Rpm drops on idle

[swehollow]

So. I have this gasgas 250 from 2003. I just renovated the engine With new connecting Rod, all gaskets, piston, piston ring, main bearing etc. The bike was not idling before the overhaul and I still have a problem.

I have a ne1c needle set to first position, a 40 pilot and a 168 main. Nr 6 slide. Ive set the slide height to 1 mm, set my float level, put AS to 1,5. Idle screw out.

Here is what happens. It fires up, and as Long as i keep reving slighty its ok, when i release it Will idle fine for a few seconds, after That time the rpm suddenly drops. Way low, to a Point where its barely staying Alive. And most Times it dies.

What is this? Happens evvvery time.

I cant figure it out.

 

[gassergrant]

Maybe worth trying the needle in pos 2 or 3 ??

 

[Todd5774]

You have played with the idle screw?

 

[swehollow]

Maybe worth trying the needle in pos 2 or 3 ??

Had the needle on third to begin with. Same story

 

[swehollow]

You have played with the idle screw?

Yeah ive toyed with it a little but no real results. Doesnt the idle screw just push your slide up/down? How high can u set the slide, and what happens if you go too high ? I would have somewhat better result idling with the slide higher. But it ends up dying from too much gas it seems, so not really an option

 

[Todd5774]

Do you have another needle to play with, as my 300 won't idle unless it has the JD red needle in, and then will idle all day but when it was a 250 it didn't like the red needle and would die after 30 seconds or so..

 

[swehollow]

Actually i dont.. Would you recommend me one ? I would appreciate an ebay link or something similar.

Do you have another needle to play with, as my 300 won't idle unless it has the JD red needle in, and then will idle all day but when it was a 250 it didn't like the red needle and would die after 30 seconds or so..

 

[Todd5774]

Sorry no, our resident forum jetting juru (jakobi) will be along to recommend the right needle.

 

[Jakobi]

I know nothing about the early models. I've posted loads of info on how to fine tune your bike based on how it behaves though.

Check the jetting database for ideas of good starting points.

 

[swehollow]

I Will defenitly read through it. Just sometimes the language acts as a barrier for Deep understanding.

 

[@enrico@]

So. I have this gasgas 250 from 2003. I just renovated the engine With new connecting Rod, all gaskets, piston, piston ring, main bearing etc. The bike was not idling before the overhaul and I still have a problem.

I have a ne1c needle set to first position, a 40 pilot and a 168 main. Nr 6 slide. Ive set the slide height to 1 mm, set my float level, put AS to 1,5. Idle screw out.

Here is what happens. It fires up, and as Long as i keep reving slighty its ok, when i release it Will idle fine for a few seconds, after That time the rpm suddenly drops. Way low, to a Point where its barely staying Alive. And most Times it dies.

What is this? Happens evvvery time.

I cant figure it out.

I don't know the 2003 model but needle n1ec is really very fat which combined with the valve 6 makes idle really fat.

How much does it consume?

If you have a smaller idle jet trying to put one, you'll see that the situation will improve.

Then you should change needle with N1EF or G or NOZF or H if you want to keep that family of needles or else switch to a pin of the family N2 / N8.

 

[Jim Cook]

For your carb, I really like the N1EG needle. I set mine with the clip in the second groove from the top.

 

[swehollow]

That is some seriously good advice. I will defenitly try getting one of the needles below. Anyone one of them will do right?

It has a huge drinking problem. I thought there was a hole in the tank for real. I had the float set right but put it more on the lean side just to try.

I don't know the 2003 model but needle n1ec is really very fat which combined with the valve 6 makes idle really fat.

How much does it consume?

If you have a smaller idle jet trying to put one, you'll see that the situation will improve.

Then you should change needle with N1EF or G or NOZF or H if you want to keep that family of needles or else switch to a pin of the family N2 / N8.

 

[swehollow]

Thanks, ill give it a shot.

For your carb, I really like the N1EG needle. I set mine with the clip in the second groove from the top.

 

[Jakobi]

The the G diameter needles are what this year likes, you could consider trying an N3EG/N3CG as well. It'll be a pretty aggressive setup though with a strong mid range transition, or for a smoother deal possibly an NEDG/NECG (suzuki).

When I say try though, thats exactly what it is. From there you'd need to gauge how you think the bike is performing and make any changes required to address lean areas/richness.

 

[swehollow]

Alright i just got my N1EG needle and a 38 pilot. I have the option of 168,175 or 182 main. What would you suggest to start with?

Put the needle in the lowest position?

The the G diameter needles are what this year likes, you could consider trying an N3EG/N3CG as well. It'll be a pretty aggressive setup though with a strong mid range transition, or for a smoother deal possibly an NEDG/NECG (suzuki).

When I say try though, thats exactly what it is. From there you'd need to gauge how you think the bike is performing and make any changes required to address lean areas/richness.

 

[Jim Cook]

Alright i just got my N1EG needle and a 38 pilot. I have the option of 168,175 or 182 main. What would you suggest to start with?

Put the needle in the lowest position?

175 main ought to be the best starting point of the three, so long as you don't hold it WFO for long periods.

Also, try the 40 pilot, and maybe the 42 pilot jet. The 38 is pretty lean for the AS1 carburetor. Your bike will idle better without raising the slide and needle up and out of the pilot circuit.

 

[swehollow]

175 main ought to be the best starting point of the three, so long as you don't hold it WFO for long periods.

Also, try the 40 pilot, and maybe the 42 pilot jet. The 38 is pretty lean for the AS1 carburetor. Your bike will idle better without raising the slide and needle up and out of the pilot circuit.

So let me get this. Slide set all the way down? Disregarding the 1mm opening That everyone suggests ? I have 38,40 and 42 Pilots. Needle clip top position?

 

[Jakobi]

So let me get this. Slide set all the way down? Disregarding the 1mm opening That everyone suggests ? I have 38,40 and 42 Pilots. Needle clip top position?

Jim is agreeing, keep the slide low. 1mm generally leaves enough of a window to still sustain an idle. If the slide is completely shut you will have zero airflow under it - it won't idle, and could be a pain to start. If its wound up several mm's you run the risk of bypassing the pilot circuit and lifting the needle past the straight section.

 

[Jim Cook]

Thanks for clarifying that Jakobi. You said it very well.

My suggestion is to first put the needle clip in the second groove from the top.

My favorite "all around" AS1 carb set-up for the low elevations (-3K') is a N1EG, clip in the second groove, 42 pilot, and either a 175, 178, or 180 main jet. (Main jet selection depended on ambient temperature and type of riding; enduro, wide open or tight woods hare scramble, mx, trail riding, or trail working. Basically, how long the throttle would be held wide open during the ride, and matching the main jet to that and the temp.)