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I have an 81 CB650 C. Petcock is flowing properly but I am not getting gas into my float bowls. All hoses are hooked up correctly. This CV style carb (VB44A) has a Vacuum Valve that is mounted to the 3 &4 carbs. I suspect this is the problem but does anyone have any other ideas?
The floats are installed properly and the carbs have been cleaned. I did not separate them.
When I put a set of 81 carbs on my 80 CB750, I removed the vacuum valve and hooked the fuel line directly to the connection next to the no. 1 carb, gravity did the rest, you just have to make sure the fuel cap is venting properly or it will be fuel starved.
Not sure how to make sure my fuel cap is ventilated properly, its a sealed gas cap with a key how can this be ventilated? Also what did you do with the vacuum hose on the #2 carb that attached to the automatic petcock?
Are you talking about when the bike is not running? If its not running, there is no vacuum and so no gas, you'll need to put the petcock in the 'Prime' position to get fuel to flow. This will allow you to fill the carb float bowls. Then turn to 'On' to start and run the bike.
If there is no fuel flowing when in the 'Prime' position, then I'd think the float valve is stuck (doubtful all four are stuck though), or some kind of blockage within the fuel 'rail' (not familiar with the VB44A carbs so not sure how its delivered to each carb).
Yeah I do not have a prime. On my 81 CB650 C there is a part that is called the automatic petcock which sits on top of my carbs. This part I believe is bad, when I take the vacuum hose off and I suck on it my self there is no gas flow. Based on the handbook if when sucking on the vacuum hose you do not get any gas flow then the "automatic petcock" is bad and needs replacing. I am hoping I can go straight in to the carbs and cap the vacuum off.
All I did was plug the vac line to the carb. I was wondering, has the bike set outside or in a barn with the fuel line removed? If you did that around here the mud dawbers would have that fuel distribution tube filled to capacity. Also, that vacuum pump works on a pulse, so to get it to work you would have to apply vacuum, release vacuum...over and over.
I went straight in and put a cap on the # vacuum valve and got it running. The idle is acting very odd but I hope to work though that this weekend. Thanks for the tip on going straight in.
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