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Discussion Starter · #1 ·
Out riding my 1971 cl350 last week and bike suddenly got louder and louder. Pulled over and checked everything and all seemed well. I was almost to my buddy’s place so I figured I’d check it there. Started it back up to a loud rattling in the top end and immediately shut her down. Pushed it to my friend’s place and gave me a ride home in his truck.

Well, it quickly became clear that something was terribly wrong with the camshaft. Either it was a broken chain or broken cam sprocket bolts.

Took the engine out and top end off and found the culprit was a sheared off cam sprocket bolt. The shouldered bolt was still on but the cam sprocket was loose enough that it wouldn’t allow the engine to rotate properly. Whoever had rebuilt this bike years ago only had one correct bolt and did not use the correct non-shouldered bolt. Looks like it came from a hardware store.

Luckily, when I took the cam out I found the sheared bolt head and I’m in the process of getting parts and planning on reassembling. Cam is good, rockers are good. Valves seem ok but not really certain.

What do you think I should do from here? Take off valve assembly and check pistons and valve faces? That seems like the logical next step. Other than that, if all seems well I guess I just put it back together (with correct torque specs on cam sprocket bolts, of course), and see how she runs?

I’ve got this thing with an open top end so now‘s the time to do anything else.
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Hello, Because the torque has been removed from the cylinder/head assembly it is likely the seal has been lost for the cylinder base gasket, and cylinder head. To not replace those gaskets would invite oil leaks.
Buy the complete gasket set and remove the top end and inspect the cam chain center roller, and tensioner roller, and the rubber inserts for the pivot. Clean up where needed, use a torque wrench. Always good to send photos. Good Luck. HondaJohn
 

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You should definitely check the piston tops for signs of valve contact. If so, then pull the valves and Make sure they aren’t bent. And absolutely check the cam chain tensioner parts while your in there, if it’s original, it’s probably shot.
 

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Discussion Starter · #4 ·
Thanks for the advice. It was clear that I needed to take the whole top end off. Piston heads were a carbonized mess but they did not show signs of having been struck by the valves, so that was a good sign.

Clearly needs new rings and the cam slide was also nearly worn through so I pulled the cylinders and removed the pistons. Cam chain rollers are as hard as a rock so I’ll have to find replacements for that as well. Accidentally dropped one of the little rubber roller axle covers into the oil sump so that will be fun to find or not.

Next step is to take it to the machine shop and have valves (and everything else) checked and cleaned up
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Discussion Starter · #6 ·
Yes, yes, I think that was me. Head and cylinders off to the machine shop. Here’s where I am now. Most parts arriving this week reassembly week after probably
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Discussion Starter · #7 ·
Update - machine shop had Coronavirus outbreak. Won’t get head and cylinders back until next week. Spending my time polishing the aluminum engine covers.

I also have several spare cam sprocket shoulder bolts if someone needs one. PM me and a couple bucks will put one in your hands.
 

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Discussion Starter · #8 ·
I did a little more research on the sheared bolt from the cam sprocket.
The sheared bolt has A2 70 on the bolt head. The proper bolt is a hardness of 11 (which I think is class 10.9 on the chart below). Check out the chart comparing the strength of these two bolts. The proper bolt is at least twice as strong as the AS 70 bolt, if I'm reading the chart correctly.
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Discussion Starter · #9 ·
I have the head and cylinders back from the shop. Just waiting on the correct +0.5mm piston rings to arrive today and I will start the rebuild.
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That is NOT a correct "shouldered" bolt, it is simply a not completely threaded example.....The length between underside of the head and where the threading/shoulder stop the bolt is critical......
 

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Discussion Starter · #15 ·
Used the scissor jack from the Subaru to lift the engine into place. I have used that jack for so many side projects in 20 years of ownership but never once to actually lift the Subaru itself. Knock on wood....
 

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Discussion Starter · #16 ·
Chain installed. Back brake pedal installed. Carbs on and rebuilt. Timing and valves set. Air filters on. Tach cable installed. Exhaust installed. Clutch cable installed and adjusted.
Now just need to wait for kick start spindle washer to arrive so I can put on the right side cover. On goes the gas tank. Then fill her up with oil, kick start a bunch of times to move oil around (check little hole near points cover for oil flow) and then start her up!! Woo hoo!!!
312934
 

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Discussion Starter · #17 ·
Success!!! Bike is up and running with strong power, no oil leaks, and smooth shifting. Clutch cable has correct amount of slop but feels tight. Maybe it’s just that I haven’t ridden for a while.

Here is a video link.
 

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Discussion Starter · #18 ·
So I’ve been bombing round the neighborhood this week trying to decide if I trust the bike or not. The answer is that I do not. I’ve been having classic running rich problems with the bike. Stalling out at odd times and not quite idling like it should.

Took off the carbs and did another bench sync and I’ve slowly worked out the rich mixture. It is something of an art form, and I’m still drawing stick figures, but I think I got her sorted out tonight.

One more nice day tomorrow and then the weather takes a turn for the worse. Wish me luck.
 

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Discussion Starter · #19 · (Edited)
So I rode as much as I could today and the bike was running well but not not great. Sharp turns at corners would cause a stall sometimes. It would start right back up, often while I was still moving and it only happened on right turns.

so what I think is going on is that the fuel level in one of the carbs is just barely adequate and when I turn sharply it sucks air and stalls and then recovers easily.

its going to rain for a few days here and I’m going to pull the carbs and lower the float levels just a little bit. I think that will finally dial me in.
 

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Discussion Starter · #20 ·
On the brighter side I’ve improved the problems with the fuel mix running rich. I’ve been monitoring the carbon on the spark plugs and making adjustments that have reduced the carbon built up on the plugs.
 
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