Compression test reults

I just did a compression test and I got me a bad to semi bad engine

#1 135
#2 30 dry, 240 wet
#3 30 dry, 240 wet
#4 135

I have the bike and I've always liked these so I'm gonna go for it and rebuild it, I wanted to find something to work on and I do believe that I've found it.

What I want to know is if y'all think its a ring problem and not something else.

Thanks

 

2 low readings in the center holes? - bad head gasket is my opinion

 

I agree; but now there's only one "next step." (Pull the head.)

Be sure to take pics.

 

didn't check the wet test on outer two cyliners?

 

Did you check valve clearance yet? How much oil did you put in there 240 is way off the chart too much oil can bend a connecting rod, lock up the motor or blow out a gasket? Try again with a different gage before you do anything else just to be sure

 

I only did a wet test on the two cylinders that were off spec, should I do the other two as well?

The valve specs are:
EX IN
#1 0.127 (.005) 0.076 (.003)
#2 0.229 (.009) 0.229 (.009)
#3 0.279 (.011) 0.152 (.006)
#4 0.152 (.006) 0.127 (.005)

I put appx a tablespoon of oil in each cylinder, I didn't think it was all that much just a quick shot down the funnel.

Do you mean another compression gauge?

 

Sorry the columns looked pretty before I posted.
Probably don't need to say this but, 1st column in exhaust, 2nd column in intake.

 

Massimo if you have a manual read up on doing the compression test on the XJ. The compression readings in the XJ manual are for an engine that has been warmed up 2-3 minutes not stone cold. When doing the wet test it says to put in a few drops of oil regardless it needs to be a measured amount for comparison sake. I would try another gage just to make sure before spending a lot of time and money. You do have some valves out of spec but some of the gaps are bigger than they should be they actually get smaller as they wear so someone has been in there already. Another thing you can do if you have access to it is to hook up an air compressor to the bad cylinders and see where your leak is that way when you tear it down you know what to look at

 

Those valve clearances NEED to be attended to. They're all over the place.

 

This bike was a rescue from the back of a garage, as far as I can tell it was back the appx 10 yrs or so, so it hasn't been ridden (or even thought of being ridden), just trying to breath life back into it. The valves were already on the list, already had the carbs off, just about started those until I saw Ricks post about compression test and Thought I should check that first, since if that's screwed it doesn't matter what else I do until that's fixed.

 

The results of the Compression Test show you that you have got a problem with the 2 and 3 Hole.
Since they both "Pumped-up" superbly during the "Wet Test", ... We have a good idea that the troubles are going to be related to Piston Rings or Cylinder Wall issues, ... (possibly both).

If you want to investigate --> further, ... you can Fabricate a "Blow-by Tool" and do some more testing.

You need a Tank of Compresses Air
A Spark Plug
Rubber Valve Stem

Break-up the Ceramic Insert of the Spark Plug and "Gut-the-Plug"
Your left with ONLY the Hexagonal Metal Section ==> Empty.
Chuck the Valve Stem in your Drill.
Sand it down until it FITS inside the Spark Plug Hex Base.

Epoxy the Valve Stem into the Spark Plug Base
(Stick a Soda Straw in the Valve Stem so the Epoxy doesn't plug-up the Air Hole.)
When the Epoxy cures, ... Clip the Straw and you have your Tool.

Adjust the Crank to position the Stroke to where the Valves are CLOSED on the Cylinder you are Testing.
Insert the Tool in the Spark Plug Hole.
Hit it with some Air.
Look for, ... and Listen for Leaking Air.

Listen for Air leaking past the Rings.
Listen to the Crankcase by listening at the Oil Filler Cap Hole.
Look for and LISTEN for Leaks.

 

Break-up the Ceramic Insert of the Spark Plug and "Gut-the-Plug"<quote>

Don't underestimate how hard that is to do........

 

Yeah no kidding.

Before you freak out too bad about the motor; get the valves in spec and re-test. That being said, something other than valves is likely going on with cylinders #2 and #3; quite possibly a head gasket failure at the camchain tunnel area.

 

Alright, so I found an adapter, made a leak checker and it seems that I hear air when I listen at the oil inlet hole when it is on cylinder TWO. When it is on cylinder THREE it more subjective, it doesn't really sound like it is coming from the oil inlet as much as it seem to be coming from the cam chain area. I guess its time to pull the cylinder head and see whats going on, will take pictures and post them sometime tomorrow. Wish me luck.

 

Right after I posted the last update I saw Fitz's previous post, should I fix the shims first or at this point am I better off pulling the cylinder head and fixing the shims on the rebuild?

 

Your valve clearances are so wonky I'd get them in spec and re-test, just to have a better set of "before" resadings. However, as I said earlier, there is still something not right in that motor other than the valves.

 

bigfitz knows his stuff. two heavie hitters have re'd to this topic....it's my thought that you do exactly what they mentioned. I'm betting your numbers come up a bit when the valves r in spec, but there is somethig amiss in the two and three hole

 

Okay. so I got my bucket tool this week (Thanks Chacal!) and before I did anything I decided to check the valve clearances one more time, trying to be as precise in the lobe placement as possible. My clearances came up a bit different than the first time I checked them, I'm hoping that they're different due to the fact that I was trying to be as precise as possible (w/o driving myself batty) and not because I'm an idiot. But here is what I came up with on round two measurements:

EX:--------------IN:
1 .004 (.102)- -.004 (.102)
2 .006 (.152)- -.006 (.152)
3 .007 (.178)- -.005 (.127)
4 .005 (.127)- -.005 (.127)

First Round Was:

EX:---------------- -IN:
#1 .005(.127)- - .003(.076)
#2 .009(.229)- - .009(.229)
#3 .011(.279)- - .006(.152)
#4 .006(.152)- - .005(.127)

With the notable differences in the #2 & 3 cylinders, but I think these are better numbers in that I tried to get the cams spot on today, where I was going with close enough last time.

In looking at the number I believe that #1, 2, 4 EX and #1, 2, 4 IN need to be re-shimmed? Although 2 and 4 IN are very close and on the loose side rather than being tight, so I'm guessing they will tighten up naturally as the bike is ridden more.

Any thoughts?

 

My first thought would be to get a metric feeler gauge; it makes this so much easier. KD Tools' 2274: http://www.wescotools.com/p-10604-kd-22 ... gauge.aspx is widely available, some Sears even.

That being said, I would let intakes 2, 3 and 4 alone for now and recheck with a metric gauge; re-shim #1 intake and exhausts 1, 2, and 4.

 

Fitz, as always thank you for your advice, it is much appreciated.
The second measurement was with a newly purchased metric feeler gauge. Sorry, I should have noted that.

 

If that bike sat for 10 years, there is the possibility of the valves having stems that are cruded up and keeping them from closing all the way and with a teaspoon of oil they would build pressure because they would be sealed by the oil.
The valve gasket is a possibility too!
but DON"T shim the valves until you find out that they are seating all the way. I had this problem on my bike as it had sat for 10 years before I got it too.

 

This may sound dumb, but how do I know if the valves are seating all the way, will I have to pull the cylinder head to find out? Or does the oil test tell you that ?

 

The results of your "Wet Test" pretty much fill-in the blanks on what you are dealing with.

Dry --> 30 / Wet --> +200

It's NOT the Head Gasket.
It's NOT Valve related.

It IS related to Gasses passing-by the Rings.

On a Rip Van Winkle job, ... where the Bike didn't budge an inch for a decade, ... I venture to say the Engine's two center Cylinders got situated where the Valves were open and both Cylinders subject to environmental changes resulting in a severe oxidation and pitting.

Possibly cracked Rings.

The Valves have to Close to allow the Compression to rise.
The Oil seals whatever problem lurks in the 2/3 Holes.

The Silver Lining on the dark cloud hovering over that Plant is:

The thing turned-over.
You might have had to deal with a seizure.
You don't.

 

The other thing I didn't mention is that you may have a couple of rings that are stuck in the piston ring groves which doesn't always mean the rings are worn out, but like Rick said, the elements may have cruded them and they got stuck.
At any case, you will find yourself having to pull the head to at least check the valves. If the center 2 valves were stuck in an open position then the rings very well may be stuck or the valves might not be going all the way shut but just a hair open like mine were. So it could be a couple of things but it looks like you will have to open her up..... sorry!

If you pull the head, then you might as well pull the cylinder and clean the pistons and ring groves and check the rings.

 

Yeah not knowing much about about one of thiese bikes myself, i did a compression test on my 650 motor while it was on the floor just to see what i'd come up with, and it showed about 90psi cross the board. But my motor got knocked over and i lost a cam sprocket in the deal.

The worlds not coming to an end because you might have to crack the motor open, besides its half the fun when you know somthing about the inside of a motor, and you can feel your way threw the process of $75 pistons, and $140 set of rings, plus the cost for a new set of stretch bolts and heat sheath that need to be shrunk onto each head bolt before you put it all back together, besides you might get lucky and get threw this for under $500 to $600 :roll:

 

I hope those cost estimates are off. We are dealing with the same thing. Our compression test came out 85 on the outside cylinders. 35 on number two and almost undetectable on 3. We did it on a cold engine . Throw in a sticking intake valve on 3.

If it cost that much, I will take it to the junk yard.

 

gman.
If it cost that much. Let me know. I will come pick it up!!

Ghost

 

Okay, so I have the cams out, the timing chain tied off, notes and pictures for reassembly and cam position. But tonight when I started to remove the shim buckets and shims I noticed that all four of the shim on the exhaust side were upside down, two of the numbers were worn off and two were barely visible. Since I was going to have to measure the two shims anyway, my OCD self measured all 8. I noticed that all the values were different from what was printed on the shim. Which numbers should I use?

shims : printed value

EX--------IN
1 280-----280
2 ???------285
3 270-----290
4 ???------280

Measured value:

EX---------IN
1 265------260
2 265------260
3 255------290
4 260------260

Thanks for any and all input/thoughts on this.....

 

I am not sure why the measurements and the indicated measurements don't match up on the shims.....ANYONE ELSE GOT AN IDEA!?

 

If the instrument you used to measure the Shims is a quality tool, its accuracy determined by a correct reading of the test pieces, and you are well versed in using it for accurately taking measurements, ... no brainer.

Go with your measurements.
Make the calculations for new shims.
Use the Chart and select the values indicated.

Use caution.

After you insert the new shims; jack-over the Plant by hand.
Slowly move the Crank through four complete revolutions.
Check TDC.
Measure the Clearances on all the Valves.

Be sure the Valves are in Specs before firing it up.

 

Thanks Rick!

Pictures:
http://www1.snapfish.com/snapfish/thumb ... =snapfish/

Okay now to the good, the bad & the ugly

The good:

Valves, pistons, cylinders for 1&4
Overall condition of all the cylinders, all four felt smooth, except 2, which has about an inch or so of crud build up at the top (Ricks theory is falling into place)

The chain looks like it is in good shape

The head and exhaust came off without huge dilemma

The ugly:

#2 piston looks bad, at least the crown and #3 is probably questionable
#2 valves look bad, not sure how bad yet
#3 valves are in question as well
Cylinder head gasket looked to be in good shape, but still an oil leak on the front of the engine.

The bad:

Maybe not sssooo bad after all, but that is always subject to change... 8O

 

Thanks Rick, all I could think is that maybe the mic was off or he didn't know how to use one!?
No offence meant to Massimo but just wanted some other input.

 

I'm not sure if the picture link is working, if not let me know and I'll figure something else out.

 

I didnt want to join snap fish cause of all the e\junk e-mail they send.
So it wont let me see the pics

 

I'll move the picture to fish bucket later tonight. At work and don't have the pictures with me.

 

I set up an album on photo bucket as well, this link should get you there.

Hvnbnd, no offense taken at all.

http://s1224.photobucket.com/albums/ee375/Massimo33/

 

I see you're in Denver. If you want to bring parts down to the Springs on Saturday, we could try cleaning them up with my soda blaster.

Let me know.

Paul

 

SQL, thanks for the offer, but I can't this weekend, I'm working all day Saturday. perhaps a raincheck?

 

Sure. Sunday afternoon might be a possibility too. Let me know.

 

Massimo,
Looking at the rust in those middle cylinders (2&3) I'd say that you no doubt have some rust on those valve stems that might be keeping them from closing and sealing off all the way.
I'd take SQL up on his offer. Those cylinders really do need to be cleaned up! and the valves probably need to be pulled and checked.
I usually let a machinist do valve work for me.... but if youre really good at it you might try yourself.
At any rate the rust in those 2 cylinders says that moisture got into those holes and that would be my 1st best guess for not being able to build compression.
Good thing you opened her up.

 

SQL, I don't think I will be able to make it down this weekend, thank you for your offer, but family obligations are gonna take up Sunday.

 

So I got the head off and the jugs off. Thanks SQL for the offer to help clean them up, but I decide to send them both to a shop. The heads to have the valves checked over, and the jugs to check for correct dimensions and to hone out the corrosion.

Piston 2 had the rings totally stuck in the grooves, which is what I am guessing caused the 30 psi in cylinder 2, but Piston 3s rings were gritty, but not stuck, so not sure why it only had 30 psi as well. Piston 1 and 4 looked good and the rings seemed fine on both of them, but if I have to do one set, may as well do them all.

I did not notice any signs of a head gasket leak or a base gasket leak. I hope I just missed the sign of the leak and the compression will rise when reassembled. I'm going to have the head checked for warping by the machinist

Here is a link for the piston pictures, if interested...

http://i1224.photobucket.com/albums/ee3 ... C00670.jpg

 

I wonder if the valves will be the reason for the low compression in #3? But best to know that the jugs are in good shape as well.

 

I would bet that the valve is the reason.
You shouldn't have to replace the rings unless you break one...
Just clean out the piston ring grooves with a ring groove cleaner tool.
Clean the rings up and lube them well also be sure to clean the ridge off the top of the jugs.
I wouldn't hone the cylinders unless I was going to replace the rings.
If using the old rings, just use some light emry paper to rough up the cylinders a bit... but just a little.
Looks like your going to be riding soon!!!!
Also, I'd get a shop to work over the valves too.

 

Sorry, bad link earlier, this one should be for the album

http://s1224.photobucket.com/albums/ee375/Massimo33/

I am wondering if I should be worried about one of the head bolts, the heat sheathing is split at the top and some corrosion is present, any advice? There is a picture of it in the gallery link.

 

Sorry, I didn't see which one you were talking about.
Which pic was it?

 

It's the one that says split sheathing, bottom of first page, cylinder holes have red rags in them.

 

Those studs are in good order.

 

That was what I thought which is why I asked, just incase I was not getting it.

 

Cool, I just saw the splitting on one of the sheathes and some corrosion on the front bolt between 3&4 and just wanted to make sure that it was still good and not a cause of great concern.