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Fuel Bowl level 1 month 3 weeks ago #30581

  • scotch
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Been asked a couple of times recently how I pre-set my Brass Floats  to 7.5mm consistently.  The metal attachment at the top of the tube fits into a notch and is held in place by a magnet.
1980 KZ 1300 sr# KZT30A-009997
Always High - Know Fear !
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Last edit: by scotch.

Fuel Bowl level 1 month 1 day ago #30633

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Hi Scotch, fitted the new brass floats with the settings as they came from you. When left with the fuel on, and bench tested with the fuel gauge tubes . I can see after about 15 minuets im still getting a overflow ! and all of the tube levels start creeping up. Then one of them seems to be the weakest link and flows from the rear of the carb.  I move the floats about and still having a overflow from different carbs. With no obvious results. ????

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Fuel Bowl level 1 month 12 hours ago #30637

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First off, it's not the floats, so don't bugger around with the float height setting. Scotch presets the floats so you shouldn't have to mess with them. After installed, the float bowl level can be checked and it should be correct knowing Scotch's attention to detail.

There are 2 flow paths for the gasoline to enter the  float bowl. The obvious one is past the needle and seat when the needle is open. If there's still leakage past the needle seat, it may be debris stuck to the seat or needle. The float needles should be a steel needle although I have seen Viton tipped needles in the past and they can wear and leak and should be replaced. If they are steel needles then I like to polish them with Autosol metal polish and also polish the brass seat with a Q-tip and Autosol. Then clean with Lacquer Thinner.

But in your case with all 3 leaking I suspect that the second flow path is what's troubling you. If the o-ring on the brass needle seat has shrunk due to ethanol in the gasoline, then gasoline is passing around the needle seat, between the needle seat and the carb body. You need to replace those 3 o-rings with new ones and I suggest you find an o-ring dealer that can supply o-rings in Viton 75 rather than Buna-N nitrile. Viton 75 handles the ethanol better than Buna -N

Viton 75 O-ring for the Needle Seat Body 7.5mm X 1.5mm  (as seen in attached pic)

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Last edit: by Kawboy.

Fuel Bowl level 1 month 9 hours ago #30638

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First off, it's not the floats, Scotch presets the floats so you shouldn't have to mess with them. After installed, the float bowl level can be checked and it should be correct knowing Scotch's attention to detail.

Correcto-mundo !    
Brass floats are leak-checked through-out the assembly process including after sealing the "vent".  They are set for the correct level and rechecked 3 times after this setting has been made.  Drain - fill - repeat. 3X !  When they go in a box for shipping I'm 100% confident they are correct...... and will last many many years.
".............so don't bugger around with the float height setting.  "   By all means do your due-diligence and check for your own satisfaction.  

Further to kawboys comment:  If the bore that the valve body fits in to has been aggressively cleaned to remove scale/debris, the surface can be damaged - allowing fuel to pass by an otherwise good o-ring.  It may seem like a good idea to spin - with a drill - a stainless steel tube cleaner to clean-up this area but Nylon only - if this is your intended method.

If  "Kits " have been installed - be very leery of the supplied needle retaining spring.  Some are known to be of an incorrect shape and will cause needle travel issues and hang-ups.  The aftermarket kits themselves are otherwise reliable.....or so I've found.

It's a popular misconception that fuel from the center and right carbs will flow into the left carb when the bike is on the side stand.  Fuel in a bowl remains in that bowl.  Flooding (of the left carb) is due to fuel in the fuel line migrating to the lowest point and leaking past the needle and seat.  This is indicative of the tank shut-off, (petcock) leaking and a less then perfect needle/seat fit.


 



 
1980 KZ 1300 sr# KZT30A-009997
Always High - Know Fear !

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Fuel Bowl level 3 weeks 6 days ago #30660

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Bumping this forward to make sure you saw it  Z13Phil. The O-ring on the float needle seat has been known to plague many with issues of overfilled float bowls. You've been responding to another topic regarding carb overhaul/ jetting and not responding to this topic which is more specific to your issues so I'm wondering if you read this response and looked  at the o-rings on the float needle seats  ????

First off, it's not the floats, so don't bugger around with the float height setting. Scotch presets the floats so you shouldn't have to mess with them. After installed, the float bowl level can be checked and it should be correct knowing Scotch's attention to detail.

There are 2 flow paths for the gasoline to enter the  float bowl. The obvious one is past the needle and seat when the needle is open. If there's still leakage past the needle seat, it may be debris stuck to the seat or needle. The float needles should be a steel needle although I have seen Viton tipped needles in the past and they can wear and leak and should be replaced. If they are steel needles then I like to polish them with Autosol metal polish and also polish the brass seat with a Q-tip and Autosol. Then clean with Lacquer Thinner.

But in your case with all 3 leaking I suspect that the second flow path is what's troubling you. If the o-ring on the brass needle seat has shrunk due to ethanol in the gasoline, then gasoline is passing around the needle seat, between the needle seat and the carb body. You need to replace those 3 o-rings with new ones and I suggest you find an o-ring dealer that can supply o-rings in Viton 75 rather than Buna-N nitrile. Viton 75 handles the ethanol better than Buna -N

Viton 75 O-ring for the Needle Seat Body 7.5mm X 1.5mm  (as seen in attached pic)


 

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Last edit: by Kawboy.

Fuel Bowl level 3 weeks 6 days ago #30662

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Really good info Kawboy, Thank You.

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