2013 Crf 80 full throttle problem

[Speed Wobbs]

I have a question about my 2013 Crf 80f.

The bike idles perfect, starts first kick, revs good through every gear. But when it's idling and I open the throttle all the way quickly it starts to bog down and wants to shut off. Even if I am in gear rolling but no throttle and I pin it quickly it does the same thing. I was wondering if anyone could inform me on the issue or if it's even an issue at all. Thank you!

 

[OlGertyBastard]

Is it completely warmed up when you snap the throttle open?

[Speed Wobbs]

2 minutes ago, OlGertyBastard said:

Is it completely warmed up when you snap the throttle open?

Yes it is. I read on some other threads that they have the same problem and that's just how they are. I have cleaned the carbs multiple times and everything is fine except when I snap it. I read on some other threads that's how bikes some are. I find it hard to believe but i haven't had experience with a ton of dirt bikes 

 

[mxkid108]

Ours does the same thing

[SenorThumpy]

Happens on some 4t bikes with out acc pump carbs, if I recall correctly. The way I understand it is when you snap the throttle wide open from idle, the bike is pulling more air than the carb can supply fuel for. For an instant the volume of air being pulled into the motor is greater than the vacuum (of the motor) can pull fuel from the carb so you bog. I THINK (emphasis on think) that a different needle taper will help the cause. Or you could just roll on the throttle hard instead of snapping it. Or does this happen when you roll on the throttle too? 

Edited March 31, 2017 by SenorThumpy

[mxkid108]

Depends on the rpm of the motor. For instance if ur in 2nd gear and bobble on a small incline and get off and back on the throttle it will bog out.

[HappyAndy]

Is the rubber part of the intake manifold cracked? A vacuum leak will cause a bog problem too. Has this bike always had this issue, or is it new? Its easy to test by spraying carb cleaner around the carb and inlet manifold while the engine is running. If the idle speed changes there is a leak. 

Another thing to consider is that these are quite lean from the factory, and come with the idle mixture screw covered by a brass cap. You can pluck that cap off to get at the screw, it may not have a regular screw head though. Adjusting the mixture to be richer can help, as can going up one size on the pilot jet. While you are in there make sure the float height is set right. 

 

 

[mxkid108]

Is the rubber part of the intake manifold cracked? A vacuum leak will cause a bog problem too. Has this bike always had this issue, or is it new? Its easy to test by spraying carb cleaner around the carb and inlet manifold while the engine is running. If the idle speed changes there is a leak. 
Another thing to consider is that these are quite lean from the factory, and come with the idle mixture screw covered by a brass cap. You can pluck that cap off to get at the screw, it may not have a regular screw head though. Adjusting the mixture to be richer can help, as can going up one size on the pilot jet. While you are in there make sure the float height is set right. 
 
 

Thanks I will try the air screw if I can get that cap off. I didn't realize it was just a cap/insert covering the air screw

[Speed Wobbs]

3 hours ago, SenorThumpy said:

Happens on some 4t bikes with out acc pump carbs, if I recall correctly. The way I understand it is when you snap the throttle wide open from idle, the bike is pulling more air than the carb can supply fuel for. For an instant the volume of air being pulled into the motor is greater than the vacuum (of the motor) can pull fuel from the carb so you bog. I THINK (emphasis on think) that a different needle taper will help the cause. Or you could just roll on the throttle hard instead of snapping it. Or does this happen when you roll on the throttle too? 

It rolls on the throttle fine. Thanks for the input!