General Dirt Bike Questions

[Cascadia]

Once I had the fuel screw that far out it idled great for about a minute. Then I tried to give it throttle and it bogged and died. Can't get it started now. Probably flooded for some reason. Should I adjust it back in some and see if I can get it started in a little while?

I tried the choke once for a second but the rpm's dropped so I pushed it back in.

 

[jentzschman]

The rpm's should not drop with the choke out as I understand it.

I would set everything back to stock and go over the process again. I know it's a pain, but that is the war we wage with carbs. Don't get discouraged. There are a lot of great people here to help.

 

[Cascadia]

I let it sit for an hour. Set it back to 3/4 out and turned it out a 1/4 until it idled. I got it to idle at 3.25 turns out. It idled for 5 minutes on the stand. Put it in first and let it spin in idle. It ran for 5 minutes but if I tried to give it gas it would bog and cut out. After about 5 minutes it instantly quit and couldn't get it restarted.

 

[sixstringsteve]

when you say "try to give it gas" are you going from 0-100% throttle in a split second, or are you easing it on?

 

[Cascadia]

I'm barely easing on it. A lot easier than riding the other day.

 

[Caleb]

The rpm's should not drop with the choke out as I understand it.

I'm not sure how correct that is. Every bike I've had ran great (i.e. they were jetted pretty much spot on), but all would idle a bit higher with the choke on.

 

[anderson750]

Did you pull the pilot jet out and clean it? The passage in a pilot is so small that a deposit from stale fuel could block it off 50% and it would be hard to see with the bare eye. If you did not already, soak it in ammonia for 15 minutes to break down any deposits.

 

[Cascadia]

I pulled out my main jet, idling jet, and starting jet. Is main the same thing as pilot? I soaked them all for 30 minutes in ammonia, rinsed with water and dried and reinstalled.

 

[sixstringsteve]

I believe the pilot is the idling jet.

 

[anderson750]

Make sure there is not something blocking the passage that the pilot jet screws into.

 

[Tonkaman]

First of all I would clean the ENTIRE carb since the gas was brown.
Second check the needle type and clip position
Third remember that most "stock" settings are for sea level and 70* so be sure to adjust for that

 

[Cascadia]

What pilot jet should I be running in this elevation and temperature? Stock is 40.

 

[Tonkaman]

Not sure for your bike but my bike has a cool chart in the owners manual. The x value is elevation, the y value is temperature which gives you all jet sizes, needle, and clip

 

[jentzschman]

What pilot jet should I be running in this elevation and temperature? Stock is 40.

Stock pilot on my yz250 is 50 and right now I have a 48 in. Each bike is different. I think Steve is ruining 2 pilot sizes leaner. From what I understand at our elevation going at least one pilot size smaller is a good starting point.

Sent from my HTC VLE_U using Tapatalk 2

 

[Rot Box]

First:

Remover carb completely. Once it is off the bike and on your work bench:

-Point the intake side (engine side) of the carb away from you and away from anything you don't want fuel on. Quickly twist/rotate the throttle wheel, linkage or whatever you want to call the round thing where the cables attach. You should see a nice stream of fuel spray out of the carb.

If you do not. Report back. This actuates your accelerator pump it is absolutely critical that this sprays fuel out or you will get a nasty bog every time you twist the throttle.

Next:

Clean the carb and make 100% certain the entire pilot circuit is clean. After you take the pilot jet out and ensure it is clean--reinstall it. Then take the red straw of the carb cleaner can and spray through the pilot jet. Once you get a good seal between the jet and straw (this will take some work) you should be able to see carb cleaner spray out in two places. 1. In the throat of the carb (front) and 2. straight up towards the slide of the carb.


I would not change the pilot jet size until you've verified these things. Remember the fuel screw is only efficient between .75 and 3 turns out. If you need more turns out you need a bigger pilot jet.

Hope this helps. On the bright side once you get it dialed in you should never have to touch it again

 

[Cascadia]

I found a chart for an 09 of my bike that says a 35 pilot jet at our elevation and a 165 main jet. I may try that tomorrow.

 

[Cascadia]

Never mind for now. I will try and follow your directions tomorrow Andrew. Where will the fuel be coming from when I turn the throttle wheel since it will no longer be hooked to the tank? Just leftover gas that's in the bowl?

 

[Rot Box]

There's always a residual amount of fuel left in the accelerator pump housing. Should be plenty to tell if it is working or not.

 

[Cascadia]

First:

Remover carb completely. Once it is off the bike and on your work bench:

-Point the intake side (engine side) of the carb away from you and away from anything you don't want fuel on. Quickly twist/rotate the throttle wheel, linkage or whatever you want to call the round thing where the cables attach. You should see a nice stream of fuel spray out of the carb.

If you do not. Report back. This actuates your accelerator pump it is absolutely critical that this sprays fuel out or you will get a nasty bog every time you twist the throttle.

Next:

Clean the carb and make 100% certain the entire pilot circuit is clean. After you take the pilot jet out and ensure it is clean--reinstall it. Then take the red straw of the carb cleaner can and spray through the pilot jet. Once you get a good seal between the jet and straw (this will take some work) you should be able to see carb cleaner spray out in two places. 1. In the throat of the carb (front) and 2. straight up towards the slide of the carb.


I would not change the pilot jet size until you've verified these things. Remember the fuel screw is only efficient between .75 and 3 turns out. If you need more turns out you need a bigger pilot jet.

Hope this helps. On the bright side once you get it dialed in you should never have to touch it again

Andrew, I did what you said. Took the carb completely out. Turned the wheel where the throttle cables attach and no fuel squirted from anywhere. It's been 2 days since I ran it. Would there still be fuel left for the accelerator pump to spray? I got no spray. But when I took the big nut out of the bottom of the bowl it had plenty of fuel leak out. Do I have a problem? What's next on the list of things to do, other than spray carb cleaner through it?
I really want this thing running for Saturday.

 

[anderson750]

Sounds to me like your pilot/accelerator circuit is blocked.