I've been looking at getting an aftermarket carb for a little more top-end for riding at the dunes, and I think a bigger carb would get the job done. But, even a Quiksilver is $300, which is a pretty good chunk of change. Hell, my Edelbrock 750 4-barrel for my Bronco engine was only $260! Anyways, I was wondering if anyone knew if it were possible to bore out the stock carb to around 38-39mm? And if so, would it perform as well as a similar sized aftermarket carb (like the FCR or Edelbrock)? I'm not afraid to put a few hours of work into this. And worse case, if I screw up the carb, I'll just end up buying an aftermarket one anyways.

 

If you want to buy a carb call TC Racing and get his Lectron tuned for your bike. Same design as the Edelbrock and only 240$. The factory carb is limited since it has a throttle blade and fat slide. The others are flat slide carbs. I did a cheap mod to mine that I love. I took the carb off and put it on the bench. I removed the screws and choke butterfly and pulled the shaft out of the left side. I ground the round side of the shaft until about three threads will hold. I did this with a bench grinder. Go slow so the heat won't bend the shaft. Only do the part that is in the bore. Then I reinstalled it put loc-tite on the screws and took my Dremel tool and ground the excess off the screws. I took about an 1/8th inch off the shaft and rounded the leading edges. The front shaft is already shaved but the screws can be trimmed. Then blow out the shavings and put it back in. I also raised my jet size 5 thousandths. NIce improvemant. Oh yeah I also knife edged the choke butterfly don't mess with the main butterfly I think it is too critical... Good Luck.

 

Thanks for the advice. Isn't the Lectron carb lacking an accelerator pump? I've heard that can make a big difference in low-end throttle response, so that's why I figured I'd go with the Edelbrock (it has an accelerator pump).

I took my carb off tonight for the first time and got a good look at it. I decided that boring out the carb would probably be possible, but a real serious pain-in-the-butt. I thought it would only have a short restriction, like the venturi on an auto carburetor, but the carb actually necks down at the jet, and stays that diameter all the way to the front of the carb. And whats with the Slide AND butterfly setup?? I thought they'd be one or the other, but not both! I'm sure there must be some reason for it, but I can't think of it. Maybe the slide by itself can't create enough of a restriction to pull the engine down to idle?

Anyways, to sum up, I'm definitely not going to try to bore out the stock carb, so plan B, I get a new carb. Guess I better start saving up.

 

TC Racing says the 400 has a accelerator pump because to meet emissions they are lean on the bottom end and need the pump to perform. He said a properly set up Lectron has no bog and will add 5hp to a built motor. For only 235$ built by the pro's can't beat it. tcracing 814-723-3514.

 

I have not yet felt a low end bog on my Lectron. Tom Carlson told me that if its set up properly it should be one of the best carbs out there on the market.

 

The stock carb has a pump for the same reason other carbs have pumps, for quick response at low rpm's (below 3000) to get your booty out of trouble when you need power. If it were an emissions problem they would richen the carb or buy Lectron's for $235.

 

Heh, you guys are assuming I know how to 'properly set up' a Lectron.
Thanks for the advice though, I'll have to look into the Lectrons as well as the Edelbrocks. Should they run more or less identically, ignoring the accelerator pump? Or is one a better performance carb than the other?