The thing was running really lean and gutless when I bought it, I think it had stock jetting. It ran so hot the exhaust pipe glowed red and it was pretty doggy on acceleration. I cleaned the carb until it was absolutely spotless, and replaced the sticky choke, which works now. Everything is stock, the bike only has 2200 original miles, stock exhaust. I don't want it be loud and have more horsepower, 100% about running right and easy to ride.

I ordered a jet kit and drew a little pictures of the original values before I changed them. I probably should've taken a picture, but forgot:



I don't even know whether that's their actual names but I changed them from a 35 to a 38, and the other jet from a 118 to a 120. I didn't change the needle position.

It has tons more power now, but burbles coming off idle like I got it a bit too rich. It also seems like it just loads up and you have to open it up to sort of blow it out. Which one of these jets should I change back?

 

No idea what brand of jets, so not sure about comparison. Using Kawasaki Kiehin parts I jetted per D. Pippin's listings, using a 128 main and I think a 40 pilot along with the other work, I'm at around 1000 ft elevation. My bike starts near instantly and runs out great click here. If you are using dyno jet, look up klxster's jetting recommendations by doing a search here in this forum.

Now as for exhaust heat, if you let the bike sit and run without any wind blowing over the exhaust it will absolutely glow, even with correct jetting. It's single wall steel and exhaust will be around 1000°F well above a red glow. I've had my Yamaha SR500 glow bright red in freezing February weather one time. Had a picture of a factory Kaw MX bike on the start with the exhaust glowing. That is no real indicator of jetting. Only an indication that the bike has been sitting running without riding too long. Within a minute or two after taking off on the bike the glow is gone.

 

Jet Kit ?
What Jet Kit ?

A #38 pilot jet and a K120 main jet, on a stock bike, are not going to cause issues. Neither are responsible for your issues.

The "burbling" is due to you not setting the fuel screw correctly. Set the idle to spec ( 1250 rpm ) then set the fuel screw to halfway between idle drops ( By screwing it out until idle drop, then in until idle drop.)

There may be more wrong but I cannot tell with the info you've shared so far.

You will need to read my thread on CVK troubleshooting - the link is on my signature line below.

 

Hey cool, I'll set that and see what happens!

 

I assume the fuel screw is this big screw on the side of the carb? Should the bike be warmed up before attempting to set this?

 

No, that is the idle set to set your idle rpm, which should be around 1200 rpm. The idle mix is in the bottom center of the carb on the cylinder side of the carb. Darn ner impossible to get to, one reason I'm glad the 2.5 turns Doug recommended worked so well. I didn't mess with it.

 

If you are at or near sea level, and
If you are running the stock #35 pilot jet, and
If your fuel screw seat is undamaged from over torquing the screw closed,
then you can get a good "ballpark" setting with 2.5 turns out on a 1200 - 1250 rpm idle.

Otherwise, best to do it right - halfway between idle drops, with idle set to 1250 rpm.

 

So is this it?



How can you get to it with out right-angle fingers? Looks like really close to the case, needle nose maybe? It's about 3/4" from the starter and you can't get a screwdriver in there. Maybe I can lean the carb over to get a better angle, but then the bike wouldn't run while adjusting it.

 

Odds are you'll need to try to turn the carb to get inside to the screw. But if it runs good as it is I'd say run it. I forget exactly how many turns out they are in factory setting. There should have been a plug in the hole where the screw is, that is to be removed if you look back at D Pippin's web site. It was also mentioned that there are thumb screw type replacements and one is shown. I turned mine to 2-1/2 turns out from seated (do not tighten into seat, that can ruin the screw and carb seating surfaces.), it has worked fine in all weather. My brother did the same.

 

I wonder if I can just loosen the clamps and turn it, or if I have to disconnect the throttle linkage. I haven't had this bike long, it's only got 2200 miles on it, so hopefully it'll run forever once I get it set.

I can't imagine doing anything with the carb trailside, which is a real bummer, I've had to numerous times with big XR's.