Honda VFR 750 RC24 '86 doesn't start after carburetors overhaul

LOL ok, I’ll buy the quick start

Brand new

 

Just tried:

• cold start without choke and starts immediately. Giving full choke at once and it shuts off after “coughing”.
  
  
• Restart immediately, giving full choke but slowly this time and I feel a little vacuum in the engine for a split second and then raise rpms

 

You can't just slam the choke lever down all at once on an idling engine.

But you're bike should start in it's current configuration (Stock jets, 2 turns out on pilot screws) if properly assembled / tuned:

Key on
Choke* lever full
Press start button (no throttle) - bike starts.
Adjust choke lever down to approx 2000-2500 RPM for a bit
Slowly reduce choke as bike warms until idles on it's own with no choke @ approx 1200 RPM.

Ride away and enjoy.

*"Choke" is actually an enrichment circuit and can be adversely affected by a few factors, like improperly installed / routed / adjusted cable.

 

I’m gonna remember this one, I never knew how to properly start this bike with choke and stuff.

anyway, cold start and it starts immediately: don’t know if this is good or not.

Tomorrow I’ll try with full choke before start the engine and see how it behaves

 

normal. a warm engine doesnt like choke. if you use it for starting try choke halfway on, not full.

unless the bike hasnt been ridden in weeks or its cold below below 55 F. it probably doesnt need much choke for starting. on my bikes i boost cold idle speed with the screw and dont use any choke, them lower idle once engine is warm.

 

Great, good to know. I’m assuming there’s no need for leaking test, but I want to do it anyway.

Just left the start with full choke on cold engine to see what happens and valve sync. Any other suggestions for a fine tuning?

 

synch has nothing to do with valves instead, it sets all throttle butterflies to the same positions.

 

The start procedure I posted is of course for a "cold" engine. It is applicable to 99% of my bikes. I have a couple that are jetted on the rich side on the bottom that I can dial out the "choke" nearly immediately. But the basic start procedure is still the same.

An intake leak test is still probably a good idea to know you're not chasing that problem for fine tuning.

 

Yes I meant those for “valves”, in italian they’re called “valvole a farfalla” or “valvole” for short

 

Tried start with full choke, two attempts and the bike started. Left the choke on until, from hardly 1.000rpm, went to 2.000 rpm and than closed choke (gently), bike stayed on 1.000/1.1000 rpm. Fair enough to me.

waiting for amazon to deliver me the vacuum gauge. Maybe in a month gonna check the spark plugs to see if I'm rich or lean

 

Another doubt crossed my mind:
the repair kit I purchased comes with a 115 main jet, whereas the original one was 118.
How might this impact the proper functioning of the engine?

 

Make sure they are Keihin jets …


Sent from my iPhone using Tapatalk

 

Aftermarket jets size may not coincide with keihin size


Sent from my iPhone using Tapatalk

 

I guess they are, because the repair kit was meant for rc36, which mounts keihin carburetors as well.
furthermore it suits perfectly in the stock main air jet

 

the reduced size (115 instead of stock 118) could affect the engine, in the long run?

 

It’s not 118 for no reason

 

Ok, but my question is something else: what problems could bring a slightly lower jet?

 

You could run lean, higher engine temperature as well as fuel starvation at higher rpm.
Stay with stock or Captains suggestions


Sent from my iPhone using Tapatalk

 

Thanks for the reply.
so is it recommended to set a little richer, since this reduced jet?

 

Yes … well here in California they come lean to pass the communist epa laws that are ridiculous ( sorry for the rant ).
In any case lean is not good and too rich is not good … there is a sweat spot that I’m sure someone will let you know the best jet size. I believe Captain mentioned it somewhere on the thread…


Sent from my iPhone using Tapatalk