1975 CB360 Freeze-dried Hell Ride
- Thread starter irk miller
- Start date
I got the Dyna coils set up and the bike ran really really well. I put about 40 miles on it when the cam chain popped. The same tappet screw loosened and fell into the chain and broke it. I don't know what the hell I'm doing wrong that I keep having tappets loosen. The last time I set the valves on the bench so I was sure to get good access to the tappets. Maybe I should invest in a special tappet wrench. It shouldn't be this complicated- a set screw and locknut. I took the top end off again and everything looks fine. The oil shows no metal shavings. This time, though, I've got a helluva job finding the missing tappet. It has to be in the bottom of the case.
crazypj
Split personality, I fake being smart
Threads are probably buggered up in the rocker arm.
The bottom threads and top of valve are probably damaged as well, I've seen rockers that have run directly onto valve tip, real lucky the cotters didn't jump out and drop valve as well
How tight are you getting locknut?
Too tight is as bad as too loose
The bottom threads and top of valve are probably damaged as well, I've seen rockers that have run directly onto valve tip, real lucky the cotters didn't jump out and drop valve as well
How tight are you getting locknut?
Too tight is as bad as too loose
I took a quickie gander at the suspect rocker arm, and it looks like the thread hole is slightly oval. Considering it's happened twice to the same arm, this has to be my culprit. I don't know if the ovaling could have come after the tappet popped out, or if it caused it to come out in the first place. It also is happening on the cylinder that didn't fire when I bought the bike. Could this all be signs of a common issue that starts with the rocker arm?crazypj said:
I pulled the valves last night, and as crazy as it sounds, they are all clean and straight. I can't find any damage to the valves. The tappet hole on the rocker may or may not be oval.
Sometimes it looks like it is and sometimes it doesn't. What I originally thought was oval was oil that filled the threads and made them look smoothed. I did however find some spalling in the casing at the cam sleeves and these marks which look like bad casting, I'm not sure.
Sometimes it looks like it is and sometimes it doesn't. What I originally thought was oval was oil that filled the threads and made them look smoothed. I did however find some spalling in the casing at the cam sleeves and these marks which look like bad casting, I'm not sure.
Alternated tappets to see what I've got. Everything seems precision. It just occurred to me that I could have had a bent tappet, not a bent rocker. At least that makes some sense. Of course, I am open to the possibility that I over torqued that tappet. It doesn't show in the rocker threads, though. Regardless, new rockers are being ordered.xb33bsa said:
Now, as far as the cam lobes, they look good from my perspective. No flatspots, and smooth.
There is one small void, similar those in the rocker arms (just below the "R" stamp), in the lobe pictured here. Whether or not that is acceptable, I'm not sure on such tolerances.
The rest of the lobes look good. The cam chain cog looks good too.
The cylinders are shiny clean, with no vertical scoring and a mirror-like finish.
crazypj
Split personality, I fake being smart
I wouldn't worry about any of that stuff, it isn't serious enough to cause any further damage
You'll probably need a 10x jewelers loup or similar to check threads although they look OK in pics (I'll take a look on desktop, bigger monitor with better resolution than laptop)
You'll probably need a 10x jewelers loup or similar to check threads although they look OK in pics (I'll take a look on desktop, bigger monitor with better resolution than laptop)
Ellwood
Vintage person on vintage bikes...
I have a lot of engineering knowledge but little experience in these things. But what would be the reasoning not to use some high temperature thread lock? If that little bastard did that twice to me I'd be ready to make it stay. I'm guessing you'd run out of adjustment?
crazypj
Split personality, I fake being smart
The adjusters need to be adjusted, relatively frequently (1,500 miles) so loctite isn't a good idea.
I had a better look at rockers, one has a 'flat' across it and needs changing
Oh, don't put sealer on the section where the two inner bolts are, they are under breather over so don't need anything, plus, there is a chance sealer can affect oil flow to bearing
I had a better look at rockers, one has a 'flat' across it and needs changing
Oh, don't put sealer on the section where the two inner bolts are, they are under breather over so don't need anything, plus, there is a chance sealer can affect oil flow to bearing
Got a new cam chain in. Yay.
Lapped the valves and ready to re-assemble. The tappet screw actually hadn't fallen all the way in. It was laying beside the lower cam chain cog, on top of the lower adjustment arm. Again, no internal damage. It's hard to be stupid and lucky at the same time, but somehow I've been successful at it so far.
Lapped the valves and ready to re-assemble. The tappet screw actually hadn't fallen all the way in. It was laying beside the lower cam chain cog, on top of the lower adjustment arm. Again, no internal damage. It's hard to be stupid and lucky at the same time, but somehow I've been successful at it so far.
The motor is back together. I should have it back in the bike tonight and on the road tomorrow. If we weren't at the precipice of AP exams, I'd be wrenching all day. Goddamn teenagers.
Is it bad when you have taken a motor apart so much that you don't need the manual, and you know all of the torque settings by heart?
Is it bad when you have taken a motor apart so much that you don't need the manual, and you know all of the torque settings by heart?
