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Cant get 85 kx500 fired up after top-end rebuild?

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rumpelstiltskin:
This is really confusing me.Fresh piston etc,checked for spark before i tried to fire her up for the first time,nice fat,regular spark,great i thought.Now when i first tried to start it it fired for a split second and died,done this a couple of times,felt like a fuel fault.Found out new fuel pipe i got from the tank to the carb was crap,it was collapsing behind the air filter casing as the casing was pressing against it slightly,ditched that got new pipe.Now there is no fuel getting to the spark plug which is weird,as carb is spotlessly clean and when i pulled the reed block it was wet with fuel??How in the hell can the reeds have fuel but the plug not??Reeds aren't stuck or broken,and they're the correct way up!Anyone any ideas,this is driving me nuts!!

Polar-Bus:

--- Quote from: rumpelstiltskin on July 06, 2011, 10:26:19 PM ---This is really confusing me.Fresh piston etc,checked for spark before i tried to fire her up for the first time,nice fat,regular spark,great i thought.Now when i first tried to start it it fired for a split second and died,done this a couple of times,felt like a fuel fault.Found out new fuel pipe i got from the tank to the carb was crap,it was collapsing behind the air filter casing as the casing was pressing against it slightly,ditched that got new pipe.Now there is no fuel getting to the spark plug which is weird,as carb is spotlessly clean and when i pulled the reed block it was wet with fuel??How in the hell can the reeds have fuel but the plug not??Reeds aren't stuck or broken,and they're the correct way up!Anyone any ideas,this is driving me nuts!!

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Need more history on the engine. Did your engine run good prior to the top end job ? Why did you change the top end ? Do you have a compression tester ?

rumpelstiltskin:
I bought the bike in boxes of spares.All that was missing was a cylinder barrel and piston.Bought a fantastic barrel/jug from the states,original bore(86mm)it was like new!!Then bought original size 86mm piston kit for it.Bike has lots of compression when trying to kick it over.Haven't tried compression test on it though.When i pour some neat fuel down the spark plug hole there's smoke comes out the silencer like it's wanting to fire up!!I can't understand why the reeds are wet with fuel but the spark plug is totally dry when i pull it out?

Polar-Bus:

--- Quote from: rumpelstiltskin on July 07, 2011, 03:27:39 AM ---I bought the bike in boxes of spares.All that was missing was a cylinder barrel and piston.Bought a fantastic barrel/jug from the states,original bore(86mm)it was like new!!Then bought original size 86mm piston kit for it.Bike has lots of compression when trying to kick it over.Haven't tried compression test on it though.When i pour some neat fuel down the spark plug hole there's smoke comes out the silencer like it's wanting to fire up!!I can't understand why the reeds are wet with fuel but the spark plug is totally dry when i pull it out?

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I've herd your exact story MANY times here. Most all instances end up being low compression.  before you go crazy guessing, get yourself a compression tester and get REAL compression numbers.  The common term "it feels like good compression" doesn't mean anything. You need to be around 160 psi measured by a gauge.  Weak compression explains possibly why your engine is not drawing any fuel into the crankcase.  The only other things i can think of is a gap in the reed petals, or possibly a blown crank seal(s).  With no history of this basket case engine running, you need to do some systematic diagnostics to figure out what's going on.

rumpelstiltskin:
Just for the record all bottom end seals,bearings i replaced.I only have a cheap push in compression tester which will be a pain to fit in this bike,will have to get screw in one.

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