Help with First Restart After Carb Rebuild

So I have post for my 81 750 LTD under the Project forum, but have separate questions on getting the bike running for the first time. So I rebuilt the carbs myself over the Winter. In addition I rejetted the carbs since I was going ro be running pods (help from a post on this site). I am getting ready to fire the bike for the first time after working on it all Winter. I am hoping to get some help from this forum on what should be looking at for a checklist. the bike is together. I have the tank off and will be trying to restart the bike using the motion pro auxiliary tank connected. Do I just add some fuel and go for it or should have a list of items to cover beforehand? Thanks for reading.

Hi, it is always best to crank over the engine a few times without fuel to get the oil circulating around the engine after it has been unused for any long periods. You might find that when you first run fuel into freshly rebuilt carbs, and ones sitting for long periods, that the float needle/s sometimes stick and fuel overflows. Don’t touch the throttle at all when ready to start  just feather the choke when fired until it will idle. 
Hope this helps.
Rich.

kimchella wrote:

Hi, it is always best to crank over the engine a few times without fuel to get the oil circulating around the engine after it has been unused for any long periods. You might find that when you first run fuel into freshly rebuilt carbs, and ones sitting for long periods, that the float needle/s sometimes stick and fuel overflows. Don’t touch the throttle at all when ready to start  just feather the choke when fired until it will idle. 
Hope this helps.
Rich.

So I fired it up today for the first time. It started right away, but went into a very high idle. Sound great for a few seconds. I cut the power and attempted to start it again. Same result, went into a very high idle again. Checked things out, no fuel leaks and carb boot looked fine. Tried starting it a third time and this time it was idling lower, but had no firing in cylinders 2 and 3 this time. So not sure next steps. I am praying a coil didn't suddenly decide to fail.

Did you try backing off the throttle stop screw?  Sounds like the idle is set too high.

Nessism wrote:

Did you try backing off the throttle stop screw?  Sounds like the idle is set too high.

I have not tried that, but will. Also, I unplugged spark boots 2 and 3 and put boots 1 and 4 on the 2 and 3 spot (left 1 and 4 unplugged). Attempted a start and only got a couple of backfire pops from the exhaust. I plugged spark boots back in with 2 and 3 on left coil and 1 and 4 on right coil. Attempted a start and fired up with all for pipes heating up, but still with an idle at 2500 or so. I am also here some small pops from what sounds like the top of the cylinder head. Not sure what that is. I will adjust the throttle stop screw.

UPDATE: The pops I am hear seem to be from the vacuum hose that is currently not connected as I have the tank off.

You must plug all unplugged vacuum ports, otherwise the bike won't run right.

Nessism wrote:

You must plug all unplugged vacuum ports, otherwise the bike won't run right.

All the vaccum ports are now capped. Still running slightly off. I am getting a popping and puff of vapor from the carb holder on cylinder 3. I assume it is a bad boot.

If you didn't replace the boots, do it now.  Nothing good comes from 45 year old carb boots.

Nessism wrote:

If you didn't replace the boots, do it now.  Nothing good comes from 45 year old carb boots.

I added a set to my Z1 cart. I don't know the history or age of the boots currently installed.

Nessism wrote:

If you didn't replace the boots, do it now.  Nothing good comes from 45 year old carb boots.

New boots installed, stock jets installed, stock air box installed. I also reset the mixture screws to 2 turns out. Attempted to start it up and while it turned over it just wouldn't fire up. It sounded like it was trying to fire. I then twisted the throttle a bit while turning it over and it sorta fired up, but was super rough sounding like only 2 cylinders were firing. As soon as I removed the throttle it died. So, don't know where I am at at this point.

Are both coils producing a spark ?

Wookie58 wrote:

Are both coils producing a spark ?

Hey Wookie!! I am assuming I am getting spark since sometimes it seems to fire up fine and can tell by the sound when all four are firing, not to mention the down pipes are all hot. I mean I suppose the coil could have an intermittent issue? When it does start up correctly it sounds so good with the 4 in 1 exhaust. As I side note I found that the gas tank is leaking at the fuel level switch.