kx 250 jet question

[teamgreenrider91]

i run a 40:1 fuel ratio and the bike has a full pro circuit exhaust. my elevation is pretty much sea level and i was wondering where i should be at with jetting for this time of year? also if it helps i run 93 octane in it. thanx for any help

[teamgreenrider91]

btw the jetting in it right now is 168 main and 45 pilot. the bike is smoking pretty bad and seems to be dumping oil in the exhaust. i thought it was a powervalve problem but the shop is telling me its a jetting issue.

[Jeekinz]

When was the last time you did a top end?

I never had to jet my kx250's for weather, just my opinion.

[teamgreenrider91]

Just did it and just finished putting it through heat cycles and its smokin real bad, I also just put new boyesen reeds in too

[Jeekinz]

Takes a few rides to seat the rings, dont change anything yet.

[teamgreenrider91]

so like even though the exhaust is covered in spooge oil where the header meets the exhaust port and the bike wont even pull the front tire up i should just ride it a few more times?

[DBMX 925]

You should check to see if your transmission oil is going down. Bad seals allowing oil from transmission to motor. Any of these symptoms before the top end?

[teamgreenrider91]

ran great before doing the rebuild and when it blew up. and it was a full rebuild not just top end. i let the dirtbike shop near me mess with the powervalves because ive never worked on them. so they took everything out and were supposed to have put new seals in i think thats the problem but there just telling me its jetting.crank seal is fine too btw i already went and checked that again idk how to tell if the governor is bad or not.

[DBMX 925]

Do you have an owners manual or shop manual? I don't think its a big deal to adjust the PV. Jetting could be the problem, but if it ran fine before she blew, I would think it would be lean...... Is the float in the carb stuck dumping fuel into the crankcase, also filling the exhaust with fuel? I've had that happen before.........

[teamgreenrider91]

If the float was getting stuck then wouldn't it also be dumping fuel from the carb? I don't think that's my problem but I'm sure its a possibility

[teamgreenrider91]

and if it is the powervalve then its on the shop that did the work on it, i spent like 600 in labor with them and if they screwed something up then the need to own up and fix it instead of giving me every other excuse in the book that it could be

[moose_338]

If the float was getting stuck then wouldn't it also be dumping fuel from the carb? I don't think that's my problem but I'm sure its a possibility

That is if the vent line isn't clogged with dirt...

[teamgreenrider91]

the line isnt clogged. im gonna run the bike for a while tomorrow and see if its pulling oil from the bottom end. i checked the crank seal and thats all good so if it is pulling oil where else would it be able to do so from?

[youngztr]

Hummm… What I want to know is how does oil get into the cylinder through the power valve???? The PV is an exhaust circuit. It is normal for oil to pass through the PV. The PV is scavenging the cylinder. The oil got into the cylinder from somewhere, but not the PV. Is the bike fouling sparkplugs? The 45 pilot sounds good. The 168 main sounds a bit big, even for sea level. What groove is the needle clip in? Check the float level. If the fuel level in the bowl is too high by 1 or 1.5mm it will reek havoc in the spooge department. Also, what 2t oil are you using? Some oils burn better than others.

[Jeekinz]

Omg dude. Run it a bit and seat the rings! haha

[teamgreenrider91]

i didnt say that oil was going though the powervalve it was just a thought. i dont know much about powervalves which is why ive been asking about it. im not sure what clip the needle is on but i never had a problem like this before i rebuilt the motor. i always used to run belray h1r and i was also running almost a 50:1 ratio and now im running superM at a 40:1. and jeekinz believe me i wanna ride it im just a bit apprehensive to ride the bike if its pulling oil from the bottom end. i cant afford to have this motor blow up again my quad just snapped a timing chain yesterday and that motor is toast now

[KDXGarage]

Same as many posters on here, vacuum test it and pressure test it. If that is OK, buy a one step lower pilot jet and install it. Get the pilot jet right first, then worry about the needle, then the main. There is a "how to jet" thread as a sticky (at the top of the forum).

[Jeekinz]

Same as many posters on here, vacuum test it and pressure test it. If that is OK, buy a one step lower pilot jet and install it. Get the pilot jet right first, then worry about the needle, then the main. There is a "how to jet" thread as a sticky (at the top of the forum).

Yes, a pressure test will tell you everything you need to know. If it checks out ok and you actually rode it enough to seat the rings, I would drop the main to a 160. Assuming you're using stock jetting. Me, I like stock jetting on my 94, but the main does feel a touch fat.

[teamgreenrider91]

ok great, where can i get a pressure test done at?

[moose_338]

ok great, where can i get a pressure test done at?

Your really going to ask everything you can, aren't you?

Try the search function it works wonders I am told.?