Jetting question for a 250r.

[Ryah]

I'm open to suggestions for where to start with jetting on my 85 250r with the stock carb. The bike ran perfect, perfect plug color, engine mods are as follows, ported , Aftermarket pipe (unknown brand but it looks just like the Bills pipe on my TriZ) and K&N filter with air box lid on. Current jetting was a 150 main. I've just added some boyesen reeds and have decided to go without the airbox lid. Should I go to a 152, 155, leave it as is. Just trying to get some opinions on where to start or just leave it alone. Thanks

[Wickedfinger]

I would start rich and work your way back. Usually (but not always) when you uncork an airbox, you have to go up at least 2 std. Main jet sizes - but - every bike is different. I would also probably go down one clip on your needle and see how your mid-range is. This is all just guesstimation. Check out our carb chart.

[Mr. Sandman]

Start fat (160ish) and work your way up or down as neceessary. You don't want to start lean and burn up the piston experimenting.

[TimSr]

Non of the things you mentioned are likely to have very drastic effects. Id start right where your at and run some plug tests, and then see which direction, if any you need to go. Factory jetting is always setup to error on the rich side. Boysen reeds will make it a tad richer. The airbox lid removed might make it leaner on top, and the K&N filter mght make it run just a tad leaner, and a pipe can make it go either way (or not at all) depending on what proper band they are trying to achieve. Your not going to melt a piston doing a plug test.

[3WW Star-Yamahondaman]

Get a PWK 39 ....178 Main,CEG Needle,55 or 58 Pilot !!!
Them 20 YR. Old Round Carb's are................"OLD"