Symptoms:

Chugging along fine, long line of stop signs on my street that I'm too lazy  to stop for, so I roll through at around 5mph.  Wasn't hitting the clutch, so my bike was kind of unhappy.

Long straight away comes up, my bike is handling strangely on the gas.  If I let off throttle, the engine braking is extreme, hitting the throttle also gives an exaggerated effect.  I'm in first gear this whole time.  I come down to about 5-7mph and my bike just dies.  It won't start again easily.  I have to sit there and hold the starter down for about 8-10 seconds before it starts again, and it's fine.

Did I do this myself, or is this a sign that the carburetor needs some tuning?

Also - My RPMs haven't been going back to idle after a tug of the throttle.  I hit it to about 6k, and it will slowly drop, then settle at about 3k for half a second, then 2k, then finally back down to around 1-1.2k where it usually idles.

I know nothing about this, I just got this bike about a month ago.  It's got 2,000 miles on it, 2006 model. 

Thanks guys!

Sounds lean.

First off, does it have any mods that you know of? Air filter, exhaust, anything that's not stock? If so, that could be it. The PO may not have jetted/adjusted properly for the mods. Check the air box under the tank for a K&N filter. The stock exhaust is black, with a chrome outer on the muffler.

If it's all stock, it could be a vacuum leak or a slightly clogged jet. Whatever the cause, it's a fuel/air issue. I'd personally start with vacuum lines and carb boots before you tear into 2,000 mile carbs.

How fast was the engine running before the rolling stop signs? I would guess fuel starvation due to a gas tank vent / carb vent being clogged, but that usually happens after higher rpms.

It sounds like fuel to me too, particularly if it will run "fine" afterwards. Also, is vapor lock possible?

Good call, Rich. Clogged tank vents will do that, too. Doesn't prime bypass the vacuum..?

If that's the case, running it on prime should alleviate the symptoms, pointing to clogged vents.

An inline filter could also cause fuel starvation. Some on here use them, but others say they're the bane of this bike's fuel system, and I've heard nothing bit horror stories with them.

Rally, I dunno about vapor lock. I would assume that's what clogged vents cause..? But we don't have a fuel pump, so I dunno.

I think vapor lock may not require a pump. A vacuum or gravity may suffice provided there is a gas (a vapor not gasoline) in the fuel line that will cause the floats to drain. I wonder if that's happened.

Quote from: JAS6377 on June 26, 2015, 08:16:37 PM
Sounds lean.

First off, does it have any mods that you know of? Air filter, exhaust, anything that's not stock? If so, that could be it. The PO may not have jetted/adjusted properly for the mods. Check the air box under the tank for a K&N filter. The stock exhaust is black, with a chrome outer on the muffler.

If it's all stock, it could be a vacuum leak or a slightly clogged jet. Whatever the cause, it's a fuel/air issue. I'd personally start with vacuum lines and carb boots before you tear into 2,000 mile carbs.

Bike is completely stock.  Before I bought it, it had a fresh oil change, valve clearance check, some other odds and ends done.

Is this something I can do myself?  I'm pretty handy, I have the big detailed manual, I was just hoping to start slower before jumping into the real maintenance, but I guess I have to start sometime.  I have a pretty extensively compiled tool box.

Is there anything you guys can think of to help with the diagnosis?  I'm going to try to take it around the neighborhood tomorrow for a bit.  I have been smelling the sweet smell of gasoline upon startup and idle, I was thinking it was running rich, not lean, but I'm not too familiar with how carburetors work to be honest, I've never had one apart in my hands.

Quote from: Big Rich on June 26, 2015, 08:30:13 PM
How fast was the engine running before the rolling stop signs? I would guess fuel starvation due to a gas tank vent / carb vent being clogged, but that usually happens after higher rpms.

Well I was going through the neighborhoods in second gear, rolling the stop signs.  I came to a complete stop, put it into first gear, then proceeded.  So first gear, about 20-25 mph, probably about 6k RPM.  I've never stalled the bike before, and it's not like I was TRYING to do it, but I was amusing myself at how slow I could go without engaging the clutch without it stalling out.  Not sure if I got what I asked for, or if I discovered a potential problem.

Torrential rain until Sunday. 

Where are you from man?

And who did the valve check? I'm always very skeptical when somebody says "the seller said the valves were just done". Some people will say anything to sell a bike.... But there are a couple special tools to check the valves (not usually expensive). You can however check for a vacuum lock from the gas tank by simply opening the filler cap next time it stalls. If you hear a "whoosh" of air, it's the gas tank vent. The carb vent line is a little tougher - usually just taking the hose off and checking for a blockage.

Jas might have a good point about a dirty carb problem as well. 2000 miles on a 9 year old bike means it sat for a good bit. Which means possible sediment from the tank getting in the carbs, or the old gasoline turning to varnish.

Quote from: Big Rich on June 27, 2015, 04:51:00 AM
Where are you from man?

And who did the valve check? I'm always very skeptical when somebody says "the seller said the valves were just done". Some people will say anything to sell a bike.... But there are a couple special tools to check the valves (not usually expensive). You can however check for a vacuum lock from the gas tank by simply opening the filler cap next time it stalls. If you hear a "whoosh" of air, it's the gas tank vent. The carb vent line is a little tougher - usually just taking the hose off and checking for a blockage.

Jas might have a good point about a dirty carb problem as well. 2000 miles on a 9 year old bike means it sat for a good bit. Which means possible sediment from the tank getting in the carbs, or the old gasoline turning to varnish.

The guy I bought it from is pretty handy, I know him somewhat well.  He had the carbs cleaned when he purchased the bike, because as you said, the bike was not running and full of varnished gas.  He is quite the wrencher, I would be very surprised if he did something wrong or mis-advertised the bike.

I will try taking it around close to town in areas where I can park it on the side of the road safely (street parking).  If it happens again, I will start taking it apart to diagnose.  I've been looking forward to tearing it down, I was just hoping to get a lot more miles out of it before I needed to.

Can I get the carburetor opened to inspect the bowl and jets without having to resync and adjust everything?  I've seen the video on cleaning the jets and it doesn't look like he really does much with it aside from blow it out and soak the parts. 

I am in Virginia.

Valves were done were those ... oh so wonderful "breakeable design? of shims specially made by the Chinese for our bikes" used for it

Ok if you had one of those break, you're be not just complaining of stalling when rolling through a stop sign. So there is that.

Yea fuel starvation - you have a massive tank bag ? Those clog the vent too.
Cool.
Buddha.

Quote from: The Buddha on June 27, 2015, 05:17:54 AM
Valves were done were those ... oh so wonderful "breakeable design? of shims specially made by the Chinese for our bikes" used for it

Ok if you had one of those break, you're be not just complaining of stalling when rolling through a stop sign. So there is that.

Yea fuel starvation - you have a massive tank bag ? Those clog the vent too.
Cool.
Buddha.

No tank bag, and according to the notes the valves were checked and were perfectly within tolerances, so no valves were replaced. 

Quote from: kharper4289 on June 27, 2015, 06:22:57 AM

Quote from: The Buddha on June 27, 2015, 05:17:54 AM
Valves were done were those ... oh so wonderful "breakeable design? of shims specially made by the Chinese for our bikes" used for it

Ok if you had one of those break, you're be not just complaining of stalling when rolling through a stop sign. So there is that.

Yea fuel starvation - you have a massive tank bag ? Those clog the vent too.
Cool.
Buddha.

No tank bag, and according to the notes the valve shims were checked and were perfectly within tolerances, so no shims were replaced.

Okay guys, weird problems.

Starts fine, runs fine.  Take it across the street to a big parking lot, ride it around start stop for about 5 minutes.  Bike dies, this time WITH the clutch pulled in.  Won't start again, even with choke all the way on.  Pop it to "Reserve", start it, give it gas, it starts again and runs fine.  Come home, put it back to "On" (petcock), let it side and idle for about 15 minutes, no issues, slam the gas while it's in neutral up to 8k RPMs a few times, hold it at 5k for about 45 seconds, fine. 

Too scared to take it out again.

Any ideas?

Just making sure - you have a full tank of gas, correct?

I have 120 miles on the full tank.  I look into the gas tank and I see about 5-6" of gas in it.

I don't think the petcock switch actually did anything, to be honest.