ec125 -01 power valve issue?

[Nicolas89]

But then it would rev but not accelerate!?

 

[Elvis74]

correct, but my intention is, when it works in the 2. or 3. gear, there must be something else wrong.

 

[Nicolas89]

I understand. But it runs bad also in neutral.
So what is the leanest and richest jet i need to try with

 

[Elvis74]

like I wrote already,

I use 185 - 195 depends on the weather.
Are you sure that everything else is OK.
Have you checked the carb, the reeds, and so on?!?!?
Maybe your ignition is wrong positioned.

 

[Nicolas89]

The carb seems ok. What can be wrong? The reeds are tight. How to check the ignition?

 

[Elvis74]

I have to take a picture to explain, will do this later!

 

[Jakobi]

I understand. But it runs bad also in neutral.
So what is the leanest and richest jet i need to try with

Work with a methodical approach and you'll start getting somewhere.

No idea on engine hours, no idea on engine conditions. Ideally you'd pull the cylinder, check the tolerances, check the compression ratio and squish, put some new rings in it, check the PV governor, and check the reeds. Then move onto carb side of things.

Check the float height first. Without you are wasting your time.
Then make single changes and evaluate what effect it has. I personally start with the needle clip as it gives the biggest/most noticable change. Then come back and fine tune the pilot, air screw and needle diameter (if req), and finish off on the main.

Its probably not what you want to hear, but when you have a load of unknowns you're really going to have to start checking things off the list before you start seeing progress.

 

[Nicolas89]

The ONLY unknown fact that you mention is the hours... i cant imagine an engine run bad only in mid range due to low compression?

 

[Nicolas89]

Info about the float height would be great.
Thx to all involved so far

 

[Elvis74]

When the piston is in top dead center, the ignition must be located like this:

Check the gas cap too, maybe the tank vent is blocked and due to this the fuel is only able to go slowly down into the carb.

The squish should be around 1,4mm when using all original parts.

 

[Nicolas89]

I've now checked the float level, it was 16 mm.

I ran it without the fuel cap a few days ago, no difference.

The idea of measuring the piston, rings and cylinder is of course not a stupid idea but is it really believeable that it will run bad only in the mid range due to lack of compression?

 

[Neil E.]

Likely not, but it could start showing up there the most. At least do a compression test to see that it is in the ballpark. I'm not sure about the 125cc motor, but 150 psi would be good enough that it should run OK.

 

[Jakobi]

It could be a main seal as well (either pulling air through the flywheel side, or trans oil from the rhs).

Have you tried going a step richer on the needle? or a step leaner? What effect does it have on how the bike runs?

How did the piston skirt and cylinder look through the exhaust port? At least pulling the head you'll get an idea of how the bike has been running in terms of piston wash.

 

[Nicolas89]

Ive tried NOZI N1EG and N3EG. No noticable difference. I shall measure the compression

 

[Nicolas89]

If I kick it over a few times I reach 140 - 150 PSI.

I tried to run it with 175 jet and a 190.. runs bad with both, with the 190 it feels somene hits the killing switch a few times when Im trying to make it rev out down the street..

 

[Elvis74]

I bet there is something else wrong, like a gasket or so.

 

[motopsycho87]

http://www.manualslib.com/manual/386933/Gas-Gas-Ec-125-2003.html?page=42

Thank me later.

Also, my 300 PV opens a lot sooner than that, yours may be different, but check for play in all mechanisms.


http://www.gasgasmotos.es/en/manuals/6.html, 2003 125 seems to be the earliest listed.

 

[Jakobi]

It could be a main seal as well (either pulling air through the flywheel side, or trans oil from the rhs).

Have you tried going a step richer on the needle? or a step leaner? What effect does it have on how the bike runs?

How did the piston skirt and cylinder look through the exhaust port? At least pulling the head you'll get an idea of how the bike has been running in terms of piston wash.

Going huge on the main has showed a rich condition at WOT, but thats not what you're trying to do. When you tried all these different needles have you tried different positions?

What exactly is the bike doing? Have you pulled the choke to see if it helps or hinders?

I still don't think its jetting related, but would happily be proven wrong.

 

[Nicolas89]

Which needle shall i continue to test with? N1eg n3eg or nozi? It cuts off even with 182 main jet but not as often. It runs bad also with 175 but not with this distinct cut offs. How to check the seals? I shall repack the silencer tonight also.

 

[Nicolas89]

Which needle shall i continue to test with? N1eg n3eg or nozi? It cuts off even with 182 main jet but not as often. It runs bad also with 175 but not with this distinct cut offs. How to check the seals? I shall repack the silencer tonight also.