Has anyone ever drilled the carb slide and installed the softer spring that comes with the dyno kit. I installed the softer spring but it still hasn't given me the throttle response that I would like. It is better, but still lacks the punch I would like. I guess I remember the throttle response from my kdx250 2 stroke days. Would it hurt to drill the slide with the softer spring. I know I will never get the response that I would with a 2 stroke , but it's hard to get the front wheel off the ground sometimes when I need too. Maybe need to go to the 13 tooth sprocket to help that also. Any suggestions would be appreciated.

 

This may not encourage you but a lot of guys seem to prefer the NITC needle and I've read on here where guys who tune swear it tunes better than the dyno.

That aside I've read where guys have indeed both drilled and swapped. Some guys have had issues with the softer spring not returning the slide well enough on low mileage bikes, but I dont recall any where guys had issues with the drilling side of things.

The drilling really shouldn't affect your spring selection. drilling is all about helping the pressure in the top of the carb equalize faster to help with quicker throttle response. The slide can open and close faster with a bigger port to equalize pressure through you just don't want to overdrill because you need enough vacuum for it to function properly.

The spring on the other hand does affect speed, but it is what stabilizes and returns the slide, not restricts it's speed of movement. Too weak a spring could result in sloppy throttle (like having it cutting out or revving unbidden while bouncing through the bumpies because the slide moves too easily) Having too strong a spring will restrict and slow throttle response but make it very steady in the bumps. On my KTM LC4 many guys cut 3 links out of the stock spring to 'soften' it a bit for example.

In short, I'd definitely drill because the tiny hole will absolutely restrict speed of movement, regardless of spring selection, then try both springs and see which you prefer for your riding. It's so fast to swap it no sense in guessing.

 

i think you need a pumper if you want it like a 2 smoke. 13 tooth helps heaps if you havent done that.

 

A pumper carb is the only way to go to get that snap feeling in the throttle. The DynoJet spring does help improve the throttle response better than stock. But it does lag a little behind from what a pumper carb can give.

Gotta remember, the KLX has a CV carb. So even at wide open throttle, it is not truely fully open till the slide comes up from the vaccum build up behind the slide.

 

Some good points are presented here about pumper and CV carbs, but there are some positives to consider with the CV. On a groomed track or trail where traction is optimum, the quick, hard power delivery snap of a pumper is very good. On a scrabbly, loose trail, especially on a climb, the smoother power delivery of a well tuned CV carb can be better. We all know that the KLX is no horsepower monster, but there's probably no one-size-fits-all carb application. The CV carb also allows some fudge factor for short stints over high altitude passes and overall better fuel mileage compared to a pumper carb. Like most things mechanical, compromise is involved to some degree...and understand that I'm not slamming the pumper carb...but I think some folks get the impression that the application of a pumper carb will transform the KLX into a fire-breathing monster.

 

Having a pumper makes a aftermarket piped machine livelier add a big bore & you get a completely different bike. Throttle response & on demand torque help a stock geared 09 pull wheelies w/o tugging on the bars... something unheard of w/ a cv carb. MPG and smooth power delivery are the only benefits of a cv carb.

 

I think one other CV benefit is the altitude flexibility on settings. Being able to transition a few thousand feet in a ride without rejetting or adjusting is a plus if you live in a real mountainous region.