Author Topic: Does anyone have a Yoshimura ported head?  (Read 349 times)

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Offline gschuld

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Does anyone have a Yoshimura ported head?
« on: February 03, 2019, 04:19:17 am »
I’m looking to find someone with a head ported by the Yoshimura company in the 70-80s.  Cb750 head preferable, but others OK too.  I’m looking to see the style of porting they incorporated, specifically “valve guide out” porting or “valve guide in” porting.

George

Offline teebee67

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Re: Does anyone have a Yoshimura ported head?
« Reply #1 on: February 03, 2019, 12:02:21 pm »
George,
I have a Yoshimura ported head which was done back on the day. It is fitted to my Yoshimura engine but a can try to get pics from outside the ports if that is any use to you?
Tony
I'm only old on the outside.

Offline gschuld

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Re: Does anyone have a Yoshimura ported head?
« Reply #2 on: February 03, 2019, 12:54:09 pm »
George,
I have a Yoshimura ported head which was done back on the day. It is fitted to my Yoshimura engine but a can try to get pics from outside the ports if that is any use to you?
Tony

Yes, that would be fantastic😉.  A few good pictures up the intake ports with a smart phone with the flash on would be great.  Exhaust port a secondary interest.  That would tell me a lot.

George

Offline turboguzzi

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Re: Does anyone have a Yoshimura ported head?
« Reply #3 on: February 04, 2019, 05:18:13 am »
george, pics are better than nothing but honestly, seek someone who can make silicon castings... see attached pdf.
im working quite a bit on the subject and exact shape and dimensions are super important for flow numbers, nearly impossible to judge from port pics

i use this

https://www.smooth-on.com/products/mold-max-30/



Offline gschuld

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Re: Does anyone have a Yoshimura ported head?
« Reply #4 on: February 04, 2019, 07:00:09 am »
Yossef,

I totally agree, I am first trying to identify the porting styles in general and more specifically whether the particular cb750 head I have was plausibly ported by Yoshimura as was suggested possible by the seller(as 3rd owner of engine, 1st owner reportedly spent a pile with Yoshimura in the mid 70s, it had a hand bent Yoshimura stove pipe race exhaust and a set of Smoothbores 29s on it at the time that Ted (Ricky Racer) has kept.

Knowing whether Yoshimura stamped the parts they modified would be a great help too.  That was common back then(RC Engineering, etc)

George

Offline gschuld

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Re: Does anyone have a Yoshimura ported head?
« Reply #5 on: February 04, 2019, 07:02:19 am »
For example, this is the intake port of a cb550 head that is also attributed to Yoshimura.  Notice both are “valve guide in” style.

George

Offline teebee67

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Re: Does anyone have a Yoshimura ported head?
« Reply #6 on: February 04, 2019, 08:03:20 am »
Took some pics George but the quality is poor, I will try to get some better ones in the week if you
want me too. I haven't had the head off so don't know if there are any marks or stampings.
I'm only old on the outside.

Offline gschuld

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Re: Does anyone have a Yoshimura ported head?
« Reply #7 on: February 04, 2019, 09:20:00 am »
Mine vs your head.  They sure look similar...😉

George


Offline teebee67

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Re: Does anyone have a Yoshimura ported head?
« Reply #8 on: February 05, 2019, 02:21:02 am »
Yes they do George.
I'm only old on the outside.

Offline PeWe

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Re: Does anyone have a Yoshimura ported head?
« Reply #9 on: February 05, 2019, 04:45:18 am »
I could not resist to adjust a little for a clearer view ;) 
« Last Edit: February 05, 2019, 06:11:24 am by PeWe »
CB750 K6-76 1005cc JMR Billet block.
CB750 K2-75 stock looking project started 2017

Offline Medyo Bastos

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Re: Does anyone have a Yoshimura ported head?
« Reply #10 on: February 05, 2019, 04:59:29 am »





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Offline gschuld

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Re: Does anyone have a Yoshimura ported head?
« Reply #11 on: February 05, 2019, 07:16:30 am »
Thanks Per.

Medyo, is that one yours?

Is it stamped Yoshimura anywhere?  It sure looks like a comparable porting style to other assumed Yoshimura porting examples.

George

 

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