Needs choke for higher revs?

[Morocco]

Can someone please help me. My 1977 C50 starts on the button and ticks over nicely, but when riding it needs full choke to allow the engine to rev cleanly and keep pulling to achieve a reasonable speed. It seems to starve from fuel or air until the choke is pulled out and the engine then starts to rev cleanly and makes good speed. I've stripped the carb numerous times and cleaned the jets and then replaced them, but it makes no difference. The float bowl is always full, I've even removed the float system to make sure that's there's no shortage of fuel, the tank is clean and I fitted new fuel lines and a filter on the reserve line only. I've removed the air filter and airbox and yet again it made no different. I've adjusted the fuel/air screw by half a turn right out then back in, but it doesn't fix the problem. I finally swapped the carb for a second hand carb after stripping it and cleaning the jets but it is exactly the same, the bike simply won't pull until the choke is pulled out?

I'm clean out of ideas and would greatly appreciated some help regarding this one.

Many thanks
Mark.

[Bern]

Try running it with the filler cap off, possibly a blocked fuel tank vent

[Morocco]

I'll try that - Thanks I'll keep you posted.

[Morocco]

I finally got it sorted, I installed the original 1977 main jet and it fixed the problem. I bought new Honda parts to rebuild the carb and it appears the new main jet is somewhat defective. I'm well pleased I could find the original parts!

Thanks for your help on this one.

[slowboy]

I finally got it sorted, I installed the original 1977 main jet and it fixed the problem. I bought new Honda parts to rebuild the carb and it appears the new main jet is somewhat defective. I'm well pleased I could find the original parts!

Thanks for your help on this one.

Thanks for the update, always useful for someone else in the same pickle.