Ok I changed my stock pipes on my 695 (stock air box stock ECU) and I have noticed that
It pops alot when I get off the throttle between 4-5K. not a loud "BOOM" like backfiring but a series of pops and gurgles some loud some not.
Is this normal?
Will it do any damage?
I checked for leaks and they look ok.
I can't really say on the Duc (mine does it with slip-ons as well) but I know on my old cruiser, it really always popped, you just never noticed it with the quieter pipes, the popping was quieter as well!
I've kept an eye on the temperature and fuel consumption, both look normal.
Quote from: optiato on September 03, 2008, 08:30:18 AM
I can't really say on the Duc (mine does it with slip-ons as well) but I know on my old cruiser, it really always popped, you just never noticed it with the quieter pipes, the popping was quieter as well!
I've kept an eye on the temperature and fuel consumption, both look normal.
Ok so if I notice any high temps then something is not good, to early to tell about the fuel I have only ridden about 20 miles so far.
I'm definitely no expert.. but I'd think if it's running lean (your fuel mixture would/should only go lean if changing the pipes had problem, rich shouldn't be the issue) then you'd have higher temps.
you coud also check your sparkplugs to see if it's lean (white) they should be a light tan color is everything is running shiny
My ST2 has been doing that lately. It used to only do it at high altitudes when hot, but now it does it at lower altitudes too.
Since it only happens at higher altitudes and when hot, that would lead me to believe it's the opposite of a lean condition, unless the fuel injection computer is over-compensating or something. Being too lean would be worse at lower altitudes and when the engine is cold, wouldn't it?
How bad is a lean condition to the motor? what can happen by running to lean?
Quote from: DEVO! on September 04, 2008, 03:50:10 PM
How bad is a lean condition to the motor? what can happen by running to lean?
You are running lean by conventional wisdom most of the time. Closed loop, 14.7:1 controlled by computer. Unless you modify it is running the way it is supposed to. As optiato said, louder pipes, louder popping.
695's run lean to begin with (stock), and by installing the pipes alone you've made it run leaner. I don't think it'll hurt anything, but if you want it to run right you've got to spring for the Termi kit with DP ECU and open airbox. I know, it's way too much money, but trust me, you won't be sorry. Totally transforms the 695.
I did the exact same thing as you. I bought Staintune slip-ons. Great pipes, sounded awesome, but the bike ran slightly worse than stock. I finally sold them and got the Termi kit. It's worth every penny.
You can check for richness/ leanness on the plugs, if things look good don't worry about it. It's fine. I actually like that my bike does this, sounds hot rod like.
If it's making you worry a lot or if you've noticed a substantial decrease in performance or mpg then something shady might be going on, otherwise it's a Ducati, it's going to make all kinds of popping, gurgling, surging etc.. noises :) enjoy it.
Quote from: ScottRNelson on September 04, 2008, 02:36:53 PM
My ST2 has been doing that lately. It used to only do it at high altitudes when hot, but now it does it at lower altitudes too.
Since it only happens at higher altitudes and when hot, that would lead me to believe it's the opposite of a lean condition, unless the fuel injection computer is over-compensating or something. Being too lean would be worse at lower altitudes and when the engine is cold, wouldn't it?
You're right for the most part. Hot thin air = rich. Cool dense air = lean.
The popping comes from fuel that isn't burnt during the compression stroke. Then this fuel is exhausted where it ignites in the exhaust pipes. Also, when the bike is really hot, the gases are going to more readily ignite in the exhaust pipe.
A lean condition creates this because the engine is so lean, that it doesn't create a rich enough mixture to burn the gas. So it is exhausted and the next exhaust stroke then ignites the gas already in the exhaust header.
A rich condition can cause this for the same reason (excess fuel), although a rich condition usually dumps more fuel in the pipes, so you usually get a more pronouced bang (a backfire). If you want to try this out, get to moving at a decent speed in mid-gear or so and hit the kill switch, but leave the clutch engaged so the engine still pulls fuel in. After a couple rotations, turn the kill switch back off so the engine refires. And BANG!!! [evil] Probably not the best thing for your pipes though. (Carbie bikes only)
So really rich is a loud bang, and lean is more popping.
This is extremely common on overrun because the air/fuel mixture is rapidly changed and the excess fuel is burnt off. If watch any racing event, you will see flames shot out of the exhaust pipes when they let off the throttle. There also some timing related issues that cause this.