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250 to 305 conversion

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jvmills
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Location: Wilmington, DE

250 to 305 conversion

Post by jvmills » Mon Feb 20, 2012 9:37 am

Just purchased a 1965 CL72. The top end has been changed to 305, What are the consequences? Motor and frame numbers indicate an original motor.

LOUD MOUSE
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Re: 250 to 305 conversion

Post by LOUD MOUSE » Mon Feb 20, 2012 10:28 am

Ya can bet the top engine case has been machined so the 305 sleeves would install.
Check for carb spacers with 25-26 on top.
22-22 would be 250.
Check carbs to see if CL77A has been stamped at the top of the mounting flange.
Ya have all that ya basically have a 305

jvmills wrote:Just purchased a 1965 CL72. The top end has been changed to 305, What are the consequences? Motor and frame numbers indicate an original motor.

conbs
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250 to 305

Post by conbs » Mon Feb 20, 2012 4:18 pm

Are the holes in the counterweights different sizes for the 250 vs 305 and if so, will that be a problem for a 305 top end on a 250 crank?

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Hotshoe
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Post by Hotshoe » Mon Feb 20, 2012 4:19 pm

If it's a 305 with 247 barrels, one of the consequences could be that you'll have a very competitive 250 class vintage racer.

jvmills
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Post by jvmills » Mon Feb 20, 2012 4:43 pm

Thanks for you reply and info. Gotta love the internet and people willing to share their passion. Have turned a wrench or two in my younger days, but would call myself a newbie. Have maintained my 87 Electra glide classic last 15 years, but new to Honda. Have been bitten by classic bike bug. I saw a article few years ago about the American Motogiro and have dreamed of participating. I just treated myself to a qualifying bike. I want a daily rider type bike. Not a museum piece. Am concerned about the added stress on the lower end. It is one of the first hundred of the line. Don't want to screw up anything of value (not in the $$$ sense. Bought it to ride) Has been "customized" and would like to restore it to what it once looked like. Don't have the bike yet. will pick up next week. Link to ebay site i got it from.
http://cgi.ebay.com/ebaymotors/ws/eBayI ... 1439.l2649

LOUD MOUSE
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Re: 250 to 305

Post by LOUD MOUSE » Mon Feb 20, 2012 4:52 pm

The crank weight is different for sure but as there are LOTS of this type mod running today with no problems I'd not worry. .....lm

conbs wrote:Are the holes in the counterweights different sizes for the 250 vs 305 and if so, will that be a problem for a 305 top end on a 250 crank?

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davomoto
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Post by davomoto » Tue Feb 21, 2012 11:54 am

I hve a CL72 lower end wit a 3mm overbore 305 top end. It runs great, no excessive vibration. I wouldn't worry about it.

Davo

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