Motorcycle Repair: Top end seens noisy, camshaft lobes, honda sl350

Question
Bill
 Hi, I am in San Diego and have a 1970 Honda Sl350 KO. I just got it running and it seems to me that the top end is noisy, (hard to explain) Do you know a good mechanic in San Diego that knows these old HONDA'S.  I would really appreciate your help on this matter.  You don't remember me but a long time ago I bought some 305 parts from you.  Hope you are doing well.
Craig

Answer
Hi, Craig....  I am back in SD now, mostly working on 305s lately.


"Top end noisy" can be a couple of things....

Loose camchain tension....  check cam chain tensioner setting and adjust as needed.

Worn camshaft/rocker arms... if excessively worn, requires parts replacements, plus determining cause of the lubrication failure. There are service bulletins about early clutch and dyno cover gasket failures causing oil starvation to the top end.

Valves need adjusting and/or were adjusted on the wrong stroke.... overlap instead of compression. Valve clearances are .002" intake and .004" exhaust.

The ends of the valve adjustment cams have a mark on the ends: Should be not be -/    \- located. If spun around so they are -\   /- it changes the geometry of the rockers to the camshaft lobes.

Worn camshaft end cap bearings/camshaft journals. This causes the end of the camshaft with the spark advancer to move around, causing erratic movement of the points cam, which causes incorrect ignition timing. Expensive fix.. cam, cam bearings.

There was a tech service bulletin about some of the replacement cam boxes needing to be relieved where the cam lobes were hitting the casting.

Loose camshaft sprocket retaining bolts. There are two types.. one has a shoulder on it. Superseded to the same bolt now for both sides.

http://www.cmsnl.com/sl350-motosport-350-k0-us_model732/partslist/?q=sl350

Bill Silver