Topic: Carbs problem, when throttle open, engine dies

[vetec]

I have finished complete restoration of my Honda CB650C RC05 (1980). All is good apart from tuning my carburators.
I clean it and rebuild it with new seals and new main jest (number 95), I had leaks I managed to fix it, I couldn't get normal idle, I fix it. So lots of problems. Now.

When engine warm, I can get idle around 1100 - 1500 ( I connected other rev counter from my other honda from 1980 to be sure that is correct) with choke valves open and when I open throttle normaly - engine dies. When I open throttle slowly it dies or it gets higher revs.
When I cover airbox air inlet, engine is running faster.

I will check air leaks from airbox side (again) and I will check spark plugs (brand new) and sprak plugs cables from ignition coils (cables and plugs are brand new also)

Timing is correct, valve clearance is ok, all other tuning is done. I have sync carburators with clocks and I change fuel screws from 2 turns to almost 3 turns out.

Any help will be appreciated.

[newday777]

I have finished complete restoration of my Honda CB650C RC05 (1980). All is good apart from tuning my carburators.
I clean it and rebuild it with new seals and new main jest (number 95), I had leaks I managed to fix it, I couldn't get normal idle, I fix it. So lots of problems. Now.

When engine warm, I can get idle around 1100 - 1500 ( I connected other rev counter from my other honda from 1980 to be sure that is correct) with choke valves open and when I open throttle normaly - engine dies. When I open throttle slowly it dies or it gets higher revs.
When I cover airbox air inlet, engine is running faster.

I will check air leaks from airbox side (again) and I will check spark plugs (brand new) and sprak plugs cables from ignition coils (cables and plugs are brand new also)

Timing is correct, valve clearance is ok, all other tuning is done. I have sync carburators with clocks and I change fuel screws from 2 turns to almost 3 turns out.

Any help will be appreciated.

Welcome to the forum vectec
How did you clean your carburetors? (What process did you use?)

[fizzlebottom]

Check to see that your advancer is moving freely. I feel like a lot of folks lately have benefited from giving the ole clean-n-lube job to their mechanical advancers, especially if they've never been off the bike in ~40 years.

If everything else (timing, chain tension, valves) are adjusted properly and you have good compression, then something is definitely up with your carbs. A vacuum leak, they're wildly out of sync, terrible A/F mix, or all of the above. I'm familiar with the CB650's CV carbs, but not the  PD variety so i can't give more detailed opinions. The approach I'd take is to read through the FSM and see if you followed the rebuild / assembly instructions to a T.

[vetec]

Thanks,

I have bathed dismantled carbs in acid and I have cleaned passages etc with thin string. 

My carbs are Keihin PD50A.

Only thing I add were air valve cut. Originally there was no valves.

Maybe its a problem?


Today:

I change spark plugs and cables to old set - no difference.

Best I can run engine is with choke valves half closed - I can rev from idle normally.
I have also removed today air filter and its cover - engine barely  run.

I will read forum and will gather more info.
thanks!

[vetec]

I will check advancer too.