Engine wants to suffocate when opening throttle

[Micha]

After assembling the carbs on my R51/3 and adjusting them according to the manufacturer's instructions, I encounter the above phenomenon when I open the throttle suddenly, both when the engine is cold and when it is hot.
While opening the throttle slowly - it revs up ok.
I am aware that after adjusting according to the instructions, a more subtle calibration is needed.
I would be happy for instructions and explanations (it is also a hard starter but when idling it is neat as a sewing machine).
Thank you.

[schrader7032]

Have you made your adjustments and synching of the carbs when the engine/carbs have warmed up from a ride? What sort of settings have you finalized on in terms of turns of mixture and speed screws?

[Micha]

Evening Kurt,
Thanks for your interest.
I did exactly as these instructions say:
I think I might need help like whether to enrich the mix or something like this, no?
What do you think?

[schrader7032]

Seems to hit all the right things. But it says to just engine run. I think it's important to get everything warm before attempting to make adjustments.

[jwonder]

Micha,

I really wanted someone else to chime in to see if I am wrong, but I figured no one else would. My R51/3 does exactly the same thing. The carbs are small bore and I think it’s just what they do.

When I have it in gear and it’s pulling, or getting rolling in first gear, it takes the throttle happily. I can open the throttle quickly in every gear with no bobble.

If it comes off idle when not in gear even moderately quickly I would happily ride it!!

If anyone else has an idea please chime in.

[Micha]

Thanks a lot guys.
I will find some time this afternoon and warm her up and try again.
If there will be no change, I will live with this phenomena happily.
Take care.

[R68]

Your running a bit lean. When starting, close the air filter intake by around 80%, start, and ride for a few minutes until the engine warms up, and then reach down and open the intake fully. If you have a non adjustable air filter (late twins, R69S), then just reach in between the battery and the intake and occlude the intake port with your palm: motor will take throttle better...this is the procedure for Israel (hot!!!); in cold climes, close off the intake completely and the motor will run off the carb preheat system air flow.

[Micha]

Update (I thing there's a much more serious problem):

The carbs are disconnected from the suction pipes I just removed.
It is very difficult to start the engine: When opening the throttle a bit more then normal, the lever kicks back and the nozzle of the idle screw on that side spits fuel.
So it lasts about 10-15 kicks until the engine wakes up.
When finally engine works and I warmed her up:
The left seems to be the one that is taking all the work: Left side becomes really hot, it beats strongly. I can actually hear the suction from the carb intake. On the EMPI synchrometer I get a reading of 5: I have no idea if it is good or not but on the right side carb - there is nothing. When I block the air entry to the right carb with the palm of my hand nothing happens. When I do so on the left carb, the engine stops. The right side is unable to proceed alone. On the right side by the way I have a fuel leak from the idle screw nozzle.
When standing behind the working bike, the left exhaust really beats and breathes, the right exhaust just participates and mechanically knocks.
On both sides the valves where carefully set.
Both sides get fuel supply and there's a spark on the new plugs. It is like the left side is not working, although it gets now much hotter on the exhaust pipe (not as on the l/h which I can not touch, but quiet warm).
I will arrange again from my friend the pressure gauge to read what the right cylinder has to say, but I am truly worried, that I will not be able to escape an engine head & cylinder dismantling.

[skyler.robbins]

Check your compression again.
Double check your valve adjustments on compression stroke.
Are you getting good spark on both sides?
Correct fuel flow to both carbs?

[R68]

...engine running lean: check timing, and fouled plug on the right: switch plugs right to left, and put the air intake tubes back in position/close the air filter choke...
I seem to recall you rebuilt that motorcycle from a real beater?