82 250 CR OUT OF IDEAS??

bought this bike last fall. put in a new (weisco) piston and bored 1st over.
started it up this spring and it blubbers and foggs smoke. ok this is what ive tried.
had the carb off a dozen times to clean, and have swapped it with two other carbs.
I should mention a friend has the same bike he is restoring i used for parts swapping.
I have tryed his reeds,stator,exhaust pipe,3 differant coils.
drained oil started it (no i did'nt ride it around). performed a leek down test it held 9.5 psi with no loss.
all jetting was factory.
I'll stop there for now any ideas???
thanks>>

This sounds like an obvious suggestion but be absolutely sure you have fresh gas/oil in the tank. I myself have chased a problem around a couple of bikes like this and checked and tried all that you have done and it turned out to be bad or old gas. Hope this helps,

Marty

jetting is all factory.
410 main
R4 needle jet
45 idling
6dh20 needle
stock clip is 4th down i think i was at 3rd.
fresh gas 50 to 1 mix even tried differant oil started with klotz because thats what i ran in my ktm and then tried lucas.

Here are couple ideas:

Make sure all engine to frame to electrical mounts are clean and grounding. Even clean stator mount threads out with tap and sand stator mounting areas/motor/frame mounts.

You don't by chance stuck a resistor spark plug in? I did that once!

Do you have a broken piston ring? Maybe do compression test?

Do you have a broken piston skirt?

Any schrapnel marks on top piston?

Does your crank web have accessible oil in bottom of it or even water?

Air cleaner? Is it clean or hard as rock from old oil on it?

Try unplugging kill switch?

I just bought an '83 250WR . The PO or someone rebuilt the top end and put the piston in backwards (ports in piston facing the exhaust port) . Sold it as parts bike and said it might need a carb cleaning or other work to run right, but the carb is brand new. You never know!

Bad clutch side crank seal?

Sounds like it's running way to rich.
So start with a new float needle [ and seat if it's replaceable ] .
Then put all your jetting back to standard. [ done ]
30 to 1 fuel to oil mix [ using a good modern oil ]
Clean out your exhaust port and burn out the exhaust.
New standard air cleaner.

And the weirdest one of all , check to see that your piston is in the right way [ tiny arrow points to the exhaust/front ] as this can also cause the same problem.
Cheers

Good point about the piston Dukkman, I have seen this more than once!

Would a leak down test show if the clutch side seal had failed?

If the fuel tap leaks you could have oil in the crankcase, fuel leaks down and evaprorates, oil doesn't.

did the plug switch resister to non.
cleaned all electrical connections (did'nt chase the threads out with a tap)
brand new air filter though maybe to much oil on it so i pulled it and started it with no differance.
piston all looks good.(yes it was in the right way).
and i removed the kill button.
motor is stripped down on the bench was determined it was crank seals or center gasket until i did the leek down test.
pulled the cylinder off to see if the old piston matched up with the new one,(intake ports compression height skirt length).and there is excess gas in the lower end.
so i'm leaning back to the carb. but i've had 3 differant carbs on this thing all with the same results.
i road this bike at unadilla and another race with a carb off one of my 390s jetted to the 250 specks except i left the R2 needle jet in. seemed to run good but noticed on the starting line when reving it up at about half throttle it would cut out and smoke.
thanks for any input..

There was another topic here somewhere that suggested that the fuel taps should be left in the off position when not in use for this very reason, fuel seeps past the needle and seat and ends up in the crankcase, if it is doing this when running then your float level is too high or your needle and seat is cactus.
Tony.

Running a fuel mix of 50:1 and near stock jetting will certainly make it run rich. If it was me I would start leaning it out. The factory jetting was set up for 25:1 mix and sea level altitude.

Marty

Demmick By any chance did I help you get your bike started at Unadilla ?

my first mix after rebuild was 25 to1 was told may be the issue do to much oil for todays synthedic, semi-synthedic oils.
garym. had someone come by and offer to help me bumpstart it but my friemds came back from practice and helped.(yes that was do to leaving petcock on and flooding the engine)

My Huskies do not appreciate having the fuel petcock left on. Somehow all seem to load up and need a bump. Turn it off and it starts first time on the kicker.

ignition timing.....??

When mine are left in the shed or travelling, in addition to emptying the tank I always pull the fuel pipe of the carb, there is always a bit left in the tank unless you take it right off, I have filled the crankcases right up after a long journey!

timing was spot on 2.43mm btdc.
it starts first or second kick everytime just loads up when giving it gas.
think i'm going to throw the crank seals i had already bought in. and try to get it to clean out by rejetting don't think i should have to make that big of jetting changes from a top end rebuild but out of ideas.
thanks to all...