now I know why I am not getting power....(M5B 2 stroke)

So here I am thinking....i'm not getting any higher RPM's because the carb float is wrong, or the throttle friction piece is worn....

when I worked on the motor over the winter the cylinder head looked perfect. after rebuilding the water pump and carb, I am thinking EASY STREET....wrong...after tank testing at home, it seemed to be OK...but wasn't really able to rev her up in the small tub. so i went out today and took the boat out...could not get much past maybe half throttle, and it still seemed to lose power somewhat. (was like that at start of year)...

total power loss but was able to sail back onto the mooring...

poked around and saw this....argh....

QUESTION: In looking at Parts Catalog - it states Cylinder Head part # 369010010M CYLINDER HEAD is NOT INTERCHANGEABLE....what does this mean...?

If your head is cracked, get


and

Paul, thanks for the info, I called the supplier and they told me that there was a new part number.

The re-assembly instructions in the service manual (I have the Clymer and Factory manual) seems straight forward.

At any rate, the head bolts came off painlessly...just a little liquid wrench/PB Blaster. What are your thoughts about the condition below? Does the piston seem to have a "hot spot?"

The crank case water jacket seems OK - i poked around inside there with a soft plastic tie and it didn't appear clogged - just scaly as you can see. I assume one cannot poke around inside there with a soft wire brush to clean it out....

The head, on the other hand, seemed quite clogged. Is this something you think one should clean our every 5-10 years? The biggest hassle was getting the gas tank empty and off...

Piston top looks normal. With proper flushing, no need to periodically pull the head for cleaning.

Paul

As I am waiting for parts, I'm thinking of cleaning some of the scale in the powerhead around the Cylinder housing - at least the section I can reach. With the head off, do you see any problems if I use the flush plug and rinse with some saltaway or vinegar? Or should I wait until after the new head is back on?

That would be OK. Just keep the acid out of the cylinder. It will work slower at room temps than when in a warm cooling system.