what is lean surging?

[TheOzTurkish]

hay guys so its the middle of summer here loving the 30+ weather and I've been out and about on the bike more and more.

Something I've noticed when riding at 60KPH in 4th at 4k revs with less then 1/4 throttle (barely off closed) the bike seems to be....... well surging only slightly. almost like its hopping away under me.

Is this whats called lean surging??? or is it because I have the throttle so closed its between circuits in the carb?  it has no pops or miss fires starts first time and idles like a dream, pulls cleanly and there's nothing "wrong" with it.

we did richen the mixture BEFORE putting in the k&n with restriction although as I've read it would still lean out the mix because the element is so thin.

[GS500F2004]

IIRC 60 km/h in 4th gear is actually under 4k RPM? You should really be in 3rd at 60km/h. The engine is most probably 'lugging' slightly.

[The Buddha]

40 mph in 4th is 4k I think he's right, with deference to gearing and tar sizes.

You may be lean surging ... and you're just getting to needle range @ 1/4 throttle.
You may try shimming it up a hair with another washer - you put the washer that is on top of the e clip under the e clip right ? If not - that is your first step ... In fact it will be a lot leaner than slight if the washer wasn't under the clip.
If its under, try adding another of 1/2 of its thickness, or my famous O ring trick (put an O ring instead of that washer) That should give you about 50% more spacing.

Cool.
Buddha.

[TheOzTurkish]

40 mph in 4th is 4k I think he's right, with deference to gearing and tar sizes.

You may be lean surging ... and you're just getting to needle range @ 1/4 throttle.
You may try shimming it up a hair with another washer - you put the washer that is on top of the e clip under the e clip right ? If not - that is your first step ... In fact it will be a lot leaner than slight if the washer wasn't under the clip.
If its under, try adding another of 1/2 of its thickness, or my famous O ring trick (put an O ring instead of that washer) That should give you about 50% more spacing.

Cool.
Buddha.

Yep under the clip, I'll look at adding a tad more in there.

Is it going to be doing any harm to the engine?

IIRC 60 km/h in 4th gear is actually under 4k RPM? You should really be in 3rd at 60km/h. The engine is most probably 'lugging' slightly.

yer its near as abouts 4K maybe 3.8 it pulls fine from there if i crack the throttle, if I'm in 3rd then its around the 5K mark and the buzz irritates me on the daly commute lol

[radodrill]

if I'm in 3rd then its around the 5K mark and the buzz irritates me on the daly commute lol

My former bike was a 2007 Ninja 250 and didn't have much power below 3.5K RPM; so I was generally running that 4-7K and near 10K on the freeway (~75 MPH).
With stock jetting my bike sounded like it wanted me to shift near 5-6K rpm and the power was very flat over that.  After the rejet it pulls hard at any RPM and will happily run all day at 5K rpm.

[nathaniel2910]

I recently had a similar problem which I put down to dirt in the carbs, but in the end all it turned out to be was the breather pipe for the carb was sticking out into the open air, once it was routed so the opening was behind the engine the problem was sorted.

[radodrill]

I recently had a similar problem which I put down to dirt in the carbs, but in the end all it turned out to be was the breather pipe for the carb was sticking out into the open air, once it was routed so the opening was behind the engine the problem was sorted.

Wasn't the case for me; stock airbox and the carb breather tube was routed over the airbox to the battery tray.