Tuning issue or bad engine?

[Jus2krazy2007]

My stock 21bb for my savage hasn’t been able to run through a whole tank for about a week and when I have it stopped at an idle the engine doesn’t keep the same purr it starts to bog then gets back up to high rpms and then dies.... what’s the problem?

 

[scottm]

It may be running lean, possably from a change of fuel or some dirt in the needle valve.

 

[militarymaxx]

Check for air leaks, seal them up if any found, give everything a once over replacing fuel line where needed, check your banjo fittings (two washers on top and bottom of fuel fitting on the HSN side), make sure they're not overtightened, give the glow plug a good look as well, it can tell you how things have been running by it's condition, and the last thing is to put everything back to factory settings on the LSN/HSN. That should get you back in the ball park, probably on the rich side. Take it from there.

 

[olds97_lss]

Whens the last time you checked the head bolts? I had one work it's way loose on me and it ran like crap.

 

[Rolex]

Pull the head. If the carb is set correctly, the top of the head, and the top of the piston should have a transparent color evenly across. The glow plug should be bright and silver.
I run Blue Thunder which leaves the green color. If it looks good in there, you probably have an air leak somewhere.
Something that's often overlooked is the rubber gasket seal on the fuel cap. If the cap isn't sealing tightly, you lose pressure on the fuel feed.