Question for the big bore klxers. Getting my stock carb ready for my 330 kit. I have searched and checked the spreadsheet but still unsure.

My bike was powerbomb, Q4 and stock snorkle. Stage one DJ with 120 main and 38 pilot was spot on at sea level.

Now bike will be same exhaust with KDX snorkel and 330 cc.

I was thinking starting at stage two 128 main. Tempted to put the 132 in but don't want to over fuel and judging from the 250 piston the jetting was perfect to a tad rich. I will post a pic.

Any bigbore sea level klx'S out there. What's your jetting?

Thoughts on larger engine pulling more fuel threw same size jet?

http://i.picresize.com/UGYG

Thanks

 

So here is a little deep thinking about "pulling more fuel through the same jet size."

I propose that main jets operate at their max flow rates @ WOT. Case in point - I have seen/posted the AFR chart evidence of the effects of main jets from DJ132 to DJ150 on our KLX's. As you go bigger, the AFR richens up @ WOT - as anyone would expect. But think about what that really means.. The engine (stockbore) and the carb design, together, cause all those jets to flow at max rate because otherwise, larger jets would, at some point, not provide a richer AFR due to it being "underutilized" by the engine/carb combo - and we do not ever see this happen.

So, if/when already at max flow rate, how much more can you "force" it to flow by increasing the vacuum signaling (I.E. 351BB) ?

How bout next to none!

 

I tend to agree. The hole size is the size. It's only going to flow what fits (basically). The larger engine signaling was a suggested theory from DJ.

 

s10gto,

I am at sea-level, as you can see in my sig, we were setup similarly before the big bore kit with the large exceptions of the Stock Snorkel (you) v. KDX snorkel and I had been running the MCM (un-did the cam timing mod when installing the BB), and I had been running a 128 main jet pre-BB.

Since you can't really "rubber stamp" a tune and expect it to work for everyone at the same elevation, my gut tells me that if the 120 main was right for you, changing to the 330 and KDX snorkel - you may want to start at a 128. While I have trimmed away much of the KDX snorkel once inside the box, I'm not so sure that our baseline tunes would be so far apart (120 v 128) just due to the snorkel (though that stocker is about half the opening...), sooooo... maybe it is? Another thing that may contribute to the 128 working for me is that I am in Western WA where we are surrounded water and cooler air, ie. good air density.
While the MCM drastically changes the airflow characteristics, I think it is a matter of where the MCM flows more efficiently, not that it flows more absolute volume.

Things to consider...

 

Thanks Tim. That's just what I did. Worst case I will swap the 128 for the 132. We'll see. My kit is in plating so shouldn't be long now.

Snowing today anyways......

 

I will be watching this thread also. I just ordered a 330 kit also, currently running the recommended DJ Stage 2 settings, with DJ 128 and the stock Kawi 35 pilot (2.5 turns out). No snorkel, 4 1" holes in airbox lid, stock header, FMF Q4, Uni air filter. Starter drilled with whatever was recommended on here (forget the size).

Running like an absolute champ in 250 mode, perfect throttle response ~60mpg, good bottom, mid, and top end, I am at about 900-1000ft.

I think I am going to throw the 330 kit on whenever it comes and leave my settings as is. I too am in the camp of more CC's=more volume so in theory may pull more vacuum (and gas) from the carb to compensate for the extra CC's.