When I attempt to start my bike (Mornings or after work - after the bikes been sitting for a while), the engine just keeps cycling without ever turning over. I know the battery is good, otherwise I would hear it, in the way the engine cycles. If I'm lucky; after
10 + attempts the engine will attempt to turn over. when I get it to the point where it's ready to turn over, I have to hold the throttle wide open to get the rev's up and along the way - the bikes back firing..... Any clue as to what wrong?

working on other things right now, so pardon my grammatical errors



thanks in advance

Topic changed by Buddha.

Just have to ask- are you choking the carbs? And how exactly do you know the battery is good?

If you put something more than just "Question" in the subject line you will get more people reading your question that can help.  "Question" doesn't tell us anything. I clicked on it, but not everyone will.

Quote from: Big Rich on March 03, 2011, 08:25:29 PM
Just have to ask- are you choking the carbs? And how exactly do you know the battery is good?

yes the choke is completely on... the bike is an 09; but to be perfectly honest, I don't know that the
battery is not bad. I checked the water levels and they were fine.... but if the battery were bad; wouldn't
rev's start to slow when the engine is cycling to turn over? As it stands, the engine cycles normally - just
not turning over.

what concerns me is the putt putting and the back fires, when the bike finally does turn over.                        

Quote from: zirconx on March 03, 2011, 08:51:58 PM
If you put something more than just "Question" in the subject line you will get more people reading your question that can help.  "Question" doesn't tell us anything. I clicked on it, but not everyone will.

good point

Just to clarify, with full choke on and when attempting to start the motor turns over but doesn't fire and when it does start it backfires?

Have you checked that the choke is actually working?

Somethign is misadjusted. You buy it new ? ever had it in the shop for something ... you could also have a tight valve, though if it has very low miles it could be something else.
Cool.
Buddha.

Changed the title - wasn't sure if you can change the title or not.
Cool.
Buddha.

Does it just backfire right after it starts, or does it backfire consistently once it's idling? After trying to start the bike that many times you squirted quite a bit of gas through the system. Some of it would build up in the headers/exhaust and that would cause a backfire. If it's doing it a lot after it's running it might be the change with the cold air messing up your fuel/air mixture? I believe using the choke increases the fuel side of the mixture, so it might make the bike back fire more because not all of the fuel is igniting until it's passed the cylinder.

Quote from: uninhibited on March 04, 2011, 04:33:35 AM
Just to clarify, with full choke on and when attempting to start the motor turns over but doesn't fire and when it does start it backfires?

Have you checked that the choke is actually working?

no I have not... but when the bike fires up, the rev's are at 5k+

Classic symptoms of a faulty throttle position sensor. I would start by checking it out along with the associated wiring.

Quote from: sledge on March 04, 2011, 12:37:43 PM
Classic symptoms of a faulty throttle position sensor. I would start by checking it out along with the associated wiring.

Yea but ... but ... but ... what throttle position sensor ... The bike is only pretending to have a TPS my friend.

Yea it has TPS, but it does nothing. Which is why people toss the 89-00 carbs in and have no further issues. Or toss the 04+ carbs on the older bike.

Cool.
Buddha.

Quote from: The Buddha on March 04, 2011, 01:01:12 PM
Yea it has TPS, but it does nothing.

So what is it there for then?.....to fill a hole on the side of the carb perhaps 

Quote from: nozomicannabis on March 04, 2011, 10:47:40 AM
no I have not... but when the bike fires up, the rev's are at 5k+

Sounds too rich for one reason or another.

Is the bike parked outside?

Have you tried leaving it on prime for a minute before starting?

When was the last time you checked/changed the spark plugs?

Michael

 Found out what the problem was.... I had missed a major inspection for the bike (14 or 16 k inspection) and continued to ride my daily ride with canyons on the weekend.    After finally taking the bike to the shop (at 24,000 miles) and getting a valve adjustment (the Valve had 0 clearance) and a carb sync, we found that one of the valves were bent 

Just bought a Gixxer 750 and I plan to replace the valve myself.... 

I am not familiar with working on bikes, when it comes to the engine. How difficult will this task be? Also; the bike will need to sit
for a while - Is there anything I need to do to the bike, if I'm not ridding it?


Thanks in advance

P.S. the Gixxer has more power and looks cool; but I really miss ridding my GS   

Sorry to hear about your bent valve. I was having the exact same problem as you last month--difficult to start cold, then backfiring when it did start. When I checked the valves I found that both exhaust valves had under-spec clearances, and one had zero clearance. I put in smaller shims and haven't had a single backfire since. I had been riding it for awhile before adjusting the valves though--hope I don't have a bent valve too  Good luck replacing the valve, I'm sure you'll learn a ton about your GS in the process. 

Oh yea I also am betting the valve isn't bent ...

Sledge - The TPS on a bike as well as vacuum or any other contraption is all there essentially to provide retard. Get rid of the TPS and it works jus tfine, in fact it runs better. Get the vacuum sensor plugged and again same thing. The one and only way to reliably fire a motor is to use rpm for advance and a crank or cam position sensor to time it. All the rest are icing on the cake ...
Writing a computer like statement, if the rpm is x fire it at y degrees below tdc, and if throttle position is a subtact b degrees from y, if vacuum is c subtract d from y, if bla bla ... then subtract e, f, g, h etc etc. from y. Y is the correct advance you need to run right, start retarding if things are going this way and that ...
Of course once you do a injection system, all these will also add in what the air fuel ratio needs to be. The sensors @ this point in a 04+ GS do nothing.
Maybe they can be used as a jumping off point for an FI system.
Cool.
Buddha.

Quote from: paalak on June 07, 2011, 01:06:45 PM
Sorry to hear about your bent valve. I was having the exact same problem as you last month--difficult to start cold, then backfiring when it did start. When I checked the valves I found that both exhaust valves had under-spec clearances, and one had zero clearance. I put in smaller shims and haven't had a single backfire since. I had been riding it for awhile before adjusting the valves though--hope I don't have a bent valve too  Good luck replacing the valve, I'm sure you'll learn a ton about your GS in the process. 

thanks for the kind words Paalak... Good luck with your bike.