DirtRider . Net MX, SX, Arena Cross, Off-Road Community

This is the text version of DirtRider.Net
Click Here for the Full Version

Pages: 1

low rev stutter
(Click here to view the original thread with full colors/images)

Posted by: jonooffler---------------------

Hi I have a 2003 220 I think its stock, it has a stutter at low revs, it feels like a misfire/ over fueling.
It pulls well at high revs.
So far I have changed the plug, cleaned the filter, refilled with new petrol with a 40-1 mix .
It is running a 42 pilot with the air screw at about 2 turns out. when the screw is in it dies but as the screw comes out there is little change in the revs.
Help the dam thing is starting to get to me .
Jono

Posted by: dirt bike dave---------------------

What altitude? What weather conditions? Did it used to run better, or are you a new owner of the bike?

Sounds like a slightly rich condition under load.

Personally, I would try turning the airscrew out to 2.5 turns or putting in a 40 pilot and see if it helps.

Posted by: porterdog---------------------

Some amount of stutter at low revs is inevitable IMO, especially if you're at a low throttle opening... The exhaust resonance just won't work there so the bike runs a little funny. Gas it!

Posted by: liven07---------------------

If it sounds like a miss but is running fine it's just a 2 stroke but if you got a loss of power or seems like it gets over a certain rpm's then takes off you got a problem. Don't know where to tell you to go first, it could be many different things. I would start with a carb cleaning if it has not had one recently and check the reed valves well you got the carb off and check the numbers on the jets to make sure they are stock since it has got no mods. I seen some other guys in a other post talking about not repacking silencers can cause loss of power in low rpm's, i would like to get more info on that myself. good luck

Posted by: jonooffler---------------------

Well I have just got back from my local Kawasaki off road dealer he tried the bike out and said that it was running rich and said change the pilot jet and may be change the clip , he had a look at the offical Kawasaki parts book and the 2003 KDX220 should have a 38 jet but mine is a 42.I'm going to get one and see what happens.
Thanks for all the input so far.
Jono

Posted by: NCFRC---------------------

Let us know as this seems to be a 220 trait , not common on a 200 .

Posted by: jonooffler---------------------

Well I have changed to a 38 pilot and it's a little better but not much.
Any more ideas out there, I'm off to my local Kaw dirt dealer today to see if they have any ideas. I'm getting into the mind set of giving up with the bike now, so If any one in the UK wants a 2003 KDX220 drop me a line.
Jono

Posted by: NCFRC---------------------

Don't give up on it as once you sell it and the next person finds the right combo to make it run better you'll regret your impatience.

I've spent an entire summer tuning a H.P. Honda four-stroke but when I hit the right cam timing , jetting ect. it was worth every minute. Yes , I wanted to throw it over a bank many times up to that point.

Did you know Edison made over a hundred light bulbs before one worked ?
How many of us would have given up way before that.

Posted by: dirt bike dave---------------------

Slide cutaway also plays a big role in low end response.

Unfortunately, slides are much more expensive than pilot jets.

You can grind material from the bottom of your slide to get more cutaway and lean out the low rpm range. Grinding is cheaper than buying a new slide (or a new bike, lol).

Posted by: jonooffler---------------------

Quote:

Originally Posted by NCFRC

Don't give up on it as once you sell it and the next person finds the right combo to make it run better you'll regret your impatience.

I've spent an entire summer tuning a H.P. Honda four-stroke but when I hit the right cam timing , jetting ect. it was worth every minute. Yes , I wanted to throw it over a bank many times up to that point.

Did you know Edison made over a hundred light bulbs before one worked ?
How many of us would have given up way before that.

Hi I hear what your saying and yes your right it's just that I'm married to high maintenance and complex I just wanted my other ride to be a bit more simple

.
I spoke to the guys at the local MX shop and they rode it it and came back saying that it was running rich and lean at the same time, when the the slide comes off the stop it runs rich to start with but then starts to lean untill it opens over the 1/4 to 1/2 mark, they suggested that I should lift the needle to the 3 clip and try that.So I now running 40-1 38 pilot 3rd clip and no snorkel I have yet to ride this setting but I will let you know how it goes.
As for Mr Edison ,it is said that he once told a reporter that actually had 3,000 attempts to create the lightbulb. When asked about the failures he said "I didn't fail 3,000 times. I found 3,000 ways how not to create a lightbulb"
So looking at that I'm just finding ways of not making a KDX run right

Thanks again Jono

Posted by: jonooffler---------------------

Quote:

Originally Posted by dirt bike dave

Slide cutaway also plays a big role in low end response.

Unfortunately, slides are much more expensive than pilot jets.

You can grind material from the bottom of your slide to get more cutaway and lean out the low rpm range. Grinding is cheaper than buying a new slide (or a new bike, lol).

Hi mate thanks for the input I might try that as a last resort, it's odd all the reviews say that the 220 is a great woods bike this one is stock and hates slowish trails and woods.
I will keep you all posted.
Jono

Posted by: NCFRC---------------------

Quote:

Originally Posted by jonooffler

Probably the most important thing to remember is that these bikes were mass produced on an assembly line . Thats why we can give each other general advise but every bike is different. If you have time this coming winter pull the cylinder off and just clean up the ports . You'll be amazed at the factory casting slag . Thats all I basically did when I rebuilt my son's 200 and that bike runs extremely smooth. Plane that head .015 to .020 also .
Run the 50:1 if your synthetic oil allows it , it will make a difference.

So I don't start a war , send the head off to Ron Black , $45 is cheap for someone who knows what their doing.

Posted by: mechanos---------------------

Just went through this with my sons 200, you may want to check float level, his was running too rich even with smaller jetting. I lowered the float level (to recc. setting) and problem went away.

My 220 works great with stock jetting in the woods, so don't give up.

Posted by: whenfoxforks-ruled---------------------

Your air screw adjusted to max idle rpm's will tell you if the pilot size is correct. The float height needs to be correct, the float valve should be replaced yearly, reeds and silencer packing changed often. 2 smokes can load up when not cleared out, rode a lot under the power band. By ignorantly running leaner oil ratios than the bike was originally set up for, fighting the rich condition is futile, you would be dumping more gas in!

Text Version Home

This is the text version of DirtRider.Net Click Here for the Full Version

low rev stutter

This is the text version of DirtRider.Net
Click Here for the Full Version