I've not had to do a leak down in 20 years. I replace the seals. They are like 3 bucks each. IMO, your time would be better spent changing the seals. Then we can do the top end.

 

"I've not had to do a leak down in 20 years."

I agree, I have never done a leak down test. What does it tell you that a compression test doesn't? Yes, possibly what is causing loss of compression, but you find that out anyway when you take the head and cylinder off.

 

Merryman, "It was lightly seized because the oil injector had failed." This is why I'd like a compression test.
A compression test checks the compression of the motor (checks piston/cylinder).
A leak down test checks for a leak in the bottom end (seals/gaskets).

 

reply, ya Ill go ahead and put new seals, and then do comp test.
is it only the left and right crank seals that I need to change?
are there any more that could cause vaccum leak on bottom end?
thanks for the advice.
cheers
T

 

Where the cases join.. which usually never ever happens.
Left and right seals. I use Suzuki parts They only like 3 bucks each.. I do not like the aftermarket seals.

 

ok thanks,
I suppose the bearings wont come out without the case being split?
are they usually worth doing same time or ?

 

They would if you needed to split the cases. Thankfully you don't need to. I wouldn't split the cases for bearings at this point. All this stuff can be done with the motor in frame. You can spin the crank (as you are going to have the top end off anyways) if it feels like rocks in it, then you would need to do the bearings.

The seals simply push in from the outside. You will need a puller to pull the flywheel (rt seal is behind it).. The left seal is behind the front clutch.
FYI: some say there is 2 part numbers for right/left seals. Both are identical and I have no clue as to why there are 2 part numbers.

 

Hey LT,
so I replaced the crank seals, am gonna put the exhuast in a fire,
servicing the clutches while im at it and replacing reeds and some gaskets.

my question to you is...
while im in there ill take the head off, how do I know if I need to rebore as opposed to just new rings or if its all ok as it is?
Im sure the real answer is more expierience but hoping you can shed a bit of light.
Last year I replaced rings in my sportsman and felt pretty good about it, but I did no honing or boring or anything .

I know the obvious, like if there are scratches on the cylinder other that the x pattern from factory hone them out. and if they are deep then maybe rebore is necessary , but what other light can you shed for me pls.
thanks for all your wonderful insight and taking the time to help.
cheers
Tarik

 

A compression test before it's tore down would be the best was to tell about the cylinder. If taken apart you can expect to see no crosshatch and quite possibly 2 aluminum strips up and down in the front. It also could be in great shape. See how it looks and get back.
I've never been a rings only guy. I go by the theory that if the rings are wore, so is the piston. For 30 more bucks and a bore It's 100%. That's just me and LT80's.

 

My $0.02, but I'd personally follow Jack's advice...do it right and run it all night!!! If you're not sure Jack can take care of you as well...My boy's custom LT80R would have nothing else but a Moore motor in it...

And don't even think about the Chinese cheapo Ebay kits...I had lots of fun with one of those on my neighbors LT80...