Not all silent bikes want to be ridden...

Be warned, this is a long winded story about my experience with my XJ. Read on if you have the time.

I have a great love for motorcycles, all motorcycles, and always have. I think that motorcycles have their own personality. I have ressurected a few from the dark over the years that sat unloved and silent in garage corners and sheds. Some projects worked out better than others. I've never encountered a bike more unwilling to be brought back to life than my current 81 XJ750 SECA.

A beautiful bike, that lived out the majority of its life with only one owner, who spared no expense in maintaining it. Very frequent valve adjustments and service, but hardly ever ridden. He sold it to the second owner in 2008, who never even rode it. It had 13,000 miles on it. Never even transferred the title. He moved it to his garage, put it on the center stand, and let it sit until May of this year. Then I bought it. I was still new here, so I hadnt read much yet. I did know that I needed to replace my brake shoes, which I did. I found out later that the dust mask to keep out the asbestos wasn't optional. Flushed out the carbs and fired it up. It ran OK for about 2 weeks. Then it wouldn't idle. So, off the carbs came. They were of course filthy, so they got an ultrasonic cleaning. Put it back together, and it ran great for a while. Then, it died with an electrical problem. The (new) battery suddenly went dead. Checking all of the electrical connections, I ruled out everything but the fusebox. So I replaced it. During the period of time it took to get the fusebox from chacal and get it installed, I noticed my oil level had risen. #4 float had stuck, and flooded the engine. Overhauled the petcock, and this time, had a professional overhaul the carbs and install new needles and seats and set the float height.

While waiting for the carbs to get back, I pull a sparkplug out of the #1 cylinder just to check the condition. Whoever installed it last crossthreaded it. Repaired that with a tap and insert. Got the carbs back and installed. The bike is running well, but the sparkplug insert is leaking. I manage to get the insert out, and try again. The second attempt at repairing the hole is successful. The bike is finally running, and running well. I check and I have 14 volts at 5000 RPM at the battery. I ride it about a mile, and park it so I can ride it to work the next morning.

The next day, I go to ride it to work. It fires up straight away, and purrs happily. This doesnt last for long, though. 2 or 3 miles in, something isnt right. I dont have the power I should, and I think I feel a misfire. Yes, definitely a misfire. I limp it to work (Im an auto technician), and discover that the #4 cylinder is the misfire. Its not getting any fuel, as the floatbowl is dry. I rap the bowl with a small hammer, and suddenly it fills with fuel. Start the bike, and it runs fine. I had it towed home anyway. I get home and pull the floatbowl. Everything is looking good. So I put it back and start the bike, and it is running fine. I decided to take it on a quick ride, just to be sure the float was working. 1 mile in, its good. 2 miles... good. 5 miles... Good. Then, the misfire comes back. Im close enough to the house, so I decide to limp it back. The misfire is getting worse, and the bike wants to die. 2 miles from the house, it does die and will not restart. It's cranking over way faster than I think it should. I push it the two miles home, in the dark, on the road shoulder.

So, this is where I am at now. My initial guess is that another float stuck, causing a lean condition, and the YICS spread that lean condition across all cylinders. This caused the valves to burn. I dont know yet, as I literally just got home and decided to post this.

I'm beginning to question whether or not this particular XJ wants to be ridden again. After so many years in the dark, I'm getting the vibe that this bike wants to stay there. I have nearly a grand, not including what I paid for it invested, and now I believe it's going to need an entire top end overhaul at 15,000 miles. Then what? The bike will find another reason to be put back into the corner of a garage for another 30 years. I know there are some here that will argue "Well, you didnt do this." and "You didn't do that" but I really did do all of that. This XJ just wants to be left alone.

 

Honestly, it sounds like the carbs were not done right......I know you said a professional did them--prefessional in what sense? someone who know THESE carbs inside out, or someone who has all kinds of motorcycle repair certificates hanging on their wall......and know how 'clean old carbs by spraying them a few times and call it good' rather than totally disassemble them and clean EVERYTHING?

Also, if the valves were checked often, do you have a list of what the checks and swaps were? Do you know what's in there now? What if they used the wrong chart or wrong book? There are some out there that have the incorrect measurements------

Are you sure the valves are burned, or are you just guessing at that? I'd be highly surprised if you need a top end job........

dave fox

 

I think you will have to check things by yourself, instead of assuming that everything was done right.

 

The professional who did the carburetors, is actually the PO (second) owner. The person I bought it from. He has over 30 years experience, more recently running service departments, but when he did wrench it was on XJs. Thats actually why he purchased the bike initially. He wanted his old long gone XJ back, but long hours at the shop and on the homefront got it pushed to the back of the garage to be enjoyed visually. He recently decided that it was too nice of a bike to be hidden, and sold it to me for a penance. When the carbs were cleaned, they were zestfully cleaned, including a nice soak in the ultrasonic.

What I don't have, is what the valves were at/adjusted to. I havent checked them, as the last time they were adjusted was many moons, but only a few miles. They were also making normal tapping sounds. Ive been on various bikes over the years, and I know what sloppy, tight, and normal valves usually sound like. Going by the paperwork, and what I know, Id up to this point had no reason to assume valve clearance was out of spec.

The reason I believe the valves to be burned, is how it came to an end. It was abrupt, and the whole ordeal happened over less than 2 miles. Ive never seen valves burn that fast in a normally aspirated engine, but I dont know what extent the lean condition was. If the YICS works how I have read, if one or two carbs ran dry then it would by default cause the whole system to run dangerously lean, as the other carbs would then be forced to feed fuel to all 4 cylinders. It now cranks over WAY too fast and wont start, like a no compression condition. Yes, I am guessing, but it's an educated guess. Its still dark outside, Im still beat from pushing the bike for 2 miles, and all I did so far was pull the plug from cylinder #4. Its a bit too clean for my liking, and should show more soot and discoloration.

 

It would be interesting to actually see what your spark plugs look like, and a compression test would give us crucial information. Easy stuff first!

 

This said, I had a very bad experience with an experimented and skilled bike mechanic who forgot to put back one small washer and one small bolt in my Maxim-X engine after a valve job. I'v had all kinds of problems with the bike overheating on a random basis. When I was frustrated enough, I removed the clutch-water-pump cover and discovered that the missing pieces were intended to keep a metal gear in contact with the water pump plastic gear. Bought these bits, put them back in and the problem was gone. I was lucky enough the bike didn't overheat to death.

Different problem than yours, but this story is to show you that even professionnals make mistakes too.

 

I've known several professional mechanics; most with their own shops. The mechanic's bike is the last one to get worked on, and the first one to have parts stolen off of it to fix customer's bikes.

 

I repair cars, so I can attest that this holds true at every turn.

Ill pull plugs, and hopefully remember to bring home the compression gauge tomorrow. My fingers are crossed. I WANT the valves to just be out of adjustment, but I am afraid this isnt going to be the case. All of the stuff going wrong with this bike, not all of it age and maintenance related, is really giving me the vibe that it WANTS to stay parked. As I said, I believe motorcycles to have a character and personality to them, and this one has made it this far and in this good of condition by being parked. The original owner kept it parked for 25 years, the second owner never even rode it, and now its telling me to park it as well. Many would argue that it's a machine and doesnt think for itself, but there are a million variables involved, right on down to if it came off the assembly line on a Monday morning or a Friday afternoon.

 

A good-used head will run much less than having yours rebuilt if it turns out that the valves are toasted.

 

You should see my turdwagon I drive. I waited until one of the front hub bearings was so bad, the noise was deafening. One of my struts is physically broken, has been broken for over a year, and I fully intend to fix it sooner or later. Probably later.

 

If needed, Ill be purchasing a good used head and rebuilding it myself, regardless of where or who it comes from. Even a head with chacals blessing will be rebuilt. Pulling carbs out to do something that should have been done the first time is a pain, but its doable. Pulling a head off an engine is on a level far greater. Unless its some NOS head found on a shelf somewhere fully assembled, its getting overhauled.

We will see, however. In the perfect world we all live in, the exhaust valves on all 4 cylinders have just become tight and are holding open just enough to not let the engine fire.

 

I got a smell right before my XJ died. It was a metallic smell. My eyesight is bad so my nose is hightened. I smelled my exhaust valves going out the exhaust. It was misfiring and whatnot. Right before I pulled into that front yard on the road I was on, I smelled metal in the air. It was sick-sweet.

 

I think you got that back to front, it's not that the bike doesn't want to be ridden, bikes, like most machines, are better for being used, than left for years.

 

Wow.

All sorts of conclusions are being jumped to here, and not a whole lot of diagnosis taking place. DIAGNOSE, don't guess.

You can't shortcut the process of resurrecting one of theses bikes; and don't assume (yet anyway) that you've damaged it trying.

Forget the compression test until you check the valve clearances yourself. Tight valves will cause inconsistent results and cause more conclusion-jumping.

Check the valve clearances. Fix any that are out of spec. If you discover any that are WAY TOO wide, then that can indicate a stuck valve or hunk of carbon on a valve seat.

Once the valves are in spec, do your compression tests. Tests plural, yes. Do a couple of "dry" tests, and then based on the results you may want to do a couple of "wet" tests.

But get the valves in spec first and quit trying to run the motor until you know what you're dealing with.

 

That would be a great premise for an Independent Film. . . .

An XJ750 SECA owned by a gently caring soul, meticuosly cared for until the owner passes away mysteriously.
The bike then changes owners, perhaps stolen by a greedy neighbor. Or begrudgingly taken off the property by some slacker nephew, who then procedes to painfully neglect and abuse the fine machine.
This then brings out the dark side of the XJ and she grows surly and stubborn - eventually causing the demise of the 2nd 'owner' . . . .

Then she sits in the dark and sits and sits; brooding in quite desperation of longing for a life that once was so vivid and robust!
Finally someone finds her!
She still holds on to her mistrust that was conditioned into her from the previous owner.
After frustration yet persistence of the new owner, she finally recognizes a 'like-mindness' in the new owner that starts to re-kindle her deeply hidden memories of her first owner - and suddenly she roars back to life, spry and agile in corners, snappy to throttle responses . . .. my god! it looks like she is smiling as she tears down the curvy mountain road into the sunset . . . . . . . . . .

 

BF,
I agree the valve clearances need to be checked, but why disregard a compression check before checking the valves? A compression check is relatively quick and not difficult. The info gathered could be enlightening when combined with that garnered from the valve check.
John

 

That's exactly what I think, too.

 

Ill have compression check results, photos of the plugs, and hopefully valve clearance specs tomorrow. I dont have a garage, but it is supposed to be a spectacular day so Im not afraid to open the engine up in front of the house tomorrow just to see whats going on.

 

A valve that is far enough out of spec will open all of the time, and the cylinder will blow low, or no, compression. Even being just a little out of spec can cause the valves to close late, and blow low compression.

 

Again, I agree that too tight valves will cause low to no compression but doing a non-invasive, easy test first seems a better idea. Even when the valves also have to be checked. Just trying to get the thinking behind not doing the compression test. And if one listens carefully when spinning the engine over the always open valve should be able to be heard blowing by, it surely will sound differently. If the valves were that far tight to have lost compression would it have run so well initially?

 

Now, my understanding of what k-moe and fitz said is that doing a compression test first would be simply a waste of time. Checking and adjusting valve clearance and then testing the compression will be more efficient than testing the compression before and after.

 

this is why somebody invented leak-down testers. it tests the ability of the cylinder to hold compression and if it doesn't, it's easy to hear where the problem is.
but it doesn't make it any easier to fix

 

The valves are a regular maintainance item. They'll have to be adjusted no matter what. In my experience, valves are the second most common cause for poor running (after gummed up carbs), because the vast majority of owners never bother to do anything with them (this is true across all makes of motorcycles).

 

Whatever you do, don't feed it belladonna...

The Mangler

 

Hard to say. I have been asked to not touch anything until the bike can be brought to my expert, who setup the carbs, as it is possible that more than maladjusted valves could be at fault. As an auto technician, I can appreciate someone with far more experience than I asking me to stand down until he can get a good look. I trust his judgement more than I do mine. I can wait until spring to get the bike back on the road. I love this bike, enough to have me walk it home several miles in the dark, to the point the battery finally went dead as I made the final push across the road to the house. My favorite colors are black and burnt orange, and thats exactly what the 81 XJ is painted as.

So, this thread here, it might die. We have to prepare his garage for this winter project. We have to move some stuff out and prepare a suitable spot for my XJ, and get into it proper. If I dont update this thread, Ill make a new one. Maybe Ill have some nice machine porn of bent valves, and crazyness. Or maybe not. We will see.

 

Whoa, wait a minute.
Do NOT sell yourself short. The items that need attention and are being recommended are not that difficult especially for an auto technician.
You do NOT need an "expert" - that expert is YOU! (With some conditioning of course).

There are wizards here who know more about these bikes than the original Japanese Engineers that designed them. These people are here to help and to keep you from digging a hole. No one, not even your 'expert' will pay attention to detail as closely as you will.

When I got my XJ all I pretty much knew mechanically was "righty tighty; lefty loosey".
Some of the maintenance tasks may sound daunting, but going at things slowly and having meticulous attention to detail (take digital pics, lots of notes, keep work area organized, ask questions here) and you will find that you can become your own expert.

Honestly, I did my carbs this spring, shaking with fear and intimidation . . . . I practiced what I preached above and when I put the rack on and the bike ACTUALLY STARTED! I was overjoyed, proud, and giddy like a schoolgirl.
If I can do this stuff anyone can.

 

Well, Ill be there the entire time. I'm not dropping it off at the shop and picking it up when it's done, just taking advantage of a valuable resource (and an actual garage, something I don't currently have myself.)

 

I did check my valve clearances this spring and found it is an easy job, compared to anything related to my old Goldwing water pump...

 

Once it's running well you should name the bike Bob.

 

Why Bob?

 

Because it's a silent bike......

 

I am resurrecting this thread.

Todays compression check resulted in 165 PSI on 1, 175 on 2, and 180pst on 3 and 4. So I am going to adjust the valves and sinc the carbs.

 

Pretty good readings, let's see if you find tight valves on cyl #1.

 

Good to read you are back with it and there appears to not be any significant engine damage.

Compression spec for the XJ750 is 156 PSI with a maximum deviation of 14 PSI per the FSM. It will be interesting to see what the numbers are after the valve adjustment.

I just re-read through the post and there doesn't seem to be much mentioned on why #4 carb bowl was dry. You mentioned you had to tap #4 with a hammer, as if the float valve was stuck in the closed position. Sticking float valves in the shut position I would think is a rare occurrence, especially since new float valves were just installed. Maybe some more experienced members can weigh in on this as the fuel starvation issue seemed to be the root of the problem.

Since #4 carb is last in line to receive fuel perhaps there is a fuel flow issue and a couple of thoughts:

Petcock not working properly
Restrictive fuel filter installed
Vapor lock in tank caused by cap vent not functioning

 

Thats what I am getting at now. After the float on #4 was unstuck, it ran fine. I rode it about 5 miles, and it was fine, then suddenly misfire everywhere and I was left stranded and pushed it several miles home in the dark.

My hypothesis is that once the bike is at temp, the valves tighten up (as they should) and that meets carb imbalance (as it should) and it becomes a muddled mess that wont run.

So, I am looking at Sunday to be the day I can pull the valve cover and check lash. I am also suspect that I will find a tight exhaust valve on #1 or #2. Of course, Ill need to get the valves in spec before syncing the carbs. They have to be out of sync... Ive only had them out like 3 times now without syncing them.

 

This is pretty much a motorcycle version of Wangan Midnight. Likely more interesting too.