General Dirt Bike Questions

[glockman]

My bike always backfires when the gas has sat in it for a few months.

Steve get a brush with long bristles to wag your bike. I noticed a pro mechanic using one at supercross one year so I bought one. It makes it really easy to get all the odd shapes on a bike. That and simple green work great. I usually wipe it down with WD- 40 after.


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[sixstringsteve]

like a toilet bowl cleaner?

 

[Cascadia]

I started to tear into my bike a little today to try and get the carb tuned. But after I took the seat, tank, and loosened up the carb I decided to put it back together and decided to empty the gas instead and fill it with new gas. Once I poured the old stuff out I couldn't believe the color. It was an orangish brown color, pretty nasty. I could see how that would make it run how it is running. I filled it up with fresh gas and took it around the block. It was about twice as good as it was before. But it still bogs down a little right off the bat but only in first and second gear. I then adjusted the fuel up a little bit. After that it did idle a lot better and it ran a lot better. But there is still a hesitation. After this weekend I will take the carb apart. Are there certain jets I should soak? Main and pilot?

 

[sixstringsteve]

If the gas was that nasty it probably gummed up the carb and jets. The pilot affects The first 1/8 of your throttle. Its not any harder to pull the main at that point. I'd soak em both.

 

[Cascadia]

Sounds like that's my issue then. Hopefully.

 

[sixstringsteve]

Steps:

- turn fuel petcock to off position
- drain float bowl (the bolt on the bottom of the carb)
- loosen rubber boot clamps attached to carb
- rotate carb so bowl is towards you
- remove bowl and gasket (4 Phillips screws)
- look at the pictures Jentzchman posted to identify the two jets
- unscrew the jets and soak them in ammonia
- rinse jets with water
- do everything in the reverse order, being careful not to mess up the float bowl gasket.

That should do it

 

[jentzschman]

Also, watch for the float pin that keeps the floats in.... I was messing with mine one day and the pin fell out followed by the needle valve and floats. This shows the pin removed, but gives you an idea:

 

[rholbrook]

Easy to do. I rejected a bike today, bigger main, bigger pilot and raised the clip on the needle. Runs great now and idles perfectly

 

[glockman]

like a toilet bowl cleaner?

I bought mine at walmart. It looks like this.

 

[Cascadia]

Ok. I got my jets out. They are as follows: main jet is a 162. Owners manual says stock is 168. Idling jet is a 40 and stock is 40. Starting jet is a 185 and stock is 185. What should I do?

 

[sixstringsteve]

Did it run better when you first bought it? If so, soak the jets in ammonia, clean them out, then see how it does.

 

[Cascadia]

It ran great the day I test drove it. Maybe the old gas really clogged it up. Guess I should check and soak them first before changing them.

 

[sixstringsteve]

That's what I'd do. Then you can make changes and compare it to that baseline.

 

[Cascadia]

It's easy but seems like a lot of work to go through for trial and error. Someone should make a carb that has the jets accessible from the outside somehow. I just put them in ammonia but I don't know that it'll help. They look really clean and I can see through them.

 

[sixstringsteve]

or you could just get a fuel injected bike and not have to worry about jets.

You problem may be something entirely different from jetting, but after hearing how bad your gas was, you sure aren't hurting anything by cleaning the carb. Once the jets are dialed, you really don't have to mess with them unless you ride in a place with a drastically different elevation.

 

[Cascadia]

I could. But I'd have to sell my truck to pay for it.

 

[Cascadia]

Got the bike back together. I set the fuel mixture to stock which was .75 turns out. When I got it running it died quickly. I couldn't get it to idle until 4.75 turns out. Should that tell me something? And when I rode it it would still big at first throttle. What should this tell me?

 

[GAR]

What does pulling the choke do?

 

[glockman]

You need a bigger pilot jet. If the bike idles the smoothest at less than 1 turn out you need a smaller pilot, more than 3 turns means you need a larger pilot.

 

[anderson750]

If the fuel screw needs to be turned that far out it is not getting enough fuel.