CB160, CB350, CB360, CB450
5 posts • Page 1 of 1
Took my CB350 out for the first time this year and after @4 miles at about 50mph it tightened up and felt like it might have seized. It restarted but was blowing a LOT of smoke out of the cambox breather.
Limped it back home and changed bikes and later ( when cold ) put a compression tester on and both cylinders seem OK, the oil level was low.
Havent done anymore and probably won't as half way through another project but I wondered if the cam had picked up in the head ( apparently not unknown on these style Hondas ) would that have caused the "tightness" and the oil blowing ?
Anyone out there had the cam seizure and able to say what the symptoms were ?
I don't see why partial seizure of the cam should affect oil getting past the valve guides or piston rings.
More likely the cause of the problem - blocked or reduced oil supply - should have affected the other parts as well as the cam. i.e. if there was no oil getting to the cambox area then the valves and guides would have beem starved also.
The piston gets its oil thrown off the big end so that could mean blocked sludge traps in the big end or blocked oilways in the centre main bearings or centrifuge to the big end.
It sounds like a full strip to investigate.....
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F
My thinking was that if the clearance between the cam and carriers was too big the oil might have been escaping and over filling the cambox and then crankcase pressure could cause it to blow.
Probably grasping at straws and I agree it will only show up when stripped; I know cam seizures were perceived to be a 70s/80s issue but didn't know what the symptoms were.
The bike is going in the naughty corner for now as I have other things to finish ( hopefully ) this summer.
Remove the points cover and back off the valve adjustments to relieve the spring pressure on all the rockers. Now grab the end of the spark advancer and try to move it up and down. If the cam end bearing is still in good shape there should be very little(if any) movement there.
'72 750 Commando
my company car is a Kenworth