Bike starts fine but dies down/runs poor about 5-10min later

[f355berlinetta]

Hi, this is on a 2000 600 with only 2800 miles on it. It will start up fine, seem like it is running fine, but then when it warms up a little bit (about 5-10min) it starts to die at idle and runs very poor when you accelerate. It will die at idle and then will not restart that well. Sometimes it won't restart until the bike sits for 15min or so. I changed the air filter and fuel filter, but same problem. I am just wondering if anyone else has had the same problem and if it is a coil that is bad...

Thanks,

Rod

[audionick12]

If you think its a coil then start it and let it run for 10-15 minutes then test the spark. Sounds more like a carb/fuel problem.

[The CyberPoet]

My best guess:

Fuel delivery problem causing insufficient fuel to the carbs. This would be commonly caused by a failing petcock vacuum diaphram.

Some simple tests I'd like you to run:

(A) Put a spare key in the gas cap. If you are riding and it starts acting up, pull over, and using the spark key without shutting down the engine, open the gas cap. Does the problem disappear within 30-60 seconds? If yes, then gas tank vent/drain hose blocked or gas tank cap bad.

(B) If you are riding and it starts acting up, switch the petcock to PRIME. Does the problem disappear within 30-60 seconds? If yes, then petcock vacuum diaphram bad.

(C) If no to both (A) and (B), then unhook your fuel line at the petcock, attach a bit of spare fuel line and drain out a half cup of fuel into a glass container. Is it clear, or does it contain water, particles, debris, etc? If it contains anything other than clear fuel, drain the carbs, clean, then drain the tank and treat for rust if necessary, plus clear or replace the fuel tank vent/drain hoes.

(D) If no to all of the above, replace spark plugs with correct NGK type for your bike and see if problem goes away.

(E) If problem is still there, remove coils, test cold, then use a hair dryer on them for 5 minutes and retest. Pass/fail?

My guess is that it will be (B).

Cheers,
=-= The CyberPoet

[f355berlinetta]

I tried (A) and (B), but still same problem... Also, I forgot to mention that when it does warm up and starts to die at idle and runs rough, it also has a hard time going if in gear/under load... in neutral you can rev it up and keep it running, but when in gear, it barely wants to go and dies if trying to go up a little hill. It runs fine and has power when cold.

I tested the coils cold and they were about 3 ohms or so, and when they got hot, they were about 3.8 ohms or so.

I don't quite understand why the fuel would be temperature related...

Since the bike only has 2800 miles on it, do the spark plugs need changing? Or, how often should they be replaced anyways...

Thanks for the info...

[The CyberPoet]

I don't quite understand why the fuel would be temperature related...

Since the bike only has 2800 miles on it, do the spark plugs need changing? Or, how often should they be replaced anyways...

Fuel is temp sensitive because as the engine heats up, the fuel sprayed into the inbound air vaporizes better, increasing the effective richness of the mixture. Thus, a bike that's tuned cold can be mis-tuned when at full operating temp (which is also why dyno tuning and for that matter all carb tuning should normally be done with the engine all the way up to temp).

Plugs normally need to be changed at 7500 miles per the schedule, but if plugs foul (which can easily happen if the bike is running too rich), you may need to change them much earlier -- in fact, it's not uncommon for someone with carb issues to have to swap plugs within a hundred miles or even tens of miles if they are badly fouling up.

Cheers,
=-= The CyberPoet

[dragkota]

If it only has 2800 miles is it still under warranty?

[The CyberPoet]

If it only has 2800 miles is it still under warranty?

Not as a 2000 model... unless he bought it new-on-floor after 5/02 and got the four year extended warrantee.

Cheers,
=-= The CyberPoet

[TRH1]

I had a similar problem, bike stalling at traffic lights and running rough in lower rev range, it turned out to be running too rich, so I adjusted the float levels to 16mm in all carburettors which leaned it out and it now runs fine.

[f355berlinetta]

Bike is not under warranty... bought off eBay last year. I guess I should have at least looked at the spark plugs... I will try adjusting the float levels too.

Thanks again for all the info and suggestions...

[riogigalo]

just checking to see if you found out what was going on with your bike... mine is doing the same exact thing right now.. im about to go get a new set of plugs, we pulled one out and it was black im hoping that fixes teh problem.... if you found the problem please respond........ thanks

[f355berlinetta]

My plugs were black also, I guess meaning too rich, so I changed them out, it ran better for longer but still ended up wanting to clunk out at idle after it ran for about 15-20min. I still haven't figured out/had the time to adjust the air/fuel mixture and/or float levels on the carbs.

[The CyberPoet]

Also look for a sticking/stuck choke cable (and/or choke plungers, which attach to the rail the choke cable activates), which would artificially richen the mix up.

Good Luck!
=-= The CyberPoet

[f355berlinetta]

Just in case anybody will read this, I took the carbs off, tried to adjust the float levels to 16mm, changed the pilot screws on each to about 2 1/4 to 2 1/2 turns out, put it all back together and it still runs like crap. Also, when I take off the little plug on the drain tube at the bottom of the bike that comes from the air filter housing, gas comes out. And on one of the carbs... the drain screw I tightened all the way and now gas leaks from it.

[md86]

Well , might be that your float o-rings aren't doing their job , letting too much gas get through and getting into your airbox (AND cylinders . Might wanna check your oil ...) , and the drain screw was probably over-tightened and is now FUBAR . Maybe some silicone tape around the threads in the short-term .

[riogigalo]

anything new on this.. im still having the same trouble...