idle slows as the ride goes on

[theo]

Out on my new '17 300RR today for the first real ride. I just rolled 5 hours on the timer. As the ride went on my idle got worse and worse to the point where it wouldn't run at all without feathering the throttle. I adjusted the idle once(1/4 turn), but the problem just happened again. A few more points:
- I don't think its clutch drag as I didn't encounter this on any other ride (you'd think clutch drag would be a constant, no?)
-fresh oil in it, 850ml, rotella
-air filter was fresh, clean and dry
-it was muddy, the exhaust was coated...could it be running too warm?
- jetted by the dealer for my area


What should I start troubleshooting?

[wwguy]

These bikes seem to be notorious for shipping from the factory with the carb float set a bit too high.

I'd also inspect the spark plug for fouling and visual feedback regarding whether the engine is running rich or lean.

[Enmerdeur]

Dropping idle usual indicates you are running too rich. Try backing out the air screw a 1/4 turn at a time and see if that helps.

Oh and to wwguy's point, a high float level will cause a rich condition.

[Johnno]

I did the float level pretty quick ( I was near passing out driving home with the bike in the van after a ride ) then I tried a few different needles and got my 300 running pretty decent.

Then, it started doing a similar thing to what you are describing. It didn't bother me as I'd never had a 2 stroke that idled all that well, as in like a 4 stroke.

But then it started this deal where it'd stall.. It would do it at the absolute worst times imaginable and I would fall down the side of a mountain.

So, I pulled the plug and cleaned it, then once I had the bike at true operating temp tickled the idle up a bit, not much, then tidied it up with a very slight adjustment on the mixture.

So what I did from new was: fixed the float level ( if your's is right from new, Mario was hung over or something ) got the thing fueling right ( a needle is usually enough ) optimized my fine tune settings ie: idle and mixture screw. it idles great now and doesn't stall when I've sat idling contemplating my next move on the side of a cliff and then move off with a minute amount of throttle applied.

= Happy Johnno.

[theo]

Thanks for the tips guys. Last night I pulled the plug and it was oily/black. My first tank was pre mixed 40:1 (from the dealer) and my second 100:1 so it isn't strange to have a fouled plug. I'll try it now with straight gas and see what happens.

The float bowl is my next project. I get terrible gas mileage at the moment. I barely got 40km out of my last tank and 70km on the first tank. My '16 XT got 80km on a tank! This new bike also has fuel coming out the overflow when it is cold. It eventually stops, but it does "leak" a lot at first.

How many Km's do you guys get on a tank?

Stay tuned for more as I pick through the troubleshooting. Thanks again!

[bikesparky]

Thanks for the tips guys. Last night I pulled the plug and it was oily/black. My first tank was pre mixed 40:1 (from the dealer) and my second 100:1 so it isn't strange to have a fouled plug. I'll try it now with straight gas and see what happens.

The float bowl is my next project. I get terrible gas mileage at the moment. I barely got 40km out of my last tank and 70km on the first tank. My '16 XT got 80km on a tank! This new bike also has fuel coming out the overflow when it is cold. It eventually stops, but it does "leak" a lot at first.

How many Km's do you guys get on a tank?

Stay tuned for more as I pick through the troubleshooting. Thanks again!

If it's leaking out of the overflow all the time do the float level!
I get +90 km out of a tank on my '16, it varies a bit if it's a slow or hard ride.

[theo]

I pulled the carb tonight to have a look at the jetting and the floats. I'm still having idling problems. It actually got a lot worse on the last ride. I'm pretty sure the float is out to lunch. I have a couple of questions of what exactly I'm looking at. When I follow the manual's description, the float's position (sides parallel to carb body) have the entire shut off closed (or what I think is closed)- not just touching. When the tang just hits the smaller "nipple" (I think this is what they refer to in the manual), the float's position is no where near parallel.

What exactly am I looking for when the float is parallel to the carb body? Should the shut off be fully visible (as in pic DSC4002)?

Hopefully this isn't too confusing to read.

Thanks for any input.

[OscarFox]

From my understanding, the manual spec is wrong. Parallel will cause a rich condition. Others on the forum have commented that the height should be set at 7-8mm. That's just what I've seen, I'm sure others will chime in here...

[Johnno]

I didn't measure. I took it as a given that the float wasn't shutting the gas off well enough.

I proceeded to bend the tang a " bit " I then held the carb at eye level with a piece of fuel hose connected to the fuel inlet which I blew air through and then raised the float with my finger watching when it shut off. I might have bent the tang a fraction more.

It looked right so I refitted the bowl and put the carb back on the bike.

This is what I've always done to adjust the float level either way.