Honda CB360 Cam Chain

CJcochran

CJcochran

No pain, no gain
Been on a long journey to rebuild my 1975 Honda CB360. This winter, had the cylinders honed to take new overbore pistons. Now put it all back together...dealt with a few minor issues...and started it up...

Then something went "clunk" and everything stopped. I had the covers off - could see the stator turning, but the cam motionless.

Long story short, I think I did not tighten up one of the bolts on the cam sprocket...it got loose...and got caught between the sprocket and the chain...and SNAP....cam chain busted. I should have taken a picture....it was pretty sweet...Sprocket is bent...thank goodness I have a spare from another engine...

Very depressed.

So now... I just ordered a new chain, master link. I don't want to have to split the case to put in the new chain. I will if I have to, but would love to ride it this August...not next spring (knowing my schedule...and pace).

So can this be done? Do I need to be concerned about bottom end damage? I haven't pulled the tensioner yet...

Appreciate any advice. Mockery is ok too... ;)

CJ
 
Here is more fuel for the fire. I haven't found much on broken cam chains or replacement: either this is a totally common occurrence or an incredible feat.

1fb4f7626eb9ae2a008c32afc2f619bb.jpg



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So you got "all" of the broken bits out and you want to just put a new chain and cam gear in right?? It is possible to do, you would normally pull the "new" chain through with the old by linking them together... BUT I see you have the chain in your grubby hands :-X so you now need to find your inner fisherman to fish the new one through and link them with a master link or peen fit link.

I have a chain and peen fit link I would sell you for $50 + shipping, but should you go this rout I would like to ask... How the fuck you got the broken bits out of the bottom end?? ??? :eek:
 
Busted chain, sprocket that came off... I would bet all the dollars in my wallet right now (which ain't enough to buy a stripper a drink lol) that you have a bent valve or two as well.

Ideally you use an endless cam chain on these engines which will require you to open the bottom end and remove the crankshaft.
 
CJsCB360 said:
Here is more fuel for the fire. I haven't found much on broken cam chains or replacement: either this is a totally common occurrence or an incredible feat.

1fb4f7626eb9ae2a008c32afc2f619bb.jpg



Sent from my iPhone using Tapatalk
Click to expand...
?

Or it's neither.

There is almost surely more damage than just a broken chain and a bent sprocket. Valves will be the start of it. Seats and guides are next. If you're real lucky you can even break pistons when that happens.

The head needs to come off for internal inspections. Looks like you need the practice anyway.

barnett468 said:
but its no fun if you say its ok.
Click to expand...
Hmmm, no. It was still fun.
 
Do a leak-down test to check for bent valves
CB350t win and CB750 four heavy duty chains are too long by a few links but you can get 'soft links' for them and cut to length.
If valves are OK, connect new to old and turn crank (take plugs out first) and re-rivet
 
I had a eureka moment...

I ordered a new 219 chain ... A longer one to make sure I had enough links. Had to order a chain tool for 219 tools (thanks to those kart guys out there). I got the chain linked back, and fitted it all back together. Time to set valves and points... Hmm something is not quite right... Damn I didn't check the valves... Sure enough crazypj was right... Bent left intake valve...


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So I replaced the valve... Did a "leak test"... Now let's put it together again!!!

a82ce8652117f27b42ce4e6e2192f395.jpg



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.
looks like the piston rings might have some blow by too or its way rich or something because of all the build up on the valves . . that is what a chevy valve looks like after 100,000 miles . . i can only imagine what the exhaust valves look like . . you can probably get 10 more hp just by cleaning them all.

also, what beat the f_ck out of the inside AND outside of your cylinder head . . i would consider surfacing the head a little.
.
 
DohcBikes said:
As were other people that posted before pj. Sorry just cant stand it when people do that.
Click to expand...

But there were only 2 others that said bent valves before him...


Post 4
frogman said:
I would bet all the dollars in my wallet right now (which ain't enough to buy a stripper a drink lol) that you have a bent valve or two as well.
Click to expand...

Post 5
DohcBikes said:
There is almost surely more damage than just a broken chain and a bent sprocket. Valves will be the start of it. The head needs to come off for internal inspections.
Click to expand...

Post 6
crazypj said:
Do a leak-down test to check for bent valves
Click to expand...
 
Hell, it don't even matter. The other valve in the pic is bent too. The combustion chamber is destroyed, and I can just about gaurantee the valve seats are as well. He will probably just skip this post anyway.

Anyone else see the bubbles?

That head is super dirty. It should be perfectly clean after having been removed and reinstalled. Look at all the trash in there.
 
Ok, ok ... My apologies for not giving credits due.

At this point, just trying to get this POS back together again before investing any more time on performance.

Appreciate the support folks!


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DohcBikes said:
Hell, it don't even matter. The other valve in the pic is bent too. The combustion chamber is destroyed......
Click to expand...


I agree, combustion chamber looks really rough, like that engine has eaten a valve once before......

What fluid did you use for a leak test?
 
When valve gets bent like that it generally crack the valve guide, quite often 'inside' the head. You find it when new valve 'sticks'. It looks like guide is bent but really it's cracked
BTW, that isn't how you check for leaking valves, you pour fluid into port and check combustion chamber stay's dry. It's slightly more time consuming but much more accurate test
 
Yep Crazy is correct, now throw the fuckin thing on the trash and buy something new that you can understand :eek:
 
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