Not quite a carb tech tip?

[tommystinson]

I think it would be pretty cool to come up with a trick worth including on the tech tip side of the web site, so I'll continue to try. I replaced the brass floats in my '79 carbs with the plastic ones from Mikes XS. They fit perfectly, but I had doubts as to the float height specs with different style floats. Like many others, I wanted to directly observe the fuel level in the bowls. A hose barb and some clear hose in a "J" shape would do it, but try finding M8x1 hose barbs! While browsing the local NAPA store I found M8x1 zerk (grease) fittings. A couple seconds with the grinding wheel and I could pop out the check valve ball and spring. For $5, I had "hose barbs" that I wasted an entire day trying to find in every catalog I could get my hands on. Wrap a little teflon tape on the threads, push on some clear poly tubing, and zip tie it to the carb bodies. Level the bike and you can see the fuel level in each bowl. Useful for resoldered floats that might be a little heavier, an oddball plastic float if you need to replace only one, etc. It also helps to identify the rogue sticking float valve that seeps fuel. If you would like to attach the tubing a little more securely, twist some florists wire around the tubing at the waist of the fitting. You can keep the tubing attached to the fittings this way, and the teflon tape does the sealing so you can spin them in and out by hand. Smoking of any type is not recommended during this procedure. A link to the NAPA part:
http://www.napaonline.com/MasterPage...Grease+Fitting

[81xsproject]

another though for the old carbs might be using the newer rubber tipped needle valves. I think they might be a little taller, but probably nothing that couldn't be compensated for by a little bend of the tang.

[TopCatGr58]

Hey Jesse,

I thought I remembered Prom telling us that the Viton tipped float needles won't work/fit inside the older needle seats that take the solid metal ones that screw in!? Nice thought though!

Tommy, good idea, now get some photos of your modification to remove the check valve ball/spring, and of it in action, and I think you could find this thread in the tech tips very soon!
T.C.

[prometheus578]

T.C.,
He says that I can't smoke while doing this operation.
(Uhmm, I really don't think that we need tips like that. I mean... tips where I can't smoke while doing something. Might as well lock up my tool box right now.)
Other than that...I think the use of the Zerk fittings most inventive.
Really good job, Tommy.

[tommystinson]

Regarding the smoking; just checking to see if anyone actually reads my long-winded posts! As I've been known to sneak a cigarette out in the garage, once in a while. After I'll wipe my hands with carb cleaner or motor oil to cover my tracks. he he he SWMBO, what happens in the garage, stays in the garage. I'll take some photos next weekend. Should I e-mail them to you TC?

[TopCatGr58]

Hey Prom,

Sure you can smoke, as long as you've got your fire Xtinguisher nearby!
T.C.

[skids]

To tell you the truth, I dislike doing manometer methods on carbs. What I think would really be useful is your results when comparing a used OEM float against an aftermarket one and then flipping the carb upside down to measure the "float height" differences the usual way. Then you could determine a float height using a caliper for that brand. Yeah, I know...I am whining again. I am thinking that the errors involved in the manometer method might throw off the significant digits when using a caliper however.

[fredintoon]

Float height

Hi Tommy,
FWIW, the Clymer's supplement for '80 & 81 plastic float carbs sez the float height should be 23mm.
Fred Hill, S'toon.

[skids]

I wonder if a person could set the oem float and a non eom float on a pivot rod, float them on gasoline, and somehow take direct height measurements using a caliper? I might at least give you an idea into how much that 23mm would change in regular measurements.

[HobbyMan]

I have a question: You set the float height from the base of the float. If you measure the height of the fuel using a hose of some sort, how do you know what the fuel height is supposed to be?

[fredintoon]

Start at the beginning

Hi Hobbyman,
First set the floats how the book sez and then be sure the bike runs nice.
Now you have to make a jump of faith and tell yourself "The fuel level is now where it aught to be."
Then use the manometer method to find out where that is.
Thereafter you can check the fuel level height whenever you want to.
Check all 4 carbs. Finding different heights in different carbs could help a person attempting to discover what's going on in Carb City.
Fred Hill, S'toon.

[81xsproject]

That is a good point hobbyman. By setting the floats at what is the base when the carbs are right side up, then there is a buoyancy factor to the floats themselves. The different floats probably have different buoyancies. I think that for the first time I set the floats, I would do the upright-with-fuel-clear-hose-method. To get the right fuel height, then measure the float height on upside down carbs, get the average between the two sides, and then set all the floats to THAT height. Long and involved, but after the one time you would know for sure what the new float hight should be.

I know this is pretty much what fredintoon says above, sorry

[eroellig]

Great tip! I'm interested to see the pic's. I picked up some clear fuel line last year, but I hand't given much thought to how to get the line attached to the carb bowls yet.

I'll be doing bench adjusting "soon"....

Eric

[yamtom]

manometer float height

Hi,

I know this is an old topic, but my Clymers manual in the late model ,,back area, of the book, shows what is a yamaha tool that does what stimsons assembled tool does. Only Gawd knows whether this tool is available, but why care when Tommys tool should work so well. Also, the appropo height of that fuel level, as seen from the side, is just a bit lower, than the dividing line between the bowl and the carb body.

[TomRodgers]

This may be WAAAAAAAAAAAAYYYYYYY out there.....and a little more info on the float bowl covers may be needed.....I dont have the resources to do it...but i may know someone who is out of work that would try.....

What about making a clear float bowl cover to use while 'tuning'...or would that be too much of a pain?

They guy i know is very resourceful when it comes to working with plastics. only issue would be the orfices in the bowl itself.....but at low idle....just to check float height....

Tommy's idea probably A LOT easier....

Ill go back to work now....