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stpauls

Won't start.

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Hi.  

2014 Sherco ST 125.

My bike was running ok but as I am on holiday I decided to take the Keihin carb off and clean it.  I have done this at least 3 times before, with no issues.

I noted all the adjustment screw positions, then stripped down the carb, cleaned everything and blew through all the holes and jets etc with an air line.

While I had the carb off, I removed the reed valve cage and checked the reeds and fixing screws.  Everything was fine.

I then put everything back together.

Now the bike will not start or run without the choke on.  With the choke on the engine screams.  Close the choke and it dies.

What have I done wrong?  Ideas please.

Thanks in anticipation. 

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air leak from the carb to the air box?

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check floats are correctly positioned, check needle & slide,double check everything you touched, is the fuel fresh,

 

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Yup what they said above. The good news is you did this to yourself which means it's something you can fix fairly easily. Everyone on here who's taken a carb off to clean or adjust has been in the same situation where we put the carb back on and realized something ain't right.

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First question is did you remove the jets (particularly the pilot jet) or just blow air through them to clean them?

many people do not remove the jets to clean them and this is where the trouble can start.

the pilot jet requires a small flat blade screwdriver to remove it and some people don't have one to fit and just blow air into it.

this can plug the jet as the orifices in it are very small and dirtcan be forced into it.  The pilot jet controls fuel flow at idle and just above idle throttle positions. The fact that it runs on the choke but not without usually indicates a clog in the pilot jet circuit.

remove the jet, look through it. Blow through it. Can you see through the center passage way? If not, get a  piece of small copper multi strand insulated wire (probably 18-22 gauge) strip back about 1.5" or so of the insulation.

using 1 strand of the wire gently push it into the jet twisting it like a drill. Use some contact cleaner spray in the jet and repeat till clean now blow compressed air through. Make sure if their are holes on the side of the jet that they are clean too.

spray contact cleaner into the hole you took the jet out of and blow air through it.

if all is clear then reassemble.

 

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 Blowing air through a Keihin can kill it. Who ever originally thought blowing compressed air through small passageways was helpful was an idiot. Now everyone thinks this is normal. I hope you find you have done something else and it again runs great. Otherwise there is hope. There is a tower inside the body that can be removed. It`s held in place with security screws. This allows further access to the other passages. Trouble is you cannot buy the o ring type seal that seals the tower, so be careful. Good luck. 

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Can be Air leak at reed valve gaskets....

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Posted (edited)

Hi all

Thall1 - I am sure that there is not a leak between the carb and the air box.

Digger144 - Floats look correct.  Needle and slide seem to fit and work ok.  Fuel is fresh.

Dan Williams - no-one else to blame but me!

Beta_blocker - I removed the jets and cleaned them.  They were fine,  I will have another look at the pilot jet.  

Lineaway - Will try the tower if nothing else works.

Cascao - The reed valve cage gaskets looked dodgy.  I will check these.

 

 

 

Edited by stpauls

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Had a chap with a Beta with a carb' problem..... screaming it's nuts off, it turned out he'd not seated the cable properly in the carb' cap. Tapped it with a screwdriver, it dropped into place and sorted.....

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Posted (edited)

On ‎23‎/‎07‎/‎2017 at 6:45 PM, stpauls said:

Hi.  

2014 Sherco ST 125.

My bike was running ok but as I am on holiday I decided to take the Keihin carb off and clean it. 

 

While I had the carb off, I removed the reed valve cage and checked the reeds and fixing screws.  Everything was fine.

 

What have I done wrong?  Ideas please.

 

You broke rule number 1.............'If it ain't broke don't fix it'

taking things apart just risks creating a problem......as you stated...your bike was running ok....you messed about with it and now it does not even start.

Good luck with fixing it.... its probably something minor like a blocked passage way and probably on the pilot circuit......I'm with lineway on the blowing  compressed air through the carb..I have never done it,

If your blowing compressed air through a passage or jet it should be done so that the air is flowing through in the reverse way to that of the fuel/air flow direction.

Edited by oni nou

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Sorted.  It was the reed valve gaskets.  The rubber one looked a bit dodgy.  I used some Instant Gasket to seal them up.  Replaced everything and it started after half a dozen kicks.  It is running ok now.  I will order a new set of gaskets and replace them when I next clean the carb.

Thanks everyone.

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