620 surging

[Privateer]

04 620, ~88k.  recent valve service.  ecu immob delete. 800SS dash.  stock airbox. slipons.

noticed yesterday when at constant throttle, ~40mph, lane sharing in the afternoon commute, engine surges intermittently.  I searched here and see a lot of posts about running lean.  I've also noticed i get an exhaust pop on engine braking, which I thought was a lean condition as well.

can't say that's happened before and nothing really mechanically is different so I'm a little perplexed.

any thoughts on the lean condition?

is there something I can adjust/change at home?

[DarkMonster620]

04 620, ~88k.  recent valve service.  ecu immob delete. 800SS dash.  stock airbox. slipons.

noticed yesterday when at constant throttle, ~40mph, lane sharing in the afternoon commute, engine surges intermittently.  I searched here and see a lot of posts about running lean.  I've also noticed i get an exhaust pop on engine braking, which I thought was a lean condition as well.

can't say that's happened before and nothing really mechanically is different so I'm a little perplexed.

any thoughts on the lean condition?

is there something I can adjust/change at home?

if it's lean, you will need an electronic tool to set TRIM . . .

recheck ALL electrical connections and spark plugs . . .

[Langanobob]

What about a vacuum leak?  Might cause those symptoms too.

[ducpainter]

Never experienced an intermittent surge. They always seemed to be there...usually at constant throttle.

Could be vacuum, or a TPS, or perhaps not enough slack in the throttle cable.

It could be lots of things.

Why not have Nick take a look?

[Privateer]

Why not have Nick take a look?

it's not easy for me to get to Nick, which is why I was hoping there was something I could adjust at home.

[Howie]

One thing you can DYI is look for an intermittent vacuum leak.  Spray suspect areas with, while moving suspect parts like the plastic intake tubes, well, carb cleaner works, but could damage paint.  A light oil spray might be better.  Any change in RPM means leak.

[Gimpy]

I have a 2001 m900ie, with the same condition.  Sorry for the noobness, but what exactly should I consider suspect?

[Privateer]

small update.

I swapped in some Cycleworks ignition coils and the bike seems to run better.  The surging at small throttle seems to have gone away.  I still get the decel popping, and what seems like a missfire once in a while, but the worst of it seems to have gone away with the new coils.

by the way, whoever decided on that airbox location for the h-cylinder coil deserves a special place in hell.

[DarkMonster620]

small update.
~~~

by the way, whoever decided on that airbox location for the h-cylinder coil deserves a special place in hell.

Are you close to Speeddog? You might need to have your trim reset . . . Need electronic tool to do . . .

[Privateer]

i shouldn't have posted.  returned today.  in the 3500rpm area, at 30-40mph, get this stumbling/surging with a constant throttle.

[Speeddog]

I should have my magic electronics box back from repair soon, or have a similar unit in house.

Stay tuned.