Black deposits on pistons

UPDATE:
The following has been done:
valve lapping
ran taps through every thread
degreased
cleaned with soap and water
very lightly wet-sanded gasket areas with 400 wet paper
very lightly wet-sanded gasket areas with 600 wet paper
oiled valve guides
cleaned all oil passages

Now for the leak test:
I turned the head over and inserted the valves and spark plug.
I filled the combustion areas with carb cleaner, and rubbed a blue dry-erase marker into each opening.
The exhaust and intake areas were stuffed with dry paper towels to track any leaks.








#4



#3



#2



#1




I put them in about an hour ago.
How long do you think I should wait to investigate?

It should be noted that NO springs are installed- the valves were just slid into the holders.

Also, Is carb cleaner too thin to use for this purpose? I tried to use the closest weight to gasoline, without using gasoline... Thoughts?

Put the valve springs back on the motor,then flip the on its back(intake side).
Fill exhaust ports with solvent,then blow compressed air around edge of each exhaust valve where it meets the valve seat.Watch for bubbles in the solvent.
Flip the head over and repeat on intake side.

So, I would be pointing the compressed air right next to the spark plug firing area (combustion chamber side), correct?

And use one of these?



How close do I get to the valve? I have a 1.5hp pancake compressor (light duty).

Thanks for the tip.

Do it right around the edge of the valve where it meets the seat like youre trying to blow the air under the valve,thats more like the conditions the valve is under when engine is running.
That blower will work.

After more than 90 minutes:




1 & 2



3 & 4



I'd say that's a pretty good seal for having to springs attached for pressure, right?

Remember the combustion chamber is pressurized when engine is running.

I just turn it on it's side complete, fill with gas and watch for leaks. About 5 minutes each. Remember, the valves will seat in further when run so check their adjustment at 500 miles.
I was planning to say, after my valve seal,valve and spring install, my valve train sings like when it was new, no clatter, no oil burning and I feel comfortable going to red line. In fact I have to watch the tach to keep from going past it.
"God I love it when a good plan comes together." (Hannable Hayes, the A team)
Steve

Can't wait for that... and the warm weather.

Did the exhaust side tonight, will try and get the intake done tomorrow.

The valve seal is fine. I wouldn't bother testing it with the head sidewise.

Did you measure the valve seat width yet? Spec is 1.2mm max. If the seat width is too wide the seal won't hold up with mileage.
www.harborfreight.com/6-inch-digital-caliper-47257.html

Ed,
I'm assuming you were talking about the exhaust valves; are the intakes a different spec?
The average is 1.6mm

Nessism wrote: The valve seal is fine. I wouldn't bother testing it with the head sidewise.

Did you measure the valve seat width yet? Spec is 1.2mm max. If the seat width is too wide the seal won't hold up with mileage.
www.harborfreight.com/6-inch-digital-caliper-47257.html

I measured off the valve, not the seat. I can only assume they will be identical, correct?