What are those plugs on my carbs?

Hello,

I noticed something strange on my newly bought KZ1000ST. There're some caps on 3 of the carbs. Here's a picture:



Here's a closeup:


The carbs are (non-US) Mikuni VM28SS.

BTW, the motorbike carburation isn't good. I only rode the motorbike for 30km for the moment. I'll fully clean the carbs. One interesting thing to notice is that the carburetor where there was no cap looks different than the others inside:



Do you know what those plugs are for? Should there be any caps on them? Should I remove the caps?

There is a device called a Manometer that measures vacume differences between the four carbs, for the purposes of balancing. Those four caps cover the hose fittings that the technician uses to hook up all four individual carbs to the meter.

The missing cap meant a massive vacume leak on that carb. This had to have contributed to your rough running engine (an assumption) .

Get another cap, or replace all four.

Qdude wrote:

There is a device called a Manometer that measures vacume differences between the four carbs, for the purposes of balancing. Those four caps cover the hose fittings that the technician uses to hook up all four individual carbs to the meter.

The missing cap meant a massive vacume leak on that carb. This had to have contributed to your rough running engine (an assumption) .

Get another cap, or replace all four.

Thanks Qdude!

I was hesitating between:
a) find and put a new cap
b) remove the 3 caps
The good answer was a)

Are you sure those are for the manometer? They look like bowl vents to me, if they are vents then they would need long hoses connected to them and NOT plugs. I would go to wiredgeorges website and ask, or see what your manual says....by the way what year is this bike?

Another thought (and I may be all wrong), are they the stock carbs for that bike?

Do all 4 intake manifolds have a similiar brass fitting?

OKC_Kent wrote:

Are you sure those are for the manometer? They look like bowl vents to me, if they are vents then they would need long hoses connected to them and NOT plugs. I would go to wiredgeorges website and ask, or see what your manual says....by the way what year is this bike?

June 1979.

OKC_Kent wrote:

Another thought (and I may be all wrong), are they the stock carbs for that bike?

Well, I don't know. I don't have any information about the history of that bike.

OKC_Kent wrote:

Do all 4 intake manifolds have a similiar brass fitting?

Yes.

This is a European KZ1000ST. The carburetors aren't the same as the American version. There's no accelerator pump on those.

I had a look at that page:
www.wgcarbs.com/88724.html

However, the pictures of the carbs do not seem to tally with my carbs. :S

Put a hose on the brass fittings and blow through it. If the air comes out through the bowl area, then it is a vent. If it goes to the engine side of the carbs, then it would be a vacuum source. I would think that they are bowl vents. Check all of them, because on some models, the vacuum operated petcock uses a simular fitting and draws vacuum from the engine side of the carbs. Bowl vents should be vented to the air and not plugged.
The US versions dont have 4 individual vents on our carbs, usuall they have 2 vents on the outer carbs (see pic- the 2 pairs of carbs are linked together and vent through 1 hose) and some have a vacuum source on #3 for the petcock.
Fish

Dang it. Edit again. Whats different about the carb that you have circled?

Post edited by: The Fish, at: 2007/02/22 19:18

Post edited by: The Fish, at: 2007/02/22 19:20

Post edited by: The Fish, at: 2007/02/22 19:22

Those aren't ST carbs. Here's what the right carbs look like. I don't think those came stock on any KZ.

Conti wrote:

...caps on 3 of the carbs

Do you know what those plugs are for? Should there be any caps on them? Should I remove the caps?

With engine running, is there suction (vacuum) at the brass fitting? If so, they should be capped. If you have a vacuum operated petcock, it is conceivable the uncapped fitting should have a hose running to the petcock. If there are similar fittings on the intake manifolds (holding the carbs to the engine), those on the intake manifolds are the vacuum nipples (should be capped) and the fittings shown in your picture would logically be for something else besides vacuum (perhaps for vent hoses as already suggested).

Patton wrote:

With engine running, is there suction (vacuum) at the brass fitting? If so, they should be capped. If you have a vacuum operated petcock, it is conceivable the uncapped fitting should have a hose running to the petcock. If there are similar fittings on the intake manifolds (holding the carbs to the engine), those on the intake manifolds are the vacuum nipples (should be capped) and the fittings shown in your picture would logically be for something else besides vacuum (perhaps for vent hoses as already suggested).

I know the petcock is vacuum operated since there's a prime position on it. There was a hose connected to the petcock. I'll check on the bike on this WE how that hose was connected (the bike isn't at home right now).

RonKZ650

Those aren't ST carbs. Here's what the right carbs look like. I don't think those came stock on any KZ.

I checked for other pictures of ST carbs, and those carbs definitely aren't stock.

How can identify them?

Conti wrote:

How can identify them?

tinyurl.com/28q9p2

Ask wiredgeorge at the link above..

OKC_Kent wrote:

Conti wrote:

How can identify them?

tinyurl.com/28q9p2

Ask wiredgeorge at the link above..

OK. I'll take some closeup pictures of the carbs on this WE too. Some numbers are supposed to be written on the carbs, I'll try to locate them. Than will be easier when the carbs are clean. :laugh: