Getting engine to run right.

[The Artist]

Out of ideas now.

00' rs50. Exhaust de coked, new top end, carb cleaned, new air filter.
Reeds fine, spark plug new.

It won't rev above 7.5k and lacks any sort of power when you set off. I know it is only 50cc but topping out at 30mph when it is not restricted isn't good.

I used my see through spark plug today and set it up right. It now burns nice pretty colours that it says it should inside. In neurtral it will not go above 7.5k, on the road, not go above 6k unless downhill but even then 7.5k is the limit.

What else could this be? Cheers

[duhawkz]

is the carb set up properly, i know you have said is been cleaned but have double checked nothings blocked inside it.

is it sealed correctly

could it be an electrical fault somewhere?

[The Artist]

Carb cannot be set up at all. Only adjustment is jet size and I have tried everything from standard which is 63 to 75 going up in 2's with no luck. Just gets worse. best performance is with standard jet.

No air mixture screw at all on it. It is a flatslide carb with nothing to adjust which is a right pain in the ass.

[.]

If the bike is only reaching those revs in neutral and you don't have an electronic limiter, it sounds like you're only running on the carbs idle and transitional circuits.

Check to see the needle clip hasn't dropped out and the bleed holes in the jet needle are completely clear, which means removing the jet needle to visually check. They tend to clog up pretty quickly if a bike is left standing for any length of time with fuel in the carb.

[The Artist]

Like I said before.

Carb is spotless
There is no adjustable needle. The brass tube with 2 holes in is fitted in right.

I will try and find a picture of the carb in question

[The Artist]

Right here are a few pictures, not of the carb I am working on but exactly the same model.

https://www.morinifrancousa.com/accessories/sha_carb.jpg

https://shrani.si/f/24/n9/4EIqJqDA/dsc00730.jpg

https://img529.imageshack.us/img529/4260/pict1653ys5.jpg

https://img403.imageshack.us/img403/8751/pict1649vf9.jpg

https://img202.imageshack.us/img202/7959/carbsha4qr.jpg

and from post #8 downwards is the carb I am talking about. The exploded parts diagram is different to mine as it seems to have other screws but the proper pictures show the brass tube I am talking about. My choke is not cable operated though, it is a lever on the side but that is the only difference.
https://motorbicycling.com/f13/high-performance-dellorto-carb-found-2314.html

Thanks

[ms51ves3]

Have you checked the timing?

[The Artist]

inlet manifold is metal and doesn't leak. tested with bubbly water.

Spark is beasty. Through the see through spark plug it is big and bright.

compression is pretty high. engine is barely run in.

Can't see how timing would be able to change without it being done manually. I will check if no other ideas come to light.

[.]

Seems a very basic carb, on the assumption that it's a fuelling problem, if there is enough fuel getting in perhaps the choke is remaining down restricting the amount of air.

The only thing I can think of is that the choke plate mechanism is remaining in the closed position and not resetting itself when the throttle is fully opened (if that's the setup you have)

[The Artist]

Nope, choke works fine.