Why will it not run - it Used to pre carb cleaning.

[urbane]

You guys have a lot of good threads here. I am helping my friend fix her GS500 as it had that hunting idle problem. 2004 Suzuki GS500 Blue tank white fairing.

First thought? Clean the carbs.

We did that, put the carbs back together and followed that Youtube video detailing everything. Didn't miss a step. https://www.youtube.com/watch?v=AJh1hxNf7BA

Start the bike and the hunting idle is back, but now bike died quick.

Try to start - the bike will now not catch as all. Just cycles over and over and over. Never "catching" and trying to start.

I checked the ignition coils and they read I think around 60 ohms each in resistance so they have not gone bad.

I've run out of things to try. All of the wiring is good. I've checked, rechecked, and triple checked routing of fuel hoses and made sure to follow all the correct procedures. Fuel comes out of the bowls if I drain them. So what else could it be?

I've checked the spark plug wiring and spark plugs, the spark plugs are sparking when we try to start the bike with them out of the cylinder, so it's not those.

Just testing the battery, it has 12.5V before starting, and 10.2V when starter turns.

This crank trigger thing some mentioned somewhere else isn't even on google. It just links me to this: http://gstwins.com/gsboard/index.php?topic=46028.0

I really need help with this. I've done tons of carb cleanings before, but never have I been so stumped by a bike. And a sporty standard at that!!!!

So a reply would be appreciated... Happy New Years, and Merry X-Mas.

tl;dr - Bike was running with hunting idle, so cleaned carbs, after cleaning still hunted, now it won't start and run (catch) at all. What do I do?

PS: Your captchas are SUPER HARD to answer, I had trouble searching for some of the answers.

[Watcher]

4 things are required for an engine to start.

Fuel
Air
Spark
Compression.

Sounds like you're getting spark so we can rule that out.
Checking to see if it's getting air is as simple as looking at the filter element to see if it's clogged.

Even though your carbs have been stripped and cleaned and fuel DOES get to the bowls there may still be something preventing enough fuel from being drawn into the cylinders.  A vacuum leak can do this if it's really bad, and vacuum leaks are notorious for causing idle issues.  It would be a good idea to inspect the engine side intake boots and all vacuum lines for damage and proper routing.

I'd just as a precaution leave the petcock on "PRI" for the duration of testing.
Also make sure your choke is operating properly and that you are engaging it before starting.

If you CAN get it started and idling, a spray bottle of water is a cheap and effective way to find vacuum leaks by misting the carbs.  A drop in idle is a dead giveaway.


Hopefully it won't come down to compression, but it could be as simple as your valves are WAY out of spec...

[urbane]

Thank you for the quick reply, I cannot even get it to turn over at the moment.

I will look at the hose routing guide in the service manual to make absolutely sure something isn't blocked or unhooked. But it seemed correct. Someone has been in there before me though... 

If I can even get it to run I hope I can start testing these issues! I tried to run it without even connecting the air box - so I could see the fuel spraying in/diaphragms moving.

Can't get it started for now.

[Watcher]

Thank you for the quick reply, I cannot even get it to turn over at the moment.

I need you to clarify this because to me "turning over" is literally the act of the engine spinning.  An engine "turns over" when it isn't seized, the starter is working, and the battery is strong.

Will it ignite but won't run under it's own power?  Like, can you hear it attempting to fire?  Or is it just spinning dead?



I would get to the parts store and pick up a can of starting fluid and see if you can get it to run on that.  Be sure to read the directions on the can.

[urbane]

Thank you for the quick reply, I cannot even get it to turn over at the moment.

I need you to clarify this because to me "turning over" is literally the act of the engine spinning.  An engine "turns over" when it isn't seized, the starter is working, and the battery is strong.

Will it ignite but won't run under it's own power?  Like, can you hear it attempting to fire?  Or is it just spinning dead?



I would get to the parts store and pick up a can of starting fluid and see if you can get it to run on that.  Be sure to read the directions on the can.

I'm not perfect with my choice of words here BUT it will TRY to start (starter turns engine, engine pistons move) but it will not run (as I let OFF of the starter, bike is not running).

Like this Puerto Rican's bike lol: https://www.youtube.com/watch?v=RetXjwuH6iM

[Arpee]

A couple of things can happen when removing and replacing the carbs.  Pretty easy to have happen:  the act of pulling and bending/twisting to get the carbs up and out of the engine bay can cause a crack or two to form on the intake boots thus allowing in way too much air.  This actually MAY have been the original issue you were trying to solve.  With this, the O-rings behind the rubber intakes can dry out and allow air to pass as well.  Remove and inspect these boots VERY carefully where the "tube" part meets the "flange" part.  That's the most common area to crack.  Very hard to see.

The second thing could simply just be the float heights or the float seats maybe letting a little too much gas into the cylinders.  When you pulled the plugs, were they wet or dry?  A wet plug won't fire, likewise a cylinder full of fuel won't fire off either.  Check these things out and let us know.

[mr72]

The other problem that might happen is if you sprayed carb cleaner on the assembled carbs it may have gotten to the rubber diaphragms under the plastic covers and ruined them. A hole in one of those diaphragms would probably result in no-start.

Or, you cleaned it and wound up driving some debris into the pilot circuit orifices so they are clogged and you get no fuel while starting. Just some ideas.

[urbane]

I went back in and checked the intake clamps, unfortunately no damage so those are not the problem.

I did NOT check where the tube met the flange that would make sense.

The spark plugs did not stink of fuel like a bike that couldn't start would. So if I spray starter fluid into the engine and it still wont start I have a problem will test.

Also need to check the fuel levels in the bowls.

Thank you for all of these recommendations.

A couple of things can happen when removing and replacing the carbs.  Pretty easy to have happen:  the act of pulling and bending/twisting to get the carbs up and out of the engine bay can cause a crack or two to form on the intake boots thus allowing in way too much air.  This actually MAY have been the original issue you were trying to solve.  With this, the O-rings behind the rubber intakes can dry out and allow air to pass as well.  Remove and inspect these boots VERY carefully where the "tube" part meets the "flange" part.  That's the most common area to crack.  Very hard to see.

The second thing could simply just be the float heights or the float seats maybe letting a little too much gas into the cylinders.  When you pulled the plugs, were they wet or dry?  A wet plug won't fire, likewise a cylinder full of fuel won't fire off either.  Check these things out and let us know.

The other problem that might happen is if you sprayed carb cleaner on the assembled carbs it may have gotten to the rubber diaphragms under the plastic covers and ruined them. A hole in one of those diaphragms would probably result in no-start.

Or, you cleaned it and wound up driving some debris into the pilot circuit orifices so they are clogged and you get no fuel while starting. Just some ideas.

I remember an old man telling me this. I started cleaning around the carbs with my latex gloves on and used some carb cleaner. IMMEDIATELY the gloves just broke down into like 20 different pieces and I had no glove anymore... I learned to NOT use carb cleaner around rubber. Thank you for the recommendation, but the slide rubber/diaphragm is intact and does not leak. I don't think debris could've got through the fuel areas, but heck I better check!

[Arpee]

If everything checks out, I'd go back to the floats.  Be sure you're getting fuel to the carbs.  You can quickly check that by opening the drain on the bottom a little and see if any fuel comes out.  Check both carbs to be sure.  It does take several cranks after a carb cleaning to get the motor to fire up sometimes.

[mr72]

Yeah I've had the float needles stick closed from time to time, causing the bike to run on one cylinder or refuse to start. Good thing to check.

Also you can run a guitar string through the pilot orifices ... like a 0.013" string if you have one or if you know a friend with guitars, just a length of it works great to knock it out. The pilot jet is like 0.375 or 0.4 mm which is about 0.0147" which is why I'd choose a 0.013" wire. You can snake the wire into the pilot jet and through the whole port, verify it is getting fuel.

Also, in case you didn't check it, look at the pilot needle (idle mixture) setting and make sure you didn't inadvertently leave them turned all the way in, which would close off the pilot jet. The mechanic who rebuilt my GS did this on one of the carbs! Bike still started and ran fine but had a lot of "hanging idle" when it was hot and I only discovered it when trying to correct the hanging idle. One carb was half a turn out, the other all the way in. Nuts. The dude just skipped a step. I guess since it ran fine it didn't seem to make sense to verify the idle mixture.

[urbane]

Float level is the next check, and the engine side of the carb boots, as they are known to have hairline cracks.

I just learned you may adjust the float height by bending that metal bridge that sticks back near the needle valve.

Fuel definitely comes out of the carbs, usually a cap full at minimum each. The port?/left side has more fuel though.

If everything checks out, I'd go back to the floats.  Be sure you're getting fuel to the carbs.  You can quickly check that by opening the drain on the bottom a little and see if any fuel comes out.  Check both carbs to be sure.  It does take several cranks after a carb cleaning to get the motor to fire up sometimes.

Rebuilt them twice, pretty sure it's not the jets or the main jet needle. I know the passages are clear also on the idle jet adjuster. Used that size, or a very similar sized guitar string! Specialty equipment I suppose .

Idle jets are at 3 turns each. Spark plugs seem to be not getting fuel right now.

Your super moderator says new spark plugs are the reason the bike doesn't run... Uh.. Okay.

Yeah I've had the float needles stick closed from time to time, causing the bike to run on one cylinder or refuse to start. Good thing to check.

Also you can run a guitar string through the pilot orifices ... like a 0.013" string if you have one or if you know a friend with guitars, just a length of it works great to knock it out. The pilot jet is like 0.375 or 0.4 mm which is about 0.0147" which is why I'd choose a 0.013" wire. You can snake the wire into the pilot jet and through the whole port, verify it is getting fuel.

Also, in case you didn't check it, look at the pilot needle (idle mixture) setting and make sure you didn't inadvertently leave them turned all the way in, which would close off the pilot jet. The mechanic who rebuilt my GS did this on one of the carbs! Bike still started and ran fine but had a lot of "hanging idle" when it was hot and I only discovered it when trying to correct the hanging idle. One carb was half a turn out, the other all the way in. Nuts. The dude just skipped a step. I guess since it ran fine it didn't seem to make sense to verify the idle mixture.

[Arpee]

If you're only getting a "cap full" out of each carb, that's not going to be enough fuel!

I like this video of how to check float height.  Also recommended by the GS gurus here.

https://www.youtube.com/watch?v=PHuB1lyagKM

[urbane]

If you're only getting a "cap full" out of each carb, that's not going to be enough fuel!

I like this video of how to check float height.  Also recommended by the GS gurus here.

https://www.youtube.com/watch?v=PHuB1lyagKM

This is well simpler then the method I devised to check the levels. TYVM.

[urbane]

Had a few issues here - BUT GOT IT RUNNING!

Had to rebuild the fuel petcock as it was sticking, now it moves freely, like new, and presumably flows better.

Now I have a hanging idle problem. Another poster said his may have been related to exhaust gasket/bolt failure. That is the next thing to check. Oh bother.