California Smog Crap Removal

Hey guys,

Today I removed all the smog stuff... canisters, several feet of hose and other crap from my '86 VF500 today, and I blocked off all the vacuum ports on the carbs.

I've done this before on multiple bikes before with no problems. Well... I turned a very well running bike into one that now starts very hard, won't idle consistently (750 to 3000 rpm), and is starving for fuel when ridden even with just a little throttle. Really weird!!

Here's the CA smog plumbing diagram:



Am I missing something, or are there some others here that have gone through the same thing? I think the problem is stemming from the vacuum activated fuel supply valve, and a lack of vacuum possibly?

Any thoughts?
Thanks,
BLIGHT

 

You probably know this already but on a bike without the PAIR kit there is a rubber hose running from the vacuum take off on (as you sit on bike) the rear left intake manifold. This goes to the petcock. You need a vacuum in this line for fuel to flow. Not a big vacuum either, you can take the hose off and suck it and hear the fuel flow if your floats are empty. If you have that covered I cannot help. It does sound like the bike is running lean so are you sure every port has been blanked off?

 

Per the diagram line #6 looks like the float bowl vent, that WILL need to be open to atmosphere and check to make sure the pet cock vacuum line is not kinked.

 

Thanks guys, I think the fuel petcock is malfunctioning. I can turn it to ON and RES, and fuel flows (without a vacuum in the port) That's not right, and it might be a weak 'pressure' or an intermittent flow. (i did a quick test with gas flowing into a cup) I have a spare petcock in the garage and it seems to work correctly.

I'm gonna swap them today and see if I can make it run properly. Seems weird that this petcock 'malfunction' happened right after I took off the evaporative plumbing. It was running fine before! I may have plugged the bowl vent and that could hamper fuel flow. I'll make sure it's clear.

Thanks for the tips and I'll let you know if I solve it!
BLIGHT

 

Hey, it was the bowl vent line... I plugged it yesterday when I was plugging the vacuum lines. Removed the plug and now it runs like a champ again!
Makes sense, fuel can't flow into the bowls unless the air has a way out!

Thanks for the help!
BLIGHT

 

I love a happy ending.