I just scored a 1986 250r off craigslist for $800.00 starts and idles great but when I ride it, it bogs down on top end under load like its not getting enough fuel. Has a 41.5mm keihin pwk carb on it, vforce reed cage with carbon fiber reeds, roost boost, fmf gold pipe and silencer, bored 3mm over, br7 ngk spark plug ( kind of dark like too much oil in mix). I dont know what size jets are in the carb.

 

Before I would do anything at all, I would trash that fuel and start fresh with the gas and oil mix and ratio that you intend to use because if you don't you will end up having to fine tune things again even when you get it straightened out for now.
My first guess is going to be that you are running a far too rich ratio of oil to gas. If changing to your fuel doesn't help, try looking for something that is restricting air,..which is in making you get too much fuel. Dirty filter,..dirt dobbers nest in the air intake tube, etc,etc.

The other scenario would be that you are getting too much air caused by an air leak. You can spray some WD40 around the carburetor area with it running to see if it revs up.

A spark plug check using a brand new plug will tell you what your air to fuel is looking like.

Also, does it bog on the topend when idling in neutral or just when you are riding it? Sometimes a bog on the topend that only occurs under load is a sign of bad compression.

But as stated, I would change your fuel and check out your airbox before getting deeper.

I would save the carb cleaning and possible rejetting theories for the last thing to do on my list and only do them then if all else checks out ok.

 

I just put in fresh gas 93 octane and 32:1 mix, It dosent die out or anything while in neutral just while under load. I dont have a compression tester but It will almost always start 2nd kick when cold and I will try the wd-40 tomorrow.

Also what needs be be done with the vent on the crankcase? There are no hoses running to it.

 

I messed with it some today adjusted the float and drove it down the road with no air box or duct on it and it ran pretty good it didnt bog down. but i still dont really think it should have the top end speed like it should but it ran through the gears good. also looked at my jets and the main was a 180 and I think the pilot was a 52?? so with the mods my 250r has do you think I should change the jets? Also what do I need to do so it will run right with my breather on it?

 

Isn't fine tuning 250Rs sooo much fun?! :P

If getting more air made for a good mixture to run better, the theory is that you need less fuel to run smoothly with the airbox in place.
The question is going to be whether or not it will take a clip position change or a main jet change,..or both, to correct. I don't know that I have ever messed with an R running the carburetor that you are running but in most cases, a 52 pilot is fine. That wouldn't have anything to do with your bog in the upper RPM range anyway.
I would put the airbox back on, lower the needle one notch and use that as my starting point.
Taking care to have paper and pen in hand to note every single change in case you need to start over entirely.

 

I put in a new stock spark plug and lowered the needle 1 notch and now the lock washer is at the very top last notch. It runs a lot better but I havent ran it with the airbox on yet. Thank you for your help