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Discussion Starter · #1 ·
Hi all,

1971 CB450, about 25k miles and bottom end has never been rebuilt to my knowledge:

In the process of replacing my cam chain and setting my timing, I think I noticed a small amount of lateral play at the rotor. It's of course bolted to the crankshaft, so I have to assume that this means there's a small amount of lateral play in the crankshaft. How much lateral play (end play, endplay, etc... along the axis of the crankshaft) is allowable? Is this a common issue with these engines?

The bike ran OK before the new cam chain, and runs like a champ after the new cam chain (despite being difficult to start up cold). But now I'm worried that the bottom end might be about to go kaput on me, hopefully not in a violent or painful way, but it has me a little bit scared! Am I right to be concerned about this, or is it normal to have a stator with a small amount of end play?

(I'll measure the play once I get back in the garage next week...)

Thanks,
Max
 

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There's no end play limits stated in any manuals that I've ever seen. It's determined by the gap between the bronze spacer that's behind the oil spinner and the crank main bearing. I measured the worn sections compared to the unworn and determined didn't find any cause for alarm and determined a .025"? gap was normal. If it's not knocking I'd say you're fine.
 

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I stand corrected, part 3 is a thrust washer and the outer race looks as if its pegged to c/case, so end float controlled that way, apologies......

https://images.cmsnl.com/img/partslists/honda-cb450k2-usa-e-10-crankshaft_big3IMG01175113_14d0.gif

this may not be the correct bike you have but find your correct bike....
Yep, and part 4 is the other thrust washer which is steel. The clearance may seem excessive but as long as the bores are straight and the bike wasn't severely neglected you should be good. If its knocking, that's bad.
 

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Discussion Starter · #7 ·
Thanks guys. The engine isn't knocking, so I feel a lot better about this now after your input. I'll focus instead on my leaking fork and challenging electrical system! :)
 

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Discussion Starter · #8 ·
Hi guys,

Today I took off the left side engine covers, stator, rotor, and starter clutch. I measured the crankshaft end play at 0.027" (0.70mm). Lefty, you mentioned above that 0.025" crankshaft end play is normal and OK?

I haven't disassembled the right side of the engine/oil spinner yet. I thought that perhaps I should check the condition of the thrust washer behind the oil spinner (#20 in this link: https://images.cmsnl.com/img/partslists/honda-cb450k4-usa-e-13-crankshaft_big3IMG01171583_5ce7.gif). Is that the thrust washer that controls end play? I'm thinking I should probably pull apart the right side of the engine to inspect this thrust washer - what do you guys think?

I uploaded a video to YouTube showing my end play. Lefty, could you take a look at this and let me know if this looks normal in your experience?

I'm a little concerned about this end play because I see some bad evidence of the rotor retaining bolt grinding on the inside of the round stator cover. See attached pic. I have two theories on this:
1) Excessive crankshaft end play is allowing this bolt to grind on the inside of the stator cover.
2) The head of the bolt got deformed by the PO, and then that protruding material started grinding off the stator cover.
Has anyone else seen this on the inside of their rotor cover and determined a cause?

IMG_4910.jpg
IMG_4911.jpg
 

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I can't imagine that much play is okay. I have a 450 out back and will see about tugging on it and will report back.

Edit: I just went out back and removed the stator and cover and pushed and pulled on the rotor. I couldn't detect any movement.
 

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I've seen the rotor bolt make contact with the cover before, but never that bad. Yeah, 19 and 20 are the thrust washers. You won't be able to check 20 without splitting the cases and it's a steel part. Maybe a gasket got left off the alt cover at one time? .025" seems like what I've measured as normal. I had a big end bearing blow up once. I partially blame it on the guy who bored the cylinders(bored too big and probably not real straight either). It ran ok for 500 or so miles and then started knocking for probably 500 or so miles before it went out and I tried to convince myself it was normal even though the oil had tiny metal chips in it. Idk what to tell ya. If there's anything more than fine black dust in the spinner than somethings wrong.
 

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I recently had my engine apart so I remember somewhat.
theres a circlip that locates the left bearing race against the cheek, there is a spacer/thrust washer on the right and there are solid dowels that locate the 4 bearing races. The crank should not have that much free play.
It’s possible your bottom end has been apart sometime in its life, and one of those things is missing.
At this point I’d be tempted to turn the engine upside down, unbolt the cases and have a look.
 

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Check the oil cup spinner to be sure the nut and washer are installed correct and the cup is held solid against the gear. If it's not it could cause excessive end play.
 

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See if this works
This is your end play. The spinner cup holds the gear and thrust washer hard against the bearing shoulder of the crank. The washer is concave in order to ensure this. The oil spinner transfer piece is spring loaded to work with this end play.
 

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Discussion Starter · #14 ·
Hi all,
I believe I solved the mystery. See this video for the explanation:

Looking at this parts fiche:
https://images.cmsnl.com/img/partslists/honda-cb450k4-usa-e-9-oil-pump_big3IMG01171579_3edc.gif
#9 was loose. The entire oil spinner housing could be moved back and forth by hand, once I got the right side cover off. I pulled the spinner cap off and found that the lock nut (#9) was partially unthreaded and could be unscrewed by hand! Not good. So, there was nothing applying any pressure to the final drive gear or crankshaft - everything was just floating.

Good news: the oil spinner had a bunch of ancient sludge in it but no evidence of metal shavings.

I need a special spanner socket to tighten this nut down again. I found one on Common Motor: https://www.common-motor.com/produc...hycfqCMy-CsE4IzRui-s4ZhJN4VyKzUBoCu9EQAvD_BwE
And a slew of cheaper alternatives on amazon by searching for the Honda part number: 07716-0020100
(Just putting this info here so others can find it later!)

Thanks for all the help. I'll post back here once I've sourced all the parts and get it back together.
 

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Yep, Lefty nailed it. I've never bothered to check for end play when things were disassembled, but I can absolutely see how it would exist.
 
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