!981 cb 750k fuel delivery

[rob13]

I bought this bike from a 19 year old kid that thought he was a builder.Crankcase vacuum lines were hooked in but left loose at air box,cause there is not one.Please know,I am not a bike builder.I am a sheet metal guy.Looking for some knowledge.The carbs have pods,so I put pods on the crankcase breathers.Now I don't have fuel delivery.Starter fluid will crank it,but wont stay running because no gas.I don't get the fuel vacuum,and it is to vague in the Clymers manual.Petcock runs straight to #1 carb.Any suggestions?

[shultz_1978]

Not to good with the daul over head cams But watch using the starting fluid. That stuff is had on the cylinder walls.

their are a few DOHC guys on here that know their stuff. some one will be able to Help with some info.

Good luck

[Johnnylevi]

Are you sure that your not getting gas? It could be because of the pods... it will run really lean with the stock jetting and since you're not a bike builder I would try looking on ebay for the stock air box. Did you check to see if you had flow with the fuel line off the carbs? just make sure you dont get gas everywhere. I would bet that it isn't idling because of all that air flow... just a guess. I'm no builder either. Maybe hoosier or sees will provide some more wisdom here

[sgtslag]

Most likely, the vacuum hose which operates the fuel petcock is disconnected, OR... The Spawn of Satan (SoS) petcock is shot.  They are worthless.  Try installing a manual petcock -- the 1979 models used a manual petcock, but they may not fit your gas tank -- sorry.

To test the SoS, bypass it with a straight hose, to see if you get gas flowing, and if it will start then.  DO NOT LEAVE IT LIKE THIS!  It is very unsafe...

The pods are extremely difficult to make work, and they don't really seem to give much of a performance boost, in the end.  The stock air box is quite good, even better with a foam air filter, or a K&N air filter.  Cheers!

[seestheday]

I have an 81K as well, and there is a manual petcock right on the tank.  No need to install a new one unless the PO removed it for some reason (that would be bizarre and very unsafe).

Sarge, is that why you don't recommend running a straight hose?  I run a hose from the petcock on the tank to a fuel filter direct into my carbs.  No issues.

Agreed on the pods, bite the bullet and either get a stock airbox from somewhere or buy new carbs that will work with pods.  Unless you really know what you're doing you're likely going to be in a world of pain getting the pods to run at all, much less well.  Stock airbox is the much cheaper route.  Carbs that will work with pods will likely cost you more than you paid for the whole bike.

Sounds to me like the issue could be the vacuum teat on the carbs not being blocked like you said, or the carbs are badly gunked up and need to be cleaned.  Plugged jets don't let fuel through.

OP, have you pulled the plugs to check to see if they're dry (confirming that the issue is lack of fuel)?

[sgtslag]

Wasn't sure if the SoS screws into the tank, or if it connects with a hose.  My 79's petcock screwed into the tank, directly, with a soft hose running to the carbs.  It would take a genuine idiot to put a soft hose on a gas tank's outlet...  Sarge:  Here's your (my) sign! 

[LukeM]

The SoS is right next to the carb bank, on the right side (sitting on the bike). There is a vacuum line going to the carb bank (supplies vacuum to the valve when the engine is running), a line from the petcock, and the other line goes to the fuel rail for the carbs.  The advantage of the SoS is it keeps fuel going as long as the engine is running: should the bike tip over or stop running, fuel to the engine is cut off. If you leave the bike sit for a week or so, it's possible you'll have to crank the engine a bunch to get enough fuel into the carbs.

You can bypass the SoS, but you'll need to be religious about using the petcock on the tank. In either event, using it or not using it, I highly recommend a good fuel filter inbetween the tank and the valve (or fuel rail). Find a small engine filter with 1/4" inlet and outlet fittings.

Luke M

[seestheday]

Yep, what LukeM said.

I removed my SOS and kept it off because when I did I saw an immediate cold start, hard throttle, and idle improvement.

Mine was likely failing badly, so instead of fixing/replacing I just removed it completely.  I don't miss it at all.

[barelycompetent]

Not to be a thread hijacker, but can anyone post a pic of SOS for me?  Just so Im clear with what I am looking at?  Thanks all.