So my bike is still being "jerky" when I give it low-mid throttle and also under deceleration (engine braking).  I'm currently riding in Serowbot's petcock "test mode" (I think that's what you call it) where I've pulled the vac line off the carb, capped the vac port and the hose (with a golf tee), and set the petcock to Prime.  I've only been riding like this for a few days, so I'll give it at least 2 tank fulls before I make the final call on whether this problem is caused by my petcock.

One thing I noticed the other day is that if I ride with the choke out, the jerkiness goes away (almost completely).  But with the choke in, the bike becomes jerky again.  I think what I mean by jerking is "lurching" but I'm not 100% sure what lurching is.

Anyway, does the fact that the problem improves with the choke out point to any possible issues that I should look at next?

Dave, you're right, I didn't really give any details about the bike.  It's a 2005 Savage which is bone stock.  I've changed the oil, replaced the air filter and I'm doing the Serowbot petcock test right now.  Other than that, I haven't done anything.

As for history, before I reconfigured my petcock, it would always need choke when starting, even on very warm (over 90 deg) days.  This surprised me.  Once started, if I put the choke in too soon (with the petcock set to "on" not "prime"), it would die.  Lot's of moving parts so I started with the petcock, knowing that many have issues with it.  Additionally, it almost stalled on me at a red light a few weeks back.  This was after having ridden for ~15 min at highway speeds so the engine was warm.

I haven't heard of removing washers from the top of the needle.  Are you referring to the float needle?  What does this mod do, exactly?

Once the source of Jerkiness is located & the solution found, it needs to applied to Many, & mankind will be much improved.

I can't give you my idle number in RPMs because I've never hooked up a tach.  But when I first got the bike, I was afraid it was a bit low so I adjusted it to be higher.  I *believe* it's on the high side, but I can't say for sure.

Thanks for the suggestions.  I'm still a noob, so just for my own knowledge/curiosity ... let's say the pilot jet is a bit gummed up in my carb.  Why would I experience less jerkiness if (1) the choke is opened up and (2) as the bike warms up?  This is what I'm seeing and, in my simple view of things, I would thing that if the jet is gummed up, it would continue to cause jerkiness regardless of the choke position or as the bike gets warm.  Any theories?

justin_o_guy2 wrote on 11/14/12 at 09:05:34:



   

Yep, Justin is correct.   Bad gas, bad plastic float assembly, it makes no difference --- once you find the source of the Jerkiness you have to eradicate it.  

Sounds good, Toes.  Good to know.  I'm in Austin, TX, so the weather is still great for riding here - just gotta layer up.  Hopefully the bike won't sit for long.