According to FMF's site you should have a 185 Main, clip in the middle, and the air screw 1.5 turns out. They didn't say anything about the pilot jet, is the 62 stock?

 

I take it thats a kehin carb. Unless your about 5000ft BELOW sea level lol, you shouldnt need a pilot that big. Back that pilot down to a 50 or so. Put the needle clip back in the middle position and give it a shot. That should clear ya up a bit.

 

1988 cr250

Here is some more info. The top end has maybe 15 minutes on it. The bike wouldn't run when it was brought to me. No compression, scarred cylinder around exhaust port, scarred piston, stuck rings. I don't know the history of the bike. Someone gave it to my neighbor. The piston and rings were replaced with Wiseco parts. I have had the cylinder off several times fighting a cylinder to case sealing issue. Everything is sealed up now, but I have noticed when I pull the cylinder off there is oil puddled in the crank case. Smells like it has gas in it also. Everything is coated with oil. The exhaust port is oily black. I can rotate the crank and pick up oil on it as it rotates. I'm not sure if it's oily from running so rich or if it's trans oil. Could it be leaking in between the case halves? I'm running 32:1 927 and I am runnin the same mix from the same can in my banshee with no problems. The trans oil is rotella 15-40. So both oils are currently gold and I don't know which one is in the crankcase. I might try a stinky light gear oil or red auto trans fluid in the trans so it will be easier to detect. I also have some red Motul premix I could try. Is the jetting really that far off? The main is leaner than stock and the pilot is the same as stock according to the clymer manual.

 

What carb is it for sure. Im not familiar with bikes but I am familiar with carb setups If the manual calls for that big of a pilot, maybe it does. But that is one big pilot. I run a 55 pilot on my zilla if Im running gas, and its still rich but makes it easier to start. If you are getting trans oil in the bottom end its comming from your clutch side crank seal. You should be able to change that without splitting the cases.

 

Also were the cases ever split after the last piston blew up?If not then it is possible that a piston piece got wedged under the crank and broke the case and is letting in trans oil.If the cases checked out good than it is most likely the right side crank seal..Also are you sure it's gas and oil and not antifreeze?After pulling a top end it is a must to use new gaskets.especially the top .

 

My 88 CR125 had the same issue when I just recently rebuilt it. You are supposed to be running a 1367N needle which explains a lot. The main and pilot are the correct stock jets.
Get the right needle as the one you currently have is to small and is probably flooding your engine.

 

By the way MRCycles has that needle and it sells for $15.25

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The carb is a Kehin PJ. As a side note, I am also running a smaller version of this carb on my 85 cr125 with the same size pilot and no problems running or idling with 62 pilot. Is there something in that carb that I could be missing that would cause it to run rich? Something worn out? Also, it is possible the rh seal is leaking but I have replaced it along with a new collar for it to seal against.
The piston wasn't blown up when the bike came in my shop, just scarred up with stuck rings, but another one could have blown up in the past and damaged the cases. I'm almost sure it's not coolant in the crank case. It's a clear goldish color and I'm not loosing or pushing any water out of the radiators. Anyway, please don't take me wrong all the suggestions are appreciated. I'm looking at about 3 possible causes, 1. oil coming in thru rh seal 2. oil coming in somehow (cracked, damaged cased, damaged gasket) thru trans case into crank case 3. jetting too rich ( pilot jet).
I can try to rig up a leak tester to verify 1 and 2 and try a smaller pilot for #3.
One more bit of info. Once I get the bike pulled off and running, it won't idle so I have to keep reving it. It smokes bad and doesn't rev cleanly. It 4 strokes. When I take off in first it won't rev much, it just four strokes, but it keeps getting better until I hit 3rd or 4th gear then it clears up and revs, but still smokes bad. I can keep the revs up and it doesn't run too bad. It will spin the tire, which is about 85%, in all gears up and down my gravel drive, but as soon as I let the revs come down it loads up again and starts 4 stroking. Thanks again for the help.

 

I would bet on the crank seal

Yeah the pj's use big pilots. I must have read your title wrong. I was thinking of a 98 cr which I think is the odd yr with the tmx carb. I thought it might have been the keihn air stryker

 

Then check to see if the float is sticking some. I suspect with the correct needle installed a lot of what is happening will go away. Make sure also the power valve is set correctly. If you didn't line up the marks when putting it together it can cause issues but not flooding issues. Your bike is flooding.

 

Sorry everyone, I have given you incorrect information. The bike does have the correct needle, R1367N dropped all the way down with the clip in the top groove. I tried it today with no air filter and it runs the same. Won't idle, 4 strokes when you crack the gas to keep it running, and smokes bad when you try to slowly rev it up. So it looks like I'm down to burning trans oil? What is the best way to know for sure that is happening?

 

I put the carb off my 85 cr 125 on the bike last night just to see what kind of difference it would make using a "known to be good" carb and the bike will idle now. This carb is a smaller PJ that uses the same 62 pilot jet and a 150 main with a different needle. A lot of the smoke is gone. It barely smokes when idling and blows some smoke out of the pipe when reving, but nothing like before. I could tell it was to lean idling because the motor loped kind of like it was running out of gas. I richened up the idle on the 125 carb with the air screw and rode the bike some. It revs up cleanly thru the gears and I can kick start it easily. So, sounds like I have an issue with the original carb. I have had this thing apart several times checking the idle, main, and choke circuits along with the float level and I can't find any thing wrong with it. Do I try a smaller pilot jet? Different needle? I didn't get around to trying a different premix like suggested yesterday, but most of the smoke did go away with the 125 carb. Also I have the trans filled to the top of the level plug so it barely runs out when you remove the level plug and the level hasn't dropped any after about 15 mins of running, so I'm hoping this means I can rule out burning trans oil.

 

One more thing I've noticed when running the bike without an air filter is I can sometimes see a mist coming back out of the carb. This is with the throttle cracked open to keep it running. It kinda pops (not really a backfire) and I can see the mist back out of the carb inlet. Could all of this be a reed issue?

 

sounds like the carb was ur issue ...got any pics of this bad boy?