I'm having a hard time believing what I'm about to tell you all.
I was running a RWR pipe, K&N in airbox, no lid, 190 dynojet main, 3rd groove on dynojet needle, and had perfect performance and plug color. I know I was perfect, 195 fowled my plug, so I stepped down to the 190 and all was perfect, including throttle response, wheelie capability, and a toastie tan insulator.

Anyway, I removed the RWR pipe, installed the stock headpipe w/ new gaskets and a Yoshimura slip-on. Took a ride with all the same settings as above expecting to be rich. My bottom end sucked, and the top lost a little too. I was way lean! I went to the 4th groove on the needle and put in my 200 dynojet main. I got back most of my bottom end and just about all of the top, but after over 2 hours of hard riding, I still have no plug color - its as white as it was when it was new.

From the way the bike feels, I'm not far off. I expect to end up with either a 205 or 210 at the most for the main. Once I get that straight I'll look at the needle again, but I expect it will be staying at the 4th groove.

Oh yeah, I was so amazed at these findings that I had to do a thorough inspection to insure I wasn't leaking any air around the filter, intake manifold, etc., and I also made sure my tank breather and fuel filter were allowing gas to exit the tank!

What do all you guys think of this? What could I possibly be missing? This is too good to be true, isn't it...??

 

Wow!, did you try the 195 dynojet main on the 3rd clip position with the yoshi? Man it sure sounds like the yoshi is moving a massive amount of air! Did yoshi give you any jetting instructions? Sounds like it may be the needle jet adjustment? between the 3rd and 4th clip maybe? How does it sound?

 

I'm as rich as I can be now, with what comes in the Dynojet kit. I'm on the 4th groove, which of course is richer than the 3rd. The 200 main is still too lean for full throttle, and once I get it dialed in right I can look at the needle again, but I doubt I will need to go to the 5th notch (dynojet, not stock).

I'm sad to say Yoshi does not supply any instructions at all with their pipes, and customer service over the phone is impossible. Three calls in three days, and all I get is a machine every time. I also emailed them a week ago requesting info, no response yet. Their service sucks a$$.

It sounds good - not quite as deep as the RWR 'cause the Yoshi is about a foot shorter and doesn't have nearly as big a megaphone, but its every bit as loud. At least 100 decibals. I got their T.E.C. (tunable end cap) kit to adjust for sound when I go to panzy places that have sound laws.

 

Would Denton Racing have info on jetting since they carry the Yoshi. That is brutal customer service.

 

So now I ride with a guy with a turbo charged DS??!! I'm in trouble now.

J/K there HITOWER

Can't wait for our Lil' Sahara trip in two weeks!

 

I plan to call Denton Monday morning, that's where I got the pipe from.

 

With all the additives in today's fuel jetting by how the plug appears isn't nearly as effective as it used to be. You need to listen to the engine and feel where the power is at. My X is jetted right but the plug is a little white. You just have to listen to the engine.

 

I understand what need4speed is saying, but the lack of plug color is only one of the symptoms I mentioned. I don't have the performance I should have, and I know I'm lean because of my experience.
I'm also running the same fuel I have been running in other bikes that show me appropriate plug color.
The only 100% sure way of knowing the jetting is exactly correct (to the best of my knowledge), throughout the entire rev range, is to measure the exhaust temperature at the headpipes. Since most of us don't have access to these instruments, we rely on plug color to assure us that our head temperatures are not excessive. I'd rather be a little rich and sacrifice a micro amount of power, than too lean and wear out my top end prematurely, because as we all know - water cooling systems cannot remove heat from the combustion chamber, it has to dissipate to the water jacket first.
Unless I had my exhaust temp measured, I would not ride with a white plug, especially an air cooled motor like the 300EX.

 

My engine runs a little hot. 11:1 piston, head milled 3 thousands, bored out to 300, and an oversize header. It doesn't burn oil. It revs freely and it doesn't burn up plugs. I'm not saying they are white white. There is a tint of whiteish grey on them.

 

Need4Speed - a buddy of mine just got the 330EX kit, complete with oil cooler. I think the oil cooler kit alone costs around $250. Comes with everything needed for install, no machine work needed, all bolt on stuff. Sounds like with the horses you've added, might be worth checking into. The cooler is twice the size of the one that came stock on my ATC350X.