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Last weekend I took my carb off & cleaned it for the first time. That wasn't so scary after all! When I looked through the jets, particularly the pilot there was barely a hole. I blew through them and out shot some crud now they are clean as! I used carb cleaner on everything although it all looked pretty clean. The jets were all stock, 48 pilot & 160 main, middle position on the stock needle. I turned the air screw to 1 & 1/2 turns which is stock from the manual. Back on the bike it ran way better with much better bottom end pull, the back wheel was spinning up and I could stay in 3rd in slow sections where before I'd have to drop to 2nd and keep the revs way up.

So carb is all stock... My bike is running a Pro Circuit Platinum 2 pipe with a 'factory sound 304' silencer and the PO has cut a 100x120mm hole in the top of the air box lid. (I'm at sea level - the Pacific Ocean is literally over my back fence)
So if I have an exhaust upgrade & the air box mod surely that would instigate a change to the jetting. Would you agree?

I don't know how much love there is on this site for Canadian Dave (hey we all love KDX's right?) but he suggests as a jetting 'starting point' with my set up, 42/45 & 152/155 & stock needle set up. I've ordered a #155, #45 & #42 and I'm thinking of putting in the #45 & #155, tuning the air screw & see how she goes.

I'd love to follow through the jetting guide on here (I must have read that 10 times!) but I don't have access to a long straight to do the plug chop. I might have to try to find a suitable area on my next trail ride in a couple of weeks.

What do you guys think about this approach?

Hama

Street in front of your house should work for a long straight, no? Just don't keep riding up and down annoying your neighbors over and over.

Hang on I was looking for opinions on my jetting approach not where I should do my plug chop. Although I like the idea of blasting down my street I'd be breaking a whole lot of laws that would turn it into a really bad idea if a cop just happened to drive along.

What is your elevation?

You can throw whatever jets someone tells you in there, and it will run. It will never be jetted correctly until you take the time to do it properly. 45/155 is generally considered a safe starting point for most people.

The option you list will work fine and you should see some improvement. That said, I have similar mods on my son's 2005 KDX200 (FMF Gnarly Woods, Core2 and no air box lid) and we run the stock setting. I have been thinking of going to a 155 main an 42 pilot, but honestly the bike runs great for him. Sure it could be a bit better, but not leaps and bounds. We live in Fort Worth and are only ~600ft above sea level. Of course, temperature differences will be a factor come summer time.


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+1 to all the above. Start with what you have in there and go through the guide. Every bike is different and even two identical KDXs with the same mods may jet differently. The guide and a plug chop will let you know whether you need to change your main/clip position/pilot.
Either way you'll end up with a bike that is begging to be taken out and ridden!

Thanks for all your replies. There are definitely no short cuts to this then. We have a dirt bike park half an hour away that I go to quite often just to muck around and test our bikes etc. The only thing it doesn't have is a long straight. There are some straight farm tracks on the way in. I might have to try it on them. I can easily check I have the right pilot jet or not. If I need to change the pilot I'll change the main too then do the plug chop. Thanks again!

Best practice is to make only one change at a time even if it is a little frustrating.

Your plan sounds fine and you will see improvement. I would not be too concerned about dialing in the main at this point, you can check that when opportunity arises.

One thing I would be careful of is breaking the tube the throttle cable goes through on the carb cap. I've seen many of those broken, right where the cable clips into the end of it. I've done it myself. It happen when you loosen the clamps at reed block and air cleaner and rotate the carb to get the bowl off or even when taking the carb out and not being gentle. I'd take the tank off, at least first time, when removing your carb.

Just for future reference for myself... I changed my pilot jet recently to a 45, it seems to have given me more top end rpm, more go at WOT. And man they come to life again after a good carb clean!

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You may not be aware but our 98 octane fuel down under is denser than what the 93 in the northern hemisphere is (similar octane, different measurement method/standard)? So Northern hemisphere jetting guides will likely leave you a little rich. I'm at 45 pilot and 158 main, It is still a little fat as transport sections between single trails are run WOT in 6th and I don't want it to nip up. Spooge is minimal and it pulls well with sharp throttle response (too sharp for my mates that ride 450's, they won't ride it in sand/mud/loose hills lol)

Hi Rusty, i have 38 pilot 152 main jet up here in sunny Queensland. Kdx 200 fresh recoated cyl TSP cyl head mod all good.