Honda BF25 Bottom cylinder is a no go.

I have an 2005 Honda 25 shortshaft. It's really a bit of a mess being three cylinders and 3 carburetors for only 25hp.

The motor runs ok the way it is, starts instantly and revs up decently. When adjusting the carburetors, i discovered that the bottom cylinder adjustment had no effect whatsoever. When running, I pulled the spark plug cap off and there was no drop in RPM, and it revved up just as it normally would. It had the same response with bottom spark plug taken out. At idle the motor has alot of vibration, quite wobbly really.

Things I have checked so far:

It definitely has spark (I felt it shock me)
Compression is good (100 psi on all cylinders)
I took off the bottom carburetor and the jet is clear, though I don't know much else about carburetors.

I have this motor on a 13 foot whaler, yet at full throttle it pushes the boat at 23 knots on only the top two cylinders. How is this possible?

The 25 will run on two cylinders and it will shake.

Compression should be 213 plus/minus 14 psi. Be sure to have the throttle wide open when you take compression.

There are many passages in the carburetor and just checking the one jet is not enough. If you are looking to do it yourself, I recommend the Honda Carburetor manual. http://www.helminc.com/helm/product...=&from=result&Style=helm&Sku=TM044&itemtype=N

See post on carburetor manual http://www.marineengine.com/boat-forum/showthread.php?408713-Carburetion-manual

Mike

I am having similar problem with my bf25 with a no go cylinder. What did you find out about this problem. I wanted to buy the carb book but they are out of stock. Hope you can help me. Thanks, Ron

I have the same issue but mine Fires and stops firing. It will shock you but not enough to get spark in the cylinder under compression.Coil is good Spark plug is wet when not firing. its getting fule.