TOPIC:

Hello,

I have a 1978 KZ1000-A2. I purchased this motorcycle several years back. Looks great, but I've spent A LOT more time working on it than riding it . I've had some time recently, so I am going over MANY things on the bike, but this is a specific question about the carburetor float valve needle.

I actually rebuilt the carbs a couple years ago with cheap-ish online kits. At that time I reinstalled the original float valve needles because they have this internal spring to smooth out the interaction between the seat, valve, and float (I presume). The valve needles in the rebuild kits looked just the same, but did not have the internal spring action. Not knowing how important the spring effect is... I put in the old parts in that past rebuild. With my work now, I opened up the carbs again to make sure they are clean. On inspecting the valve needles, I see that the tips are "a little worn." They are not as bad as the "bad" images in the service manual, but there are not nice straight cones either. They do have some noticeable wear in the manner that the service manual indicates. I doubt I can get a good image, because you need to look close and turn them around.

I can put the old "little worn" valve needles (with the internal spring) back in. Or, put the fresh ones from the past rebuild kit in that don't have the spring. Or, buy more, but will they have the internal spring??? So it's a call between how bad is a little wear (old ones) vs. how important that internal spring is (not on new ones). I don't know enough to make that decision with confidence. Any advice? Thank you!

Are your carbs leaking? If not then I think you are OK with the old valves.

Genuine mikuni parts over after market parts everytime.
You shoud clean the seats to ensure the concave and convex cones mate correctly. Best way I have found is toothpaste,a cotton bud and a good twizzle.

Mikuni doesn't offer float needles as a separate part, you have to buy the needle and seat together as a set. I'd get new Mikuni parts. They are vastly superior to aftermarket parts. I think the stockers are 2.3 size which indicates the hole size. Mikuni parts sold to the after market come in .5 increments so your choices are 2.0 or 2.5. Suzuki GS1000 bikes used 2.0 or maybe even smaller so those should be safe for your bike.
www.denniskirk.com/mikuni/vm26-26-needle...70235.prd/170235.sku

These look like the same parts but using a viton tip needle. www.denniskirk.com/search/786-15005.q

I once used cheap float needles from one of those kits. Pulled the carbs several time trying to adjust them so they wouldn't leak. I ended up digging the originals from the trash and reinstalled them with no more problems.
It is defiantly better to have spring loaded pins on the needles. They keep the fuel level a bit more consistent as fuel sloshes around in the bowls.

Thanks everyone for the replies!

hardrockminer,
Thank you for the very practical question. I thought I'd get that, haha. The simple answer is "no," but I have little running experience with the bike such that I'm unsure and while everything is apart, I just want to do the best I can to reassemble in good shape.

Based on several replies, I agree with Mikuni parts. At this point, although I have the original needles and seats, I don't have them matched (I won't go into why), but considering that they have different wear patterns, it make sense to go with new genuine parts. I will go for that.

I have a couple related questions about the carbs, but unrelated to the float valve, so I will likely start a new thread, as subject for this one is specific to that part. Thanls again!

Look at the number on your original float valves. I think they are 2.0. Be sure whatever you buy is the same number. Otherwise you will not have the correct float settings.

Thanks. They are 2.3, as Nessism was thinking. But, it does look like I can only buy 2.0 or 2.5. Nessism suggested 2.0, so I'll go with that if no major concerns are raised.