Bike won't start... help!

[jwyler]

How do I "drain the float bowls"?

[GRU]

this is a picture of the bottom of the carb (float bowl)...see the little screw on the side...when you turn it counter clockwise the fuel will drain on the bottom of that little metal tube...if you have a small tube, just attach it to the bottom part of the bowl (so you don't have gas leaking on the engine) and then turn the screw untill fuel come out


thanks for the pic kerry  

[jwyler]

Did just as you said... drained the float bowls, set to prime, and checked the flow.  Fuel came out of the drain on both sides just fine after that.

Time to give up and take it to a shop, or anything else to try?

I still haven't heard any attempts at an explanation of why it won't bump-start, since like I said, that's never been an issue before.

Thanks for the continued help on this, --Jon

[jwyler]

Also definitely not the clutch limit switch, as it appears a previous owner must have soldered the wires together so that it'll start with the clutch engaged or not.

[GRU]

let me get this straight......when you took the spark plugs out, you could hear the engine turning over when you press the start button, right?
if so, then all the other sensors are good and don't worry about them...

when you put the plugs back and press the start button, do you hear the engine cranking? you said you seen spark from the plugs so that is good....

if you try to start the bike and you can hear the engine turning over, you have a spark, you have fuel geting to the carbs, then everything there is good....

the only other thing i can think of is the timing...the timing could be off and that's why it doesn't want to start... just take it to the shop and hopefully they want rip you off

[dsmirnov83]

Check that the choke cable is not binding and is activating the choke.

[Kerry]

thanks for the pic kerry  

I posted a more self-explanatory version of this picture recently.  (I can't remember where.)  Hopefully it will be helpful for various purposes in the future....

http://www.bbburma.net/MiscFotos/DSCF2431_Idle_Drain_Mixture_Screws.jpg

====================================

Meanwhile ...

Jon, I'm still not convinced that your electricals are A-OK.  You seem to have fuel flow, there is no cut-out switch problem, and you're getting spark.  BUT...

..."getting spark" - in my experience at least - isn't "definitive".  I had a break in the signal generator circuit, and even though I "got spark" on both plugs when they were pulled from the block, the engine would still only run on one cylinder.

Now, your problem has a 99% chance of NOT being the same as mine, because the break in my circuit was on the left side of the bike.  But the signal generator itself is underneath that right-side cover, and there could be a problem elsewhere in the same circuit.  If you're handy with an electronic multimeter (ohmmeter) there are a few simple measurements you can take before you give up and take the bike to the shop.

If you're interested enough to wade through a multi-page message thread before surrendering, take a look at
Narrowing down the problems to a broken bike

After getting a feel for the background of the (hopefully relevant) scenario, try filling out the checklist at the bottom of the 2nd page of posts.  Let us know what you find!

EDIT: Changed link from sisna.com to bbburma.net.

[MarkusN]

Just an odd thought; its' not likely to be the culprit, as the starter manages to rev the engine over, but since you said knocked over to the right: Acid level in the battery is OK? It could have drained if the bike was laying on the right side for a considerable time.

A lame battery might drop in voltage enough when starting to cause all sorts of problems.

[jwyler]

I charged the battery with a trickle charger, and it gave me a "green light" indicating it was charged, so I assume the acid level is OK.  Looked like it could use a spash of water, but not significantly low.

I'll give the electrical checklist a try.

Another thought/question: do you think I need to rebuild the carbs?  Isn't it possible that the bowls are filling, but the cylinders aren't actually getting any fuel?  (If so, do you think the "How To" on this site is comprehensive enough for someone with limitted bike/auto mechanics experience, but is mechanically inclined?)  I should note that I was never able to get this bike over 60 mph, which I'm guessing might indicate the carbs aren't super clean, though my tank is completely rust-free.)

[GRU]

Another thought/question: do you think I need to rebuild the carbs?  Isn't it possible that the bowls are filling, but the cylinders aren't actually getting any fuel?  (If so, do you think the "How To" on this site is comprehensive enough for someone with limitted bike/auto mechanics experience, but is mechanically inclined?)  I should note that I was never able to get this bike over 60 mph, which I'm guessing might indicate the carbs aren't super clean, though my tank is completely rust-free.)

yes, i think you should rebuild the carbs....there is a big possibility that the jets are pluged from dirt and rust....after all the things i told you to do, and basicly all of them turned out OK now it's time to take out the carbs and check them out....

while you have the carbs out for a cleaning, change the main and pilot jets and inspect all the carb pieces.

[jwyler]

So I'm rebuilding the carbs now...

But they look very clean.  I'm doubting that was the problem...

The air filter is quite dirty, though.  That wouldn't keep the bike from starting, would it?

[GRU]

not really...i seen tons of dirty air filters and the engine ran fine...

rebuild the carbs and try to start it again...make sure to clean the jets if you arn't replacing them

[jwyler]

So I rebuilt the carbs, even though they didn't end up being dirty.

I'm 90% sure that I've reinstalled them correctly.  (Does one of the 4 hoses from the tank and 2 of 4 from the carburetor -- the one from the left carb and the top T -- go to ambient?)

But now I don't have fuel flowing to the bowls!  I put it on Prime and gave them a few minutes to fill, and nothing.  I did turn the fuel valve to On.

[Kerry]

_4_ hoses from the tank?  I'm only aware of 3.  Hmmmm.

See if the pictures on my Fuel Hose Routing page help at all.
If you want to print it out, Rema1000 posted a nicely-organized 1-page PDF version at
http://grapeape.specialgreen.com/~bcarlson/gs500/images/HoseRouting.pdf

There is one hose that is not mentioned here - the thin one that connects to the underside of the fuel tank itself.  It has a right angle bend in it near the upper end, and the lower end is near the right footpeg.  This hose drains overflowed fuel or rainwater (which can collect under the filler cap) to the ground.

EDIT: Changed link from sisna.com to bbburma.net.

[MarkusN]

I'm 90% sure that I've reinstalled them correctly.  (Does one of the 4 hoses from the tank and 2 of 4 from the carburetor -- the one from the left carb and the top T -- go to ambient?)

But now I don't have fuel flowing to the bowls!  I put it on Prime and gave them a few minutes to fill, and nothing.  I did turn the fuel valve to On.

Those two statements are related. The top hose from the left carb is the vacuum hose that activates the petcock. Without that, no fuel flow. (when the Engine's running, that is. To prime the carbs yo need the respective setting on the petcock, as the carbs won't deliver vacuum.

The top T hose indeed goes to ambient.

About PRI not working: Any kinks in the hoses? It's easy to get some when assembling that can of rubber worms.

[joefromsf]

Kerry, there are 4 hoses on the CA model tank. The 4th goes to the emissions canister.

[scratch]

So I rebuilt the carbs, even though they didn't end up being dirty.

But now I don't have fuel flowing to the bowls!  I put it on Prime and gave them a few minutes to fill, and nothing.  I did turn the fuel valve to On.

Even if the carbs don't appear to be dirty, if they have been sitting long enough with old gas, the gas may turn into a varnish and gum up the jets and all the little holes in the carb. Soaking in carb cleaner or spraying with the little red tube into all the little orifices and making sure you see the fluid coming out some other little orifice will help ensure that you have nothing blocked. Just be careful not to spray any rubber parts.

Did you turn on the On/Off valve under the tank? Also, put on Prime and tap the float bowl with the butt of a screwdriver to get the float valve loose, sometimes when it's dry it sticks in the seat.

[jiggersplat]

you said the bike was sitting for a while.  have you tried fresh fuel?

[scratch]

When you try to start the bike, do you open the choke all the way? Maybe try partway?

[Kerry]

now I don't have fuel flowing to the bowls! I put it on Prime and gave them a few minutes to fill, and nothing. I did turn the fuel valve to On.

How do you know the bowls aren't getting any fuel?  Try the following, with the fuel selector in the PRIme position:

1) Open the float bowl drain screws.  Does fuel come out for a minute or more? If so, then the bowls are getting fuel.  If not, then close the drain screws and continue.

2) Pull the hose from the lower T-fitting between the carbs.  Does fuel come out of the hose?  If so, then there must be a blockage between the lower T-fitting and each carb, or within the carbs themselves.  If not, then reattach the hose to the T-fitting and continue.

3) Pull the other end of the same hose from the frame-mounted petcock.  Does fuel come out of the petcock?  If so, then there must be a blockage in the hose.  If not, then reattach the hose to the petcock and continue.

4) Pull the RES hose from the frame-mounted petcock.  (It's the one attached to the right side, or rear, of the petcock.)  Does fuel come out of the hose?  If so, then there must be a blockage in the petcock.  If not, then reattach the hose and continue.

5) Pull the RES hose from the tank-mounted petcock.  (It's the one attached to the longer downtube, on the left or towards the front.)  Does fuel come out of the tube?  If so, then there must be a blockage in the RES hose.  If not, then reattach the hose and continue.

6) At this point you only have 3 options: A) There is no fuel in the tank, B) The tank-mounted petcock is not turned on after all (the screwdriver slot must be

vertical), or C) There must be a blockage in the in-tank filter or outlet.

7) Once the blockage is found and fixed, you may need to work your way back DOWN the fuel supply system, making sure that fuel flows at each junction.  Alternately, you can just try to start the bike!   [/list]

==================================

If the motor still won't start, will it at least still "crank" like before?  I'm curious about the results of your earlier plan:

I'll give the electrical checklist a try.