81 340 Invader

[Vader440]

I have a 340 Invader that I can't get to run on both cylinders. Last year it great, parked it for summer, went to start it last month and it would only run on 1 cylinder. I thought seals so I rebuilt it with new seals and gaskets still no good. Changed all the ignition parts CDI, a different Stator, coil, new plugs, cleaned both carbs still nothing but 1 cylinder. About the only I haven't done is try to run it without the muffler. Is it possible that has something to do with it. I'm at a complete loss.

[Interceptor398]

Check the primer.  An 81 340 Invader is very uncommon.

[Vader440]

I double checked the year it's a 1980. I will check the primer. Thanks!

[mswyka]

When you say only running on one cylinder how many RPMs are you able to generate?  I guess what I am wondering is whether it is only one cylinder firing or just not able to make RPMs. 

If only running on one cylinder, can you tell which cylinder may not be firing?  Can you switch the behavior from cylinder to cylinder by swapping plug leads or swapping carbs?

Like 398 says, check primer.  Try running w/o muffler, double check needles and seats in carbs.  Possibly bad fuel pump or broken/cracked impulse line.

[Vader440]

When it's running on one cylinder it won't climb above 3500 to 4000 RPM with full throttle and then slow down to the point it quits. I'll check the other things you mentioned too. Thanks!