compression test question

I have been seeking an 82 xj1100 as a touring bike for about a year here in Santa fe without
success. I love xjs having rebuilt two 82 650 maxims and an 82 650 seka in the same length of time.
I located an 83 Kawasaki 1100 shaft drive (dusty, dirty, two bald flats )in a shed near here.
It seemed remarkably similar to an xj 1100.
Here's my question. I tested the compression of all four cylinders . the ratio is 1x8.9. The psi here
at 7,000 feet is 11.33 psi. I got #1=100 lbs,#2=97 lbs,#3=95 lbs,#4=100 lbs. That seemed pretty good.
But, when I checked again with a squirt of oil in each plug hole I got #1=120 lbs,#2=100 lbs( no change)
#3=120 lbs,#4=150 lbs. Does the lack of pressure increase on cylinder #2 indicate a problem ?
Please indulge my heresy in asking a question about a non Yamaha.

 

Just wanted to say hello. I'm in Hatch NM. Just finished restoring my 82 maxim 750. Love it!

 

Come on up for the "Motorado" vintage bike show at the Eldorado subdivision
retail center outside Santa Fe on 6/19. It's a pre 1982 old bike show and competition.
I'm entering a frame up restored 82 maxim and a custom 81 maxim fake army bike.

 

That sounds like a blast! Unfortunately that is right in the middle of onion harvest here and I will be working ( like 80+ hrs a week). I didn't make my bike real pretty yet. I just concentrated on mechanical correctness and reliability. Maybe next winter I will do cosmetics

 

form info over load
h) If the readings are below spec, then shoot about a teaspoon amount of motor oil into each cylinder, crank the engine over a few revolutions with the starter (to spread the oil around), and then re-test each cylinder using the above procedure.

i) now re-install the spark plugs, let the engine warm up to operating temp.

j) re-test as above (plugs out and grounded, throttle wide open, etc.

k) compare the two results and analyze.

more info on how to analyze here
http://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

 

I was testing a non running bike to see if it as worth buying or not.I did most of what "XJ550H" suggested.
First question was at ratio 1 to 8.9 at 11.33 psi at 7,000 altitude cylinders tested, 100,95,97 and 100. Does this seem OK ?
second was with oil squirted in each cylinder they tested 150,120,100(no change) and 120 I expected them all to increase
with the oil # 2 stayed the same. Could this be a problem ?

 

Oh, by the way. Even though it was a non runner I was able to spin the motor by jumping the dead battery off my truck.

 

could be stuck rings on that one cylinder.

 

could a piston with a stuck ring give you the compression that you are looking for and then not increase with the added
motor oil on the second reading ?

 

thats exactly what im saying

 

could also be a bad valve
adding oil to the test is to eliminate rings as the issue

 

- 7000' above seal level, multiply your readings by 1.233 to get a "true" compression reading.
I got #1=100 lbs,#2=97 lbs,#3=95 lbs,#4=100 lbs.

#1 =123.3 #2=119 #3 =117 #4= 123.3 with a 6 pound spread. can you tell us what the spec is for the bike you are looking at.



In order to further analyze a low-compression condition, you should squirt a small amount of engine oil into the suspect cylinders (about a teaspoon), crank the engine over for a few revolutions to spread the oil about, and then re-test those cylinders.

g) if the compression pressures RISE by a large amount after the infusion of oil, then this typically means that the pistons, piston rings, or cylinder walls are damaged or worn in some way(s). However, be aware that if you introduced a significant amount of oil into a cylinder (1 teaspoon or more) when conducting this test, a small rise in pressure may occur, and it may instead mean that your valves are the problem, since the introduction of that much oil in a small cylinder will naturally cause the compression to rise.

h) if the compression pressures do NOT rise after the infusion of oil, then this typically means that the valve seats or faces are worn, or a valve is hanging up within its guide, or your valve clearances are way too small.

i) if two adjacent cylinders (cylinders 1 and 2, or cylinders 3 and 4) have low compression, and the oil treatment produces no greater pressures, this points to a damaged cylinder head gasket, warped head, etc.

 

1100 engines:
Minimum: 128 psi
Standard: 142 psi
Maximum: 156 psi
Max. variance between lowest and highest: 14 psi

Run the engine some and the numbers should come up. Engines that have sat for a while tend to get stuck rings and some corrosion along the ring edges that prevent them from seating fully.

Making sure that the valves clearances are in spec will help too.

You aren't that low, and they are all even enough across the cylinders.

 

I had to drive about 60 miles to do a quick assessment of this bike (83 kz1100 shaft) compression as noted above,
but also ; sat for 3 years,bald tires, carbon crusted plugs,squishy forks, dead battery, both side covers cracked,
sand blasted paint, covered with red dust, and clogged carbs. It had 35,000 miles +-. The guy was asking 950.00
on craigslist but jumped at 400.00 offer. I figure about 1200.00 in parts alot of my labor and a paint job
maybe I should walk away and wait for the 82 xj1100 that I really want.

 

Lol 400? I'll take it

 

Are we discussing a Yamaha or a Kawasaki machine in this thread?
If you're looking at a Kawak this is not the forum to get model-specific help from (though we can give general help).

 

No, just general questions about compression. And, as it is, I'm probably not going to buy it. I'll hold out for an "82"xj1100
But, I didn't mean to tweek anyones orthodoxy.

 

we have a forum
Other Motorcycles

where you should ask about anything not xj

 

No worries. I'm more concerned that you get good information. Compression mumbers shoud be simmilar enough, but I'd hate for you to spend money and find out otherwise later.

 

I'll keep my eyes open for an xj1100 down here in southern NM and let you know if I see one for sale

 

Thank you, the"83 kz 1100 " I was looking at was similar but the engineering seemed
more primative. I'm trying to avoid having to rebuild an engine unless the bike is a
model that I really want. Saw an xj1100 in CL from Colorado Springs. I'm wondering whether it's
further than I would like to haul a trailer to check out an unknown. Sellers on CL tend to exagerate
quality and ask more than blue book value. It's hard to come home empty handed after traveling that far,
even if the bike is junk.