Surging in wind gust???

[99 MAX]

Cutting out in head winds, a little help please.

I recently picked up a clean 99 Max, it has a full Kerker 4-2-1 exhaust {louder than sin} and four K&Ns under the hood, in and around town riding she runs excellent but on the highway at steady speeds like 65-75 it will surge and sputter when hit by strong wind gust, a local tech suggested it may be running lean, "shim the needles up a notch", so I did and it ran worse with some decel popping, then I went to the 3rd notch down, not good, put it back on the forth where it seems to run best till I get into a head wind, I haven't checked the plugs yet, what is the deal with the head wind making it cut out?

 

[jfeagins]

Turn around and go the other way. Should run fine with the wind.

Otherwise, you probably will have to open the carbs and change jetting to fix the lean condition.

 

[ninjaneer]

my guess (and this is a totally wild ass guess) is that the wind gust is finding its way into the air chamber under the lid effectively creating a pseduo ram-air effect, which shoves more air into the intake, leaning out your mix. a bike with a stock air box prolly wouldn't experience this, but your indy filters present more opportunity for the forced air to enter the system. OR the gust is finding its way into a crack in the intake side (manifold joints, for example). if my guess has any merit, i would look at the front profile of your bike and see how air would enter the chamber.

 

[85vmax]

What RPM are you running at at 65-75 mph?

I have that problem on my inline with pods, but never with the Max.

 

[jfeagins]

Do 4 K&N's even fit into an OEM airbox?

 

[ninjaneer]

Do 4 K&N's even fit into an OEM airbox?

hmmm. i've never had my hands around a set, but if i were a betting man, i'd say "no". one thing's for sure, you'd have to remove the velocity stacks if you were to have a fighting chance of squeezing in your k&ns. a possible alternative if you wanted to experiment would be to put on the air box without its lid and, if paranoid, affix some kind of filter to the top of the velocity stacks. this way you lower the need of having to rejet in order to experiment. snap on your faux lid and run inot some windgusts and see if the surges resurface. simliar, not the same, by close to a indy pod setup but with the protection of the air box sidewalls. again, a disclaimer: i'm am totally thinking out of my ass and make no claims as to the feasibility or practicality of my suggestions. LOL

 

[one2dmax]

Do you still have the vent lines on the carbs? You need to have them there to even pressures in the float bowls.