bike has been completely stripped down to the last nut and bolt. I shot blasted all the parts that needed to be shot blasted and I'm currently assembling a rolling chasis and fabricating all the bits I need to fab before I rip it all apart again and send everything off for the specialty coatings (ie. ceramic coating the exhaust, powder coating the frame and everything attached to it). When that is taking place I will rebuild the top end and send the jugs and head out for thermal dispersant paint. Of course I'll check the journal bearings on the crank when I'm down there.

I don't think I will need to dig down much further than that. The transmission, clutch and starter were all strong before I ripped the bike apart.

If you want a better narrative and more pictures of the rebuild I recommend reading my blog (if you subscribe by email you will be notified of every new post).

 

Gwyndwr,

I haven't been able to find a decent deal on piston rings until now. I just found a set of 4 for $39.95 plus shipping. The only size they are available in is .25mm and .50mm. The .25mm is .00984 oversize. They can be filed to fit a standard bore. Care would have to be taken to assure that they would have enough ring gap to keep it from seizing when it gets hot. This would put a bit more tension on the cylinder walls which as I said before could cause it to run a bit hotter. As long as it had a minimum of .004" gap per inch of bore I think it would be OK. In this case I think it would be wise to go .005".
I didn't know if you had the rings for yours or not. Too bad we live so far apart. Between two machinists we could build quite a machine.

Ed

 

I have a set of .25mm over rings in my inventory here. I have a nasty habit of picking up deals when I see them. Set of 4 for $30 with shipping. I have enough parts to build three bikes and for some reason I keep getting more. It's a real sickness but I love these XJ's so much.

This XJ650maxim I'm doing right now is going to be quite a looker when I'm done. I'm not going too far from the stock look but I have Secafied it a bit with the larger 750 tank and smaller 750 seat. I've yanked the air box out and am podding it. I will covert the area where the box was to an electrical room/extra secret storage, then I'm adding luggage and a fairing to the beast, I'll finish up with a new wiring harness, LED lights, and some auxiliary power for the trip. I might even add a stereo. But asides from that I'm keeping it pretty stock.

 

Sounds great, I have the same problem. Where did you find the rings for $30 at?

Ed

 

I found the rings on eBay. The guys id was honorsquad and he was a pleasure to do business with. He still drops me an email now and then when parts for my bike come up for auction.

I find the best way to search eBay is through the main page of this forum. I just click on the show all items at the bottom of the auction page and Voila! Everything for the Seca's and Maxims show up.

I search all the listings every couple of days.

If I run across any good deals on rings I will PM you.

 

I'm practically done now. I am reassembling my engine this afternoon. I have honed the cylinders, lapped and seated the valves, and set all the clearances. Now I need to reassemble. I have a couple of questions.

What 'goop' should I use when putting on the paper gaskets (ie. base gasket, head gasket)
Should I oil the O rings before I install them?
And the most important.

How do I know if my timing is right?

 

I don't remember gooping any of my gaskets, but I did lube the orings at the base of the cylinders.
Don't you have a manual for torque, timing, and other important info?

 

Do NOT use oil for lubricating o-rings! Use a non-petroleum based lubricant (if any at all).

Permatex "spray-a-gasket" can be used with the base and head gasket, if desired, although it's really not necessary.

 

I do have a manual Nick. It just sounds way too easy and I was thinking there might be a couple of things omitted. Would hate to have a piston slap a valve at this point in the game.

 

When you get everything together, turn the motor over by hand a few times and line everything up. If your cams, #1 piston and ignition timing marks all line up, you should be good!

 

Thanks Robert,

I've read over the procedure a few times now and I'm pretty comfortable with it. I'm getting pretty excited about getting this project done. Need to calm down and be patient.

 

No problems, been in your shoes a few times myself. Remember, you can adjust and reset all of the timing on the engine so don't sweat it if you find you are off. Just do not fire the beast up until you get the mechanical timing ironed out.

 

I figured as much. This is my first try rebuilding one of these engines. I have two more at my place and they will get done so much quicker.

 

When I took the cylinders off the plastic busings crumbled off the bolts that hold the heads down. Do I need to replace them or can I just leave them off.

 

Everybody has a different theory about what those sleeves are used for.
Most think they were put on to make the build go easier.
Maybe to protect the Stud Threads while the Jugs are dropped-down?

You don't need them!
They don't come with any Gasket Set I know of ...