Unbalanced carbs = Bad idle?

Hey everyone. I'm new to the world of bikes, especially ones with 4 carbs and 4 stroke engines. So I need some help with this bike I picked up.

Its an 85 VF500 Interceptor. The bike will start with some gentle guidance and will run awhile if monitored closely. But no matter how I adjust and slightly manage the idle screws, it still surges, comes back. And then sometimes dies, but sometimes doesn't.

Could this be because I haven't (and assume the previous owner didn't) balance the carbs? I notice one carb specificly, if I adjust its idle screw too much, the bike will stall out until I put it back. The one next to it is similar but less effective. The other two however, don't seem to effect anything at all.

Bikes got new plugs, carbs have been cleaned (by me, not professionally) and I've replaced the gas. What might I be looking at here? Any help would be great. Thanks

 

balance the carbs. its super easy on most bikes ( i don't know that model specifically) another thing that could cause idle issues is a vacuum leak.

 

Dija bench synch (balance) the carbs by eye when you worked on them ??

I can't agree with the above that carb balancing on a hot, cramped set of V-4 carbs is easy.

Dija remove idle mix screws and blow out the passages with carb cleaner followed by compressed air ? Reset idle mix screws from wherever they are to 2 1/2 to 3 turns out from fully closed. Assuming the engine has good compression, if the bike won't idle, most likely an air leak or carbs are still crudded-up.

Dija measure float heights and put a thin wire through the idle jets ??



Dija ??

 

The squirrel is right on here. Clean them again and set the mix screws to the initial setting, check your Honda service manual for the setting. If turning 2 of the mix screws have no affect on idle then you have a problem. Hopefully it's just the passages behind the screws are plugged. But it could be electrical. Check spark on those 2 cylinders also. Could be valves....compression check?

If the carb sync has not been adjusted since the bike was running last then it should run again with no changes. Not to say it won't need adjusting, just saying it should run as is.

Can you give more history on the bike? Was it running recently, been sitting? You're going to have to post a pic or two, thems tha rules.

 

I shall post some pics soon. Perhaps a video if I can as I have been working on the bike and recently noticed something rather odd.

I did take the carbs back off and cleaned out the idle screw ports and passages and I have noticed a small improvement, but after reinstalling the carbs and starting her up, I peaked in (Air box removed) and noticed the rear two 'slides' (I think they are called), are not fluttering while its running like the front two carbs. I assume this is bad, but I don't know what it was indicate. I know my coil for the rear plugs are working, shocked myself trying to test them >.<;;

Never the less, I can tell you that the bike will run with some love, it will get up to temp (Though rather unevenly at first), and will keep going so long as I tease the throttle. But if I leave it running, choked or not, the rpms will shoot up with the slightest throttle play, then slowly, on their own, come back down to wherever I have the idle set. Then it will stumble and die. The bike won't start immediately after this, but if I let it sit for a few moments, then turn it over again, it'll fire right up.

Could that mean a cylinder if filling with fuel? Or a carb? Sounds like flooding.. but I dunno. Anyway, hope to hear back. I'll put a video up soon.

Oh, and I did bench sync the carbs when they were off. I used proper feeler gauges to do so.

(UPDATE!! I did NOT take the carbs apart from one another for cleaning. Could this be my issue?)

 

Vacuum slide diaphrams on the 2 non-moving ones are installed incorrectly. Try again, and test them b4 putting carbs on next time.

You were correct in NOT separating carbs into individual units for cleaning as that's seldom necessary.

If you have cylinder flooding a look at your sparkplugs will confirm or deny.

 

Aside from my diaphrams (Readjusting tomorrow morning) Could my float levels be wrong? Could that cause the stumble then death, followed by a long pause before it'll start again?

 

Maybe. Why don't you study the FSM and then carefully measure the present settings ??

 

Carb boots are rotted badly. The carbs themselves are nice and clean and measured correctly. Hopefully its the boots.

Any suggestions of fixes? Can the carb boots be repaired?

 

Those boots show the unmistakable effects of a slightly-botched installation, which tore out bits of the sealing lips. Replace them with new as no repair will suffice.

Why did you choose to remove the airbox bottom plate from the set of carbs and risk damaging the fuel supply tubes and losing some small parts ?????

 

I removed the plate carefully and did not lose any parts. I felt the need to clean out the fuel lines and did so successfully. Will order the boots soon. Anywhere I can get them cheap?