Real bad news for my xj help!

Okay I am not a happy camper

I finally had my bike running perfect this summer after 2 years of work and lots of money.

I now have almost no compression in the two left cylinders.

This is what happened I ran low on gas at a friends house so he gave me some gas about a gallon. As I was filling the tank his father said that gas came out of a junked car that was sitting for years! So I stopped at that point and went to the nearest gas station and filled it with 93 oct and then road the 13 miles home. It ran good until I parked it. I let it sit for 3 days.
When I went to start it it just turned one time and came to a abrupt stop with a chuck noise. I then tried it again and it went 3 revs and did the same thing. I tried it again and it started to backfire like the plug wires where crossed.
It would start with the throttle open and run above 4k but not sounding good. It would not idle and stalled. I pulled the tank and carbs cleaned everything and put it back together. It ran a bit better but still real bad. So I got new plugs and that did not help. I then checked the compression
by pulling the plugs and putting my finger on the hole and and the two left cyl where not doing much of anything. The right side blew my finger off. I checked the comp in the spring and had 150 in all cyl. Now I just don't know what to think? Did the valves stick and get bent? Did I some how blow the head gasket?
What should I do now? I have about 2k into this bike and I do like it but when do you say uncle?

Just depressed about it!

I am just going to get dunk tonight!

 

I would start by draining the tank and also draining the carbs. Add fresh gas and give it a try. Old gas may have had a lot of water in it which is causing the rough running. Don't know if that could have anything to do with the compression issue, but I'm sure some of the really knowledgeable folks will be able to give you a lot of information and suggestions.

 

No Compression on adjacent Cylinders is a common symptom of a Blown Gasket.

Check the Oil.
Look for evidence of a blown gasket around the Head.

Stop-by AutoZone and see if they have a LEAK DOWN Tester to Loan-out.
Do a Leak-down Test.

A leak down or "cylinder leakage" test is similar to a compression test in that it tells you how well your engine's cylinders are sealing. But instead of measuring pressure, it measures pressure loss.

A leak down test requires the removal of all the spark plugs. The crankshaft is then turned so that each piston is at top dead center (both valves closed) when each cylinder is tested. Most people start with cylinder number one and follow the engine's firing order.

A threaded coupling attached to a leakage gauge is screwed into a spark plug hole. Compressed air (80 to 90 psi) is then fed into the cylinder.

An engine in great condition should generally show only 5 to 10% leakage. An engine that's still in pretty good condition may show up to 20% leakage. But more than 30% leakage indicates trouble.

The neat thing about a leakage test (as opposed to a compression test) is that it's faster and easier to figure out where the pressure is going. If you hear air coming out of the tailpipe, it indicates a leaky exhaust valve. Air coming out of the throttle body or carburetor would point to a leaky intake valve. Air coming out of the breather vent or PCV valve fitting would tell you the rings and/or cylinders are worn.

A leakage test can also be used in conjunction with a compression test to diagnose other kinds of problems.

A cylinder that has poor compression, but minimal leakage, usually has a valvetrain problem such as a worn cam lobe, broken valve spring, collapsed lifter, bent push rod, etc.

If all the cylinders have low compression, but show minimal leakage, the most likely cause is incorrect valve timing. The timing belt or chain may be off a notch or two.

If compression is good and leakage is minimal, but a cylinder is misfiring or shows up weak in a power balance test, it indicates a fuel delivery (bad injector) or ignition problem (fouled spark plug or bad plug wire).

 

never heard of a leak down test thanks - but sounds like a perfect idea - water or dirt in the old gas has entered the cylinders - this may sound nuts but did you notice any different kind of visable smoke ( steam ) coming out the pipes when it started running bad ? water in gas turns to stream in the cyclinder under the heat - on a car white foam sticks to the underside of the oil filler cap when water enters the oil - probably doesn't apply here but at this point just trying to help - needless to say removing the top end of engine for inspection is probably a wise things to do - if it seizes your 2K goes up in smoke - good luck

 

Yes I did this already I thought it was just bad gas with water.

I was wrong somehow it ended up with 2 bad cylinders that were good when I parked it in a locked shed. I think the valves stuck from the varnish like gas and hit the pistons and now don't seal. But then again the head gasket blown between the cylinders makes more sense. I will try the leak down test and see if its the valves.
If it's the head gasket then the it should leak into the other cylinder and out the open valve.

What ever it is it will be a major project and cost between $200 just the gaskets and $2000 rebuild the engine. Not to mention many hours of work.

 

Thanks I will try that!

 

Gatta agree with Rick on this. Bent, or stuck valves on two adjacent cyinders at the same time is not likely. A quick check of the valve clearances can verify this.

The bike is still running. So a broken crank can be eliminated also. Ignition pickup on the left side of the crank.

That leaves either a broken cam, or blown gasket, as the suspects. The cam can be easily checked when you check the valve clearances. An equal, but low compression, or high leak down on both cylinders would indicate a blown gasket.

Ghost

 

Gatta agree with Rick on this. Bent, or stuck valves on two adjacent cyinders at the same time is not likely. A quick check of the valve clearances can verify this.

The bike is still running. So a broken crank can be eliminated also. Ignition pickup on the left side of the crank.

That leaves either a broken cam, or blown gasket, as the suspects. The cam can be easily checked when you check the valve clearances. An equal, but low compression, or high leak down on both cylinders would indicate a blown gasket.

Ghost[/quote

I forgot to mention that I looked into the cylinders while turning it over
the valves are moving and the pistons as well. It was making a medal scraping noise while running at about 4k but not with the plugs out just turning it over.

I agree it is probably the head gasket that blew into one of the cylinders and it was scraping along the wall.

Now to find a cheap but good head gasket and go from there.
Or maybe just pull the head first and make sure that is all it needs.

What is involved in getting the timing chain off?
I never had to do that before on any of my bikes.

Thanks for your help everyone

 

Leak down is a good test. Dry/Wet compression test with a gauge also good idea. Changing out gas and 'giving it a try' NOT A GOOD IDEA. Running poorly, especially not idling but able to rev (and sound like &%#$), and showing low compression, are all signs that something is critically wrong.

Considering the way it went down, the bad gas and running fine until it was parked, I seriously doubt you have a mechanical issue with a valve, burnt perhaps but that still shouldn't cause your symptoms. Blown head gasket seems unlikely, but Rick is right that when two adjacent are low and approx the same low reading-that can be the cause. Nobody has mentioned it but you might have stuck or broken rings. Your running symptoms only indicate a lack of proper compression, many causes for this for sure but how did the head gasket blow after you stopped, how did a valve get bent after you stopped, etc. If the gas was really rusty and contained H2O it might have locked your rings in tight and if you parked on the side stand it might be worse on two out of four.

Do the leakdown first if you can, and if you do the compression test don't worry about cycling through a bunch of revolutions as broken rings would only score your piston bores more. But start there and then tell us what you find. Wouldn't hurt to put some Kroil or Liq Wrench through plug holes as insurance. Good luck.

...Friends don't let friends drive on bad gas..!

 

Start with a REAL compression test; check the valve clearances, and go from there.

A valve or two with uber-wide clearances would indicate stuck valves; valve clearances OK but no compression in two adjacent cylinders would point to a head gasket, for sure.

The timing chain stays behind. The cams get removed and slid out from under it, and the head gets lifted off with the chain still in place.

You're going to need a SERVICE MANUAL if you're going to pull the head.

 

Wonder if the chain guide didn't break. Metal scraping sound a 4 K rpm? Pull the valve cover and see how loose the chain is when you are looking at valve clearances.

 

If you go for the leakdown test be careful to keep your self away from anything that spins and take the wrench off of the crank. If it gets off of tdc that piston goes down with great force and spins the crank hard enough to smash
fingers or put a wrench in orbit. I leave 2 plugs in to slow it down should it start to rotate
You don't need 80 lbs to find a leak 20 should do.

 

Update

The kid that told me to use that gas came over ridding his bike with 2 other bikes. He brought me a compression tester and there is NO COMPRESSION
in the two left cylinders and 150 on the two right like the last time I checked it this spring. Seems to suck more then anything. I first did the test with both plugs out and then with one in and no difference.

????????????????????????

 

Looks like remove the head and see what happened.

MN

PS By the way I have an 1100 engine that I need to part out. If you need a head or pistons let me know.

 

Yeah I pulled the insurance today and put it on my xs750 triple.
It needs some work but minor in comparison. I just cant deal with the XJ at this time. I will put in storage for the winter and in the spring I will sell the 750 and take some of that money and use it to fix the XJ. Who knows I might just pull the engine and rebuild it and do the 2nd gear fix at the same time.

Thanks for the offer on the parts anyway.


Thanks for all your help guys and I will pick you brains in the spring or summer.

Take care.

 

Your first move should be acquiring a Workshop Manual.

You have both Diagnostic and Service work to perform.

Be realistic.

Rather than throwing a great deal of money into Parts and rehabbing an old Plant, ...

You might be better-off finding a used Running-Engine and just doing a transplant.

 

Can I use a XS special 1100 engine?

 

That would be a good question for the guys over on the XS11 site

 

I've never heard of an XS Plant replacing an XJ Plant.
I doubt it would fit.

 

That's a rare transplant. Chacal has a page somewhere going over all possible transplant options. I think that's the one where he says 'put the wrench down and s-l-o-w-l-y step away from the bike. There is no documentation of a transplant of this type, and anything you try will be experimental and likely require modifications to the frame and mount mechanisms', or something.

But good luck!

 

I cant see why It would not just bolt right in and work

The engine case part number is the same as the XJ and that is where it bolts to the frame. The rest off the parts seem to be the same as the XJ except the head has the YICS but that should not make any issue with a swap. I think the electronics are different but the engine is from a 1982 XS 1100 special and should have the pickup cdi system.
Can anyone tell me why it would not work?
The drive seems the same as well.

Anyone know about this?

 

XS11.com should have all the answers you need. I think it has gone the other way. XJ on a XS frame. Depending on what year the carbs are jetted slightly different.Good luck on your transplant

MN