Everyhting is new, everything has power, STILL wont start right....Grrrrr

[pnedac]

Hello,

I am in the final stages of a 77xs650 revival (at least I hope I am) and I am having a bit of a problem here. Literally almost everything on this bike is new and updated. Pamco ignition
new plugs
wires
caps
brand new VM34 carburetors,
just finished rewiring the bike and everything checks out there.

It turns over just fine and all, but the only thing it is burning is the carb cleaner I am spraying in there (I should not even need to do that!). It also has new fuel lines and filters and I can see that it IS getting fuel through the filters. I checked the floats, good to go. It seems as if it is not getting any gas though, even though I can clearly see that it has it. I am lost here for a clue. I even got new spring for the advance unit because the originals were too loose so I do not think that is it either. Any clues? Timing seems fine and all that too. It would appear to be a fuel problem, but I could easily be off base (usually am )

Any help is of course appreciated.

Pat

 

[TeeCat]

Pat -

What's the state of the battery? You should have about 13.5 volts, I believe, across the poles. And are you sure that you have spark? When you check, make sure that you have both plugs grounded, because with the Pamco, you risk damaging the coil if both plugs are not firing to something.

Also, what is the state of your enrichener (choke)? Is it activated? These bikes almost certainly will not light off from cold without a fat mix.

TC

 

[pnedac]

Hi TeeCat,

Thanks for the reply. I have a new battery that is good and charged. It starts with a lot of vigor. I am sure I have spark because it does start, but it will not stay started for more than about 5-10 seconds at best. It really seems like if I spray starter fluid it will run off of that, but it seems like it is not getting gas. Do you think that because the petcocks are orginal they might need to be replaced or rebuilt? I have taken them apart and cleaned them and they do work just fine. I am just lost on this one.

 

[smurph]

Crack the bowls on the carbs and see if they have fuel in them. Stock petcocks are vacuum operated, so be sure the vacuum line is hooked up and not cracked and you can also open the fuel cap to make sure you don't have vapor lock. I would start there.

 

[TeeCat]

Crack the bowls on the carbs and see if they have fuel in them. Stock petcocks are vacuum operated, so be sure the vacuum line is hooked up and not cracked and you can also open the fuel cap to make sure you don't have vapor lock. I would start there.

I think these are great suggestions, though maybe smurph knows better than I about the vacuum petcocks on a '77; my early bike has two manual ones.

Do check the bowls, and/or pull the fuel line off at the carb and open a petcock (with the end of the fuel line into a little container) to make sure fuel is flowing.

Also, make sure the choke is actuated. On your carbs, I'm not sure which lever/plunger position is on or off.

Oh, and what is the position of your air screws, as well as jetting, so someone who knows '34s can get you in the ballpark? Carbs somewhat synched in terms of throttle position? Carb holders okay? Cracked/dry? Plugs fresh and gapped correctly?

TC

 

[smurph]

Actually I didn't even pay attention to the year I am not sure if he has vacuum petcocks or not. Just a thought.

 

[sgallaty]

totally sounds like fuel starvation to me too.

 

[hotdog]

+ 1, turn your fuel taps to "prime" & try it then.

 

[pa23driver]

a 77 wouldn't have vacuum petcocks - if all is stock.

also you're running vm34's, make sure you didn't leave a vacuum barb unplugged somewhere, that would make for an extremely lean condition - which might seem like fuel starvation

 

[XSLeo]

On your new VM34's did you tear them down and clean and check all the setttings? Even brand new carbs that are set upight at the factory can and do get jarred in shipping and this can knock the float settings off.
Depending on who you got the carbs from they jetting and needles and needle jets can be so far outta wack as to not run.
Have you read www.amckayltd.com/vm34-36.pdf ?
Leo