Hello. I've got an interesting issue that I'm needing some assistance with on my sons 2011 Yamaha Raptor 125.

The machine was in good running order...but a friend of mine offered to do an ultrasonic cleaning for free so I figured what the heck...it's and machine and wouldn't hurt.

Turns out the Raptor 125, what is not a terribly common model, has a very complicated CV type carb. At least complicated compared to most simple slide carbs i've fixed on an average small displacement motorcycles.

I put the carb back together after the ultrasonic cleaning and it fired right up. But anything past 1/4 throttle the machine instantly dies. It idles great and starts great.
I gave up after taking it apart a few times again and putting it back together with the same issue. Everything looks correct. I broke down and bought a new carb. Put it on, and SAME issue. Anything past 1/4 throttle it straight dies. Makes me think something else it at play.

If I pull the choke, it will run like a wild banshee...but with the choke on it won't idle (stalls).

So I have no clue. I have now a brand new carb (waste of money so far) and the same issue as before. Makes me think I'm missing something simple and that the carb may not be the issue.

I checked the fuel lines and such. Perfect and good fuel delivery. But in the same, if it were the fuel lines, you would imagine it wouldn't run perfect with the choke on.

I thought perhaps something electrical that is only allowing 1/4 throttle. But not sure if that would be logical as pulling the choke allows full rev's and full throttle. So if it were electronic, it wouldn't care if the choke were on or off.

Any thoughts? I'm stumped!

 

Check your inlet manifold for cracks, strip and rebuild the old carb, being sure you put everything back in the right order. If you fitted a part wrongly on the first rebuild, you may well be putting it back the same way again, so an exploded view parts diagram like this is a help, and from now on follow the mantra "if it aint broke, don't fix it."

 

Also may want to check air filter if apply choke an runs better than it fuel or air issues, History? has it ran good before and how long sit? air snorkel blocked? run with air box lid off if runs better than have block air way