honda305 Home honda305 Auctions honda305 Gallery honda305 Forum Electronic Ignition honda305 Forum honda305 Forum honda305 Forum honda305 Racing honda305 Literature

Auctions  Mailing List    Registry   Marketplace

honda305.com Forum - FULL SCREEN

honda305.com Forum

Login
□ Search
  □ CLASSIFIED_ADS
□ FAQ 
  □ SEARCH_ADS
□ 
  □ MY_ADS
Vintage Honda Owners,
Restorers, Riders and
Admirers

What are the symptoms of the cam picking up in the head ?

CB160, CB350, CB360, CB450
Post Reply
Phil-UK
honda305.com Member
Posts: 229
Joined: Thu Oct 19, 2006 7:04 am
Location: ENGLAND

What are the symptoms of the cam picking up in the head ?

Post by Phil-UK » Mon Apr 15, 2019 2:00 am

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 ?

thanks

Phil

Phil-UK
honda305.com Member
Posts: 229
Joined: Thu Oct 19, 2006 7:04 am
Location: ENGLAND

Post by Phil-UK » Mon Apr 15, 2019 2:03 am

Forgot to make clear, oil level had been on full when left home.

User avatar
G-Man
honda305.com Member
Posts: 5665
Joined: Wed Mar 25, 2009 5:17 pm
Location: Derby, UK
Contact:

Post by G-Man » Mon Apr 15, 2019 2:13 am

Hi Phil

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.....

G
Phil-UK wrote:Forgot to make clear, oil level had been on full when left home.
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

Phil-UK
honda305.com Member
Posts: 229
Joined: Thu Oct 19, 2006 7:04 am
Location: ENGLAND

Post by Phil-UK » Mon Apr 15, 2019 9:32 am

Hi Graham

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.


cheers


Phil

mike in idaho
honda305.com Member
Posts: 402
Joined: Sun Jan 29, 2012 9:18 pm
Location: orofino, idaho

Post by mike in idaho » Thu Apr 18, 2019 8:53 am

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.
'65 YG1
'65 CB160
'66 CL160
'66 CL77
'78 XS650
'79 GL1000
'69 T100R
'68 TR6
'69 T120
'72 750 Commando
my company car is a Kenworth

Post Reply

 


 

CB-77 | CYP-77 | Road Test | Riding Log | Literature | Zen | Marketplace | VJ Survey | Links | Home