QuestionAbout 4 months ago I bought this bike that sat for the 8 years, once I got it running it has been great and I love it. But, a week ago it acted funny(ie. sputtering, power loss, hesitation) I went to shift and it died. Now it has a tap in the top end and I'm not sure what it is. I've got the top end torn down, the cams and valves appear to be fine.(appear is the key word) Any ideas would help, are there gap and spacer specs for my valves and cams?
AnswerAnthony, I would have done a little more troubleshooting before an engine teardown. And even I wouldn't tear one down without a manual.
http://autos.groups.yahoo.com/group/honda_nighthawk/msearch?query=engine+noise&s...
http://houseofmotorcycles.bikebandit.com/Honda-Motorcycle-CB700SC-NIGHTHAWK-700-...
Hondas from this era often have performance problems when the vacuum operated petcock fails and shuts off the fuel supply to the engine. You might check that as long as you have everything apart.
A tap in the top end could have been some dirt or debris in one of the lifters. There is no valve clearances to check as the wonderful maintenance free feature of these bikes is that they have hydraulic valve adjusters.
You didn't say how many miles are on it, but I would take a good look at the camchain tensioner system for wear or damaged parts.
Go to Ebay or www.helminc.com and get a factory book for this engine, so you don't have problems on reassembly.
I have heard of a few of these bikes that have tossed a rod under certain circumstances, but that is not a top end noise and if you had plenty of oil in it and the bike hasn't been hammered by the previous owner, then it should be okay.
Bill Silver
