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

[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]

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!!

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]

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?

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.

[Motorrad]

does fuel come out the Pedcock?     Have seen several of those Gunked up latly.  crappy new fuels..
also the old Nylon fuel filters melt together to not pass fuel with the new crappy fuel

[rumpelstiltskin]

Yes,tested fuel is getting to carb,then checked fuel was coming out float needle by removing floats,then noticed that fuel is reaching reeds,that's where the trail stops lol,doesn't reach the spark plug d**nit!

[dave916]

try blocking the rear of the carb with the palm of you hand while kicking it over  to see if it is sucking air ,
if no induction could be bad air leak ,ie intake manifold , boost bottle , crankcase leaking,
if good induction may be worth double checking the carb , pilot and choke circuit

[rumpelstiltskin]

Pulled the stator casing then the flywheel and couldn't believe it,the woodruff key(flywheel key) had sheared in two,half of it in the flywheel and half of it in the crank shaft!!Strange to as i've always got a good strong spark so wasn't even thinking about electrics.This doesn't solve the fact though fuel isn't getting drawn up to the spark plug though from the reeds!

[Motorrad]

Funny.  That was going to be the first thing I was going to say.. But didn't..

Had same problem with my Stewart motor when I got it back

Get some valve lapping compound and lap the flywheel into the crank.. Or it will happen again..


Also.  Just because the plug isn't wet.  Doesn't mean it's not getting fuel...

[Polar-Bus]

Pulled the stator casing then the flywheel and couldn't believe it,the woodruff key(flywheel key) had sheared in two,half of it in the flywheel and half of it in the crank shaft!!Strange to as i've always got a good strong spark so wasn't even thinking about electrics.This doesn't solve the fact though fuel isn't getting drawn up to the spark plug though from the reeds!

I'm amazed you didn't experience some type of exhaust of intake backfire attempting to start your engine with a sheared key.

[rumpelstiltskin]

Well the last couple of times i tried to kick it over before i pulled the casing i got a couple of mighty kick backs from the kickstart!Just about launched me over my house!

[rumpelstiltskin]

Well,got the woodruff/flywheel key fitted and still wont fire up,spark plug still not getting fuel,im convinced about that.If the reeds are wet and with the manifold off i can see the reeds are moving so fuel must be getting there,and compression is fine!Im just on the verge of getting rid of it,it's getting on my nerves!I've spent a fortune restoring it and it can't even do me the pleasure of firing up,the sod! 

[Podium Werx]

Hi have you tryed petrol down the plug hole if it firers then it could be seals or reeds

[rumpelstiltskin]

Im just double checking everything before i go tearing the motor down again.Tested the stator wires.One of the readings was slightly high,the reading between the yellow and the black and red wire which should have been between 14.2-21.4 reads 25??Would this cause a problem?All other readings were fine.Im just trying to rule out maybe the spark not being strong enough under combustion conditions.Timing is ok too.Fuel is now getting to the plug.