New to me 2007 w/1950 miles.  -Ran great. No backfiring, coughing, popping.  -Light fuel smell noted after very short ride.  -Raptor installed.    -Removed airbox & Emissions.    -Installed Uni foam filter & Dyna exhaust.    -No other changes.    -No backfiring.    -A couple coughs and pops on decel. during another very short ride. One more short ride WHEN SUDDENLY I heard a higher pitch repetitive fast warble clicking sound like a handheld power tool. I stopped the bike. Motor quit and would not start. VERY strong fuel odor. I pushed it home WHILE the thingy was "on". I forgot. Tried to start it at home. The mostly entire contents of the crankcase (filled with fuel) came all rushing out through the breather hose/filter. I then drained the crankcase. Almost all fuel. I checked to see if the thingy was working properly and it did stop the flow in "off" position. I pulled carb and am disassembling. I'm thinking the needle valve and or float system in screwed up. It is not stopping fuel from passing through and so when the petcock is left on, it's just like leaving a stock thingy on "Reserve".
Phew.
Finally a question...what is needed in the carb?
Any chance I didn't destroy the motor?
Once I "fix" the carb (needle/seat) HOW TO?  is there a way to test that the carb won't let fuel through when it's not supposed to, when the thingy is on, accidenltely?

Please guide me on what steps to take.

Billybobber wrote on 07/10/25 at 21:47:33:

it's just like leaving a stock thingy on "Reserve".

Finally a question...what is needed in the carb?
Any chance I didn't destroy the motor?
Once I "fix" the carb (needle/seat) HOW TO?  is there a way to test that the carb won't let fuel through when it's not supposed to, when the thingy is on, accidenltely?

The "thingy" is known as a petcock.

Doing a google search, I quickly found two other reports of LS650s severely internal leaking of fuel into the crankcase.  This is always a danger, but I've never heard of a model that was particularly predisposed towards the failure mode.  

Gasoline dilutes the oil, and bearings and piston /cylinder wall protection are compromised.  Hopefully the whirring noise you heard wasn't severe damage or a coincidental failure due to a different issue.   I'd assume that the engine died from a very rich mixture, hope for the best, replace the oil, fix the carb, and try again. Once it's running, if the noise manifests again, I'd identify it and take steps to fix it.

The solution to the fuel internal leak is to fix the float valve in the carb bowl.  Sticking floats is a pretty common problem, especially on bikes that spend a lot of time sitting.  It's safe to suppose that an 18 year old machine with under 2000 miles on the odometer is in that category.

You should invest in a service manual.  Another book that I can recommend to anyone who wants to learn to do their own work is "Motorcycles : Fundamentals, Service, and Repair Hardcover" by Bruce A Johns, David D. Edmundson, & Robert Scharff, used for training motorcycle technicians.  It contains a lot of knowledge, for very little money.  https://www.ebay.com/itm/226826374865

I'd take off the carb, remove the bowl, and inspect.  Because you are inexperienced, I recommend you disassemble as little as possible, but I'd remove and clean the main jet, the pilot jet, and note their sizes while I was in there.  I'd check the CV slide for free sliding operation, and I'd make sure the float valve seemed to be free and functional.

I'd reassemble, then use the "clear tube" method of setting the float level to check that the float valve was doing its job.  The concept of this is pictured here: https://www.kzrider.com/media/kunena/attachments/6412/cleartubecombo-2.jpg