Topic: 500/4 K2 1973 Carburettor problems

[Jon stead]

Hi

When I bought my bike teh carbs were flooding. I sent the carbs off for professional overhaul. They were set up on the bench. I got the bike running only to find oil leaks that weren't evident when it was stopped. The bike has been away and had the leaks fixed but the lad doing it couldn't get the engine to run correctly. Below are some of the comments from the emails he was sending me:

"Engine running no leaks. All the electrics are good with no issues. However, the engine hunts badly, revs to 3k when warm and when I adjust the throttle stop to set a tick over the engine dies. It won't idle at all unless I hold it on the throttle but if bring the throttle stop up to hold the throttle the rev climb to 3k again.
 
Ignition is spot on at static and full advance.
 
When I started the bike before I started work it did similar and commented that the carbs were miles out. Anyway I have removed and stripped and balanced the throttles, all of the floats are set to the same height, and all of the jets are (were) all matching across the carbs and the throttle slides are matching too.  Need to do some research on these carbs are they correct for year etc.
 
For your records
 slow running jet = 40
main jet = 100
Float height 23mm (should be 22mm but the springs in the float needles are very weak, they should hold the float a little but do not so 22mm turns into more like 20mm in use). 
Air jets turned out 1 1/2 turns.
NEVER LEAVE THE FUEL ON, the float valves fitted are brass type not Viton tipped so they will pass a little fuel over time and eventually will overflow. As the bike is used the valves will seat a little better.
 
It runs horrible, those carbs are not at all nice. Both 1 and 2 flood intermittently, the whole bank is rich and doesn't want to idle at all again. I will have a go later.
I have worked on just about every type of carb but these things are doing my head in. The float needles will not seal, the needle springs have various tensions and the carbs slowly flood. I had them in a bath, they have been blown through, I have adjust the floats between 22 and 25mm height and the running is no better. I have altered the emulsion tube needles to run at 4 standard, 3 and 2. And the air screws have been everywhere from 1 to 2.5 turns out in 1/8 th turn stages. Again no better.
 
When cold the bike tries to run ok but when hot it doesn't want to know which screams "rich mixtures". The bike won't idle but I can hold it on the throttle at say 1500rpm but if I bring the throttle stop screw up and let this hold the throttle then the engine speed rises and hunts between 2500 and 3000 rpm, if I back off the throttle stop the engine does. I have had the carbs on and off, stripped and put back together more times than can remember. All the jets are correct size assuming the numbers stamped are a true reflection. I have even fitted a harder platinum evx  plug set. "

I am now at a loss as to whether the problem is with teh carbs or somewhere else. How can I tell if the carbs are "worn out"? Any advice gratefully accepted.

Thanks in advance.

Chris

[harisuluv]

It sounds like maybe he didn't put in NEW float valves and seats, seems like it would solve the leaking/float height issues.

Saw no mention of a vacuum sync.  Those symptoms, unfortunately, could be any number of things, or combination of things.  Air leaks (manifolds, airbox, boots, whatever), aftermarket intake (pods?), carbs out of sync, improper cleaning ("soaking" and then blowing out with air is not the best method by far), improper cleaning of jets (sounds like you're running lean), or something silly like backwards slides.

There is also a phenomenon with 500 carbs running rich that is solved by replacement of the needle assy (needle, seat, emulsion tube) per Hondaman, there was even a recall on 500 carbs due to this.  I have run into it on more than one occasion and was able to correspond with the customer until we got it fixed.  In those cases also adjusting the needle clip did not help either.

With just a few well framed, well lighted pictures we could eliminate a lot of the silly stuff.  At least he has given us some information which is great, but we do need to know more, any guesses as to what the problem(s) is are just that--guesses.

[Jon stead]

Thanks for the response. I'm away at the moment and I hope to get into the problem when I get home in a few weeks time.