An easy way to check to see if the valves are seating (with the head removed) is to pour some solvent or ATF into the intake and exhaust tracts (with the valves fully closed) and see if it leaks past the valve. This is just a general indicator, but if it seeps past the valve, well, there's your trouble. Just get some lapping compound and clean up the valves and seats and you'll be golden.

 

With the condition of the cylinders and the carbon EVERYWHERE, I am pulling pistons.

 

Just noticed your updated sig. Funny.

Another thought on all the carbon...may not be due to rich running necessarily - but could be related to weak spark. Seen that a lot. just brainstorming...

 

I'm not saying that's normal carbon deposits, it looks like quite a bit more than normal from your photos, but I've seen much worse on high mileage engines that were still running okay. Of course those weren't 2 cylinder motorcycle engines. You can still read the stampings on top of the pistons, and the flycuts aren't filled in.

Let us know if the rings are carboned into their grooves. But that alone still wouldn't cause zero compression.

30 some years ago a part time teacher at my school worked during the day as a tech at a Cadillac dealer. They had a customer bring a Caddie back about a week after buying it, saying it was smoking and going through oil (this was the big block V8, 472 or 500 cid). They tore down the engine to find it had NO PISTON RINGS at all. This was back in the 70s when there was sabotage going on in some of the assembly plants. But he was driving the car for a week.

 

That is classic. No rings....

I will be pulling the pistons this weekend. There is a ring of soft carbon that you cannot see in those pics around the very top of the cylinder. It hangs into the cylinder like a cliff.

 

That's a carbon ridge, which is better than a ring ridge, since it means the cylinder walls are still straight. Since you're doing a complete tear down, are you going to upgrade with any performance parts?

And yeah, no rings at all. I wouldn't have believed it if I hadn't heard it straight from him, but there was a lot of sabotage going on at that time. Did you ever read the novel "Wheels" by Arthur Hailey, about the auto industry? It was published in 1971.

In 1976 I was teaching nights, and one of my adult students had bought a new 1976 Olds Cutlass. He took it back to the dealer to check a rattle in the rear, and they couldn't find it. Several months later he was taking the spare out in the school shop, just to make sure the jack and everything was there, and under the full sized spare was a Coke bottle with a note saying, "How long did it take you to find this?".

 

Friend of a friend worked on the Cadillac assembly line in '72 I think it was. Always bragged that he threw a loose bolt in the frame assembly somewhere in the frame before welding the frame shut, that would never come out. Just rattle and rattle away but be impossible to find or remove. I wonder how many he did.

The no rings in the motor one was best. My old boss worked on the Chevrolet line in the 50's. Had lots of good stories about tricks they did to employees they didn't like. Like accidently breaking a window when installing it when there was someone directly on the other side inside the car installing something. I remember that he had boxes and boxes of parts he took home. Real NOS stuff like that would fetch a pretty penny on ebay now.

 

I got the rear piston out. I need to get the oil pump out of my way or the front, so that requires removing the clutch cover, clutch, and so on. I will post pics when I get the ones from the head.

 

Here are some more pics. The pistons cleaned up really easy. Usually parts cleaner won't touch a carbon build up, but it melted with through (supporting the soft carbon theory). The head looked slightly cleaner than the rear, but the valves were much dirtier. One of the exhaust valves looked like hell, and I am imagining this had to do with 1:leaking valve for 900 miles or 2air system for the first part of its life. You can clearly see the buildup on this valve in the pics. They all received a fairly aggressive treatment to remove all carbon, and will be reassembled when I clean the head.

 

previous piston pic:

 

That is a lot of carbon above the top compression ring, not normal.

 

Please correct me if I am wrong, but I have seen no mention of this possibility:

Did you hold the throttle open while doing the compression check? If you forget that little step, your compression will show up as being low. I know a guy who rebuilt a Maserati V8 because of that little omission.

 

So is this still an over rich situation due to elevation?

 

I have done enough compression tests to know that I need to hold the throttle open...

I fully believe that this is a rich issue 100%. I am jetted for 500ft basically. It gets angry at 7500 feet (clingmans dome). I rode it our to 11,500 at a minimum. It was really unhappy. The only way that I could have avoided the big tear down would have been to run a full carbon cleaning when I got back before letting it cool down. The spark plugs looked great.

Well, as far as the cleaning goes, the carbon dissolves easily, not like long term carbon buildup.

 

Technically that is the way to do it, but in 34 years of teaching a 4 hour per day/5 days per week Tune-up and Emission Control vocational auto class to mostly adults, I never had them prop the throttle open. I told them about it for ASE testing purposes, but have you ever heard an engine start with the throttle propped wide open...WWWWAAAAAAAA!!!!!

With all plugs removed a healthy auto engine will push 150 psi or more, on the 5th compression stroke, easily with the throttle closed. And I say that having done or observed thousands of compression tests. My students were required to check compression every time they pulled the plugs.

I'm not saying you shouldn't open the throttle, just that in my experience it doesn't make any difference. More important is to disable the coil/coils and the EFI, if injected.

 

It really depends on the volume of the intake. If you take a look at the location of the throttle body on a car and the volume of the intake in relationship to the volume from the butterflies on the most motorcycles and the volume to the valves, there is a severe amount of pumping losses, and many times in testing I have seen where a moto engine will not develop over 60 closed, but will make 130+ open.

 

True, since the intake is about 1" long on most motorcycles.

And if the Maserati had velocity stacks with throttle bodies bolted directly to the intake ports, it would be the same situation. So I stand corrected.

 

Agreed. Technically, that's how they teach you to do it, but in practice I've found it makes no significant difference.

 

Well, got the engine back up and running at 6pm tonight. I am leaving tomorrow on an Iron Butt around Lake Michigan. Its going to be just like snowmobiling, without the hand warmers. 7 am here I come.

 

Hope you've got an electric vest.

 

ccccccold and tired....

 

All appendages intact? Then take a shower, get yourself a glas of good single malt and relax...

 

So, here is the story.
I wont say that my motorcycle was running right at the end of the journey back from CO, but I ran out of fuel on the first leg at 115miles. Lame. Something must have "relaxed" in the carbs and now it is running very rich for around here. We continued on the whole trip limited by my bike's range. That wasn't such a bad thing because the morning was freezing cold, we even had flurries around Marinette, WI. Last night when I posted was when I finally made it in to bed after unclothing and showering (long shower, felt like burning). We had sleet, hail, and rain at times and the highest the temperature got was mid 40's (which at 80mph can suck the life out of you). Fuel stops were more warming stops than fueling. I can honestly say that yesterdays Iron butt was not rough on the body, but barely survived the weather, which had me questioning sanity and hotels the whole way. The hawk will be parked until next year, I am sure.