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Discussion Starter #1
I feel like this is a question that must get asked all the time in a forum like this...but here goes:
Can anyone help me identify this noise?

This is my (new to me) 1964 CA78 that I've been tinkering on for a couple of days now. I've just finished changing the oil and going down the list of owners manual maintenance stuff:
amongst a bunch of other non-engine related adjustments i've...
Adusting the points and timing
adjusting the valve clearances
Adjusting the cam chain tensioner (including pull the tensioner out and cleaning it up a bit).

The wisdom of your collective ears is very much appreciated.
-B


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Discussion Starter #3
Thanks for the identification, Mike.
Do you expect one of these rebuild kits I’m seeing online (with new springs/rollers/caps for the clutch) will sort that issue out?
-B
 

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Discussion Starter #4
Pulled the starter clutch this evening. To someone who has never seen this particular mechanism before...everything looks pretty good. All the rollers were where they were supposed to be and the cap and spring mechanisms moved freely. The case screws were in place and staked down. Looks like you can't get the sprocket off without pulling an oil seal, but it turns smoothly and all the teeth look good. I went ahead and ordered the rebuild parts just in case. My thought was maybe the springs are weaker than they should be?
-B
 

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That's definitely the starter clutch slipping in the video.
Even though all the parts appear sound you wouldn't know if they have worn out of specs or not. These are wear items and should be replaced.
 

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Discussion Starter #7
Hey all.
Parts for the starter clutch came in last night and this morning I installed everything and buttoned it back up. Started great, first try. Adjusted around a bit on the carb and got it idling pretty decently. I rode around the block once and came back and parked. Then a few minutes later, I went to start it again and heard this noise (The sirens in the background make it even more ominous).

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I'm not sure if it's super clear on the video, but it sounded a lot like metal crashing into metal (kind of like pitching a hammer into a pile of aluminum) and I could feel the "ka-chunk" up in the handlebars. Any guesses? Have I don't something idiotic in the starter clutch reinstallation? The motor spins freely at the dynamo bolt and the bike kicked over first kick.

Also, side note on the starter clutch...while going through the box that the PO gave me with the bike, I definitely found a couple of recent-ish Ohio Cycle packages that tell me he had already swapped out at least the springs and the caps on the starter clutch. I'd assume the rollers were part of that job too...in case that info is helpful.

Thanks again for the help,
-B
 

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Time to take it apart again... though I haven't ever done a starter clutch on a 305, they're very similar to the later twins in design. My guess would be #16 is cracked or #21 has excessive wear or ridges in the gripping surface
 

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Discussion Starter #9
Yep. Headed back in!!
I gave the whole unit a close inspection, but didn't take #16 apart from #19 and #4 because I thought it best not to mess with those 3 staked fasteners (which looked well anchored). If there's a crack, will I possibly not be able to see it without tearing down that assembly?
Also, there was an oil seal(?)... #24 holding #21 onto the shaft, which I also didn't remove. When you say "gripping surface", you mean the outside surface of the smaller cylinder on #21 that contacts the rollers I just replaced, correct? (Just making sure.)

Also, am I reading this service manual right?
That gripping surface should be no less than 37.1mm?

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Always grateful for the wisdom,
-B
 

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Though the print in that screenshot is really small, it appears to be the minimum value for the diameter of the "gripping surface" (for want of a better term). Sometimes you can see if there is a crack in the outer starter clutch housing if you look at the inner areas of it while disassembled but if necessary, yes, you have to remove it from the alternator rotor. I've not done a 305 starter clutch before myself, they were out of production by the time I made it to the Honda shops at age 15 so the oil seal there is not something I've dealt with, all the others I've done were on the rotors that reside in oiled covers. Some of the 305-versed members can help better with the finer points of this than I can
 

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Discussion Starter #11
Got back into the bike this evening.
I'm still not finding an obvious crack in the dynamo/clutch assembly. Although this metal cover (on the outside of the staked screw surface) has a bit of play in it...maybe a couple of mm back and forth when I grab it and twist it against the whole assembly. And as you can see, it's openings aren't exactly centered on the staked screws. I'm also not exactly clear on how it's attached to the assembly.
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The gripping surface on the sprocket does have some very light gouging. It's definitely enough to feel when you're running a finger over it but it's very light. Would you suspect it's enough to cause me that horrible noise (which, upon further review, kind of sounds maybe like a chain/sprocket binding up?).

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308885


Thanks
-B
 

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Discussion Starter #12
Also, I'm struggling to find the torque spec on the bolt the holds the dynamo/clutch onto the shaft. Can you tell me what that should be? or what that bolt might be called in the FSM?
 

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you need to remove the 3 staked screws and cover and inspect for cracks underneath. There definitely shouldn't be any play at all
 

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Discussion Starter #14
Gotcha. I'll take it apart and check it over.
Any recommendations on the easiest way to remove the staked screws? Is it just a case of force?
Thanks,
-B
 

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Discussion Starter #16
They came off with surprisingly little effort (Using the JIS driver I was smart enough to buy when I was purchasing the clutch kit).
So...I still can't find any cracks.

My best guess is that the outer cover of the clutch housing has worked it's way (very slightly) loose and slid around and just over the staked screw heads causing that surface that faces the sprocket to warp and somehow bind up on something? I can see some very slight bulging around the holes the staked screws should go through and I had to work for a bit to ease them by that outer cover. Does that sound way off base? Seems like if it were enough of a bind to stop the starter motor in it's tracks, I'd see more pronounced gouging or something more obvious though. Any guesses?
Thanks,
-B

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You showed every view of it but the one I wanted to see... the crack that happens, if there is one, shows itself in the inner cast portion. The outer sheet metal cover often has dimples in the areas where the springs/caps get driven backwards in some cases, but the cast inner section gets a crack that allows the diameter to be larger and it's easy to miss it when you don't remove the piece from the rotor. The red lines with blue arrows pointing to them on part #3 are an example of it
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Discussion Starter #18
Ha. Of course I sent every picture but the helpful one!
I'm struggling to get a good shot. But I think maybe I get what I'm looking for now. If you can see in this picture...I can see the metal of the inner piece is chipped pretty good in the cavity between it and the outer piece. It's like that on two of the three recesses.
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Also, DEFINITELY dimpled on all three spots around the outside of the unit. It's so pronounced that I actually thought this was somehow the way that the outer piece was affixed to the inner one.


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Well, there is a fair amount of wear in the sections but there is no crack in the cast portion. It's also possible that the combination of the wear in the "ramp" areas combined with some wear on the driven portion of the sprocket is enough for it to still slip. I half expected to see a crack in the outer unit...
 

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Discussion Starter #20
Looks like OhioCycle and HondaRestoration have that part, but it's about $80. Do you suspect these clutch assemblies are specific to each bike, or might other similar era Hondas have the same system?
Also... any harm in putting the bike back together without the electric start to keep tinkering/tuning up? Would I leave out this clutch assembly and the sprocket and the chain to the starter motor? Basically just reattach the dynamo onto the tapered shaft and continue with just the kickstarter? or is that a bad idea?
-B
 
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