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HELP! XT500 running rich no matter what

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I have a friend coming over in a couple days and I am trying to get a bike running for him. I am a fairly regular rider of my 77 XT500 which seems to always work great but my 78 is putting up a huge fight.

The bike in question -

1978 XT500

K&N slip air filter

Supertrapp pipe on the back

I have put a decent number of trail miles on it and it always seems to run a tad rich but always managed to get the job done.

I have been through the carb a million times... it has been off an on in the last couple days at least 10 times.

It came with a 260 main jet 30 pilot and a double taper 6FL24 needle in the middle clip setting. I have since taken it to the leanest possible setup I can manage with my spare parts -

220 main 25 pilot and stock needle in the leanest notch and no matter what it still runs crazy rich and belches out smoke (smells like gas, not oil)

compression is around 135PSI

I tried without air filter and muffler

spark seems decent - spark plug is a little black from being so rich

I tried messing with the float level-this has the carb with the accelerator pump and extra doo-dads and I believe the spec is 23.5mm... I tried taking that alll the way up to ~26mm with no luck

Am I missing something here?

I really want to get this bike ridable today or tomorrow and I am totally out of ideas.

Sorry for so much text but I am trying to give all possible details.

Any ideas or input would be greatly appreciated.

Thanks

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Yeah I am pretty much at that point... the 77 has the older style non-pumper carb... it should prolly still be OK

for the '78 though... any solid #s for float level? It seems that for most years they say 22mm for for the later years, I see 34mm as well at 23.5mm. As far as I can tell, 23.5mm is the one for mine as 34mm does not appear possible without bending a separate limiting tang.

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is the 135 lbs of compression normal? what is the spec for it? seems low to me. Low compression and or incorrect cam timing can emulate a rich condition.

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I believe spec is 135-150. By the feel of the kick, I can tell you it is not as strong as my '77... but still seems like it should be OK for decent running.

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