Float height adjustment – gt250
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Hi everyone,
Bit confused as to setting the float height.I understand that 7mm from the top of the float to the face of the carb is the correct spec (measured as the floats just touch the float needle pin). However, when I attempt to reach this measurement the ‘springiness’ of my float needle is gone and the float tang itself is severely bent so I can reach the correct height. The other float (which is brand new) is springy but reads a much higher set height (well above 7mm and therefore out of spec). What could I be doing wrong here? Float and float needle are brand new.
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Thought I’d add more picture for further context.
Top float = unadjusted
-Fits perfectly with good travel
-Bounces on needle valve
Bottom float = adjusted to meet 7mm spec.
-Fits but has little travel. Feels as if when the tang touches the float needle pin there is little travel as I gently push the float towards the fully closed position (can reach fully open position just fine)
Pardon my ignorance, this could be perfectly normal and I’m just being paranoid. But hey it doesn’t hurt to double check.
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UPDATE:
Set floats to 7mm and put the carbs on the bike. It idles now and I am able rev the engine however only with a very slow input of throttle. If I give it a moderate turn it’ll cut out. Furthermore, If I rev it and it comes down to idle it’ll cut out (e.g. 5000rpm -> idle).
I have not made any adjustments to the needle groove settings.
I have an auxiliary tank plumbed into the carb fuel intake that is gravity fed only just in case that has anything to do with it.
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UPDATE #3
Went for a test ride and the bike doesn’t seem to accelerate correctly. At idle and revving at a stop the bike runs as normal. When I set off at the point where the carbs switch from the pilot to the main jet I get really slow acceleration. At WOT it feels as if the bike is accelerating at 1/8th throttle. Does anyone have any idea what it could be?
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Hmmm,
– If you take the carbs off 1 more time => Check the float is 7mm or (7.5 absolute max) and lift it up , if you lift up the float it should rise from 7mm to around 14-17mm ish
- Set the carb mixture screws to zero (full stop clockwise) then then then anti clockwise 2.5 times on each carb. Leave it there forever.
- Check the slide needles and follow this tutorial (click here)
Re-assemble parts together (make sure carb is firmly on the airbox first!) , then drop the whole thing down to the rubber intake pipes , make sure they don’t try to squash them down, this avoid the rubber intakes from splitting up as they are truly rare parts these days.
The carb marrying the airbox first guarantees there should be no leaks at the top.
when it is running , carefully in the open area (ventilated spaces) spray carb cleaner on the intake rubber pipes to see if you have any air leaks that will affect the overall running of the bike.
// Meditation doesn't mean you have to sit still....
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I don’t think it could be the floats as the bike seems to starts and idle virtually perfectly. I took the airbox off and ran the bike just to see if the slides were to blame and they’re also moving from 0-100% and back to 0% just fine. Pretty much I just have that weird acceleration issue when the carbs switches from the pilot circuit to the main circuit. Bit of a head scratcher.
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If the floats give you drama , go back to factory float, factory float seat well , factory float needle. Start there.
If using new floats , try with their needle seats that came with the gasket kit.
This is because there could be a slight variance of 1mm height difference , the carb needle may have a soft bounce as OEM floats a tad little smaller and more curved , the aftermarket floats would be a little more “boxy shape” with their needles from gasket kit having stronger spring (maybe 2%)
Also the float seats have a HOLE size relative to the needle it is using.
Ie. OEM float seat would say 1.0 , the carb rebuild kit version would probably say 1.5 – Hole size might allow more fuel in easier as long as it is used with it’s supplied needle (the needle may be a little wider to cover the hole) like 0.5mm wider (very marginal!)
Just my thoughts at 10am , so sorry for any grammatical errors , keep us posted!
// Meditation doesn't mean you have to sit still....
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The floats and the needle seats assembly controls the bike from idling all the way to 5th gear , sometimes 5th gear is so thirsty if the float doesn’t rise or lower properly the main jets feel like they can’t reach the fuel as it drains by engine consumption
or check fuel puimp and the fuel tap , sometimes the fuel tap in the tank is the one holding up the bike under full load (bike is moving on the road)
Regards
// Meditation doesn't mean you have to sit still....
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A wet-check is safest way to see if level is right. You need 20++cm of translucent hose ~Ø =6mm(?) for the bowl-tap…
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): GT250R-efi
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