Alotta Symtoms, whats wrong with my bike?

110 PERCENT SURE THE FLOATS ARE SET RIGHT!!!! Im getting good at this stuff the more i do it. Knowing the carbs clean and synced, compression test was good, coils are good, plugs are coming out light tan, removing the fuel filter changed nothing, she idles perfect, she just doesnt run right when i blip the throttle but runs like a champ with the CHOKE on thats not enough info to make any diagnosis?

 

You just described exactly what shes doing. Fuel flows good looks like shes taking a serious leak when i pull that hose off. NICE AND STRONG FLOW. Ya i double checked those float heights and made sure they were all EXACTLY what the manual called for. Everythings fine below 1/4 throttle it all starts aboved about 4000 RPMS thats when she starts spitting and popping and I lose most of my power so I will more than likely be going up 5 on the jets and will get back you!!!!!

 

just wondering about the needles if they are stock or not or from some other carb. Are these the original carbs from the bike? The 135 jets should be large enough.
Sorry I forgot what year bike this is and are these the stock carbs?

Just saw your other post. 84 Saber. Are the tiny fuel screens under the needle/seat cleaned good? Otherwise kind of looking at what tink asked about float height. There is a certain way to adjust. It's kind of confusing. Most who adjust them wrong usually end up to rich.

 

I don't completely agree with that assessment.






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Go pick a fight with your wife, I'm not interested.




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But why does it run so lean?

Here's what Tink has asked about:
The question is what is causing the lean condition?
...supply is good, float level is good, fuel screens in the fuel rail are clean, vacuum slide diaphragms are not torn and installed properly...
...the bike runs well at idle, runs well on the road at 1/4 throttle, runs well on the road up to around 4000rpm, runs like shit on the road at wide open throttle and loads above roughly 4000rpm

So based upon all i've read about this i would think your pilot (idle) circuit is clean and working okay, and the enrichment (choke) circuit is also.

But your main circuit is not working and you are running very lean except when using the choke.

Are you running with an air filter or just open intake?

Do your vacuum pistons slide freely without binding? Are your rubber diaphragms intact? Remove the intake plenum cover and air filter and using a straw gently blow air into the D-shaped opening at the venturi and verify that they slide up.

If the slides move freely and lift the needles, then you could rig up an auxillary fuel source and run the engine with the air cleaner removed so you can see into the venturi and watch the needles respond as you open the throttle--do they track with the throttle, eg the needles lift 1/4, 1/2, 3/4, wide open when the throttle is opened the same? You won't want to do this very long since you have a lean condition but just to verify that the vacuum piston tracks the throttle. Use the choke to keep it from running too lean. If the needles are not being pulled up proportional to the throttle then you may have a leaky rubber diaphragm on the vacuum piston.

Hold the throttle open at slightly more than wherever it runs good--right at the edge of bogging down, then use a chopstick or bamboo skewer to manual push the vacuum piston open and lift the needles--does it then run better or worse or no change?

If the rubbers are all good and the piston slides okay and tracks the throttle opening, then you likely have a fuel supply issue--clogged main jet circuit, faulty float valve, float level too low, blocked gas cap vent, clogged fuel strainers screens in the carbs, restricted fuel line, blocked carb bowl vent tubes, intake air leak, faulty fuel pump.

If you have a rusty or dirty fuel tank then don't try to run without a couple of fuel filters in the line--debris in the carbs is harder to fix than replacing external filters...

You could try to adjust the floats to raise your fuel level in the bowls, but since the choke is pulling fuel it would seem that the main jet would be covered.

Did you pull the main jet and main emulsion tube and inspect and clean all those passages?

 

Sorry Tink but the link you provided has this to say:

"High Speed System

Fuel delivery is controlled by the size of the replaceable main (needle) jet and the thickness of the jet needle."

The needles don't come out all the way. That's why the early bikes/carbs had needles with slots cut in them for tuneability.

Anarchy13 what you can do is get some real small washers that are about .020 thick and raise the needles to see if the problem changes, gets better. I think you can only put two max under each needle. Hopefully this will make it run better. Not to say this will be a total fix, but will start you in the right direction.

If you can't find any I have some and would mail to you, free of course.

 

I shimmed the VFR recently and noticed a slight difference (seat ah dah pants) and that was way above the national speed limit. .02 is the standard shim measurement, my bike had a fancy slide set-up and I was surprised to find a factory shim under the needle on the slide. If you looked at the manual it had the shim in the picture.

Anywhoo, I noticed a gud seat of the pants experience with my Kawasaki twin, same road, same speed, kinda picked up, again way over the national speed limit. I dont do dynos, dont need them.

 

Remember that guy Mike from Michigan with his '86 VFR (the worst-looking example i ever saw that was still running!!!) "Go for a ride" or whatever................did he move to Germany ????

He was SOOOOOO cheap he greased the chain with his own hair. Maybe not since his chain seemed unlubricated its whole life and wires were hanging from everywhere, missing most bodywork, bad tires. He showed up at the Niagara Falls VFR meet a few years ago. The ultimate "poor man's" VFR looking more like it just rode out of a salvage yard, but he just rode 300 miles across Canada with his wife aboard on tires that looked seriously deficient. Returned home 300 miles and began posting here like mad ?? Then changed a name and continued unabated ?? Then flew the coop ?? Mike.