YBR 125/150 running lean

[Scoops Vietnam]

Hi guys

My bike seems to be showing classic signs of running lean. The engine runs fine and smooth when its cold, but as the engine warms up,

1. the gears start to get cluncky

2. when hot and stationary, the bike wants to move away even if the clutch is fully depressed.

3. When I accelerate, the bike stutters and finally

4. The engine feels noticeably warmer than before.

Is there any way to adjust the fuel richness on the carb without re jetting?

Is re jetting a complicated procedure for a bike mechanic in Vietnam? Or do you just take the old one out and put the next size up in?

I need to educate myself properly on this. Can you help?

I had to have the piston rings replaced recently and they guy offered to bore it out up to a 150. Like a complete chump, i agreed, but it's not driven right ever since, and trying to explain things results in blank stares.

[Scoops Vietnam]

Apologies, but I'm going to give this thread a little bump because I would really like to learn more about re- jetting. The bikes going in tomorrow, and I think I have managed to explain to the guy through diagrams, that I need a larger main jet, probably the next size up. I'm thinking that my bike is running too lean and that this is the reason for my new found problems.

Anyway, once it's done , will it mean the end of my problems or do I also need to consider an exhaust modification/ upgrade? Do the other jets need to be replaced too?

[Airhead]

the clutch has nothing to do with running lean, you need to get it adjusted, perhaps there is too much slack in the cable?...perhaps it needs adjusting in the engine?

Also check the oil level is correct.

[Scoops Vietnam]

I was assuming that running lean meant running hot. I have a wet, multiple disc clutch, so I am thinking that the excessive heat is causing expansion and therefore my clutch problem. New oil and cold starts cause the clutch to run perfectly smoothly :-/