85 250r too rich

[Auto_Demon]

K so i just bought a full fmf exhaust system for my 250r and it made it more rich than before? I bought a bigger size jet like everyone says but its too rich, and by the looks of it the jet i bought is smaller than my existing jet. I dont know what to do, the clip is on the leanest setting on the needle, running 32:1 with airbox and lid (no holes). It was running perfect without the fmf exhaust and when i put it on, same settings and eveverything, it made it more rich. Does anyone have any suggestions? I dont want to change the ratio but i will if it means it will run better.

[manbearpig]

Take the airbox lid off. what are/were the numbers on the jets you have?

[Auto_Demon]

Drilled holes in the airbox lid, bought a 148 size main jet for the exhaust because everyone said it will lean it out so you will need a bigger jet but by looking at it it looks smaller than the one i had on there already

[barnett468]

Simple, if you're sure it's rich get a smaller jet from the same vendor. some of the aftermarket jets are not equal in size to the oem ones.

[manbearpig]

ok well stock jet for your bike is a 142. i have had great success with that carb jetted at 142 with a ported, polished, milled, and piped setup.. and could even step it down and still be safe. if youre concerned with your jetting and dont want to run the stock jet for fear of running too lean, but feel that 148 is too fat, drop a 145 in there and start playing with the clip on the needle.

...and, as always, DO YOUR PLUG CHOPS!

[Auto_Demon]

But its not the stock carb, its a chinese 36mm flat slide, the jet that came with it looked bigger than this one

[barnett468]

But its not the stock carb, its a chinese 36mm flat slide, the jet that came with it looked bigger than this one

Simple, if you're sure it's rich get a smaller jet from the same vendor. some of the aftermarket jets are not equal in size to the oem ones.

Get a jet from the same place you bought your new jet from.

[yamaha225dr]

What exhaust did you have before?

[Auto_Demon]

What exhaust did you have before?

Stock exhaust

[manbearpig]

swap out that mikuni. if you like the flow of a 38mm, look into the Keihin PWK 39. there are guys on here that'll swear by it.

[yamaha225dr]

Something is wrong if an aftermarket exhaust richened the air/fuel mixture or the stock setup.

[Auto_Demon]

Its not a mikuni, its a keihin knock off cuz it takes keihin jets, its an "oem std" 36mm flat slide pj, i have a 38mm keihin pj but im waiting for the guy i got it off of to get me the cap and slide

[82 250r]

I bought a bigger size jet like everyone says but its too rich,

The FMF website recommends that no jet changes are necessary for the 85-86 Honda 250r. In other words, if the trike was jetted correctly before, a FMF pipe won't change that.

http://www.fmfracing.com/RiderSupport/JettingCenter

[Auto_Demon]

Well im going to have to now, i didnt change anything when i put the exhaust on and now its super rich

[2fiftyR]

I had the same problem with my 85. I jetted it down and tuned it so it ran great with the airbox lid off and crappy(rich) with it on....dont know why,that was three years of HARD riding ago so there couldnt have been something else wrong or it would have melted down long ago.I dont remember what jet size went in it so I cant help there. This winter I see a teardown comming because I just want to see whats going on in the motor(no catastrophic failures)