Loud Bang

[CasiUSA]

OK. SO I have been trying to be good with starting my bike up every now and then for the winter months. I missed about 3 weeks due to school and work and whatnot.
So Yesterday, I tried starting it. It wouldn't go. I figured it was just too cold in my garage. So I left the space heater on it all morning, and took the battery out and charged it. I tried starting it today, and the bike wouldn't do it again. I realized that yesterday, I had left the petcock on PRI. So I drained the carbs by turning the screws on the bottom of the floats and draining into a dixie cup.
When I started the bike, a loud gunshot like bang nearly deafened me. and the bike wouldn't start.
My question is this: Does anyone know what this could be, and do you think it has potentially damaged the bike? Thanks.

[Maniac]

Sounds like it backfired to me. How long was it sitting with gas in it, anyway?

[The Buddha]

OK. SO I have been trying to be good with starting my bike up every now and then for the winter months. I missed about 3 weeks due to school and work and whatnot.
So Yesterday, I tried starting it. It wouldn't go. I figured it was just too cold in my garage. So I left the space heater on it all morning, and took the battery out and charged it. I tried starting it today, and the bike wouldn't do it again. I realized that yesterday, I had left the petcock on PRI. So I drained the carbs by turning the screws on the bottom of the floats and draining into a dixie cup.
When I started the bike, a loud gunshot like bang nearly deafened me. and the bike wouldn't start.
My question is this: Does anyone know what this could be, and do you think it has potentially damaged the bike? Thanks.

Prime... could fill the combustion chambers with gas, causing hydro lock... You hit start and the gas in the chamber will keep the piston from going up on compression stroke... bending a con rod. Very common on the bloody eliminator/zx kawis. That is why I pull the plugs out and then hit start, a few turns it will spit gas, and you'll never hrdro lock.
Cool.
Srinath.

[Rema1000]

If it takes me more than about 3 tries to start, then mine will backfire. I've been thinking I should try to start it without full choke, and see if that helps.

BTW, starting it when it's cold is pretty tricky for me: when the weather is warmer, I find that as soon as the engine catches, it starts to run... then it starts to race, and I need to turn down the choke to keep it under 3krpm.  

But when it is cold (like 32F), then when it "starts", it doesn't really start: I hear the engine firing, but if I let go of the starter, then it just stops.  Instead, I have to hold the starter, then turn the throttle a little, then the RPMs rise to 2k and I can let go of the starter.  It's quite the song-and-dance.

I think I'd scrub the carbs if I could heat the shop above freezing :brrr:

[JLKasper]

This could be a combination of things.  First, unless your needle valves aren't functioning properly, your combustion chambers shouldn't fill with gas if the 'chicken is left on prime.  What is more likely happening is that the air and combustion chamber is very cold, and the fuel air mix doesn't vaporize as readily.  A few charges don't fire and fill the exhaust pipe.  When one catches, it burns the mixture in the pipe and KERPOW!!  This could be caused by old gas, worn out plugs/wires (or improper heat range), using too high octane fuel, and >possibly< a bad needle valve in that cylinder.  You did add a fuel stabilizer in your last fillup, didn't you?  

[Maniac]

I'm gonna bet he didn't... a common mistake. Done it myself a lot of times. I'm sure everyone has!  :lol:

When you drained the gas, was it relativly clear, or pretty dark? Does it smell a little like paint thinner? If it does, it's gone bad. You may want to drain the tank, drain the carbs, and refill with some new gas. Hopefully that'll do it! If not, you may need to get the carburators cleaned.

[miket]

Change your plugs and try again. You probably just fouled them the first time you failed to start it. Very common. Like JLKasper said, the bang was probably just backfiring due to accumulation of unburnt gas in the exhaust. Again, common with fouled plugs.

[Rema1000]

Don't know about Casi, but yeah, I've been running sta-bil.  But the bike occaisionally did it when it was cold, even when I was still riding it every day (not old fuel).

But I think the weak spark might have something to do with mine:  my battery is marginal, and even more-so on cold mornings.  a weak spark could cause failure to ignite, and flooding.

In fact, I've noticed that when starting, it sometimes turns-over fine, but doesn't fire until right when I let-go of the starter button.    Maybe the battery has enough juice to turn the starter, but while it does, the spark is weak.

[The Buddha]

OK fine hydrolock is pretty rare on the GS, you tend to fill the airbox first, but I have managed it even then... Just once but still. Anyway worth checking, and I squirt a little oil in the cylinder at the same time. Many other bikes hydrolock easy, and most down draft bikes are very very bad, as are V twins and even some side draft bikes.
Cool.
Srinath.

[CasiUSA]

Thanks for the suggestions guy. Another question is: Of all the possibilities, should I be worried about any damage caused by this? Or is this a common thing among these motors? Thanks.

[mjm]

When I started the bike, a loud gunshot like bang nearly deafened me. and the bike wouldn't start.

I think it is likely that the bang was actually a backfire - that is having mixture that combusts in the intake tract and out through the carb.  I have had a backfire blow the carb bodies off the intack manifold - when that happens the bike will not start until you re-attach.

Otherwise, a loud bang is generally caused by gas in the exhaust (hit the kill switch at about 60 with the throttle wide open - wait a second for the gas to build up in the exhaust & put the switch back in run  - do it under an overpass if you like noise) that will not effect the ability of the bike to start later.

[The Buddha]

OK gunshot is 99% back fire in the pipe. I didn't read your first post in great detail. I still would do a plug pull and turn over the motor and clean the plugs. Its possible the thing back fired in the carbs too but that usually also is harmless. Clunk noises are motor related. Gunshot is back fire.
Cool.
Srinath.

[klimber]

this same thing is happening to me

been  20'F,

went to start and it would not start

gas started dripping out from under the carbs and out the one of the black tubes hanging out the right side by the foot
did not use prime
thought i'd maybe flodded it, turned it full throttle and after several several cranks it started but i had to keep giving it throttle and slowly worked off the chock, gas was leaking all over hell still ,released the throttle and it died,

put the choke  on
tried some more but just got gas all over the floor

pulled the plugs, they were black and dripping with gas
get the plugs out, turned the starter and gas squirted out , thought maybe i had expelled it , cleaned off the plugs, put them back in, ran for 3 seconds with choke on and me NOT giving any gas

pulled the plugs again  

walked away, thought i'd better get some advice before proceding

i too have gas additive in, been starting every couple weeks or so, never had a problem. the last couple weeks it has been -20'f so  when we finally had 20'F above i was eager to hear it go

advice needed!

do something now?  and hear it run some for peace of mind?  any ideas?

leave it alone till warmer weather?

could anything have been hurt in my actions?

my poor gs, kinda makes me feel ill that i could have broke somthing

[scratch]

You're flooding the engine. Turn the choke off and open the throttle WFO (Wide Full Open) and then hit the starter button (only do this when you flood it, otherwise you're just wearing down your battery and starter).

You're also going to have to pull the carbs off and give 'em a good cleaning.

Question: Did you drain the carburetors when you set up the bike for storage?

[klimber]

drain the carbs?  no, i haven't heard of anyone doing that,  couldn't that dry things out that shouldn't ?

i had additive in, did run the the bike this fall to make sure it was in the system good!

[klimber]

OK, so if the bike is cold and it is flooded due to my ineptitude,

NO CHOKE and twist it all the way?

[klimber]

well,  no choke, twisted all the way and yep, the bike started

and then looked down, gas is pouring out all over the floor

so something is stuck?  plugged?


it is about 20'f here in minnesota,  

should i just give up till a warmer day since it isn't gunna be ridden anyway,  what ever is stuck may be stuck by the cold? ya think?

suggestions are appreciated

[sanityfree]

i haven't been starting mine as often as i probably should...

the last two times i started it, i had to crank it forever, it would "fake fire" (sounds like running but really isn't) a bit, then the battery went dead. first time, i drained the carbs, reprimed them, then a friend and i push started it. long push uphill. (Don't even say it, my driveway is at the bottom of two hills.) anyway, it finally started, spit and sputtered for a while, then blew the cobwebs out and ran like a raped ape.

second time, i was push starting it alone. i could get it to fake fire a couple times, then i just gave up. went back to the garage, put the charger on it, and just hit the starter. fired right up. i think the fuel in my carbs was nasty. oh well.

i know i should take the battery out when i charge it, but i can't. how do i get the drain hose to come out with it? i don't like the idea of just yanking it off, as i'm afraid that's not the right way, and i won't be able to put it back on. what's the trick?

[AndyMC]

just pull the drainhose off at the battery it pops right off take the batt out and the house stays in place dont forget to reconnect it though

[joefromsf]

Its ok to take the battery out and leave the breather hose where it is. Its easy to re-attach when you put the battery back.

Better yet, invest in a Battery Tender. It is a smart battery charger that is safe to leave on your battery as it shuts down when battery is charged. It comes with a connector that you can leave attached to your battery and just plug in when needed.

See http://www.batterytender.com/

I have the Battery Tender Jr. Highly recommended.