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hard start sometimes, even when warmed up ... carb needs tune?

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Just bought a new 09 Kawk 250.

 

Motor will get going with the choke, on a cold start.

After warm up (15min+ driving) 

   motor will sometimes start without the choke

   BUT a lot of the time won't start without the choke. 


no rich smell from the exhaust, no gas smell .... should it do this? I'm a new motorcyclist don't know much about motorcycle engines, just cars and small utility engines

Edited by horrorfan

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sounds a little lean...maybe you are a using different premix ratio than previous owner? You can try turning in airscrew a half or full turn to richen...

that's if its a 2 stroke...4-strokes have fuel screws you would turn out to richen...

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7 hours ago, Sofiedog said:

sounds a little lean...maybe you are a using different premix ratio than previous owner? You can try turning in airscrew a half or full turn to richen...

that's if its a 2 stroke...4-strokes have fuel screws you would turn out to richen...

 

yeah you're right , prob lean not rich. 

 

I don't want to mess up the fuel air mixture ... Ive messed up carbs before like that.

Is there a manual to get the fuel correct? Would it be worth getting someone to tune it on a dyno

 

 

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41 minutes ago, Sofiedog said:

what kind of bike? 2-stroke or 4-stroke?

4 ..according to wiki

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ok...is it a KLX250 dual sport with lights and mirrors?

The choice is yours...you can take it to a dealer or shop and have them jet it or you can do it yourself with help...usually, not that hard...

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13 hours ago, Sofiedog said:

ok...is it a KLX250 dual sport with lights and mirrors?

The choice is yours...you can take it to a dealer or shop and have them jet it or you can do it yourself with help...usually, not that hard...

is rejeting the carb, getting the to carb function as it did out of the factory?

 

all I want is my motor to be happy and "healthy". 

 

I brought it to a shop today ...told the guy about what I've been noticing and he suggested that they valves are tight. I asked him for a valve adjustment quote and he said about $420 (seems way too high ill prob go somewhere else).

 

I also noticed when the bike is idling after cold start rpms will steadily jump from 1000rpm to 1100rpm back and forth.

Edited by horrorfan

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yeah...dirt bikes are expensive if you pay someone to work on them.

Shimming valves is more difficult than jetting, but several dollars for the shims and a few hours in the garage and you are good to go again...

I'm not familiar with your bike enough to know if they need frequent valve adjustments...maybe someone in this kawi thread can say.

Everyone's different. Some just get on their bike and ride...others, like me, have to have it running well and looking good...the maintenance becomes a hobby...

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What is your altitude where you are riding. These bikes are notoriously lean even at sea level. If it runs good with the choke on riding around it is NOT a valve issue. 

I believe you need to jet the bike for the altitude. Usually you go off stock jetting a percentage, however since they are super lean from the factory, you are just going to have to experiment. Since it doesn't start warm, the pilot jet needs to be larger, I would also go that same percentage to the main jet. So say the pilot is a 45 and you go to 48, you have added 3 to a 45 (3/45) or 6%. So if your main is 128 add 6% there as well while jetting. (128x1.06) or 135(round to nearest actual available jet size).

It could also be that there is varnish from old gas and just replacing the jets with the same size would solve the problem. 

Most shops will rejet bikes relatively cheap.

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On 9/3/2017 at 8:27 AM, kdxyardsale said:

What is your altitude where you are riding. These bikes are notoriously lean even at sea level. If it runs good with the choke on riding around it is NOT a valve issue. 

I believe you need to jet the bike for the altitude. Usually you go off stock jetting a percentage, however since they are super lean from the factory, you are just going to have to experiment. Since it doesn't start warm, the pilot jet needs to be larger, I would also go that same percentage to the main jet. So say the pilot is a 45 and you go to 48, you have added 3 to a 45 (3/45) or 6%. So if your main is 128 add 6% there as well while jetting. (128x1.06) or 135(round to nearest actual available jet size).

It could also be that there is varnish from old gas and just replacing the jets with the same size would solve the problem. 

Most shops will rejet bikes relatively cheap.

 

 

 

thanks, yeah I've realized that this is a bike that just needs to be PROPERLY warmed up before riding every time. Ive learned how to get it ready for the road every morning after experimenting like you said honestly I think the problem was being a new rider not used to motorcycle engines.

 

I'm glad I can check off valve issue and it doesn't look like any varnish in gas tank, I usually peek in there when I fill up its all nice and silver ...no yellowish gold

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