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Post by Deleted on Jul 30, 2014 19:45:15 GMT
Paul, I received one of your sprockets today for my 250N - 41 tooth............fantastic - thank you.
I need your help and others though as I may possibly have made a boo boo with the one I sold you.
When that one turned up from Germany six weeks or so ago, I was convinced that the thickness of the teeth looked too thin and simply assumed it was a 520 pitch.
Having received yours today it looks the same and I thought it was also a 520.
Just been out to the garage and compared it to the 530 on my 1979 250N and yours looks right compared to that. I've also done some digging and have found that a 530 pitch should be 0.343" thickness which translates to around 8.7mm - which yours is.
My 250NDB is not here with me tonight so I can't measure the thickness but I am assuming a 520 pitch will have a thickness of 0.227" which is around 5.77mm.
Can any of you guys confirm if the above sounds right?
It could mean that I have actually sold you a 530 version Paul - and I had the right sprocket all along......
Let me know your thoughts, guys.  |
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Post by Deleted on Jul 30, 2014 19:47:04 GMT
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Post by grahamb on Jul 30, 2014 19:54:43 GMT
Yep
520 is about 6mm (just under 1/4")
530 is about 9mm (just under 3/8")
not sure what you are asking but the cb250ndb should have a 520 sprocket ?
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Post by Deleted on Jul 30, 2014 20:31:59 GMT
Yes - the CB250NB and CB250NDB (and 400NB / NC) had the 520....
I wonder if Crouchy could measure the one I sold him as it is destined for his 250NDB - and I'd hate to think it is 'incorrect' being a 530...
One thing's for sure - if it is a 530, I will take it back and I will be emailing the Germans some cash as it was not their fault but stupid Fungo....
Sometimes I can be a p*ick by this 'guesswork' that I sometimes do without the back up of a part number label......get the effing ruler out man!!!!!!!
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Post by Deleted on Jul 30, 2014 20:52:35 GMT
I'll check everything in the morning Nick- shouldn't take long. Everything is at work.
I think there has always been confusion on which SD got which chain- did both the CB250NB and CB250NDB get the 520 sprockets. I think so- but check the white label on the 530 sprocket I just sent you.....
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Post by Deleted on Jul 30, 2014 21:00:26 GMT
Yes, Paul - everything from 1981 got the 520.
Sorry about this.
The sprocket you sent me is surely a 530 - I don't trust white labels - but you cannot argue with the ruler.
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Post by na44superdream on Jul 30, 2014 21:04:54 GMT
The 520 sprocket measures 5.7mm thickness at the bottom of the teeth. (it has the distinctive step just below the teeth, the rest of the sprocket is the same thickness as the 530) For info, you can see the step in thickness on this old CB400NB 36T 520 sprocket.  |
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Post by Deleted on Jul 30, 2014 21:26:49 GMT
Excellent John.
They clearly put it on a diet, didn't they. ?
It does beg the question......why?
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Post by Deleted on Jul 30, 2014 21:34:39 GMT
Excellent background info John- you seem to know a lot about these bikes for a new guy!  In that case we may be ok with the sprocket bought off Nick- copy of photo from Ebay listing below. It also opens up the prospect of turning a SD 530 sprocket into a 520 sprocket with a bit of lathe work...  |
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Post by Deleted on Jul 30, 2014 21:48:28 GMT
Now that is interesting. The one I got from you tonight had no obvious 'groove' like that Paul, so maybe the one I sent you was indeed a correct (for your 250NDB) 520........maybe I'm just having a headf*ck of a night with these sprockets....who knows. Here's the one you sent me today :  |
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Post by Deleted on Jul 30, 2014 21:51:04 GMT
P.S - John is not a new guy.  New title though. |
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Post by Deleted on Jul 31, 2014 10:47:49 GMT
All is good up in the Crouchy NOS sprocket warehouse. 530 German sprocket to the left- 520 Fungo sprocket to the right. I've measured everything on these 2 and the ONLY difference apart from gloss/matt paint, is that the 520 sprocket is machined thinner at the outer edge. Note both sides are stepped down so the chain centre stays the same. If you have an early sprocket you can convert it to a later one. The other thing I notice is that these are that they are bl**dy heavy and so the 520 version does not save much on weight- the original reason given for moving to a 520 setup....    |
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Post by Deleted on Jul 31, 2014 12:25:31 GMT
Great news.
Paul, could you PM me what I owe you and I'll send over on PP as a gift so you avoid the fees.
Cheers again
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Post by Loz on Jul 31, 2014 14:55:25 GMT
 glad that's sorted
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Post by listey on Jul 31, 2014 22:00:12 GMT
Excellent John. They clearly put it on a diet, didn't they. ? It does beg the question......why? It reduces the "chain-drag". Less surface area, less friction. |
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glad that's sorted
