Bike won't stay running and no Throttle Response

[luckyd20]

So I'm hoping you guys can help me before I just throw in the towel and take it to the dealer. Recently I have took the engine out and sent the frame for powder coating. I've finally assembled the bike but now that I have a fresh battery my bike won't stay running. It starts only with throttle twisted. But when I try to give it gas nothing happens. Once I let the throttle go it shuts off. Then occasionally it'll I can hear some popping or it'll pop and shut off. I can't figure out what's going on....

[Bob_Roller]

I would start with looking at the the throttle cables and choke cables on the carbs, quite easy to get them swapped .

I'm assuming the engine ran with no problems when you removed it !!!

[montmil]

Lucky,  Did you dismantle or do anything to the carbs while the big pieces were apart?

[luckyd20]

Carbs were left alone during the dismantle and the bike did run well prior to the tear down.

[Luca]

Provided that your carbs didn't find any gunk in the wait (now might be a good time to clean them anyways), the cables are properly routed, and fresh or stabilized gasoline is flowing from the petcock, I'd check your electrics.

Make sure your electrical grounds are good and clean.  Also test for spark.  Put a spare plug in one of your plug wires and ground the threads to a cylinder.  You should get a nice fat spark.

Maybe one of the big boys can tell you how to check that your ignition timing is proper.

[montmil]

Your newly powder coated frame could be a clue.

There are multiple grounding points on the frame. Did you grind away all paint and expose bare metal prior to attaching the ground wires. I'd definitely check the ground point near the coil/relay area as several ground wiires are tied into a single lug that attaches to the frame.

Confirm all ignition components that are frame-attached have clear ground paths; ie, coils/s, ICU and heat sink, well, you get it.

If the engine ran fine prior to the powder coating, there's no reason it should not restart and run. Address the last thing done to the bike. Powder coated frame.

Grounds, grounds, grounds. Electrical systems, coffee and divorces all begin with good grounds.

[Barry]

If it starts at all then you have a spark so that points to issues with the carbs. You can't mix up the cables on a 79 but I would manual check the choke operating arms are against the respective stops when they should be.  

Generally though if it ran fine before and you haven't touched the carbs at all  I would be thinking about the possibility of stale fuel and also maybe gummed up carbs if the bowls were not drained during the period it was laid up.

[montmil]

To add to Barry's comments...  How long were the carbs off the bike during the paint process?

Check the small float bowl reservoir for the enrichener circuit in each carb. If the "vent" at the bottom is gummed up, it will effect starts and cold engine ops. Thin strand of copper wire to confirm an open passage. Be gentle.

[luckyd20]

I got it to work today and it started up perfectly. I never adjusted the valve timing. So after I adjusted to specs and put it back together the bike started up just fine and had throttle response.

[tvrla]

My guess is the ground to the ICU. It's basically an ignition amplifier and without it, the engine will sort of run but not well.

The big tip-off to me is the powder coat. Some mounting spots need to have bare metal showing for the component to mount right to the frame as it grounds that way. The ICU and diode board are two such items.

It may now start up fine and rev, but if the problem continues, do check all the grounding points.

[luckyd20]

It's actually running fine now. I road it maybe 10 miles today. Not too far. I did notice though that the right guages we're lit so I'll have to see if it's a grounding issue.

Also as soon as this vid is loaded I want to make it's suppose to sound like this.

[luckyd20]

http://www.youtube.com/watch?v=b9q0b6_eZos&feature=plcp