Hi everyone,
new guy here. I just bought a used 2009 with 3500 miles on it. Looks like it was ridden mostly off-road, lots of scratches, etc, but seemed to run good whe I test rode it. When I got home after picking it up and getting plates (about 2.5 hours), it wouldn't start without the choke (about 72 yesterday). When I put the choke on, it fired right up, but was screaming at idle (5k rpm). I ended up modulating the choke button so as not to fry the engine. It took a few minutes, but it finally would idle normally with the choke off (1500 rpm). Is it supposed to idle at 5k with the choke on? Doesn't seem right to me. The bike started right up when I test drove it...I'm guessing the seller had already ridden it and had it warmed up...I didn't even check because I was unaware of the cold starting issues with these bikes.
thanks, f&t
BTW, I don't think any rejetting had been done to this bike, but I could be wrong. It's got the stock snorkel, and air filter. He did try a fmf slip on, but said he went back to stock because it was too loud.

 

Welcome to the club.
High revs on choke is normal. It's a cold blooded machine in stock trim.
Mine revs to around 4K on choke.

 

mine brand new would not start without the choke on

and I think its called an enricher
as it adds fuel which makes it idle higher
where a choke blocks the air flow and most times they dont idle much faster

I like the enrichers better they for sure keep the bike running and the faster idle makes them warm up quicker

ive found now I still have to use it on a cold start but only until once it starts
then I take it off and it keeps running long enough to get gear on and thats warm enough to drive it

 

Since I bought mine new last year I needed choke or else it would never start. Even if it was 30C outside, no start without choke. Although on a hot day once it was warmed up I didn't need any choke the rest of the day (unless I parked it for 3+ hours). Since I installed my full FMF (PC4+Megabomb) and various other little mods I had to rejet and now she starts without choke in warm weather!

Cheers

 

I find the bike needs the choke pulled to start when it gets cool outside. Even so, it only needs to be pulled for about 5 seconds. Push it in and it should idle (1,300 rpm) fine. 1,500 is a little fast.

 

You just described the characteristics of the KLX250S to a tee. Cold start needs the choke/enricher engaged, it'll idle high and after a minute or two you can hear it smooth out, then turn off the choke/enricher, and it purrs. Once it's warm, it will generally fire right up. I have an FMF, not sure if the jetting was changed, but she likes just a quick twist of throttle on a restart; push the button, she may not start; push the button and tick the throttle a quarter inch, she fires up.

Welcome to the club!

 

The Mikuni doesn't have a true choke, it is an enrichener with minimal adjustment that can be done, but isn't actually intended to be done with it.

If you do the jetting that is commonly done on the bike, which I did on my 09:

16009-1912 Kawi Needle-Jet, N1TC
92037-1401 Kawi Clamp, Jet Needle
92143-1667 Kawi Collar
Needle clip slot 2 down from the top
92063-1069 Kawi Main Jet #125 or 92063-1074 Kawi Main Jet #128
92064-1108 pilot jet #40 Air screw at 2 turns out to start
drill the slide vent to 7/64ths

Airbox snorkel (14073-1577) high flow unit

And I also did the Marcelino Cam Mod and disabled the compression release...

It will likely start extremely easy and at 72 deg be off choke in about 15 seconds. Mine does. It is no longer cold blooded at all, so far as low as around 45 deg. We shall see how it does in serious cold now that it has hit. We will also see how it does without the compression release, but I don't see any problem there.

 

Wow, thanks for all the replies!! I've been reading about rejetting it and I'll get around to that this winter. To KLX678: what elevation are you at? I'm just wondering what jet size I'll need for my elevation (1400') and will be riding up to 4000-5000'.
thanks again!

 

If it starts hard in winter, even when "choked," consider drilling out the enricher jet to 0.018". This is a common mod for hard to start KLXs. If it isn't hard starting with the choke, leave that be.

If you really want the correct jets, study up on jetting and adjustments. I'm using the stock 35 pilot which gives me the best high-idle rpm at about 2 1/4 turns out on the fuel screw. Elevation and mods make a difference. I'm around 2800 ft and ride up from here.

Welcome to KF!