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Author Topic: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?  (Read 544 times)

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Online halmic

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1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« on: January 10, 2017, 06:56:37 AM »
I picked up a complete running 1969 YR3 (title said 1970, but I'm getting that corrected).  The frame number matched the title, but where it looks like the s/n should be stamped on the engine case it's blank.  Should I assume this means the case has been replaced somewhere in the past?


Offline m in sc

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #1 on: January 10, 2017, 07:08:56 AM »
probably so.
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Online halmic

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #2 on: January 10, 2017, 07:46:24 AM »
So was it common for replacement cases to come sterile, with no s/n stamped?

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #3 on: January 10, 2017, 11:58:55 AM »
yes. Kawasaki's are particularly known for this. the dealer was supposed to stamp in the original number from the motor they replaced with an asterisk or something (cant remember exactly) to denote it was a replaced case, which usually didn't happen.
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Online halmic

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #4 on: January 10, 2017, 01:49:02 PM »
yes. Kawasaki's are particularly known for this. the dealer was supposed to stamp in the original number from the motor they replaced with an asterisk or something (cant remember exactly) to denote it was a replaced case, which usually didn't happen.

Thanks for the info, so much for it being "all original", oh well.


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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #5 on: January 10, 2017, 02:28:07 PM »
cool bike. however, im sure it was a period repair so I wouldn't sweat it. its actually kind of cool that repair happened.
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Offline MarkT

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #6 on: January 10, 2017, 07:49:34 PM »
Could it be an imported bike not originally sold in the US?  I've heard rumors that Yamaha did not stamp engine numbers on early models sold in Japan and possibly other countries as it was not required.   

And the replacement Yamaha cases I've seen are completely blank... but those were later models and of course anything is possible! 

Great bike you have there no matter what!   :thumbsup:
1963 Yamaha YG1-T, 1965 Yamaha MG1-T,  1966 Sears Allstate 250, 1970 Yamaha CT1, 1972 Yamaha R5 - 400 project bike, 1981 Yamaha DT175, 1988 Yamaha DT50, 1990 Yamaha Super-DT50

Online halmic

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #7 on: January 10, 2017, 09:39:44 PM »
It's possible I suppose, I'm not too far from the northern border, eh?  I haven't dig up much for resources on these older bikes.  I may very well go the route of an RD instead for my cafe project!

Offline evan_calgary

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #8 on: January 10, 2017, 10:05:54 PM »
by 'import' he means further than Canada.  We have had serials stamped as far back as I have seen.

I have Yamaha cases I assumed were replacements with just the model prefix like you have there. 

Offline 50gary

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #9 on: January 14, 2017, 08:45:55 PM »
Yep, a lack of S/N should mean what has been said, it's likely a replacement case, I know a guy with an RT360 that's numberless.
  Cheers, 50gary
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Online halmic

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #10 on: January 15, 2017, 03:56:48 PM »
Thanks guys, they must have Ben replaced a long time ago, the case patina matches the cylinder patina quite well!

Offline MarkT

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #11 on: January 15, 2017, 05:32:20 PM »
The other possibility:  JDM (Japanese Domestic Market).   They didn't always mark frames and engines the same in Japan.  (I know from experience this is true for 1970's JDM cars)

Here's more info... 

"Engines with only a model ID stamped on the cases are similarly not rare of special; Japanese market cases often never carried a full engine number. The key piece of information the Yambits team needs to establish what bike it is supplying parts for is the chassis number, everything else can, may or has the potential to be changed or altered over the vehicle’s life."

From article on Yambits originally published by "Classic Mechanics" and found here: http://www.classic-japanese-bikes.com/Yamaha-2-strokes.html

Maybe Yambits could help ID what you have and if they're replacement cases or a JDM import?

1963 Yamaha YG1-T, 1965 Yamaha MG1-T,  1966 Sears Allstate 250, 1970 Yamaha CT1, 1972 Yamaha R5 - 400 project bike, 1981 Yamaha DT175, 1988 Yamaha DT50, 1990 Yamaha Super-DT50

Offline MarkT

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #12 on: February 09, 2017, 06:50:08 AM »
A bit late  :doh:

I asked a friend who has experience with early "JDM" models and he just sent me this photo of an example of the stamping on a Yamaha engine originally sold in Japan and not intended for export...  only the model prefix was stamped.

He says new replacement Yamaha cases were supplied completely blank with no prefix or number or anything at all stamped into them in the engine number area.  (I've bought new replacement cases halves for a 1970, 1977, and 2012 Yamaha and all were completely blank)



1963 Yamaha YG1-T, 1965 Yamaha MG1-T,  1966 Sears Allstate 250, 1970 Yamaha CT1, 1972 Yamaha R5 - 400 project bike, 1981 Yamaha DT175, 1988 Yamaha DT50, 1990 Yamaha Super-DT50

Offline boredinballard

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #13 on: February 09, 2017, 12:24:42 PM »
Well that is good to know!

The bike has a neat little bit of history to it now, seems it was an imported JDM model R3.

Sorry it didn't sell when it was up on eBay, still blows my mind. Someone will pick it up come spring/summer.

Offline Eric P

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Re: 1969 YR3 Engine Case NOT STAMPED with S/N? Help?
« Reply #14 on: February 09, 2017, 02:49:50 PM »
That's a neat bit of history. I wouldn't sweat it too much. There are a lot of original bikes out there. There aren't a lot of unstamped ones!

On a side note, the title year doesn't necessarily match the vin plate on a lot of bikes. Typically titles were issued stating the year the bike was sold. I have a CB350 that says 1973 on the title. It's actually a 1972, but it sat on the showroom floor and didn't sell until 1973 when my dad bought it.

The year discrepancy is a just another neat piece of history.
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