2 sets of carbs - both smoothbores?

[Guest]

Need some clarification on these carbs. The ones on the left measure 29mm, so I assume they are 29mm smoothbores. 2 screws on caps. Came on a Z1R project I got.

The ones on the right came on my '78 GS1000. They measure 30mm and I was told they were smoothbores. 3 screws on cap. So they are 30mm smoothbores?.......

[Steve]

I can't say for sure about the left carbs, but the right carbs appear to be STOCK carbs for your GS.
Although it appears that the bores have been shined up a bit, that is not what makes them smoothbores.

.

[SqDancerLynn1]

Left I believe are Kaw, the rt are Smooth bores ID by the large plug on the float bowl for quick jet changes

[russr33]

Correct on the left being Kaw. I believe they were stock on the Z1R. Mainly wondering about the ones that came with the GS. They are definitely 30mm, which I'm not familiar with. Found this thread but didn't see any mention of a 30mm. Could they be 29's?

http://www.thegsresources.com/_forum/showthread.php?t=82239&highlight=roundslides

Hell I guess I have most the carb bases covered. I have flatslides on my 1000 now and roundslides on my 80 '1100.

[Old Colt]

Two ways to ID 29mm smoothbores, The big difference will be seen if you open the slide, a smoothbore has a sleeve inside the slide allowing the main bore to be round rather than having the depression where the slide travels.
A second, looking in the bore from the inlet the smoothbore has 3 bosses, one is the open passage for the metering circuit and one plugged for the idle circuit. The third is undrilled.
Looking at the 28mm carbs you have you see 5 bosses.

[russr33]

Understood. So then what would the GS carbs be? Here's a pic of the inlet. Couldn't get the camera to focus, but it is dead on 30mm at the inner radius.

[srsupertrap]

SqDancerLynn1 is correct: The easiest way to id the VM29 S/B's are they have the 17mm nut on the float bowl for main jet access. If you are going to measure the ID use a digital caliper with no pressure exerted for an accurate measurement. I bet they measure 29mm.

Not as familiar with the Kawi's but they late model KZ1000's were all equipped with VM28's before CV's. I recall reading the Cycle World article on the Z-1R but don't recall if they were messaged. Jeff Saunders would know for sure. Regardless the Z-!R carbs are priceless to the right person

[srsupertrap]

Old Colt Pic Request

Would you mind sharing a full blown pic of your 1975 Ducati 750 Sport . I would like to learn as much as about these as I can in the off chance I ever get the opportunity . . .

[Old Colt]

Right now the engine is out of my 750 Sport since I have decided to pull the heads and change the exhaust valve seats to Copper beryilium so it will live on todays street fuel. I do not have any digital pics of the bike together. I expect I must have some on film that I could scan but the bike will not be assembled till late this year. Its value is climbing rapidly and I want to make the bike real pretty so when someone finds it in my barn after I die they will be happy.
I also need to make a correction to my previous post, I just went down to my shop to measure my smoothbores, they have 5 cast bosses not the 3 I described.
Mine measure about 29.7 near the outlet and 29.4 as far as the calipers will reach in.
Have you slid your carbs open and looked to see if yours are smoothbores or just assuming from measuring them?

[russr33]

SqDancerLynn1 is correct: The easiest way to id the VM29 S/B's are they have the 17mm nut on the float bowl for main jet access. If you are going to measure the ID use a digital caliper with no pressure exerted for an accurate measurement. I bet they measure 29mm.

Not as familiar with the Kawi's but they late model KZ1000's were all equipped with VM28's before CV's. I recall reading the Cycle World article on the Z-1R but don't recall if they were messaged. Jeff Saunders would know for sure. Regardless the Z-!R carbs are priceless to the right person

Ok. I was just being thrown off by the id measurement. Yes, it is a 17mm nut on the float bowl. Thanks for the help guys

[hampshirehog]

Just to throw in some confusion, VM28s have a 29mm bore (may be a tad under say 28.9mm).

(That nut on the bottom is the giveaway for smoothbores).

[jed.only]

odd, my bike (79 GS1000) came with carbs like the ones on the left.