What is the needle clips function and how would i tune it to help the sport perform better? I ride at low elevation and in hot weather.(damn hot all last week)Barleylegal, you would be proud, I just spent another 150$ on new rear tires.It had 25x12x10 on it and I replaced them with 22x11x10 holeshots. that improved my accleration alot, and the top feels the same. I still back off the throttle before it maxes out.I guess there is always $$ for one more mod.

98 sport 400L
rcr stage one
hpd clutched
v force reed cage
42 mm flatside

 

I'm not the best carb tuner in here, but the taper of the needle mostly effects you at 1/2 throttle. You can adjust the clip on the needle higher (to lean it out) or lower (to richen it) to allow you to go from 1/4 to 3/4 without any hesitation (bogging or sputtering?.

If at either end of the spectrum the clip position is not correcting the problem, then you need to try a different taper needle.

1/4 throttle is controlled by the straight part of the needle, as you go to 1/2 throttle the taper of the needle controls the carb, and as you hit 3/4 through WOT the main jet is controling the circuit. Of course there are several more variables involved, but that is the basic system.

How YOU would need to tune your carb is dependant upon those other variables (elevation, mods, riding style, ect...). I would suggest the middle for starters and take it from there. I have'nt ever used the 42 flatside so I don't have any other pointers for you, other than its always better to error on the rich side to avoid a meltdown.

 

The reason I posted this is because I have a small lag when I peg the throttle from a dead stop.However the sport will fly like a bat out of hell if I peg the throttle from a slow roll. I am tempted to think this is clutch lag, not carb tuning.Thank for the advice.Where do you get decent graphics for the sport,mine runs good but looks like a 2$ hooker

 

Biggin, I'll be able to post those needle and slide numbers in the morning (finally, sorry for the delay) These two pieces take care of any and all hesitations encountered with the 42. I'm not familiar with RCR's porting (I know their work is great)in comparison with the HPD race port. There shouldn't be a problem getting the 42 dialed for it. Once again sorry for the delay...the joys of working in the "post Bin Ladin" world.

God Bless America,
Ken

 

Here's the ticket for the 42. A 6.0 slide, and a 6ej12-55 needle. Always try to get your jetting so one of the mid clip positions is usable. Good luck, and hang on. Rob at Hot Seat, or any dealer that carries the 42 should be able to hook you up. Remember the air filter should be a free flow, depends on your reeds, porting and pipe also....sorry if that sounds like a lawyer's disclaimer. This is what works very well for me.

Ken

 

Modquad,
I am prtty much ignorant when it comes to carbs.What exactly does 6.0 slide and 6ej12-15 needle mean? Is that differnt than what came with the carb from hotseat? As far as the airboxis concerned I have done the rcr mod,should that be changed to a K&N? Thanks for your patience and tips!

 

Unless you ride in wet/muddy conditions switch to the open filter element.

As for the slide and needle numbers thode are specific PN's for those, like I referred to in my post, different taper needles have different PN's, and so with the slide.

I suggest you call HSP for the specs on what they ship their stuff with.

 

I would wonder why you worry about the needle when you are running a 42mm carb? It's too big for good low-mid range performance on the 400 motor regardles of the needle. Unless you run full throttle all the time, that is part of the problem.

 

Don't mean to get in a pissing match Jack, but when ATV Sport radar gunned my quad, why was it commented that the 0-30 times were the fastest of any.....yes I said any quad they had ever had a radar gun on??? Biggin, like AZ400 suggested I would call Rob at Hot Seat since that is where you got it. I talked to him when I was out there today, so he is aware of the situation, and probably expecting your call. The RCR box mod is great, but like AZ400 also suggested, unless you ride in water as deep as your carb, the open K&N with the water repellent Outerwear works great. There are two kinds of the Outerwear, so specify (Hot Seat handles them). Buy the K&N filter oil, but use household 409 to clean the filter...it's virtually the same as the K&N cleaner.

Good Luck, and don't be afraid to ask questions....we've all learned a ton from these forums.

Ken Thompson

 

By the way, the speed produced is a complement to people like HPD, Hot Seat, RCR who spend countless hours on dynos and test runs developing these machines to elevate our grin factor.

Ken