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Author Topic: carb sputter...at a loss here.  (Read 5943 times)

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Offline TMKIWI

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carb sputter...at a loss here.
« Reply #15 on: June 06, 2012, 04:08:10 AM »
Don't hold the carb upside down when cheacking float level. If the needle has a spring in it the weight of the float will depress it. ( just like you found).
Hold the carb at 90 deg to how it normally sits with the float pivot at the top. Slowly rotate the carb upside down ( only a couple of deg ) till the float touches the needle. That will give you an actual reading.
As a rule of thumb most floats are set level with the carb along the seam where the bowl sits. Normally the top of the float is flat and that is what you should be looking at. Not the rounded bottom.
Hope you get it sorted.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline Sapper

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carb sputter...at a loss here.
« Reply #16 on: June 06, 2012, 12:35:57 PM »
TMKIWI, Thanks for for clarifying it. I wasn't sure. I haven't gotten it completely set yet. I got it to where it'll get fuel but runs out. So it'll come off again tonite for more R&D. What really ticks me off is the sputter is still there.

Then the kicker....Another guy showed up at the track, my son was practicing at, last night with a ...03 KX125...EXACT same problem. But he just bought the bike so he has no clue what jets are in it, etc.

After doing alot of internet searches, this is very common with the 03. Everyone talks about it and everyone recommends different solutions, but, NO ONE posts up what they did when / if they got it fixed. ><img src=" title="Angry" class="smiley">
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline SachsGS

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carb sputter...at a loss here.
« Reply #17 on: June 06, 2012, 03:17:36 PM »
Hold the carb upside down and sight the needle.The float assy. should be parallel to the float bowl contact surface prior to compressing the float needle pin.When the float needle pin is compressed the floats should NOT contact anything in the carb.As carbs wear,and Keihins are the worst,you have to hold the carb upside down to make sure you are removing all of the wear related slop in the float/float pin/float needle and seat assy otherwise you won't  "see it".

On Keihin carbs the pin upon which the floats pivot is a sliding fit and will simply fall out if held in the 90 degree position.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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carb sputter...at a loss here.
« Reply #18 on: June 07, 2012, 07:38:31 AM »
The other 90 deg sachs. ;)
Not side ways.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline SachsGS

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carb sputter...at a loss here.
« Reply #19 on: June 07, 2012, 02:46:41 PM »
Since you guys are all upside down,your upside down is my right side up and we are all talking about the same thing,correct? ;D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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carb sputter...at a loss here.
« Reply #20 on: June 08, 2012, 06:21:40 AM »
Yep sure are. ;D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline ford832

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carb sputter...at a loss here.
« Reply #21 on: June 08, 2012, 01:48:43 PM »
Quote from: TMKIWI on June 06, 2012, 11:08:10 AM
Don't hold the carb upside down when cheacking float level. If the needle has a spring in it the weight of the float will depress it. ( just like you found).
Hold the carb at 90 deg to how it normally sits with the float pivot at the top. Slowly rotate the carb upside down ( only a couple of deg ) till the float touches the needle. That will give you an actual reading.
As a rule of thumb most floats are set level with the carb along the seam where the bowl sits. Normally the top of the float is flat and that is what you should be looking at. Not the rounded bottom.
Hope you get it sorted.

I do mine like this but always set the float a bit higher than level.This won't effect jetting but will stop a lot of your fuel from going on the ground from the overflow(mileage and range is everything when you're trying to make it to the end of a race without refueling :D ) or from wanting to leak out when you've got it leaned against a tree.Over time it changes anyway so it's good to keep an eye on it.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline Sapper

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carb sputter...at a loss here.
« Reply #22 on: June 10, 2012, 01:27:13 PM »
UHHHGGGGGG!!!!!

latest update:
Set everything Friday night. The best I can get it to run with just a very slight sputter, no go lean and just totally rip when on the pipe, the floats were set to 8mm. Pulled it up in the trailer, put it up on the stand, checked it all over. Looked great, ran great. Came out Sat. morning...there's a nice big wet spot on my blacktop driveway. A half tank of fuel worth that ate right into it.

Dropped the ramp and it hit me. That beautiful smell of race fuel. But not how I wanted to smell it...soaked into my trailer floor.

So, here's heres what I've encountered so far:
9.5mm-no fuel, 9mm- very little fuel, 8.5-runs lean/out of fuel, 8mm runs good = leaks fuel.

So now what??
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline VintageBlueSmoke

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carb sputter...at a loss here.
« Reply #23 on: June 10, 2012, 02:08:00 PM »
Not trying to be a smart ass but...

That is what the petcock on the tank is for.

Sorry. I'll shut up now.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline SachsGS

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carb sputter...at a loss here.
« Reply #24 on: June 10, 2012, 02:40:09 PM »
Is your needle and seat assy. o.k.?
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline teampryor

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carb sputter...at a loss here.
« Reply #25 on: June 10, 2012, 02:59:51 PM »
Our experience with superminis and 125s that a bike that was previously jetted correctly its usually worn/frayed reeds that causes sputter. Have you inspected the reeds for wear or chipped or seperated edges?
We find the need to replace our v-force reed petals around 20 hours. The corners chip and the edges swell then do not seal as well resulting in the bike sputtering.
Hope this helps. Good luck
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline Sapper

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carb sputter...at a loss here.
« Reply #26 on: June 10, 2012, 07:16:38 PM »
Vintage, You...a smartass??? Noooo. LOL
I've never, ever had to shut off the fuel with a bike just sitting there. Now when it's being transported, yes. But even then I only lose just a few drops in the trailer, truck, etc on any of my bikes if we forget to shut off the fuel.

Sachs, yes, I checked it very closely.

TP, We ave V-force as well and I checked the reeds as we were putting it back together. They looked new and still fit tight to the box. Either way, I still need to get these floats right now that I moved them around. I think I'm gonna fab up my own level gauge from the bowl. It's supposed to be 10mm above the bowl mating surface.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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If you want cheap & fast, it won't be good.
If you want cheap & good, it won't be fast.
If you want good & fast, it won't be CHEAP

Offline SachsGS

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carb sputter...at a loss here.
« Reply #27 on: June 11, 2012, 12:50:44 AM »
Somehow your needle and seat assy. is leaking,either it is worn,dirty,defective seat O-ring,leaking floats or subject to an incorrect float height but you should not have "a half a tank of fuel on the floor".
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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