KDX220 Jetting problems

If you have a crank seal leak you will see a drop in oil level. Assuming you are not using gear oil, I suspect jetting or a float that is sticking or the float valve (is that right?) has a bad seat. Start with the float by checking it's full movement with the bowl off. Should move freely without any resistance. Check the seat by attaching a fuel line to the carb, blow lightly and move the float up with your finger. You should feel resistance to where you can no longer blow air. If you use a clean hose, pull a vacume by sucking lightly and see if it holds. NOt accurate but it will tell you if you got a serious problem. If your bike is more than 3 years old, I would change it out just on GP's. Then check the jetting. Those Boyesen reeds, pipe and air box lid removed allows for the bike to be jetted much leaner. Both FMF and Boyesen recommend a leaner jet with their installation. I have mine as: Main-140 pilot-35 airscrew 1 turn out, needle stock 1173L on the top clip. It works well on either top or second to top without much difference in performance. I am also in Northern California near Placerville about the 2000 ft elevation but jetted for 4-6K ft. This bike starts first kick unless warm, then 2 kicks. Idle is perfect and it has such a small bog when snapping the throttle off idle that it isn't worth the work to figure out. Good luck and if you are near, maybe we can get together to figure this out. I'm always looking for someone to ride with.

When I said do you use gear oil, I really meant, does your engine gear oil deplete between changes? Is it disapearing? If you need to add additional oil between changes or notice it is low when you change, then it is going somewhere and that is probably due to a crank seal. I've had this on a previous KDX and that was the symtoms: Bad low end, oily exaust, tranny oil disaperaring. Georgetown AKA Rock Creek OHV riding area is one of my favorites and very close for me. Sounds like you know what your'e doing with the carb so just keep going the way you are and it will start working right for you. One thing I am changeing is going to race gas. Not for any performance enhancement but for the consistancy in the fuel and ease of jetting. It seems that every tank from the gas station varies in quality and that is why I was having problems jetting. Using race gas eliminates the variable in fuel as well as avoiding the ethenal / alcohol blends. Did you know that as little as a teaspoon of water in alcohol blended gas will pull all the alcohol out and put it straight to the bottom of the tank. NOw you get a huge slug of alcohol and water, no two stroke oil and can seize the bike. Happened to my riding buddy after dumping in a creek. Avoid alcohol blends like the plague it is. But, I digress....good luck getting the jetting squared away.

You might check the needle number. Maybe it's been changed?

What condition is the choke plunger in?

I can't get past the first sentence. With the idle screw all the way in, something is very much wrong if the bike isn't screaming.

You don't mention the air screw. Sorry..but the AS is the brass one, and the idle screw is the black nylon one...right?

Not to be pedantic...but I've been 'round that horn before with a posted 'won't idle' problem. Turned out he thought the idle screw was brass........

Lee, those bikes really need a leaner number 6 slide or a needle profile change to work properly at low throttle.

I used to have a '98 220 (FMF/TC2) which when jetted stock blubbered down low and spooged. I changed the carb, going to a 35mm with a #6 slide, which calibrated perfectly. The #6 should work OK in the stock 33mm carb as well. BTW, for my bike, the upgrade to the 35mm carb made very little difference to the top end or mid range.

Selection of the right needle profile may obviate the slide change, therefore check this site for jetting and needle specs, as this has been dealt with in the past.

re: too low an octane?

Yes. Spec is 91 in an '00. '97 is still an 'H' model, so would assume it to be the same?

re: slides

Get ahold of ron @ RB designs. He usually has slides on the shelf for cheap (like $45 or so). I tried for months to get a leaner slide (oem is 5mm) from a local shop. I got two large body PWK slides, but never the correct one.

Ron got one to me in two days! He's HERE

re: AS spec

There isn't one. You set it to best 'seat-of-the-pants' response. Best set in (example) 2nd gear, walking speed, under load (slightly uphill) and a quick twist should get you instantaneous reponse. A misadjusted AS will be evidenced by a bog when you wick-it-quick.

For some great jetting input, check the archives for the RB designs carb thread. Pay special attention to JDs input.

Thanks for clearing up the AS/idle part. ;)

1. The search function is experiencing a SARS attack. It's barely breathing. You can search by username, but word delimiters haven't been working.

2. Don't know if it's RB Designs you're looking for, or threads referencing the company. When I said, Ron got one to me in two days! He's HERE above, the <HERE> is a link that you can click on to go to his site. If it's threads you're searching for, goto #1 ;)

3. And I think you mean RB designs? His name is ron black, btw. 'JD' is james dean, a jetting gehru/mechanical engineer that knows stuff.

4. AS set using 'lean roll' method. That's a 4-str 'tool' for sure. Not applicable to 2-str.

5. I'd had a hankerin' for a 700SC since, oh......about '86 (second year they were made). Having ridden r5's and rd's for decades, I finally decided it was time to 'graduate' to a UJM (universal japanese m'cycle..or 4cyl transverse mounted in-line bike). I DO like it quite a bit. It's a noisey SOB, though. The little 1/4 fairing dumps turbulent air from the square headlight right on my head. Raise up on the pegs just 10", and the ensuing quiet is wonderful! One of the reasons I went 4-str is to get more miles on a tank. Ha! The 700SC tank is of course, PUNY! When it hits its sweet spot (about 9500rpm), it's FUN! And a set of battle ax tires can make your head devoid of all fluids on corners! YeeHAW!!!

6. The tech-8 remark is kind of an inside joke, I guess.

7. Here's a link to the archived thread I was talking about...with JD's valuable input:

http://www.dirtrider.net/forums3/showthread.php?s=&threadid=19686


This is in 'archived posts'. If you go to the forum front page (that lists all the forums) it's next to the last board listed. It comes up with 'no new topics added in the last 30 days', but change the display to 'since the beginning' and you can see all sorts of good stuff.

Have fun!

Re: too much stuff

A day without learning is a like a day without.......well....hemorrhoids maybe?;)

Take a look at the coil rewind post on the archives board. Read techman's posts. Cripes! There are a lot of people out there that know a lot of stuff!!

......I like the square wire idea. Didn't see that developed, though.

Have fun!! Don't give up on it yet!!