Solex

[oldjapanesebikes]

I'm looking for either confirmation, or denial whether any of the BS40 carburettors used on the GT750 had SOLEX cast on the top cap covering the diaphragm. If true, then these would likely have appeared on early 1974 'L' model GT750's, possibly only in some markets.



Anyone have a bike with these ? If so, please email me a photo ( ian(at)oldjapanesebikes(dot)com )and I'll include it in the next update of the GT750 Field Guide - thanks !

[oldjapanesebikes]

Well - I finally was able to get to the bottom of this thanks to Steve in Melbourne (his shop/museum by the way is found at http://www.antiquemotorcycle.com.au" onclick="window.open(this.href);return false; and well worth a visit) who pointed out that the owners manual clearly shows SOLEX on the photos of the carburettor caps.These are found around page 40 to 43 in most copies I've checked.

So the question then would be whether any GT750's were actually sold with SOLEX carburettor caps, or whether the photos are just from a pre-production model used for the company documentation prior to general manufacture.

[Suzsmokeyallan]

Ian I believe your findings as the only place I've actually seen the Solex lettering was on some BS38s. I'm constantly looking for that elusive Solex cover on any 74 GT750 carbs that come up for sale as well.
Heres some Yamaha XS top covers for sale on Ebay at present, some with and some without Solex on them.

http://www.ebay.com/itm/Yamaha-XS650-Ca ... 73&vxp=mtr" onclick="window.open(this.href);return false;

[old racer]

My official uk bike, registered in march 74 does not have SOLEX Tops.

[oldjapanesebikes]

My official uk bike, registered in march 74 does not have SOLEX Tops.

That matches what I have seen so far - I suspect there must have been a change in the licencing rights held by Mikuni. The ones used on the Yamaha XS650 in 1975 and later do not have SOLEX on them either, the 1973 and earlier do, and the 1974 ones seem to be mixed - most don't have it, but some do.

[old racer]

Maybe,Just maybe Mikuni employed Solex to make parts for them for a period.
Maybe they couldn't keep up with demand.

[oldjapanesebikes]

Maybe,Just maybe Mikuni employed Solex to make parts for them for a period. Maybe they couldn't keep up with demand.

Well - if you check the company history, Mikuni signed a licencing agreement with Solex in 1960 allowing them to produce Solex carburettors. As a matter of interest, they previously in 1932 signed agreements with Amal and Galery to produce their carburettor designs under licence. In 1972 the company reformed as Tohoku Mikuni Koygo Co Lt and as mentioned earlier, the Solex name seems to have been dropped off the product for the 1974 production year, so it does appear to be a change in licencing terms which may have happened as a part of the new company formation.

It is just interesting to people like myself at least (yes I realise I should get a life ! ) , that the owner manuals clearly show Solex carburettors being used and these would have been photographed in 1973 when Solex was also marked on all the BS style Mikuni carburettors used by Yamaha, so the time line fits.

The link is here: http://www.mikuni.co.jp/e/information/history.html" onclick="window.open(this.href);return false;

[Suzsmokeyallan]

If the BS38 aluminum covers with Solex on them fit the BS 40s, put some on just for the fun of it.