125 performance

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125 performance

Postby houserjw » Sun Apr 14, 2019 10:31 pm

Somewhere I have seen an article or shop dope for performance upgrades on a 125 motor. I don't remember many details but I do recall one item was opening the ports from the cylinder to the case halves. I have my motor apart for new seals and figured this would be a good time to see if I can make it have a bit more power. Can anyone point me in the right direction please?

Jon
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Re: 125 performance

Postby Mutt » Mon Apr 15, 2019 7:57 am

try this
Puckett spec sheet 1.jpg
Puckett spec sheet 1.jpg (418.55 KiB) Viewed 1498 times

Puckett spec sheet 2.jpg
Puckett spec sheet 2.jpg (279.11 KiB) Viewed 1498 times
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Re: 125 performance

Postby billc » Mon Apr 15, 2019 10:05 am

is this the piston mod that goes with that ?
Attachments
101_3321.JPG
101_3321.JPG (278.68 KiB) Viewed 1480 times
101_3320.JPG
101_3320.JPG (104.57 KiB) Viewed 1480 times
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Re: 125 performance

Postby Mutt » Mon Apr 15, 2019 10:28 am

yes, but it looks like that's a 165 piston
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Re: 125 performance

Postby badger34 » Mon Apr 15, 2019 11:43 am

Mutt, thanks for posting the Puckett spec sheets. Maybe the first time I've seen those in full myself.

For kicks I'm posting below my grandfather's porting info for the two engines I have with my '56 ST165. The original ST165 engine is assembled and crated, it was modified by my father & grandfather shortly after my father originally purchased the cycle in Nov 1955. A modified BT175 engine is currently in the cycle, I don't know when this engine was obtained & modified by my grandpa. My grandfather was employed in the H-D Juneau Ave experimental department at the time the ST cycle was purchased and the engine work was performed.

Image
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Re: 125 performance

Postby badger34 » Mon Apr 15, 2019 11:56 am

125 engine mod article found on pg 4 in this section under topic "Article from 1954".

Image
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Re: 125 performance

Postby Mutt » Mon Apr 15, 2019 11:57 am

Those are teh stock port timings. Did they make a sheet for the 2 motors they modified?
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Re: 125 performance

Postby badger34 » Mon Apr 15, 2019 12:18 pm

Ah, thanks again Mutt! That explains why grandpa's numbers were confusing to me when I compared them to the Puckett info briefly. I will look for more info but that may be all I have. Could be grandpa just recorded the stock port dim's before performing modifications. My father does remember doing port & piston work and ordering the Puckett stuffer plate for the 165 engine. The 165 engine has been crated for probably 50 years and I'm unsure of it's running condition although it does turn over and have compression. The 175 engine currently runs and has been in the cycle since I obtained it in 1982. I've never had either engine apart to examine the internals.
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Re: 125 performance

Postby Mutt » Mon Apr 15, 2019 1:51 pm

get out that 165 and fire it up !!!!!
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Re: 125 performance

Postby houserjw » Mon Apr 15, 2019 2:02 pm

Thanks, the "Six horsed for six bucks" is the one I remember.
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