I've become the current owner of a split head type of cylinder head for the Suzuki GT750.
The story behind why Suzuki developed this type of cylinder head have been very unclear to me and many others I have asked. I received some more info recently from another GT750 owner, Tadahiko Nomura who lives in Yokohama, Japan.
Tadahiko enjoys getting in contact with GT750 owners in other parts of the world and have been very helpful. Tadahiko sent me this fine photo of his GT750 collection (check out the police model, the Wunderbaum scent tree ! and the 1971 model to the left. At first it looks like it has the split head but this type of head is the one used only on the 1971 japanese market GT750. So there remains a few details to explore further...
Tadahiko could tell enough to at least solve a major part of the mystery. His answer also gave an insight into how the japanese home market looked like in the early 70's, something which have not been told very accurately in the GT750 production story we are used to reading.
The model known to us as the GT750J existed as a 1971 model on the japanese market.
By the way all the GT750 bikes you can seen in that japanese "Wild7" TV series are 1971 bikes.
(if you had a chance to see any of these from the DVD edition that Tadahiko provided some people with a couple
of years ago)..
In the japanese parts catalog pages (see below) the 1971 model is named "1".
(The 1971 model didn't have the same cylinder block, head, carburetors, exhaust pipe flanges as on the model later
exported as the GT750J. That is another story that I hope to learn more about from Tadahiko at a later date.
The model we know as the GT750K (the 1973 GT750) existed as the 1972 year model on the japanese market, where it was named the GT750B1. All B1's have the split head. There were also a B3 model produced with this head. See the parts list below. All of these were only sold on the japanese home market.
What remains to answer regarding the split head is WHY this type of head was produced and put into serial production compared to the type of head that was used on all exported GT750's.
Stories are told that Suzuki importers around the world received some homologation bikes (pre-series for registration/approval
purposes) that was equipped with this type of head. Apparently almost identical specification GT750 machines produced
for the local japanese market was exported outside Japan with a one year delay. A few of these pre-series bikes
(most likely japanese models) have ended up in the hands of Suzuki owners outside Japan but the history about their
history have been largely unknown outside of Japan.
This shows the gasket used between the head halves.
I found it in in a japanese GT750 gasket set but it was a mystery to me at the time what it was for, I thought
it was something for a totally different vehicle that had become included by mistake !
But given the new info these gasket sets fit well into the puzzle.
Here's a photo of a split head owned by a GT750 owner in the U.K
This photo looks like a GT750L equipped with a split head.
I checked with Tadahiko and he could tell this shows the GT750 "B2", a model for the japanese market which was never put into serial production. No parts catalog exists for this model (see pages below) but part from the split head this is looks exactly like what became the 1974 GT750L export model.
This seems to be the first page in our western civilisation where these catalog pages are published !
These scans show pages from a japanese market GT750 parts catalog which Tadahiko was kind to send me per postal
mail from Japan. I have scanned them and magnified them a few times for better readability.
The pages list the models "1" (1971), "B1" (1972) och "B3" och "B4" (I
don't know any about the B3 and B4 yet). I've seen from photos that the split head was used on the B1 and B3.
Pretty interesting or what ?
Tadahiko offered to purchase new head studs for me in Japan to this type of cylinder head.
So to honor his generosity I decided to proceed and let him buy the bolts for me in Japan !
So I now have more invested in this split head than I can even motivate to myself. But probably some time in the
future I'm going to think it was a good idea that I went for these bolts.
Here the longer bolts for the split head have arrived from Japan. So I now have what's needed for installing this
head on a GT750 engine in a correct way.
Tadahiko also included a gift, a solid japanese die cast GT750J model. So I will look at returning the favour in some way.
========Earlier split head speculations=============
From: "Malcolm Evans" <moevans@t...>
Date: Tue Feb 3, 2004 1:19 am
Subject: Re: [GT750] Split head - on what models ?
Hi Gunnar
One of our members Dave Buchanan, now deceased, had a good running 'split
head' model 'K' Kettle.
See http://www.thekettleclub.org.uk/memberpics/davebuchananl.jpg
It was a mystery to him how and why this version was produced, no one here
seems to have any details at all .
Malcolm
From: "Martin Krause" <martin.krause@w...>
Date: Tue Feb 3, 2004 7:41 am
Subject: Re: [GT750] Split head - on what models ?
Hi all,
to my knowledge . . . , the split heads were used only on prototypes and some
homologation bikes.
They were used up to 1973. I know about 3 examples here in Germany.
A pic (50 k) is attached, it shows a L-prototype in K-outfit, scanned from a `73
german m/c magazine.
Regards
Martin
From: mervyn hudson <yamkwazuki@y...>
Date: Tue Feb 3, 2004 12:23 pm
Subject: Re: [GT750] Split head - on what models ?
Brian Cuttler here in OZ has one to. From what I remember this came up about 18
months ago and the count was about 5 or 6 heads in the groups possession.