83 KZ1100 Shaft BS34 float level?

I'm having a lot of trouble with the floats on my KZ1100 with BS34 carbs. The KZ1000 kz1100 service manual says to set them at 18.6 mm above the carb body gasket surface. When I do that it seems like that fuel level is very high. When I was bench testing them I had them in a jig set at the correct ride angle and pulled some float bowl screws. As soon as I had the float bowl loosened gas started pouring out around the float bowl gasket. Now in normal operation that fuel should never be that high right? In other words the clear plastic tube check shows them at or above the float bowl gasket. But I can't find a clear plastic tube level in that manual. But I do know it's supposed to be below the gasket level. When I first took these apart, new to me bike, they were set at about 20 mm. So now I'm asking if anyone has or knows the correct float level starting point?

Are you sure you are measuring correctly; carbs upside down and measuring to the correct place on the float as shown below? Ed

Yes I measured correctly. Now I'm beginning to wonder if a PO put different carbs on it? But I can tell you right now 18.6 mm allows too much fuel into the bowls. I have a set of BS34 off of my son's KZ1000 and I think I'll pull the bowls on them and see how they are set. One of the drain plug screws head is all messed up so I can't reliably measure using the clear tube on all four so that's why I'm looking for a mm measurement as a starting point. I just did 2 sets of BS34's for a couple of Suzuki I had so I'm also looking in that service manual. I wondered why when I first took them apart for cleaning the floats were all at about 19 to 21 mm.

18.6mm seems low (leading to a high fuel level). The Suzuki bikes using those same carbs typically used a float height of 22.4mm to the gasket surface. I wonder if the 18.6 mm is supposed to be measured with the gasket in place?

Another thing, when you measure float height it's important to make sure the float needle spring isn't compressed. If the weight of the float causes the needle spring to compress consider getting some new needles. At minimum, hold the float up and measure the float height when the float tang just touches the needle.

I set my floats to measure 3 mm (+/- 1 mm) below the bottom of the carb body lip that overlaps the bowls, regardless of the upside-down mechanical 18.6 mm float measurement. That measurement became non-relevant when the clear tube method was discovered (here).

Thanks for the replies. I just saw that 22.4 was what I set my Suzuki carbs and they ran great. As for the 18.6 measurement it won't work on these carbs I have. And yes I like to use the clear tube method but it helps to have a starting point measured from the carb lip where the gasket goes. Also if you read my previous reply at least one of the drain screws head is destroyed by PO and rather than drill and use extractors I'd like to get the close with my digital calipers.

I'm going to try 22.4 and see how that does, By my calculations that would lower the fuel level about 6 mm from where it is now and that would be pretty much in line with 5 mm clear tube level. Worst case is #3 will stop overflowing and it will run a little lean(must have missed on the float setting when I replaced the needle and seat on that one). I'm just getting this bike on the road so I'll keep an eye on the spark plugs for mixture.

Thanks again.

jdvorchak wrote: Thanks for the replies. I just saw that 22.4 was what I set my Suzuki carbs and they ran great. As for the 18.6 measurement it won't work on these carbs I have. And yes I like to use the clear tube method but it helps to have a starting point measured from the carb lip where the gasket goes. Also if you read my previous reply at least one of the drain screws head is destroyed by PO and rather than drill and use extractors I'd like to get the close with my digital calipers.

I'm going to try 22.4 and see how that does, By my calculations that would lower the fuel level about 6 mm from where it is now and that would be pretty much in line with 5 mm clear tube level. Worst case is #3 will stop overflowing and it will run a little lean(must have missed on the float setting when I replaced the needle and seat on that one). I'm just getting this bike on the road so I'll keep an eye on the spark plugs for mixture.

Thanks again.

That setting should get you to about right with them. I had the bowls off my retired set of BS34 carbs last night, and checked the measurements on the two outside carbs. To the metal surface under the gasket 22 mm +

Above the edge of the lip 18.6 mm +/-

Thank you daveo. Now that you mention 18.6 above the lip of the carb body I went back and looked in the service manual and you can clearly see the picture shows the 18.6 measurement from the lip not the bottom of the groove where the gasket goes. I guess i just outsmarted myself because every other manufacturer, Honda, Suzuki etc measure from the gasket base not the lip.

I am just happy that I found something wrong, float level. I bought this bike about 3 weeks ago and have been trying to get it running right since I pulled the carbs for cleanup. I have the valves set, oil leaks fixed and both MC rebuilt. it would run and you could ride it but #1 had a dead miss until about 4 or 5K RPM. It would pop and sputter a little, then catch and try to jump out from under you, So I knew I had a carb problem I just couldn't find it. Actually I had two problems with the carbs, now 3. #3 float needle and seat leaked and was stuck in the carb body. Heat and finally vice grips were used to pull that needle seat destroying it, It was leaking gas around the float seat 0-ring. New needle and seat fixed that. #1 carb was getting little to no gas in the bowl, fixed that with carb spray and compressed air. Must have had some chunk of something partially blocking the inlet screen. And now the float levels measured wrong.

I have a pretty full day of other commitments but I will find time today to set the float valves and hopefully be riding it this after noon.

Thanks again all!

Ok stick a fork in it, it's done. Set the floats to 22.4mm (18.6 above lip) and runs on all 4 now. Actually runs pretty good for not having set the mixture and sync yet. I wanted to ride it a couple of miles before I sync them and do final tuning on the mixture. After only two miles the idle was up about 800 rpm from where I set it after first fire up. So a couple more miles and it settled down. Still have some decel popping so I have to see if it's an exhaust leak or too lean. I'm thinking exhaust leak where the header collector fits into the megaphone.

Thanks again to everyone and your excellent suggestions but I think I got it now.

Nessism wrote: 18.6mm seems low (leading to a high fuel level). The Suzuki bikes using those same carbs typically used a float height of 22.4mm to the gasket surface. I wonder if the 18.6 mm is supposed to be measured with the gasket in place?

Another thing, when you measure float height it's important to make sure the float needle spring isn't compressed. If the weight of the float causes the needle spring to compress consider getting some new needles. At minimum, hold the float up and measure the float height when the float tang just touches the needle.

Thank you. The is the way I usually set float levels. I rotate the carbs until the float swings free then slowly rotate back so the tang just touching the needle. That way even the weak ones will allow me to set them all the same.

You should set the screws now then decide what to do.
Steve

swest wrote: You should set the screws now then decide what to do.
Steve

Agree and I will do that tomorrow then do the sync. I think it has settled down now. The tank is easy to pull on this one so I can sync as often as I want but want to start out synced before I take it for a long-ish ride. I'm still feeling the old girl out now. Had it up to 55 for a mile or so and nothing bad noticed. It was quite smooth. Blew a left rear turn signal bulb but got that replaced and re-adjusted the clutch free play at the lever. It was too tight for my liking so I'm not worried that the cable is worn but I do intend to lube it before I ride it again. You know all of the normal maintenance stuff that the PO should have been doing over the past several years.

But the main thing is it takes the throttle at any RPM, no off idle hesitation and no sputtering all the way to red line. I'm happy,

Oh there is one thing. I noticed it has 120 mains but I figured that is fine for now, especially how throttle responsive it is. I do have a K&N air filter (stock air box) and Vance and Hines 4 into 1 with megaphone so I think probably 120's are fine with this setup.