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Author Topic: Possibly entering the 378 club!  (Read 4174 times)

Offline Sderbyshire

  • Posts: 249
  • Into Sailing, classic Triumph cars and motorbikes.
Re: Possibly entering the 378 club!
« Reply #50 on: Jul 02, 2018, 09:13:16 »
An update, one step forwards and two back !

Dubious of the hd springs i whipped them out this morning and compared with the std springs. Wire thickness on the hd springs is thinner than the std springs, no wonder the clutch slips!

So back in with the old springs and out for short test ride, very short....... as the engine seems a little rattly then stops suddenly.

Took out plugs and span motor over, valvs not opening so off with the rocker cover and I find the timing chain is off the sprocket, which is broken and the bolts are out.

Im sure i tightened the bolts but obviously not as it looks like one undid, then the sprocket wobbled and ripped out the other bolt and destroyed itself.

Im assuming it will have bent a valve in the process, not had head off yet.

Ill obviously need a new sprocket, and probably the cam too as one thread looks knackered, or could helicoil it?

Thoughts?

Steve

Offline advCo

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Re: Possibly entering the 378 club!
« Reply #51 on: Jul 02, 2018, 09:31:04 »
That's a bummer. I always use Loc-tite on those cam sprocket bolts just in case.

You could helicoil or tap to the next size up, although I don't know if swapping up to a larger bolt (added weight?) would affect the balance of the cam while its spinning at speed...could be negligible ?
"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0 - Sold
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0 - Sold
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0
'97 BMW F650st - http://www.dotheton.com/forum/index.php?topic=75732.0

Offline Sderbyshire

  • Posts: 249
  • Into Sailing, classic Triumph cars and motorbikes.
Re: Possibly entering the 378 club!
« Reply #52 on: Jul 02, 2018, 10:46:53 »
Took a closer look at the cam and the threads are ok, one is perfect and the other cleaned out ok with an m7*1 tap ( was surprised it was m7)

So i may get away with a new sprocked and pair of bolts, any suggestions as to where to source those ? (Sprockets common on ebay in us but not sure for bolts)

I remove the head later and assess valve damage ......

Offline crazypj

  • Posts: 13155
  • Split personality, I fake being smart
Re: Possibly entering the 378 club!
« Reply #53 on: Jul 02, 2018, 12:53:01 »
Get new bolts from Honda, pretty sure they still use them on various motors but you'll need a parts guy who knows how to look up superceded numbers (probably a lot of them?)
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Sderbyshire

  • Posts: 249
  • Into Sailing, classic Triumph cars and motorbikes.
Re: Possibly entering the 378 club!
« Reply #54 on: Jul 02, 2018, 13:01:55 »
Thanks PJ

Ive found a source of bolts here in the uk, cam sprocket too but cheaper to have it shipped from the us!

I have two bent exhaust valves, one slightly and one very bent !

Inlets look ok, no marks on the valves or pistons.

Is this what youd expect 360 experts??

Im regretting not double chcking those cam sprocket bolts !

Steve

Offline irk miller

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Re: Possibly entering the 378 club!
« Reply #55 on: Jul 02, 2018, 13:28:18 »
Checking wouldn't have mattered if you over-tightened the screws.  Over-stretching from over-tightening will also cause failure- either breaking or loosening.

Offline Sderbyshire

  • Posts: 249
  • Into Sailing, classic Triumph cars and motorbikes.
Re: Possibly entering the 378 club!
« Reply #56 on: Jul 02, 2018, 13:36:17 »
In all honesty im not sure i went back to the first b9lt at all, after rotating the cam to fit the second !

New valves ordered very cheaply from isreal...... wonder if theyll turn up!

Watch out for the next episode in Steves first engine rebuild :-)

Steve

Offline MiniatureNinja

  • Posts: 454
Re: Possibly entering the 378 club!
« Reply #57 on: Jul 02, 2018, 17:56:35 »
this is precisely the thing that scares the crap out of me when building an engine

sure I was able to do my CB360 myself.... but hitting that starter button for the first time was a little nerve wracking
'75 Honda CB360 - thread

Offline crazypj

  • Posts: 13155
  • Split personality, I fake being smart
Re: Possibly entering the 378 club!
« Reply #58 on: Jul 03, 2018, 10:44:07 »
More than once I've re-stripped top ends to check cam bolts. So far, I've always had them tight but it's so 'automatic' to me I forget I've done it. I don't think it's possible to over-tighten those bolts? I use a long 1/4" drive extension and 6 point socket. so I can get 'outside' head.  Never yet had one come loose (yet). It is likely you 'got excited' and only did them finger tight? It's more normal for exhausts to bend, they can get tangled with intakes and pistons., they close 'later' as things start going wrong You need to pull intakes to check them, just in case there are any marks on edges. Is there damage on head/cam bearings where bolts backed out? Generally eay enough to filer off any burrs (I fixed a lot of CB/CJ250's before UK had 125 learner law)
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Sderbyshire

  • Posts: 249
  • Into Sailing, classic Triumph cars and motorbikes.
Re: Possibly entering the 378 club!
« Reply #59 on: Jul 03, 2018, 10:58:56 »
Thanks PJ

I may indeed have not tightened at least one of them up properly!

Thanks for the tip on intakes, thay look unmarked and were watertight when i cleaned the head in the parts washer to clear out any metal fragments, but i guess i should remove them to check edges.

Am now awaiting a sprocket amd bolts from the US and two exhaust valves from Israel, wonder which well get here first ( prob the sprocket as thats no use until i have the valves!)

Its all a fun learning exercise, lucky i have a few other vehicles :-)

Steve