help! rattler died on me!

altoidboy1 · Post by **altoidboy1** » Fri Jul 27, 2012 6:56 pm

I've had my rat for about 2.5 years now, and never had a major problem. I was riding home from work at 1am last night, and when I went to pull away from a stoplight, my engine bogged and stalled. I first thought I might have run out of gas, but there was about 1/4 tank. About a 1/2 tank of oil. The engine starts/idles, but when it is revved to get moving, it dies. I'm not super mechanical, but did I break a belt and maybe it got caught up in the variator? It wasn't running rough and the problem happened quickly. Any other worst-case ideas? I'm broke and would really appreciate some help on where to start to diy diagnose/fix it. I am usually pretty tame with the bike, I give it the beans sometimes but for the most part I just commute where I need to go. No mods to the drivetrain except airbox "de-restricting". I had driven probably 15 miles total yesterday, and about 6 at once when the problem started, at about 30-40mph cruise. No wierd noises, no poor performance that I noticed, although I wasn't pushing it so it could have been running a little weak and I might have not noticed. Ive logged about 1500 miles and not had to do anything except replace the battery, tighten a bolt here and there, (ie the exhaust came loose last year,) and have the horn serviced a few times.
Someone please help! I need a fellow forum nerd to walk me through the diagnosis and possible causes! I love my rat and need it to commute when my wife needs the car.

spr0k3t · Post by **spr0k3t** » Sat Jul 28, 2012 12:13 am

It turns over... so you are getting fuel. When you try to give it more fuel, it dies. That leads me to believe it is a fuel related issue. Check the fuel tank to make sure you don't have a vapor lock. Remove the gas cap and let it run for a couple minutes. After a minute or two, rev the engine to see if it will take. If it stalls, move up the line from the gas tank. Check the petcock, fuel filter, and possibly down to the carb. You should also check the vacuum lines to see if there are any cracks. Check the auto-choke mechanism to verify it's feeding the air/fuel mix correctly. There is a simple problem, just finding the needle in the hay-stack to hammer it out. This should give you a few areas to check to help diagnose the issue.

B02S4 · Post by **B02S4** » Sat Jul 28, 2012 1:24 am

In addition to what has already been said, it could be an intake vacuum leak (are the carb to intake mounting bolts tight?), broken reed petal (need to pull the carb & intake manifold to check the reed cage/petals), or major fuel line obstruction. Did you also pull the plug & see what it looks like?

altoidboy1 · Post by **altoidboy1** » Sat Jul 28, 2012 12:37 pm

Thanks guys. That gives me a place to start. I haven't had time yesterday to look at it and start turning bolts. Hopefully today I can start looking. Out of all the stuff you mentioned, would any of it happen while riding like that? It was the wildest thing. I took the gascap off for a second, just long enough to shine a light into the tank to see if I had run it dry. I would love if that was the only problem, but I've ridden it further, faster, on hotter days, (i live in Houston, so the day was hot, but the night was like 80.) I also thought the vaporlock usually manifested when you've just filled up. I started with about 3/4 tank, and had a little under half when it acted up.

spr0k3t · Post by **spr0k3t** » Sat Jul 28, 2012 2:37 pm

Vapor lock can happen when there is less than a full tank... just not as easy for it to happen. It all stems from the suction and capillary principals. If you were at 3/4 tank to start, it's not likely a vapor lock issue. I would put more money on the gas line all the way through the carb myself. It's possible there's a small bit of debris in the line somewhere. It's happened to me on one of my bigger bikes... turned out I had to clean the carb and from then on there was no issue.

altoidboy1 · Post by **altoidboy1** » Sat Jul 28, 2012 6:02 pm

Ok, got my tools out, all ready to start tearing body panels off to get at the engine and fuel lines, but a little voice told me to see if it started. It fired right up and I ran it for 5 minutes on the center stand. no sputtering, noises, nothing. After I mow my lawn I'll take it for a shakedown ride, but are we thinking vapor lock? A fuel line wouldn't just unclog itself, right? (Also, we had a TON of rain lately, and Friday was my second ride, first ride of any distance since. It was exposed to a lot of it, would water in the tank somehow make it do that? I didn't think so, since water is more dense and all, I would think it would cause an issue from the start.) I'm puzzled. If it WERE vapor lock, are there any other things I should be careful of? I heard about people venting the cap themselves, but I'd like some advice/guidance first. Should I keep the tank full/half full? Am I gonna be more likely to lock on longer rides or shorter? Hotter days or cold? Is there anything I can add to the gas to help prevent it? Is there anything else I could be overlooking?
On a separate note, a BIG thank you to you guys for replying so quickly!

B02S4 · Post by **B02S4** » Sat Jul 28, 2012 8:36 pm

altoidboy1 wrote:...It was exposed to a lot of it, would water in the tank somehow make it do that? ...

Yes, it could, however if it did, then the water would still be in the fuel tank, eh? And how did water get in?

I suggest draing the carb bowl & see what comes out...E-90 fuel can absorb a small amount of water, & it will phase separate out eventually & the water will stratify at the bottom of the container (bowl or tank).