Raced but had problems

[Evan]

Well I raced with my sparks kit for the first time. It did fine in practice. But when I lined up at the line, as soon as the gate dropped it sputtered and died. Fired it a couple times and kinda stumbled off the line after everyone had gone through the first turn. Well I was hot that it had messed up and really gave it H3ll, passed 3-4 people on the first lap. The motor ran fine not a bit of trouble after the start. Well I though it was a fluke, but it did it again, in the second moto and this time, they got about halfaway down the straightaway and it fired, and I let it rip and I caught them going into the first turn, (thats how strong it runs). All through that race it ran perfect, even accelerating to a tabletop with a nice straight, it pulled a wheelie in 3rd. Its defintely a midrange cam, I thought that I would want a bottom end cam but that would not be good on this track and proably any track. In a race you want the power most in the midrange, I think. Well I am pretty sure its a jetting problem but WHAT? When I first started with this kit, it had a 165 main and I turned the air screw 4 turns out. Still did not seem right so I moved to a 168 main right b4 the race. But during the race with that main it ran like it never had b4 so I am thinking it was lean, it was slightly light on the plug w/ the 165 and there was a light brown color on my exhaust which ther never has been b4 with the stock motor. So my question is: What would make it stumble and cut out that bad at aproximately 1/4 throttle, or just kinda pegging it. Usally I start in 2nd with mid-upper revs, but I even tried it in 1st and it was worse it seemed. The first race I tried 1st and the 2nd I tried 2nd gear and it didnt cut out as bad. Any help is greatly appreaciated.

[CranMan]

I recently made some changes to my 416's jetting. I have a 165 main, stock pilot. I went 1/2 turn more out on the fuel/air screw, for a total of 4 turns out. I raised the needle 1 position, I think it's in the 4th slot from the top of the needle. Now it runs like CRAP and low idle, the bottom end is horrible, but from mid on rips. I can't beieve how much those little changes affected the engine. It sounded to me like your main might be a little big, and your needle might be too high. My theory is that if you gag it at low idle it gets too much fuel before he engine has a chance to rev up it will sputter or in your case maybe stall. Try making small changes one at a time...

[MX MadMann]

you boys sound like ya need some new pilot jets maby , like some HUGE ones. but oh well. just a thought , considering the pilot ( as told from sparks racing ) controlls the low RPM's.

casey

[Evan]

Well I ran with the 165 main for awhile, it was still a light color so I moved on up to a 170 main. Anyone know what pilot comes in the FCR?

[DiceMan400]

Get a 39mm carb..... That will solve your problem....

[Evan]

What? I have one, look at my sig

[kabd69667]

He has a 39mm carb already....

[MX MadMann]

whoops , disregard what i posted , i diddnt realize yall had aftermarket carbs. mines stock. sorry.

[DiceMan400]

So why did you re-jet?...... Should have left it alone.....

[Evan]

well it runs better now than it ever did, but it did it again today, I only had a 1/4 tank of gas in it though. I dont see how this would make a difference, but it might.

[Nausty]

Originally posted by DiceMan400
So why did you re-jet?...... Should have left it alone.....

maybe because of the huge power increase for the money and it can make the biggest differance in throttle response and power especially to a modded engine.

[ride300exred]

guys you do know your supposed to change jetting for elevation and 15 degree weather incremants right ?

[DiceMan400]

Yeah on a stock carb it maks a big differance but not on a 39mm..... You wont see much at all....... That may just be my opinion though...... Well anyways, I hope you fix your problem..... Sounds like you have a sweet setup......