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repairing a broken cam sprocket (point shaft drive)

Joined
Jan 21, 2022
Total Posts
14
Total likes
1
Location
Goldendale, Washington
drill out the peened over post and drive out. when reassembling be sure to install the washer under the advance weight. Also make sure to start the weld in the center to lock the post
0104231431.jpg 0104231426_HDR.jpg 0104231422.jpg 0104231412.jpg0104231408 (1).jpg
the pictures are in reverse order ......sorry, I'm not smart enough to fix that!
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Moved to 250/305 engine section though it might also fit in Tips and Tricks.

Thanks for sharing.
 
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Great job. I wanted to replace the lost rubber bumpers on the weight stop pins with something durable to limit the advance range. Now I know how. Thanks.
 
Farm Boy, well done! Not sure if that retains the advance function, but it looks like it might.

Ballbearian, I had mine repaired by Tim Miller. ($125 back in the day) Let me know if you need contact info.

Larry
 
Farm Boy, well done! Not sure if that retains the advance function, but it looks like it might.

Ballbearian, I had mine repaired by Tim Miller. ($125 back in the day) Let me know if you need contact info.

Larry
He hasn't been around for many months. Glad he took the plunge and shared breaking one down. Wonder how it worked out. When the rubber bumpers wear out, they advance too much and I was wanting to do a permanent fix on that. I went a different route using roll pins on mine. So far so good.
Thanks anyway for the referral but if I need to go back to that I'll do like HRFB did myself.
 
Roll pins sound like a clever fix. And pretty easy, aside from what I thought a very difficult task of removing the cams. Perhaps roll pins can be added with the cams in place? If so, that’s revolutionary!

I must question Honda’s use of neoprene to prevent noise. I sure don’t hear the advance weights rattling against the stops above the normal rocker clatter on my bike.
Cheers
Larry
 
Roll pins sound like a clever fix. And pretty easy, aside from what I thought a very difficult task of removing the cams. Perhaps roll pins can be added with the cams in place? If so, that’s revolutionary!

I must question Honda’s use of neoprene to prevent noise. I sure don’t hear the advance weights rattling against the stops above the normal rocker clatter on my bike.
Cheers
Larry

When you consider the era the bike was built, and the likelihood that Honda never in their wildest dreams expected the bike to be around 55+ years later, it's easy to second-guess many things about how their were designed.
 
Roll pins sound like a clever fix. And pretty easy, aside from what I thought a very difficult task of removing the cams. Perhaps roll pins can be added with the cams in place? If so, that’s revolutionary!

I must question Honda’s use of neoprene to prevent noise. I sure don’t hear the advance weights rattling against the stops above the normal rocker clatter on my bike.
Cheers
Larry
66Sprint (Steve) came up with the roll pin idea. Here is the link to the post in my project thread and pic of the pinned advancer unit. You wouldn't by chance have a pic of the repair Tim performed on yours?



Actually scroll down to post number 389.
 
66Sprint (Steve) came up with the roll pin idea. Here is the link to the post in my project thread and pic of the pinned advancer unit. You wouldn't by chance have a pic of the repair Tim performed on yours?



Actually scroll down to post number 389.
Yes, in fact I do have pictures. I’ll see if I make it past step 2 in the (very nice) instructions. Darn, didn’t make it to step 1! No pictures Ure icon on my screen. Trying the forbidden “attach” cmd.
 
Not forbidden, it just doesn't work. So you don't see this icon on the toolbar?
View attachment 24584

Do you see the toolbar?
Just kidding about a forbidden use of attach. I’m sure I was doing something wrong when I didn’t see the mountain in a box. I did see that icon on a later attempt. Sadly, when I tried to use it to send 2 images of 300 kB each, a problem with parsing was reported snd it failed. I was able to pm the images to Ballbarian. At least, I believe they went through.
 
A test sending my uncompressed photo succeeded. I edited to delete that message. Maybe only the reduced-size pictures fail?

Sorry for taking up bandwidth on Ballbarians topic.
 
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Tim took an interesting approach, one that I had considered as well, use of bolts for the pivots would allow future repair or changes to the advance range via variation of the diameter of the replacement bushing. It's hard to see but looks like Tim used bronze to replace the rubber bushings, although they look small compared to the original in HRFB's disassembled pic at top of thread.
I've noticed too that the weights are different shaped than my CA77 ones (longer Spock ears). According to Bill Silver all the 305's have a 45-48 degree advance range. It could also be the difference in an early versus late advancer, as Tim has yours marked early. If so, then my '64 and the other two I have are all late (with Spock ears).
 
Here is the one in my Dream now. It is a roll pin job of the 'late' type.

ebJ1aOh.jpg



The pins, I did, only limit the max advance, not the minimum. My advance at idle does wander some between 0 and 5 degrees BTDC, due to slightly loose springs and, of course, no bumpers. This is why replacing the bumpers with more durable bronze bush would be the optimal fix, as Tim has done via disassembly of swagged pivot pins to get in there. Bravo Tim and HRFB. I wish he'd come back to report how it's running and if he also did something about the missing bumpers.
Most people probably don't care or realize that simply retarding a bumperless unit to stop at the max indicated on the rotor (45-48) will cause an idle advance of less than TDC, about 10 degrees ATDC. Or, they static time to FSM spec and never check dynamic advance with a strobe, to see they are over advanced, like 55+.
 
Here is the one in my Dream now. It is a roll pin job of the 'late' type.

ebJ1aOh.jpg



The pins, I did, only limit the max advance, not the minimum. My advance at idle does wander some between 0 and 5 degrees BTDC, due to slightly loose springs and, of course, no bumpers. This is why replacing the bumpers with more durable bronze bush would be the optimal fix, as Tim has done via disassembly of swagged pivot pins to get in there. Bravo Tim and HRFB. I wish he'd come back to report how it's running and if he also did something about the missing bumpers.
Most people probably don't care or realize that simply retarding a bumperless unit to stop at the max indicated on the rotor (45-48) will cause an idle advance of less than TDC, about 10 degrees ATDC. Or, they static time to FSM spec and never check dynamic advance with a strobe, to see they are over advanced, like 55+.
I believe Tim replaced the springs as part of the rebuild. Your warnings above are well taken. Before repair, when I set the timing at full advance, the static advance was after tdc by about the spacing between F and T. While most of the time my engine was at full advance, after a while the notable stumble off idle made riding around town into a chore.

With Tim’s repair, with the static timing at F, the full advance was between its marks as it should be. That should indicate the bush diameter matched the bumper. I was very happy with his work.
 
Okay, see the [ATTACH...] in the quote above? Somehow the attach button worked for you, mobile maybe?
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I’m using an iPhone 7 running IOS 15.7.6
The attach button did not work. I overcame my operator error 😜and found the picture icon. So far, I was able to transmit 1 test picture, but consistently received “parsing error” messages on the advancer images. Here’s another test image. Cannonball is underway now, by the way D2F1CFE9-21E7-4109-B3A7-3C7E41D88BAB.jpeg
 
AD
I’m using an iPhone 7 running IOS 15.7.6
The attach button did not work. I overcame my operator error 😜and found the picture icon. So far, I was able to transmit 1 test picture, but consistently received “parsing error” messages on the advancer images. Here’s another test image. Cannonball is underway now, by the way View attachment 24608

So I assume you're using the Safari browser then? If so, you should try Chrome, it seems to work best and in my experience Safari is known to have issues with more than just mobile versions of forums..
 
I believe Tim replaced the springs as part of the rebuild. Your warnings above are well taken. Before repair, when I set the timing at full advance, the static advance was after tdc by about the spacing between F and T. While most of the time my engine was at full advance, after a while the notable stumble off idle made riding around town into a chore.

With Tim’s repair, with the static timing at F, the full advance was between its marks as it should be. That should indicate the bush diameter matched the bumper. I was very happy with his work.
Sounds like Tim nailed it. Perfect. Thanks for the report.
 
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