yz 125 1994 help with power

[strmantz]

Hello.. i have a yz125 1994... i restore the engine. i put a larger carb 38mm PWK keihin but the moto cant ''kill''. i try some jetting settings but no power at the mid range. when I open the throttle quikly i hear the ''hard breathing'' in the middle and then goes away very quickly. also i see the valves and its open at 1/8 throttle.. any help?

sorry for my English

 

[strmantz]

no?

 

[Okiewan]

First, why a larger carb?
"Moto can't kill" - does that mean the kill switch doesn't kill it?

Have you tried putting the stock carb back on it?

 

[strmantz]

First, why a larger carb?
"Moto can't kill" - does that mean the kill switch doesn't kill it?

Have you tried putting the stock carb back on it?

no no i mean no much power on low and mid. I try to jet the stock carb but nothing. i put the larger one and i have more power in relation to stock but not as much as it should . I suppose the governor has the problem and the compresion is to low

 

[Okiewan]

I suppose the governor

1. Uhh... another language issue? I'll go out on a limb here and say that your bike doesn't have a governor.

2. If you tried to jet the stock carb and weren't happy with the results, the next step was NOT to replace the carb with a larger one.... the next step was to find-out why the re-jetted stock carb was not running well. Most likely, you needed to research jetting some more to come come-up with a better / correct combination.

3. I can only guess that "hard breathing" means you hear it bogging when you twist it wide open?

4. You said you just "restore the engine". I'll guess again; does that mean you did a new top-end? If that's so, why would it have low compression? Did the bike run poorly before the "restore" or only after ? If the compression loss happened after a new top-end, you need to start looking there. Have you actually checked the compression or are you just guessing?

 

[Pete Payne]

What bigger carb did you use ?

 

[strmantz]

1. Uhh... another language issue? I'll go out on a limb here and say that your bike doesn't have a governor.

2. If you tried to jet the stock carb and weren't happy with the results, the next step was NOT to replace the carb with a larger one.... the next step was to find-out why the re-jetted stock carb was not running well. Most likely, you needed to research jetting some more to come come-up with a better / correct combination.

3. I can only guess that "hard breathing" means you hear it bogging when you twist it wide open?

4. You said you just "restore the engine". I'll guess again; does that mean you did a new top-end? If that's so, why would it have low compression? Did the bike run poorly before the "restore" or only after ? If the compression loss happened after a new top-end, you need to start looking there. Have you actually checked the compression or are you just guessing?

1) it have governor! today i replace the spring but i dont run the bike yet.
3) yes bogging!
4) new top and but no nikasil.. its to expensive in Greece... i dont chech the compression with some tool.. i just guess. do you know that number i must see on the compression tool?

 

[strmantz]

What bigger carb did you use ?

keihin PWK 38

 

[strmantz]

i do compression test... 125psi only... but the top end have 20hr only (not in ring)

 

[Pete Payne]

That is really low.

 

[team-green32]

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