Sorry I've been clogging this forum up a lot lately with questions, but I need some minor clarification. I just ordered this jet kit:

Amazon.com: Dynojet Research Intake Performance Kit - Stage 1 2206: Automotive

I've got a 2006 klx 250s

I'll also be ordering either a Twin Air filter or a Uni air filter and removing the air box lid.

In time, not sure when, I will be ordering the 351 big bore kit. I've heard that you may need to change the pilot jet after installing the kit. I live in Ohio so I'm not sure if this will be something that I need to do. What # is the stock pilot jet on the bike right now? Which # jet should I get?

Thanks, and sorry for the clutter and thousands of questions! Just don't want to mess anything up

 

I used stock pilot and it worked great both before and after the 351.

David

 

The stock is a #35.
Some bump up to a #38 or #40.
I'm with David R on the stock working fine for me on the 250. No experience with the 351 yet, darn it.

Think about getting a T-handle fuel screw, like the Kouba, to simplify fuel mixture adjustment. This will really help you determine if your pilot jet is of the correct size, imo. You may be able to get a local shop to order one for you. I did, but that was easy because my local shop owner is friends with Norm Kouba.

http://www.koubalink.com/fuelscrew.html

 

Asking which pilot jet for our KLX on this board is like asking which oil to use.

I have the 40 and it has worked perfectly for me.

YMMV.

 

With the stock pilot jet I struggled to keep the engine idling once engine temps got up to running temps. And starting the bike again once it had stalled was damned near impossible. Starting it cold needed the choke to be left on for a few minutes before I could turn it off without the bike spluttering.

After putting the #38 pilot in those problems totally disappeared. BTW, I am riding at sea level with ambient temps ranging from 10C to 42C (50F to 108F) - colder temps mean more dense air meaning you will need a larger pilot or more turns out of the a/f screw.

One of the Australian aftermarket pipe makers (TK Pipes) ships a #40 pilot jet with his pipe and says his extensive testing has shown that is the best jet for the pipe - it's part of his pipe package, you don't have to order it separately.

 

Arctra, I wonder if something is different between the AUS model and the U.S. model. "Most" of us run the OEM pilot or maybe a 38, but hardly anyone runs a 40 here. I'm not sure I could get a smooth idle out of my 300 kitted '06 with a full Muzzy and fully open airbox with a 40. I tried the 38 but had the Kouba screw nearly closed. Regardless, it's probably impossible to predict the exact pilot anyone will need, even with the OEM and 38 appearing to be the more frequent choices on U.S. models.

 

Yeah, I believe (mostly from WestOzKLX) that the Aussie model has the same ignition (timing advance?) and header pipe as the KLX300 - that probably factors into it. On my bike, the #38 was perfect with just over 2 turns out on the kouba screw - the #40 would choke my bike I reckon. And I have no airbox lid, twinair filter, backfire screen delete, and the PowerCore muffler - so it should be damned near max flow through the system.

 

Wow, funny this post just came up.

I just installed a 351 kit on my bike and went with the 38 pilot. Could not for the life of me get the idle to smooth out. Went to a 40 pilot and it just got worse. So just about 2 hours ago, I switched back to the stock pilot and now she runs perfect. ???? Doesn't make sense but I wouldn't worry about it until you run into problems.

 

And just tonight I dropped back from a #38 to a stock #35 pilot among other adjustments:

Main back to #125 from #128
Added N1TC needle in middle position versus stock shimmed .060"

Still have to mark my handlebar for throttle and do a proper test ride tomorrow. We'll see how it goes then...

 

So basically you just sent everything back to stock then? Also, can you link me to the 12 oclock labs speedometer that you have installed? Thanks.