[paulR]

Hey, I can't start the bike. I use it every day and I noticed it was taking little longer to start it for the last couple of weeks. I had to straighten (with a hammer) a crooked part of the front leg shield frame (while it was attached to the bike), it got significantly harder to start afterwards until it finally decided not to start at all the next day (at the beginning of this week). So I did some tests:
1. Battery - I've got the Battery Tender today. When charged it's 12.9V and while cranking it immediately drops to 10.7 and even little below.
2. Starter - I don't remember anymore how fast should it crank, so hard to say if it's slow, but it slows down a lot after maybe 2 seconds.
3. Spark plug clean and working well.
4. Compression - very bad, now 50 PSI (even with the secondary throttle valve wide open), couple of weeks before wasn't much better.
a.) I squirted a bit of oil into the cylinder, no change.
b.) No sign of bad exhaust/smoke, no leaks from the engine, no oil consumption.
c.) No sign of power loss. Before it broke down, so a couple of days ago (it was already cranking long) it was powerful and fast.
d.) Finally I decided to adjust the valves, but it turned out they didn't need it (IN: 0.006 EX: 0.009), they seem to be in a good condition.
And here I got puzzled, a lot of power, good valves etc, but 50 PSI? So what is going on?

 

[Elliott Larron]

Sounds like ,Cylinder Loss, Rings, Or Battery, May need Checking Normally Battery's Voltage are not Suppose to drop down Below 10V

07 Models Some times Leak Under the engine Gasket area, But mostly back Piston Pressure pushing oil thru Gaskets,

If there was Pressure leaking thru Rings, IT would go thru the PCV Valve Direct to Airbox and Oil Filer Cap,

Check the Gaskets where your Cylinder Combustion Chamber for Leaks.

 

[paulR]

Sounds like ,Cylinder Loss, Rings, Or Battery, May need Checking Normally Battery's Voltage are not Suppose to drop down Below 10V

07 Models Some times Leak Under the engine Gasket area, But mostly back Piston Pressure pushing oil thru Gaskets,

If there was Pressure leaking thru Rings, IT would go thru the PCV Valve Direct to Airbox and Oil Filer Cap,

Check the Gaskets where your Cylinder Combustion Chamber for Leaks.

There are no visible leaks, the engine is dry as well as the inside of the air filter box.

 

[DougInKY]

Take your battery to an auto parts store that can test motorcycle batteries. Batteries Plus and Advance Auto Parts here where I live can test them. Have them run a load test on the battery. I would bet your battery has a bad cell.

 

[Dave_J]

I agree with Doug. A dead cell will test "kind of" OK with a meter but the cell will fall out within seconds. You could use jumper cables and hook up to a car battery with the car engine OFF and see how it cranks. The starter will only take as much amps as needed so you could even hook up to a simi trucks HUGE battery as long as its 12 Volts.

 

[paulR]

I couldn't find a place to load test the battery (Autozone etc. don't do it here), but I hooked up to a car with the car engine off as you suggested. I didn't notice any significant change. So I decided to take the engine apart. See what I found on the attached pictures. Keep in mind the engine is at least 30K old.
Just to make it clear for newbies like me, the gasket is built from 3 layers, so the white parts (looking like holes) is the inner metal, check the last picture I got from some website, just as a reference to get the idea how it's built.

 

[DougInKY]

From your pictures I don't see anything real scary. The head gasket might be blown though. Was the bike running hot?

 

[paulR]

No, it wasn't running hot. I cleaned the piston and the rings, and carbon causing leakage on the exhaust valve seats, I checked the specs on the parts, checked for distortions, plus I replaced the cylinder head gasket. The engine is in perfect condition. But... after putting it all back together nothing has changed. I'm pretty convinced now that the cranking is very slow and it's the only reason for the low compression.

 

[Elliott Larron]

No, it wasn't running hot. I cleaned the piston and the rings, and carbon causing leakage on the exhaust valve seats, I checked the specs on the parts, checked for distortions, plus I replaced the cylinder head gasket. The engine is in perfect condition. But... after putting it all back together nothing has changed. I'm pretty convinced now that the cranking is very slow and it's the only reason for the low compression.

It could be the Starter, Maybe it might have dropped in Speed, Try to take it off ,And Direct Connect and see if it's fast or Slow!!

 

[paulR]

You're right Elliot. The last piece of the puzzle is the starter and it is broken. At first when I took it off and connected to a battery it seemed to be pretty fast, but after taking it apart I found two of four brushes being almost gone and that's not all. There's a short circuit between all of the starter components (commutator, the rest of the armature and the armature shaft) which is bad and basically means that there's a short between + and - connectors of the starter and it's 0 ohms. Simple right? I could simply measure for continuity between + and - without even taking it of. It's impressive that it was still cranking though. It's life is finished, new one on it's way. Thank you all for your replies.

 

[MacDoc]

Good to know - save some troubling shooting in the future.
If you happen to have pics would be useful.