Timbone
Well-Known Member
This was supposed to be the weekend for fabricating a new center kickstand with the new welding machine I've procured. Instead I spend at least 10 hours troubleshooting with no fix.
It started Thursday afternoon on my return commute from work. I got caught in a downpour, completely soaked from the start. Still, the motorbike performed flawlessly as it has been doing for many weeks. At about mile 10 of the 12 mile trip, the motor just stopped. I was rolling along just fine and - something changed. No lockup, just a powerless purr as if there's no fuel flow or spark. It was still raining. Checked all electrical connections and the spark plug. Fuel line looked good, plenty of fuel in the tank.
I pedaled and walked about s half mile to the top of a small hill. On the downhill run I was able to restart the engine - heard a sharp pop! from the cylinder head - and made it home. Since more rain was forecast for Friday, I figured it would be a Saturday project.
Thought about possible causes - the pop was a clue of head gasket issues! - and decided to just work through all the systems. Got some carb cleaner and detached the carb for a complete clean out. The outside of the carb looks bad the the insides were pristine. Floatbowl had a nice level if very clean gas. The intake was clean, too.
I checked my spark plug connection carefully, even adding a small clamp to keep it fixed to the spark plug cap.
Removed the head and examined the surfaces. Signs of serious blow through, mostly in the front of the slant head. The stock aluminum gasket was intact but had deep lines of impression and looked lined and stressed.
Piston and jug walls look great with just some light carbon on the piston surface. No scratching. Bottom gasket looked brand new. Rings look great.
I had another aluminum head gasket. Tried it and got one really good run in that lasted about a half mile. Same symptom: engine just stopped firing.
After several tries with different heads and gaskets - I tried teflon tape, too - nothing worked. I even found another slant head and I think I got one decent run in it. Tried different spark plugs. No joy.
That was Saturday. I quit and thought about different solutions.
Today, I got up and went straight to Lowe's buying, amount other things, sandpaper and a small piece of glass.
I inverted the two cylinder heads and ground them down until they looked completely flat. No teetering at all in the glass.
I was fortunate to find a thin copper gasket that I ran on a build s couple of years ago. I annealed it, seated it on the newly sanded head. Did a test run and -Zoom!- off she went like there was never anything wrong. After one fast run of about a half mile, once again, the engine stopped running.
Maybe the CDI is the problem? I have two others and I fitted them both. I checked all my electrical connections and soldered them just to be sure. I disconnected the kill wires. I lit myself up several times touching the end of the sparkplug: plenty of juice getting to the plug. Still no start. Nothing worked.
I am pretty sure this is the head/ head gasket. I just ordered one of each. I find it very frustrating that the difference between running and being stopped is such a fine line. I was looking forward to riding this weekend and riding to work tomorrow. Instead I spent 8 hours of my weekend doing work that got me nowhere.
It started Thursday afternoon on my return commute from work. I got caught in a downpour, completely soaked from the start. Still, the motorbike performed flawlessly as it has been doing for many weeks. At about mile 10 of the 12 mile trip, the motor just stopped. I was rolling along just fine and - something changed. No lockup, just a powerless purr as if there's no fuel flow or spark. It was still raining. Checked all electrical connections and the spark plug. Fuel line looked good, plenty of fuel in the tank.
I pedaled and walked about s half mile to the top of a small hill. On the downhill run I was able to restart the engine - heard a sharp pop! from the cylinder head - and made it home. Since more rain was forecast for Friday, I figured it would be a Saturday project.
Thought about possible causes - the pop was a clue of head gasket issues! - and decided to just work through all the systems. Got some carb cleaner and detached the carb for a complete clean out. The outside of the carb looks bad the the insides were pristine. Floatbowl had a nice level if very clean gas. The intake was clean, too.
I checked my spark plug connection carefully, even adding a small clamp to keep it fixed to the spark plug cap.
Removed the head and examined the surfaces. Signs of serious blow through, mostly in the front of the slant head. The stock aluminum gasket was intact but had deep lines of impression and looked lined and stressed.
Piston and jug walls look great with just some light carbon on the piston surface. No scratching. Bottom gasket looked brand new. Rings look great.
I had another aluminum head gasket. Tried it and got one really good run in that lasted about a half mile. Same symptom: engine just stopped firing.
After several tries with different heads and gaskets - I tried teflon tape, too - nothing worked. I even found another slant head and I think I got one decent run in it. Tried different spark plugs. No joy.
That was Saturday. I quit and thought about different solutions.
Today, I got up and went straight to Lowe's buying, amount other things, sandpaper and a small piece of glass.
I inverted the two cylinder heads and ground them down until they looked completely flat. No teetering at all in the glass.
I was fortunate to find a thin copper gasket that I ran on a build s couple of years ago. I annealed it, seated it on the newly sanded head. Did a test run and -Zoom!- off she went like there was never anything wrong. After one fast run of about a half mile, once again, the engine stopped running.
Maybe the CDI is the problem? I have two others and I fitted them both. I checked all my electrical connections and soldered them just to be sure. I disconnected the kill wires. I lit myself up several times touching the end of the sparkplug: plenty of juice getting to the plug. Still no start. Nothing worked.
I am pretty sure this is the head/ head gasket. I just ordered one of each. I find it very frustrating that the difference between running and being stopped is such a fine line. I was looking forward to riding this weekend and riding to work tomorrow. Instead I spent 8 hours of my weekend doing work that got me nowhere.
