'83 GS450L - Sputter\muddy\nearly die during idle

[Guest]

I've done a lot of work on this bike now and I'm trying to finish up the last couple things. Now if I'm sitting at an intersection for awhile after it's warmed up pretty much, it'll start to die. The RPMs will start to drop. If I grab the throttle and roll back, it'll take a second for it to rev.

It doesn't do this all the time though. Does it sound like it's running too rich?

I have mikuni main jet #130 and pilot jet #47.5 with a MAC 2-to-1 exhaust system, new plugs (cheap champion brand), and new intake boot o-rings.

[chef1366]

Sounds rich
You should be able to smell gas when it's starting to die.
What has been done to the carbs?

[incarceration]

Yeah I smell gas sometimes.

I've replaced the main and pilot jets with the genuine Mikuni numbers I noted in the first post and I also did a chem dip

[chef1366]

While the bike is running take in the idle mixture screws (intake side on side of carbs) until the bikes starts to die and then bring them out until the motor runs smooth.
Do both sides but do it when the engine is warm. Not hot or cold.

[incarceration]

both at the same time? are you referring to the pilot screws that had the metal cap? or on the sides by the intake boots?

[chef1366]

both at the same time? are you referring to the pilot screws that had the metal cap? or on the sides by the intake boots?

Yes, those
At the same time? Do one side and then do the other side.

[incarceration]

the pilot screws, right? I need to screw them in so they give less fuel, right?

[chef1366]

the pilot screws, right? I need to screw them in so they give less fuel, right?

Yup
......................

[incarceration]

Also, sometimes the engine runs\idles fast. Could this also be a sign of too rich? I thought too fast of an idle meant it was running lean?

Thanks

[incarceration]

I just screwed in the pilot screws all the way on both sides and it doesn't cut off lol. I think I need to put in one main jet size down from #130, correct?

I have #127.5 I can put in.

It used to have #115 in it

[pete]

You need to go back to your stock pilot jet... I just went through all this again on mine. Definitely need the stock pilot! My mixture screws are currently at 3 1/4 turns out, stock (17.5) pilot, needle has one shim, and 142.5 mains.

Edit: Forgot to say you probably won't get it to die with the mixture screws all the way in, but it should run worse. I went back to 2 1/2 turns in and while it ran ok when warmed up fully, when cold it was a pig up to about 1/4 throttle. Hesitant and stumbling off idle.

[incarceration]

See mine is the opposite.

Cold starting it starts right up. Once it gets nice and hot though it starts to act like it's running rich - when i roll back on the throttle it'll take a second for it to catch up and it sounds like it's struggling, and sometimes it'll just come close to dying if I don't rev it beforehand

[pete]

Ok, think you might be missing my point

I may not be explaining it well...

The motor runs richer as it warms up, so if it starts real easy like that and gets worse at idle when hot, then it's definitely too rich. If winding in the mixture screws is not solving it, that means you need smaller pilots, so that's why I'm saying you need to go back to the stock pilots.

[incarceration]

Just swapped back the pilot jets and it seems better!

Thanks!

[pete]

Good stuff, glad to hear it!

Interestingly enough it turned rather hot today and mine didn't want to idle nicely at all during the commute. If I could open her up a bit before having to stop it was ok, but while ever I was at almost closed throttle constantly it was idling lower and lower, pop and a stall.

Turned the mixture screws back in a quarter turn leaner tonight and see how that goes. Definitely too rich today!