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Ktm 85 sx fuel flooding issue

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Okay so guys I've just purchased this ktm 85 sx 2006 model for my god-daughter as her pw80 is getting too slow and small for her. IMG_1596.JPG

 

I purchased the bike cheap as the owner had an issue with it. He serviced the carb and I think he messed up somewhere along the line as now as soon as you switch the petrol on and even touch the throttle a little, the card gets flooded and it starts pissing out the overflow pipe! So I've had it off and have cleaned it throughly with carb cleaner and blew through the jets.

IMG_1614.JPG

 

I even dismounted the reeds housing to check the reeds and found there's a hairline separation but I don't think this is the issue.

IMG_1615.JPG

IMG_1615.JPG

 

The main jet and pilot jet are nice and tight on and the air flow screw was screwed in all the way clockwise and turned 1 and a half turns anti clockwise. The idle screw was turned all the way in the give it a high rpm rev idle so that I could adjust it once the bike has started.

 

The bike kicks and every other kick it back fires but won't actually start. When I bumped it, it goes to start but you have to hold full throttle and that's super boggy with it shutting down as soon as you let go of the throttle ever so slightly. Please help as I was to give this bike to her as soon as possible!

P.s. It has a strong spark so I know it's not that and there's clear passage for the airflow from the air box so it's not that either, leaving the carb and fuel to be the issue.

 

Thank you in advance!

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sounds like a stuck float or a worn needle and seat - with the float bowl removed is the needle and seat doing its job shutting off the fuel when pushing up on the float ?

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sounds like a stuck float or a worn needle and seat - with the float bowl removed is the needle and seat doing its job shutting off the fuel when pushing up on the float ?


I can try this out now and get back to you, the best way to do it should I remove the carb but keep the fuel connected or just remove the float bowl?

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I agree with S.O.A.N.Z.  There could be some debris stuck in the float needle and seat.  The previous owner may have mal-adjusted the float.  Compare your float adjustment with what is in the manual.

Another possibility though unlikely is that the float doesn't float.  This was more common when floats were made of thin sheet metal soldered together.  They would develop a pinhole leak, fill with gas and no longer float.  When you remove the float bowl do not empty it.  Take the float off the carb and set it in the float bowl gasoline.  It should float (duh!). 

Good Luck

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36 minutes ago, kutenda said:

 


I can try this out now and get back to you, the best way to do it should I remove the carb but keep the fuel connected or just remove the float bowl?

you can leave the carb on if you can get the float bowl off - connect the fuel line - fuel starts to flow - push up on the float to see if it stops the flow

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sounds like a stuck float or a worn needle and seat - with the float bowl removed is the needle and seat doing its job shutting off the fuel when pushing up on the float ?

Hi so I tested this and it feels as if the float has to go higher than dead centre before it shuts off the fuel
IMG_1630.JPG

So I applied a bit of pressure onto the float to bend the section that holds the needle a little and now it's just before dead centre before it cuts out the fuel
IMG_1631.JPG

With that being said this little overflow pipe IMG_1627.JPG
Sits right between the float and the housing for the jets IMG_1628.JPG
And therefore it makes it difficult to remove the float bowl and I've got my suspicions that's the float might be catching on and staying in the in position but it might just be me speculating
IMG_1626.JPG

Could all this really affect it not starting that much? Like I said I've had it started on bump but I had to keep the throttle pinned back but that was still boggy and it moved forward but as soon as I lifted off the throttle ever so slightly the bike cut out

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I agree with S.O.A.N.Z.  There could be some debris stuck in the float needle and seat.  The previous owner may have mal-adjusted the float.  Compare your float adjustment with what is in the manual.
Another possibility though unlikely is that the float doesn't float.  This was more common when floats were made of thin sheet metal soldered together.  They would develop a pinhole leak, fill with gas and no longer float.  When you remove the float bowl do not empty it.  Take the float off the carb and set it in the float bowl gasoline.  It should float (duh!). 
Good Luck



Hi there mate I checked the float and luckily it's still working and floating IMG_1629.JPG

Also I've copied and pasted what I wrote on the other reply so it's easier for you to read

sounds like a stuck float or a worn needle and seat - with the float bowl removed is the needle and seat doing its job shutting off the fuel when pushing up on the float ?

Hi so I tested this and it feels as if the float has to go higher than dead centre before it shuts off the fuel
IMG_1630.JPG

So I applied a bit of pressure onto the float to bend the section that holds the needle a little and now it's just before dead centre before it cuts out the fuel
IMG_1631.JPG

With that being said this little overflow pipe IMG_1627.JPG
Sits right between the float and the housing for the jets IMG_1628.JPG
And therefore it makes it difficult to remove the float bowl and I've got my suspicions that's the float might be catching on and staying in the in position but it might just be me speculating
IMG_1626.JPG

Could all this really affect it not starting that much? Like I said I've had it started on bump but I had to keep the throttle pinned back but that was still boggy and it moved forward but as soon as I lifted off the throttle ever so slightly the bike cut out

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whats your transmission oil like ? does it smell like fuel ?

no fuel in your expansion chamber ?

the tube could be catching on the float - you should be able to see that as you put the bowl back on

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The brass overflow tube looks like it's in the right place.  It does require a little fiddling with the bowl to get it on though because of the tube. 

I looked in the manuals I have and didn't find any specific setting for float height.  That means that you will have to set the float bowl by trial and error.  SO be patient and just keep at it.  I would set the level so that the carburetor does not over flow when the bike is leaned over around 10 degrees.  OR...... If you have a kick stand it should not leak when on the stand.

And Yes if the float bowl causes overflow it may very well run just barely at full throttle.  In that condition, there is just enough air passing through the carb to mix with the overflowing gas to get a combustible mixture. 

Good Luck

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whats your transmission oil like ? does it smell like fuel ?
no fuel in your expansion chamber ?
the tube could be catching on the float - you should be able to see that as you put the bowl back on


Okay so I've check the transmission oil and it looks like that but it doesn't smell of petrol at all
Image1501599233.910772.jpg

I then also checked the expansion chamber and there was excess oil on the output section before joining the pipe
IMG_1633.JPG
IMG_1634.JPG

Once I attach the float bowl and shake the carb a little , I can hear the float moving so I don't think the overflow pipe is catching onto the float

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Also just checked the piston and itsnit in the best of conditions but still has compression though. Could this be another factor?

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What model carb is it? If it's a PWK28, the spec for float level height is 18-20 mm.

 

The brass overflow tube is in a horrible place. The bowl has to be "twisted" during removal or it binds on the floats. Reassembly is even more aggravating. I would also check to make sure the floats are square, i.e. parallel to the pin, or else this will also affect float level. I would also inspect with a magnifying glass the rubber tip on the needle valve for a groove. I also scrape with a fingernail the tip to make sure there is no gunk stuck to it. And to make sure the rubber is relatively soft and supple, not hardening.

 

In my opinion, I wouldn't waste another second chasing any other gremlins until I knew for sure that the valve is seating properly, without help from pressing on it. Your symptoms are textbook float needle valve.

 

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What model carb is it? If it's a PWK28, the spec for float level height is 18-20 mm.
 
The brass overflow tube is in a horrible place. The bowl has to be "twisted" during removal or it binds on the floats. Reassembly is even more aggravating. I would also check to make sure the floats are square, i.e. parallel to the pin, or else this will also affect float level. I would also inspect with a magnifying glass the rubber tip on the needle valve for a groove. I also scrape with a fingernail the tip to make sure there is no gunk stuck to it. And to make sure the rubber is relatively soft and supple, not hardening.
 
In my opinion, I wouldn't waste another second chasing any other gremlins until I knew for sure that the valve is seating properly, without help from pressing on it. Your symptoms are textbook float needle valve.
 


Hi mate cheers for this I'm going to do this 7am as soon as I get up, she's too exited for the bike and seeing as it's summer holidays we need to get it running, is it alright if I message you as soon as I check all these?

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What model carb is it? If it's a PWK28, the spec for float level height is 18-20 mm.
 
The brass overflow tube is in a horrible place. The bowl has to be "twisted" during removal or it binds on the floats. Reassembly is even more aggravating. I would also check to make sure the floats are square, i.e. parallel to the pin, or else this will also affect float level. I would also inspect with a magnifying glass the rubber tip on the needle valve for a groove. I also scrape with a finger nail the tip to make sure there is no gunk stuck to it. And to make sure the rubber is relatively soft and supple, not hardening.
 
In my opinion, I wouldn't waste another second chasing any other gremlins until I knew for sure that the valve is seating properly, without help from pressing on it. Your symptoms are textbook float needle valve.
 


My current carb is KEIHIN PKW 28.
When you mention float level do you mean the height of the float?

"I would also check to make sure the floats are square" I'm not going to lie I don't understand what you mean, the float is curved is it? I'll add a picture from earlier on today but I'll definitely double check tomorrow
IMG_1631.JPG

Do you mean that it as it's dead centre it should be parallel with and level? Because as I place it upright, the float sits low allowing the fuel to flow in.

When you say the needle valve do you mean the float needle? I'll check all that tomorrow morning

But with all that being said, if the issue is actually with the float and the float needle, would I need to to change them both and the main key as you mentioned that before?

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Hi, been following this with interest. See if you can get a hit on your search engine with 'Splat Shop - Setting the Float Height on the Keihin PWK 28'. Its well explained with pictures showing how to do it.  Good explanations on here but if you haven't seen it done, best look at pictures. Hope this helps. Bob.

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Hi, been following this with interest. See if you can get a hit on your search engine with 'Splat Shop - Setting the Float Height on the Keihin PWK 28'. Its well explained with pictures showing how to do it.  Good explanations on here but if you haven't seen it done, best look at pictures. Hope this helps. Bob.
[/

Oh my god what is this sorcery! Thank you bob!!!

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Ok let me try to get this out in 15 minutes...

 

The brass overflow can get caught between the float and the main jet housing. If a person were to get it stuck, getting it loose could cause the metal flange of the float to get bent up (don't ask me how I know! Haha) So my recommendation was to pull the bowl, and look at how the float hangs. If one side is lower than the other, it's bent and needs to be straightened. They should be parallel to the bottom mating surface of the carb and bowl.

 

Re: checking float level. Remove bowl, and hold carb horizontally, so that the float pin is up and the float(s) is hanging, swinging by the pin. Slowly turn the carb, as if you were going to turn it upside down, all the while observing the float. AS SOON AS the float stops moving, this is the point at which the needle valve is closed. The float WILL CONTINUE to move with more pressure, since the valve itself is spring loaded. But you do not want to compress the spring. I usually turn the carb back and forth, opening and closing the valve 5-10 times, so I can see clearly the angle of the carb when the float stops moving.

 

Then, when you've found this point, hold the carb at that angle, and measure the distance from the bottom of the float(s) to the bottom mating surface of the carb, where the bowl and carb mate. This is your float level. The PWK28 spec is 19mm +/- 1 mm. If it's out, just bend the little tang when the needle loosely hooks onto the metal.

 

And yes, you're more than welcome to pm me. But since this is your thread, feel free to ask all the questions you like Others here on this forum are more knowledgeable than I, so you're better off IMO asking here, so as to get a consensus of the readers.

 

Hope that helps.

 

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