troubleshooting question regarding starting

[skram]

hello again.  I inquired a couple of weeks ago about my new bike, an '83 r65.  it was recommended that I replace the coil, wire and plugs.  This I did, and I put in a high quality new battery.  And last weekend, I cleaned and rebuilt the carbs, which it turned out seemed remarkably clean.

These steps made the bike start and run exceptionally well, compared to before.  Your advice.assistance is truly appreciated.

so now, here's the next issue in need of diagnosis:
just now I went out to start the bike and it turns over really well but will not fire.  now, after countless minutes of turning over, the battery is, not surprisingly, weak.  so, . . .

1.  what can be causing the bike to turn over but not start?
2.  is it possible that i flooded it?
3.  right before the battery got too weak, the bike backfired VERY loudly.  How is this related?
4.  should I be applying the throttle at all under normal starting conditions?  Or, what is the proper starting procedure in this regard?

finally, some more background:  it's extremely warm outside and I didn't use the choke (even though i haven't started the machine for maybe 36 hours)

thanks in advance for your help with this. . .

[Bob_Roller]

The starting technique for an airhead bike, is half to full 'choke', leave the throttle closed, hit the start button, then add a little throttle after the engine fires a few times .

It is caused by a too rich fuel/air mixture, and when it finally gets to the muffler, or exiting the muffler, there is finally enough oxygen to burn the mixture, and you get a loud noise .

Just going out on a limb here, but is the fuel tap turned on ?

Have you possibly gotten the fuel level down to where you need to turn the fuel tap to the reserve position ?

[msbuck]

I always have to use my choke to start the bike - unless I've just shut it down after a ride...

[skram]

ok thanks.  yes the fuel was turned on, but i am running a bit low, so i put it on the reserve setting.  maybe i can recharge the battery and try again, this time with choke and no throttle until it runs and then a bit of throttle.  does that sound right?

 also, i don't want to damage this battery as it was expensive.  did I hurt it by running it down?  

[Bob_Roller]

As long as you don't leave the battery in a discharged state for any length of time, a few weeks or so, it won't harm it .

Just charge it up .

Keep an eye on the fluid level, if the battery is a non-sealed type .

What brand of battery did you get ?

[skram]

it's a westco battery.  any reason why i shouldn't charge it still hooked up to the bike?

[scottyintex]

      I am sure each bike is a little different...but I always have to use full choke to start my bike. Does not matter if it is 30 outside or 101.....have to use full choke. If I don’t ....it almost fires then just turns over.......not starting...will not start at all. Then..even if I put the choke on..is hard to start. If I use the full choke it fires up instantly. I roll the throttle a tiny bit when it fires off....then let the throttle go. I sit there a moment till the engines smooths out and take off. Takes longer to tell ya how to do it than it takes to start it with full choke. I turn the throttle off about half a block down the street.
      Now once started and warmed up this is not necessary..to use the choke.....unless it’s a really cold day. But I hate it when I do forget the full choke..cause is going to take me several tries before it fires off.

[montmil]

Also, confirm that the right-hand switch has the "kill" toggle set to "run". You did mention the backfire so the switch is not likely the issue. They are easily bumped to the "off" position but the engime will crank... until the battery gives up.

The choke on the BMW is not really a choke; more of a mini carburetor within the carburetor. Has its own "throttle cable" -commonly referred to as the choke cable- its personal fuel reservoir in the float bowl, and an entirely separate fuel system. Hence the advice to not apply any throttle at start up.

Since the scoot was running "exceptionally well, compared to before", I'm wondering if you need some pushaline in the tank. Unfortunately, our favorite BMW has a single petcock and leaves almost one gallon on the right side that's unaccessible unless you tip the bike and slosh it over. Looks strange at stoplights.

Monte

[msbuck]

That's a lot of double talk, Monte!   [smiley=laugh.gif]
I always charge the battery up with it still on the bike.  The westco battery is a good one - I had one that lasted 5 years and was recharged frequently.  

I can see how trying to start the bike without the bike for awhile could get some extra gas in the system that would cause a backfire.  After you charge up the battery, try it again with the choke and let us know how it goes.

[weasel01]

My bike will not start cold w/o the choke on ...with the choke on it will start on the first blip of the starter and then I can immediatly turn the choke off and gently rev the motor at low rpm's for about a minute then it's ready to go.

If the bike is warm from riding I can fire it right up w/o the choke but if it's been an hour or more I will use half choke and then immediately take it off and it will run fine.

If you just had the carbs off make sure the choke cables are adjusted so the cables at the adjusters have a little slack and the choke levers are resting at the lower stops and then when the choke is all the way on the lever should be close to the upper stop at an equal amount.

If that wrong it will be a real bear to start.

[montmil]

Too much coffee for me, MsBuck. Probably jittered the post button. I'll delete one. :-/   Monte

[k_enn]

Maybe it is just a ghost in the machine.  I had that happen to me last week.  It just would not start -- gas on, starter cranking, trying the various choke settings that usually work -- no start.  Not even getting a hint of any gasoline igniting in the engine.  Grind the battery down to dead.  

So this weekend, I checked it more closely.  Charge up the battery good.  Try to start it, -- it still won't.   Plenty of gasoline.  Petcock operating properly.  Gas is getting to the carbs.  Still no start.  Check the dreaded Crack-O-Matic (still have the original) for cracks or carbon marks -  looks fine.  Check for juice to the spark plugs, power there.  Suddenly, the engine wants to catch.  Put the gas tank back on, and it fires right up.  

Go figure.  The only explanation I have is a ghost in the machine.  

k_enn

[montmil]

 ...Go figure.  The only explanation I have is a ghost in the machine.  k_enn

I still think it's Ampy and his new voodoo chickens. All these carb and starting issues, stumbling, stuttering and lack of power started showing up soon as the birds arrived.

Hey, Amps. Are those birds on-line? Don't want them messing with my bikes.  

Monte

[msbuck]

Check the dreaded Crack-O-Matic (still have the original) for cracks or carbon marks -looks fine.  

Yep did that one with mine, and missed the miniscule cracks/burn holes the first time around...That's the way my bike behaved as well.  Put new coils on and I haven't had a problem since.

[weasel01]

Voodoo chickens indeed! My sweet hens wouldnt "fowl" me up im sure of it!

I think I've solved my mystery problem...again .

I'll post my findings on my carb thread