Float adjustment

[DavesXS]

This is probably going to sound stupid to most.


I am sitting here scratching my head at this. Those japs like it complex and precise.
The book says float hight 1.012 inch +- .04
Or 25.7mm +- 1mm
Well 25.4 is 1 inch
.012 is less than 1/64 of an inch


They could have said simply said 1 inch or 25.4mm (+- what ever)
Or simplier than that, a hairs width over an inch.

Does less than 1/64th(.012) make any difference if +- .04 is ok? Or .3mm (1/3rd of a mm)


What do some of you run float hight at?

[tarzan]

Hey davesxs,
If you multiply 25.7 x .03937 it equals 1.011809.Or 25.7/25.4=1.011811.Either way it is 1.012"
Hope that explains it

[TopCatGr58]

Hey Tarzan,

Dave understands the measurements, it's just his frustration with WHY they/Yamaha couldn't have designed the carbs so that the float height adustment would have been an EVEN 1.00 Inch, or just 25.4mm which is also an INCH, instead of the extra .012".!

Dave, folks vary their heights for a variety of reasons and levels of performance, richening or leaning them to suit their needs. Since the range they state is + 1.00 mm/.04", you would think they could have used the 1.00" even amount?

T.C.

[tarzan]

Sorry I didnt mean to insult anyones intelligence.I guess the jokes on me eh.It would make it easier if they just tried to stick with simple #'s. Like you refer, to they could call it out 1" and it is still in tolerance.

[petejw]

hi Dave
r u thinking of changing the fuel level
2 fix the off idle stumble?

[tarzan]

Hey dave, I just looked at your profile to see what bike you have.I dont know what carbs you have ,but my 80SG floats are suppose to be set at .906(23mm).I actually set them at.92.If you have the same as I do your float height isn,t supposed to be set at 1.012".I am no XS guru yet for sure but I think its the 79 and older carbs set lower in the bowl. If I'm wrong please disregard.Just a thought

[DavesXS]

Originally posted by petejw
hi Dave
r u thinking of changing the fuel level
2 fix the off idle stumble?

Yea, I could have bumped the floats on the end bowls while swapping pilots out 3 different times.
Since it doesn't change rpm when I spray the carb boots, and I can get the idle good., once the throttle begins to open it becomes off ever so slightly. So it makes sense I could have uneven float hight by just a fraction.

Originally posted by tarzan
Hey dave, I just looked at your profile to see what bike you have.I dont know what carbs you have ,but my 80SG floats are suppose to be set at .906(23mm).I actually set them at.92.If you have the same as I do your float height isn,t supposed to be set at 1.012".I am no XS guru yet for sure but I think its the 79 and older carbs set lower in the bowl. If I'm wrong please disregard.Just a thought

Factory carbs that come on the 80 special.
Where did you find that the level should be 23mm? Thats more than the +- 1mm from 25.7?


I figure I'll set them dead on 1" but from reading, the most important thing is that there all the same exact level.
If I get any flat spot in the upper rpm's then I can tweek them up a hair.


TC, thanks for explaining,

Even if they didn't make it 1" even because to them its 25.4
They could have gone with flat 25mm

[TopCatGr58]

Hey Dave,

The 78-79 series carbs with the metal floats use 25.7, but the 80-81 series aka G,SG,H, SH carbs have the plastic floats, and the new setting is 23mm. In 81 Yamaha suggested using the clear hoses on the bottom of the float bowls in actual use testing to measure and set them....but it's a PITA!! SO....if you have the 80 carbs/bike then you probably would want to set them closer to the 23mm height. SO...the stumble you have could be due to too low of a fuel level from using the older setting vs. the 23m!
T.C.

[DavesXS]

Ok Finally got to the floats this morning.

They were way off. 1,2 had the level in the bowl a few mm higher than 3,4. The PO must have leaned on the outside float on #1 because it was bad off.

This explains the reason for the big difference in idle screw turns on 3,4.
1,2 were sucking way more gas with high level in the bowls.

I set them all dead on 23mm.

Now I guess I have to sync and tune again.

This time it should tune right up. Gonna use dampeners in sync gauges this time too

Also could have been leaking air at the head/carb boots gasket on a couple. Cleaning and sealing boots now too.

Not that any of you need to know this now, but for future searchers can find all they need to know about this subject in a short easy to read thread.

I guess first thing to do before tuning carbs would be to check float levels.