250F Another 2004 KX250F Project/Build

Trfsrfr

Trfsrfr

This things is still not running so I took the carb off again today, and I'm not sure whats going on or where to start fixing it.
Leak jet is #60 - stock
Main jet is #178 - stock
Starter jet is #68 - stock
Pilot jet is #45 NOT STOCK - stock is 40 (I dont have anything smaller than a 45)
Needle is OBEKS - stock, 3rd from top - stock
Float is dead on 8mm - stock
Fuel screw 1-3/4 - stock

I've heard it run, and it pops, but dies, and after I kick it a bunch I dont smell fuel. Plug is dry.
Everything is stock except the pilot, but if it's a bigger jet wouldn't I at least smell fuel?

ProCircuit recommends a 165 main - Leaner than my 178
42 pilot - leaner than my 45
4th needle position - fatter than my 3rd
and 2 screw turns - fatter than 1-3/4

So if PC is recommending leaning things out from stock (except the clip position), wouldn't you think I would be at least smelling fuel out the tailpipe?

Scratching my head here, and gonna wait for a response from y'all before I reassemble this thing. I'm getting tired of removing this carb...
 
Mihylo33

Mihylo33

I’m not seeing a carb issue here. What I am hearing though is a valve issue, possibly a timing issue. Yeah I know the valves are new but what I remember is people having to send these heads out every time for valves and seats.
 
Rolls

Rolls

If that things got an auto decompressor on it a compression test won’t tell you anything. You might have to do a leak down test.:noidea:
 
Trfsrfr

Trfsrfr

Yep its got an auto-decomp. I was speaking about it to the buddy of mine that has a 2016 KX450, and he said that 107 was high, and that his was like 60ish...
But the YZ's ran great at the track today :ride:
 
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Trfsrfr

Trfsrfr

Called my local bike shop owner friend yesterday and asked him what the compression should be and he said the same as my 2016 kx450 buddy, actually said less, like 50ish.
It's on the back burner now cuz I got a yz250 that friggin rips!
I've become a blue guy for sure.
 
Trfsrfr

Trfsrfr

You guys aren't gonna believe this...or maybe you will! But I've never experienced this before.

So it's finally warmed up a little here and I decided to check the timing on this thing. Pulled the valve cover off and went to line the crank marks up. I typically like to stick a long screwdriver down the plug hole just to watch the piston move up and down. So I went and grabbed my favorite long handle Craftsman phillips I like to use, and it wouldn't fall down into the hole...
20190213_155958.jpg
 
Trfsrfr

Trfsrfr

Mihylo33:
What are we looking at? Those look like cam journals?
Click to expand...
It was the adapter for my compression tester stuck in the plug hole. It stayed in when I unscrewed the tester.
Its a 17mm size, but my thinnest wall 17mm socket didn't fit in the hole. I thought I was screwed.
Luckily the neighbor had an extra long needle-nose.

Also, the timing marks are still lined up, and lobes are equally facing upward and outward. I thought maybe a camshaft had spun on its sprocket as I've heard of that happening before too.
 
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