Idling problems, 04 model

[EE]

hello, i'm new here. we have an 04 model w/1000 miles and have recently experienced problems with achieving proper idle speed. it occured all of the sudden. thus far i have :
cleaned the fuel tank, new premium gas ,installed an inline filter
inspected all vacuum lines and boots.
the carb has been off and completely cleaned, with solvent and compressed air.
the air screw has been unplugged , cleaned and adjusted
new spark plug installed
air cleaner inspected

the machine will run fine at speed. no problems here or starting up. but after warming up after a good two mile ride it fails to idle. if you set the idle up with the plastic thumb screw the engine will raise in rpm's but when you blip the throttle the engine will race at a very high rpm until you unscrew the idle adjuster back down. upon doing this the engine speed will decrease until it will idle down slowly and stall. at this point it's impossible to find the proper idle speed.
one more note, after unplugging the factroy sealed air screw and making adjustments to it...it has NO effect on idle speed at all even when completely removed......? this screw should cause the rpms to change or run rough , correct??? i thoroughly cleaned this passage way ,which leads to the carb throat area as well....

this seems to be a common issue with these bikes.. i would appeciate any advice before we take it in. i must confess i am a two stroker at heart, this is really my first try with a 4 stroker. i'm suspecting that maybe one of the diapraghms on the carb could be the culprit??

thank you !

[Easy Rider]

Originally Posted by EE

this seems to be a common issue with these bikes.. i would appeciate any advice before we take it in.

What leads you to believe this is a common problem "with these bikes" ??
It is likely a common problem for ANY carb'ed vehicle that only has 1000 miles in 4 years !!! :roll:

Two likely causes: Idle jet plugged or a vacume leak ........around the boot connecting carb to engine or the vacume hose going to the petcock.

Did you do all that "tune up" work trying to solve this problem or did it show up after?
What kind of "solvent" ??

Most likely it's the idle jet. If you fill the carb with real carb cleaner (Gumout or Berryman's B12) full strength and let it sit for a few days, you might get some results. Probably need to clean that idle jet out with a fine wire, however, and then some carb cleaner in the gas after that to finish the job.

[EE]

thanks for the reply Easy,

i've just noticed a couple of other posters w/similiar experiences which led me to believe maybe there was a common issue.......

i tried all those fixes after the problem developed. for exactly the reason why you say, 1000 miles on an 04 bike, i figured there could be residue in the fuel system, hence the cleaning. i did use Gumout on the carb, with compressed air and my assortment of carb cleaning tools & gadgets from my two stroke survival kit. i checked thoroughly for any tears or deformities on the air boots as well...but one more look couldn't hurt.

when you say "idle jet" are you referring to the air mixture screw which was sealed from the factory?

two more observations ...

when the fuel line is removed from the petcock at the tank. in the "on or reserve" positions, fuel will continue to dribble out of the petcock. could this be the culprit? would this cause the engine to flood at idle ? i understand when the petcock is in the "prime" position...the fuel will flow freely w/out any vacuum. correct? the vacuum line from carb to petcock is in good shape. no leaks.

i also wondered if the float could be at fault. but at all other speeds there is no shortage of fuel supply. so the engine is not starving for gas .

thanks again for your expertise....this is driving us crazy !

[Easy Rider]

> when you say "idle jet" are you referring to the air mixture screw which was sealed from the factory?

No......but close. Near the top of that needle screw assembly is one (or more) tiny little holes. Those are the
actual jets where the fuel for idle comes in. Those are likely plugged. It may require a tiny little wire to
open them up again.

> when the fuel line is removed from the petcock at the tank. in the "on or reserve" positions, fuel will continue to dribble
> out of the petcock. could this be the culprit?

Not likely because the float in the carb will shut it off.
BUT
If that dribble continues for more than 15 seconds or so, then the diaphram in the petcock assy. might have a hole in
it. This would be a vacume leak and/or suck excess fuel directly into the engine.

> i also wondered if the float could be at fault. but at all other speeds there is no shortage of fuel supply. so the engine is
> not starving for gas .

Not impossible but highly unlikely, given the symptoms.

[Jaime]

Idle jet = pilot jet (not only for idle rpm range, anyway). Unscrew and clean it, but be careful with wires or you could enlarge the hole. Check that first.



At idle, the pressure is just enough to suck fuel throughout the pilot jet. If it's blocked, when you open the thottle for a while, with the idle screw set higher than normal (it's just a throttle top) to prevent engine stall, the cutaway valve's diaphragm moves up and fuel is sucked throughout main/needle jets by the air that gives the partially open throttle valve. Then, when going down to idle, there's no fuel sucked in the engine.

Common problem? Well, the pilot jet is the smallest hole in the carb and it's topped by fuel. It's relatively easy to get it blocked.

[Easy Rider]

Originally Posted by Jaime

Idle jet = pilot jet (not only for idle rpm range, anyway). Unscrew and clean it, but be careful with wires or you could enlarge the hole. Check that first.

HERE I COME TO SAVE THE DAY...........
Was hoping our resident carb expert would ride in on his white horse........oops, black GZ. :cool:
Thanks, Jamie.
You can take it from here.

[EE]

Jaime, thank you for the info. but let's say that the pilot jet is clean and free of any obstructions.....what would your next step be??

[Jaime]

Sorry, I didn't read the case about your "leaking" petcock... It shouldn't cause any problems unless the needle valve of the float system is worn, letting fuel in. Anyway, you should get more problems in that situation.
You can check that no fuel enters the carb when valve is closed, and also the float system height: 13 +- 0.5 mm from carb body to the bottom of the buoyancy when needle valve is closed. Running at "PRI" can help you ruling out any defects in the petcock.

Considering that the pilot jet isn't the culprit at all, and that -if I've understood finely- the idle problem appears only in warm situation, it could be not because of a lean mixture, but because of a very rich one. So, a blocked starter plunger could be the culprit, as there are no many other parts involved in the idle.

Finally, you can try the bike at the critical point without air filter, to rule out it. Remember that it gets dirty in the inner surface, so you won't see the dirt looking at it.

I wish I could inspect your bike personally, but I'm so far away. :blush:

[EE]

Jaime, muchas gracias por la ayuda otra vez, entonces yo voy a pensar y hacer un otra cosa con mi problema........ok amigo, te vaya bien, i will talk to you soon !!
EE

[Easy Rider]

Originally Posted by Jaime

Finally, you can try the bike at the critical point without air filter, to rule out it. Remember that it gets dirty in the inner surface, so you won't see the dirt looking at it.

OK, how STUPID do I feel? Answer: A LOT!

I thought the manual was wrong when it said to blow compressed air on the OUTSIDE of the filter to clean it out.
Even after looking at and screwing around with the filter over several weeks, it still did not register with me that the air flows from the center OUT.......which is the opposite of most applications.

DUH! :blush: