Today, I decided to tear into my spare engine before I work on my running engine. I got this engine in the deal with my '67 CL77 and glad I did now that I started to pull it apart. Engine is locked up solid so I had no idea what I'd find inside.
First thing I found as a broken rocker arm. It is the right intake and it broke just behind the adjuster where the arm itself begins at the adjustor boss. Looking at all the arms, it appears that when the flash was ground off the casting at the factory, the guy doing it was new, blind or drunk. He actually cut notches in the upper web of the arm. Not all the arms were like this, but at least two have severe notches. At first I thought it might have an aftermarket cam and needed some relief ground in them, but I don't think that is the case. There was a small notch right where it broke. Nice stress riser.
I'm concerned about my good engine. Never looked to see how the arms looked when I adjusted the valves. I guess I would have noticed this since it jumped right out at me on this engine. But I need to check.
Anyone seen this before. This is my first 305 adventure so it's all new to me. And talking about new, they certainly went out of their way to make bizarre cam assembly, didn't they. The CL160 I tore down a month a go was a lesson in simplicty. This beast is wild with all the splines and male and female collets, etc. I'd love to know some of the reasoning behind the cam assembly design.
Honda shop manual leaves a little to be desired, too. I had forgotten how bad those early translations were. They are funny to read unless you are trying to understand what they are telling you. The disassebly section is pretty dismal. Thank God for parts diagrams.
I would guess this is one of those instances where a Clymer's manual is superior to the OEM manual
regards,
Rob
Broken rocker arm in '65 CL77 motorBroken rocker arm in '65 CL77 motor
Last edited by Snakeoil on Sun Aug 29, 2010 12:57 pm, edited 1 time in total.
Pics of broken rocker arm and notches in othersHere is a pic of the broken rocker arm. Note how coarse the grind marks are where the casting flash was ground off. Also note the notches ground on the cam side of a couple of other rocker arms.
I found what I think is the primary culprit in what might have killed this engine. The nut holding the oil trap drive sprocket to the crank fell off. No sign of the tabbed lock washer so my guess is reassembled without it. Sprocket worked its way off the shaft and got chewed up in the process. I found metal chips in the cross-drilled oil holes in a couple rocker arm shafts and this is probably where it came from. Also found similar chips in the keyway cut in the clutch throw out cup. Probably not the correct Honda term, but just learning these engines. Lastly, sump screen around the oil pump was about 50% plugged with sludge. Very nasty looking. Definitely has given me the incentive to drop the pump from my bike to check for similar deposits. Most of the slugdge in this engine is not hard. It is soft, almost grease-like. I'll post pics in succeeding emails to show what I found when I fill up this post. Engine is not a candidate for a rebuild. But cases are good, head is good, cams are like new, tranny gears look fine. Crank is pretty rough at the big end rod area with corrosion. Both pistons are siezed to the jugs. Soaking with PB blaster and next will be heat to get them loose. Cylinders have broken fins so not going to try to save them. The engine is serial number 415 of the 1st year, 1965. regards, Rob
Oil pump screen and sludgeHere are pics of the oil pump screen.
That sludge looks almost like a quart of castor oil added to the mineral oil. I recognize it...
Or it could be old style BelRay which was more like gorilla snot than oil. That sharp notch in the rocker arms is stock. I have always speculated it was a locator for manufacturing /grinding the faces. That failed from a huge hit and probably too much lash or a bent valve from a broken cam chain wheel. I had that happen a few times. Small world, I was born in Ticonderoga and lived on Lake Champlain years ago. It never ceases to amaze me how some people will continue to run an engine with loud strange noises, just waiting for the Big Bang! 66 dream, 78 cb750k, 02fz1, 09 wing
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