Hey guys. Noob here. 2000 GS.
I pulled my carbs today to clean them up. I thought I had a stuck float because I left the bike on prime a week or two back and it flooded the engine and all over my parking garage (they were not happy). Pulled it off, cleaned everything up, adjusted the idle adjustment to 2.5 turns out from all the way in, reinstalled (the friggin airbox is such a pain to put back on!). The bike wouldn't start and the battery seemed like it wasn't turning over. This is the first time I'm working on this so I may have screwed something up.
I tried push starting it, after a bunch of tries it finally started but ran like garbage for a few seconds at first (full throttle would = pulsating acceleration), then started running. It would rev really high (5000-6000) and when I played with the idle adjustment screw it did nothing. I let it idle at that speed for no more than a minute and I had to kill it. When i did it let out a really loud backfire, almost like a gunshot. That freaked me out.
I started it up again, high idle, loud backfire when I killswitched it again. Wtf.
I started it up again, battery dead.
I don't really know what else I can do? Could it be a vacume leak somewhere? I'm pretty sure I got the carbs back on tight (I had to end up securing the carbs to the airbox first then jamming the whole thing back into the engine). I'm probably going to try to run start it again tomorrow, but before that is there anything else I can try doing?
Any help is appreciated! I'm at my wits end and exhausted.
P.S. Also when I pulled it apart the previous owner practically stripped out all the float bowl screws (they were torqued on REALLY tight -- is this normal? I just screwed em on and gave it a light torquing). Oh and he had the gas tank overflow vent hose going into the carb vent. So whenever I left my bike in the rain I had really bad bogging problems....I wondered why..now I know. I fixed that, the under tank vent is just hoseless now (Need to buy hose), carb vent goes straight down.
If the engine wont turn over and the electronics aren't on first check to make sure your battery terminals aren't loose. I had my battery terminals come loose and took apart half the bike before I realized what was wrong. I was not only late to work, but I was also pissed that I doubted my first guess due to panic. Next check fuses, finally check wires.
If the engine won't turn over but the electronics are on use a voltmeter to measure the volts across the terminals. It should be around 12V.
If the engine turns over but won't start, check your plugs, replace them and try again. If it still doesn't want to turn over you could have a starter problem. I can't help you there, I have no ability to diagnose a starter problem other than the fact the engine won't turn over consistently and anything that could mimic the problem has been checked.
Barring all this is okay:
Before doing anything make sure your carbs and airbox are seated properly and the clamps are tight.
Make sure your hose routing is correct. This is a major source of phantom problems especially since you played with them. Check against the Hayne's manual for the diagrams.
The stripped out float screws could cause a fuel starvation problem if they aren't set properly. I'd replace them out of poise, if not for the reason they could be part of the problem.
Idle adjustment and mixture screws are totally different. Which did you play with? After you clean your carbs it's important you readjust the mixture screws to their new settings from full in. You could have a bad mixture because your carbs are clean now. The idle screw wont fix a mixture problem. The backfiring, especially the loud pop when you turned it off sounds a LOT like what my bike did when I almost overheated it when it still ran super lean. It's broscience, but I'd say your solution is in your mixture screws.
http://www.urbandictionary.com/define.php?term=broscience
Thank you for the reply!
I believe the bike won't start due to a weak charge in the battery. It's a crappy autozone battery the previous owner put in and I plan on replacing it soon.
As for the running lean, I will check that out! I played with the fuel mixture screws when I took the carbs off. I'll try backing them out a turn or two more. I'm just worried because they are already at two and a half turns out.
How about the throttle cable? When I re-attached it I'm concerned I may have made it too tight, is this possibly an issue? Should it not be tight at rest?
Thank you so much!
Quote from: patleeman on October 01, 2011, 04:46:20 AM
Thank you for the reply!
I believe the bike won't start due to a weak charge in the battery. It's a crappy autozone battery the previous owner put in and I plan on replacing it soon.
As for the running lean, I will check that out! I played with the fuel mixture screws when I took the carbs off. I'll try backing them out a turn or two more. I'm just worried because they are already at two and a half turns out.
How about the throttle cable? When I re-attached it I'm concerned I may have made it too tight, is this possibly an issue? Should it not be tight at rest?
Thank you so much!
I don't know that you could attach the throttle cables so tight that the bike would not start.
It has that big thumb screw for idle speed that keeps it from closing so far you can not at least start it.
But you can easily attach it in such a manner that the throttle has a lot of binding and is very difficult to move.
A bit of common sense and figuring it out will get it connected well... or the manual will walk you through it some.
notes:
The carb vent should go up then down. (well, 'should', as my bike would leak gas some times if the connector pointed down. But my bike wasn't running well at the time anyway so....)
Why did you pull the carbs off in first place? (what were you trying to fix?)
From things i have read on this forum what you are describing could be due to a tight intake valve. Checked your valves?
Float bowl screws don't take a phillips head screw driver (they take some other sort of cross point screw driver... search the forum) so most people replace those screws with allen head screws (search for size) readily available at HomeDepot Lowe's Auto parts stores, etc.
Full Throttle at startup is a no-no. If you have to hold it wide open to start it, something is definitely wrong.
Stuck float (oh boy, fun): did you check the fuel height in the bowls before/after pulling carb? (search for carb height using u tube or clear tube method or something similar).
You said it back fired... did it back fire out of exhaust or out of the intake? (if out the exhaust = rich, if out intake = lean or normal [not normal if you see big flames]).
Good luck.
Throttle cable should have some slack in it. Haynes manual specifies 3-6mm free play at the grip.
If you've set it tight then it's possible the throttle is been held open a fraction and not sitting on the idle stop leading to the high revs.
Float bowl screws are M4x10mm. Diaphragm covers are M5x12mm
Quote from: patleeman on October 01, 2011, 04:46:20 AM
Thank you for the reply!
I believe the bike won't start due to a weak charge in the battery. It's a crappy autozone battery the previous owner put in and I plan on replacing it soon.
As for the running lean, I will check that out! I played with the fuel mixture screws when I took the carbs off. I'll try backing them out a turn or two more. I'm just worried because they are already at two and a half turns out.
How about the throttle cable? When I re-attached it I'm concerned I may have made it too tight, is this possibly an issue? Should it not be tight at rest?
Thank you so much!
Don't turn anything out or in until you've determine your bike still runs choppy after replacing the battery.
I'm not good at explaining how to adjust a throttle cable. Grab the hayne's manual if you have it or do a quick google. The throttle should have a little "pre-catch" play (something like 1-2mm iirc) before it starts giving the engine air. It should also snap back to closed when you let go of it.
EDIT apparently the free play is 3-6mm.
I got it working!
I dragged the bike to a parking lot nearby with my bag-o-tools (I live in an apartment) and broke everything apart again. The two loud bangs were my airbox connection popping off the carbs I believe because when I pulled the tank off the rubber connector piece on both carbs that connect it to the air box had popped off.
Pulled everything apart. Checked the carbs all good, everything seemed fine. Reset the fuel/air mixture screws to 3 turns out this time. Reassembled and connected the carbs to the air box first to make sure I had a good connection, clamped it down. Took the carbs and then clamped it into the engine. Took my time and rerouted the fuel lines and exhaust lines. Made sure the carb exhaust line went up and over to the battery box, made sure all the connections were fine and not pinched.
The prior owner must have taken the tank petcock off and reinstalled it backwards because the on/off screw was facing the left side which made it almost inaccessible. Flipped that back around.
Reinstalled all the fuel cables in the correct manner following the diagram on this site. I also made sure to set the throttle cable with some slack and used the nut under the handlebars to adjust it further.
Battery was dead so I ran started it (perk of working in a parking lot! :icon_razz:) it puffed for a few seconds then came alive! It roared after a few seconds and i puttered around the parking lot for a few minute then let it idle for a bit to recharge the battery. Shut it off, then waited 10 seconds, cranked it and it roared to life! :woohoo: :woohoo: :woohoo: Packed up and went for a short ride to warm it up. Warmed it up and reset the idle screw.
Works great now, I took it out for a few miles to check for any problems but seems okay. Runs even better than before IMO, there seems to be more power.
Only thing is that when I let off the throttle with the clutch in when the engine slows down there's a weird noise as the engine is settling down. Sort of a deep winding down noise. Any idea what that could be? It doesn't seem to be hurting the bike, I'm just concerned it could be an indicator for something else.
Anyways. Thanks for everyone's help! The advice and knowlege here is amazing and I couldn't have done it without you guys :cheers:
Also: the prior owner really muxed things up with this bike.
The bike says it has 5000 miles on it (I put 1000 on) and from the condition everything is in I find it pretty doubtful. That's my fault though for being an uninformed squid when buying the bike.
He attached the drain hose from the tank to the carb vent. Whenever my bike got wet (rain, washing) it would bog down or die completely. I didn't know what it was, turns out a ton of water was flowing straight into my carb vent hose.
Tank petcock installed backwards.
:mad:
At least I got it all fixed and learned a lot about this bike and bikes in general. That's pretty damn useful.
Quote from: patleeman on October 01, 2011, 12:37:19 PM
Only thing is that when I let off the throttle with the clutch in when the engine slows down there's a weird noise as the engine is settling down. Sort of a deep winding down noise. Any idea what that could be? It doesn't seem to be hurting the bike, I'm just concerned it could be an indicator for something else.
My bike does the same thing, no clue what it is.
Happens ONLY when im braking, with the front brake, not engine braking or using the rear only . I think its the speedo cable, but no way to test.
After reading another thread I think it may be cam shaft endplay. Seems to fit the bill and should be harmless. I thought it was the clutch plates or something but the clutch feels just fine.