surge after throttle

Yo.

Seems my SD has developed an issue when you give the throttle s some beans.. You get a surge of acceleration afterwards and it creates dodgy situations. Anybody else had this and how did you fix it?


Cheers

I would check with Tune ECU to see if the throttle bodies are sync'd. I could be way off though.

Sticky throttle cable?

Need more info - is it that the revs are not dropping when the throttle is closed?

It feels like after large throttle openings and with a rapid shut off the bike initially responds to the shut off/less fuel and the engine slows but then momentarily picks up again. This is dodgy because sometimes I'm changing gear and the engine kicks during the gear change.

I guess because the engine does respond to the initial shut off the cable isn't sticking - it definitely doesn't feel sticky.

Does it do it whether or not the clutch is pulled in?

The bike has aftermarket suono mivv exhausts on it but hasn't had an airbox mod yet. It also has a ScottOiler on it which is plumbed in correctly.

The bike has always had this since I bought it and didn't used to exhibit this behaviour.

Come to think of it, the bike also lags when you open the throttle hard.

I don't know if it does it with the clutch pulled in. I'll test that when I get home...

My SD had similar issue I think. When I would hit the throttle it would hesitate at times.It would also not hold constant RPMs. I had the TPS sensor replaced and carbs synced and if runs as good as day one. Love the bike even after 40k miles on the it.

Do you have a TuneECU cable?

I bought tighter gloves.

Could be several issues. As usual it could be moisture in the big grey connector which confuses the ecu and makes the idle go up and open the flies a bit.
You could also have an air leak in one of the hoses (to the vacuum sensors) and another one is a leak in the manifold rubbers. e.g. when you close the throttle there is a lot of vacuum so air could get sucked in somewhere.
A faulty TPS is not so likely as it would manifest in other ways.
How old is the bike and how many km's / miles?

How long did it sit over the winter?

How much gas you run thru with it acting this way?

Dirt bikes with carbs have a problem gaining water in the fuel bowl.

Drain the bottom of the cab and Bobs your Uncle.

Maybe you got some sediment in your tank / fuel pump / filter.

I narrow it down to 2 possibilities. Either moisture in BGC or faulty TPS.
Try to borrow the tuneecu cable from someone in your area, it helps with sync the flies and diagnostics.
Don't mess with the TPS unless you know what you're doing. It takes a watch makers touch to adjust!
Start with cleaning the BGC!

Just done a quick check of the throttle bodies, 4.5cmHg difference so they are quite a way out. Balancing this can only help - right?

How did this story end?

I balanced the throttle bodies and the surge disappeared - was great when done