Okay, heres the deal. I had my headpipes on my Sparks X6 recoated when I had a repair on my pipe. I am currently running a 686 12:1 ported and cammed. Anyhew I was running 25 pilots with the lid on and a big hole in my airbox lid. I was letting it idle for a couple minutes and I noticed the first bend in the headpipes was turning grey.... from nice shiny silver... I figure I need to go up a few sizes but dont know where I should go. I think the next size is 27.5 then 30? I dont like changing jets anymore than necessary which size should I go with??? Sparks said that my pipes turned grey the first time because I was lean and running too hot. So the question is what freakin pilot size should I be running????/ K&N, Pro flow, 4x2" hole in the lid.

 

27.5,

Patrick

 

you are a 686 with 12:1....you are going to run hotter. I would stay with the 25's and tune the fuel screws. I bet that if you add the 27's you will be fat and lose throttle response. That is what happened to me. But hey, every bike is different. If you have good throttle response and are not backfireing on deceleration I would leave things as is. I don't sit and let my bike idle either. I start it and get in gear within 1 minute. If you must sit and idle, maybe give it a little choke.

at 4,000 ft and duel filters/no airbox I ran stock pilots. At sea level I run stockers and have my fuel screws at 3 and 3.5 turns (a little lean)

 

I figured my pipes were turning grey from a lean top end but the low is obviously lean too. If I'm rich on the bottom it will bog when I nail the throttle? I think I'll try the 27.5's and see if there's a difference.

 

27s will probably be to big.What blue said is what I would suggest and if you idle for a long time in a garage making adjustments it doesn't hurt to use a fan.