I have an '86 250R w/ FMF Pipe & Silencer, V-Force Reed Valve (brand new) and a K&N Filter...the rest is pretty much stock. PS, I USE my airbox cover (no holes!)

The gas in the tank right now is about 32:1 (I think). Without saying what jets are currently in my stock Keihin PJ 35mm carb with the air screw at about 1 and 3/4 turns (I think), WHAT FRICKIN JET SETTINGS WOULD YOU USE WITH THIS SEEMINGLY SIMPLE SET UP??!! I'm about to take to my local Honda dealer and PAY HIM to jet the damn thing!!!

HELP ME if you can!

 

If you have stock porting and a stock head gasket with a stock 34mm PJ carb , I would start with a 155 main jet at your altitude.

 

With the aftermarket parts you mentioned using but using the airbox lid, I would start out using around a 150 main, clip position at 4, what is your elevation? What problems are you having currently?
Are your problems right off idle, or are they 1/2 throttle to full throttle, need more info. Also make sure your filter is clean. You're oil/fuel mixture at 32:1 is fine. Got fresh fuel and oil, new plug, BR8ES?

 

I had a 155 in the carb. The stock jet is 158. People (like the mechanics at the dealership) have told me mods like FMF and VForce make your quad run richer so I should up the size, meaning richen the jet. So I did. I put in a 160, which by the way, is FMF's recommended main jet for their pipe on this ATV. I figured the 160 would be OK considering I have 2 mods or 3 3 if you count the K&N filter. Call me crazy but if you install mods that make your quad run richer, wouldn't you lean the jet to offset it? Or am I looking it at wrong?

I could put the 155 back in but won't that hurt the engine in the long run for being too lean? Isn't going leaner on the jet from stock setting a bad idea? Plus would it be wiser to jet it according to specs and mix fuel to match it or Vice-Versa (mix gas 20:1 as it states on the gas tank and jet according to that?

 

My elevation is about 1100 to 1500 ft. rolling hills in the pocono mtns.

I guess my filter could use a cleaning but it shouldn't be affecting my quad this much.

Here's the story: Running 32:1 w/ a 155 main. It ran good. Not great. Good..I guess. I hesitated lowering the jet because I didn't want to deviate from the stock 158 too much...even though the plug always looked a teeny bit rich but not overly oily. I know it should be tan to light brown but I figured the problem must be elsewhere. I could be wrong. Yes I run the NGK R 8es. I'm not sure where the clip is and I believe the pilot is stock....but not sure. Stock would be 48 and fmf recommends a 58. I didn't install the pipe. the previous owner did. so I don't know if he changed it.

 

You are running the stock 34mm carb right? If you were running without the airbox lid I would agree with maybe a 160 main but airflow or a lack of airflow makes a huge difference. What problems are you having now? I believe the stock jet was a 148. Are you having problems with the quad running now or are you just wanting to make sure you have things dialed in? Keep in mind, these are just ballpark settings, you really need to take the quad out and do plug chops and remove the plug and see what it looks like. WOT in 5th or 6th gear for several seconds, pull in clutch, kill motor, remove plug and see what color, you're looking for a brown, like a paper bag color. If you currently have a 160 main jet installed, you will not do any damage to your motor if you think the 160 might still be a little bit too lean. But the plug checks are the only true way of telling whether your carb is properly jetted.

 

Right after installing the V-force, it didn't run clean down low (1st and 2nd gear) as I shifted in to 3rd it got crisper. But after the engine really warmed up it would stumble and/or bog at full throttle and seemed oK revving at 1/4 throttle.....strange this all seemed to happen after I opened the air screw, which after the 1st rev thru the gears was closed. I opened it almost 2 turns and it sputters mid to high. Also, the idle is set so high that the choke barely even moves. if I lower to the bottom, it won't idle well or stall. does all that help you paint the picture?

 

wheww! I just did a plug test. I had it WOT in 5th (bogging and sputtering) killed and checked the plug. It's black on the bottom....not very oily...but very black. the threads are black and oily half way up the plug. the current jet is 160 and the air screw is 1 and 3/4 or about 2

 

OK, turn your air screw all the way in, then out 1 1/2 turns, that's a good starting point. When you have problems with the quad from 1/2 throttle to WOT, that's a main jet problem. From just off idle to 1/4 throttle, that's air screw and pilot jet problem issue. You're clip position also plays a part in the mid-range throttle performance. Not to steer you away from this forum but you might want to check out and join:
http://pub20.ezboard.com/bhondatrx250r

This forum deals strictly with the 250R and there are alot of knowledgeable people that post here. There is even an entire section on carb/jetting.

 

OK, now we're getting somewhere, sounds like you need to go down one jet size and try it again, hopefully with a new plug. Dude, you doing this in the dark??? It's freezing where I'm at!! I'm jealous!!!