not sure about holding the revs at 2500, but noticed after a good long ride that head pipe #4 is hot -- not as hot as the other 3, but too hot to grab on to and hold easily. So something is happening in that cylinder -- ?
On my 1972 CB750K1, cylinder #4 is running cool enough that I can wrap my hand around the exhaust pipe. All other cylinders and systems are running ok. I swapped out the spark plug and it is not the problem. Visually the spark looks normal. No carbon deposits are building up on the plug -- it...