Super 8 125 ok on idle but cuts out when revved

[steveinengland]

Recently the bike is acting like a dog, it idles ok but as soon as you pull the throttle the engine dies. If you slowly build up the revs you can sometimes get it revving high enough to pull away, but it runs very badly, hardly making it up hills. Any ideas? It was fine up until a few days ago. I've changed the sparkplug and run some STP carb cleaner additive through it but all to no avail.

[tortoise]

idles ok but as soon as you pull the throttle the engine dies

If carb slide is not rising properly . . diaphragm resource.

! No longer available

! No longer available

[steveinengland]

Found the problem... I took the top plate off the carb, the diaphragm was fine but the needle had jumped out of position so it was not in the hole properly and the small nylon piece was upside down, so the engine was idling ok and if you could get the engine up to speed it was ok at full throttle, but not at mid speed.  I put the needle back in and it's running normally again.

[Mr. Paul]

Great posts Steve and Tortoise! Glad it worked out and I learned something! (Doesn't happen often enough)