did you check your compression yet? whats the results?

 

Drawing a blank, atm. Gonna have to ponder.
Been a bit distracted with my own beastie having a charging issue.

Ern

 

Alright, after finally getting the right adapter on my compression gauge, I have found that all of my pistons are low in compression. Ranging from 45 to 65 psi. Bummer.

 

Re-run the compression test after squirting a bit of oil into the spark-plug holes. If
the compression stays the same, it's valve seals/seats. If it goes up, it's the rings.
That can help you figure where to go from here.

Ern

 

I re-ran the compression test after squirting some oil into the spark plug hole. piston 4 stayed the same, but the other 3 gained 10 psi. Still, 75 psi was the highest reading I've gotten. would a 10 psi increase indicate its the rings? Anyone got any ideas? Thanks for the time.

 

whoa.... So i get back to wrenching and I noticed that after running the compression test with some oil in the cylinder, the oil is leaking out of the head gasket and puddling on the ground. WTF? Maybe THIS is the source of my compression leak?! This gasket was not leaking the last time the bike ran (6 months ago). Is it common for that to erode after sitting? Though it looks like the head gasket needs to be replaced, I'm still looking for any information I can get. Thanks again.

 

I don't believe the head gasket shouldn't affect compression. It joins the cylinder-head
to the bottom-end and keeps the oil contained there. The rings maintain the
compression on the lower half of the cylinder and the valves contain it at the top.

That doesn't mean you don't have a head-gasket leaking, but it shouldn't change the pressure readings.

I have to say though, I'm more of a top-end maintenance kind of wrencher, rather
than a hard-core diagnostician. This is starting to venture into my theoretical
knowledge, instead of hands-on, practical experience. I'm hoping meow, IDoDirt
or one of the other serious gurus can step in.

Good luck, though, Ern

 

Almost correct, But the head gasket has a direct effect on the compression. If its blown out and leaking like he says then that is probably his problem.

As far as it going out while the bike sits/ if this is the case then the gasket probably went out a while ago and you didn't know it, most likely the water passages for the gasket blew and leaked the water over to the metal compression side of the gasket, then rusted it out as it sit. Then first crank it gave out on you completely.

The compression is what you read as the piston goes up closer to the head, the piston force's the air tightly to make the fuel/air mixer right for the combustion. The head gasket sits between the head and the block, It's what makes the head seal to the block. when it goes your pretty much screwed. Most time its the water jacket sides of the gasket that blows and cause's the bike to loose water and overheat. But sometimes you can blow the whole thing out and loose all compression. This is why head gasket's have the metal ring, that is to contain the forces of the compression and combustion where as just a paper gasket can not.

The valve's also effect the compression in the sense that as the piston moves up one valve opens to let in fuel/one opens for air, then they seal off and BOOM (combustion) with the spark, as the piston goes down the exhaust valve's open to let off excess pressure and spent fumes. If they are not in correct adjustment then you can have a valve open to soon and let out the compression before the spark, or also let it all escape out the exhaust side before you get the force to push the piston down.


As you know the rings keep a tight seal for the pistons to the side walls of the cylinder block. This keeps the compression/combustion pressures from going down into the oil pan and also to keep the oil out of the chamber so it doesn't mix with the air/fuel and cause improper mixture.

Hope that helps explain it a bit.

 

So, I guess the real question is: What would you do? Would you invest in a $70-85 head gasket and hope that it resolves the compression leak? Would you jump into the piston rings while you've got everything half way apart? Or would you invest in a used engine all together and be done with it? Maybe you would take a totally different angle?.... I'm just looking for some opinions, information and input. Thanks for the time and for any responses.

 

Me personally, I'd stick it on craigslist and list it as a blown head gasket. Ask 900 bucks or so for it. Then hunt for a newer bike.

But if it came down to it, and I had no other choice but to keep the F3. Drop it off at a shop and ask for a second opinion. If they say same thing then ask them if they think its worth fixing or replacing the motor.

Not seeing the bike in person and seeing what other problems it may have its hard for me to tell if the bike is worth fixing or not.