Triumphrat

Sagarra · 08-14-2012, 06:05 AM

At 4k rpm on deceleration, no matter what gear, I get an afterfire. For the life of me I cannot figure this out. I have done an ECU Tune, but don't want to mess with too much in there since I am not exactly sure what to change. Does the TPS effect till this?

any suggestions would be greatly appreciated.

BTW, 05 Daytona 650.

skiTTles · 08-14-2012, 07:56 PM

I'm thinking first off a decell crackle is running rich. I'm thinking second off that 4krpm is lugging the engine. Downshift at 5k at the least $0.02

Will · 08-14-2012, 08:21 PM

If you get a really loud bang, it could also be some kind of glitch in the map that makes the spark cut out. If it happens when you slam the throttle shut, that's one thing, but if it happens when you are just decelerating, that's another. I doubt it is a TPS issue, but I cannot be 100% sure. When you look at the maps, you will notice that the timing is all fouled up between about 2.5 and 4K. That hole is there for emissions reasons. I used to match the values to what was adjacent and smooth out the timing, and it made the bike run better at lower rpms. I also found that making sure the throttle bodies were synched and the fuel idle trim (CO) or whatever it is called on a Kiehin injected bike were set up properly. The fuel idle trim regulates richness at low rpms and small throttle openings. I found richening it just a bit from factory settings made a big improvement. Your results may be different, but this is my take on things. These things may or may not solve the backfire.

Sagarra · 08-21-2012, 04:56 AM

Quote:

Originally Posted by skiTTles

I'm thinking first off a decell crackle is running rich. I'm thinking second off that 4krpm is lugging the engine. Downshift at 5k at the least $0.02

Thats what I am thinking, that it is running rich. But the engine never lugs going thru 4k, just a loud pop.

Quote:

Originally Posted by Will

If you get a really loud bang, it could also be some kind of glitch in the map that makes the spark cut out. If it happens when you slam the throttle shut, that's one thing, but if it happens when you are just decelerating, that's another. I doubt it is a TPS issue, but I cannot be 100% sure. When you look at the maps, you will notice that the timing is all fouled up between about 2.5 and 4K. That hole is there for emissions reasons. I used to match the values to what was adjacent and smooth out the timing, and it made the bike run better at lower rpms. I also found that making sure the throttle bodies were synched and the fuel idle trim (CO) or whatever it is called on a Kiehin injected bike were set up properly. The fuel idle trim regulates richness at low rpms and small throttle openings. I found richening it just a bit from factory settings made a big improvement. Your results may be different, but this is my take on things. These things may or may not solve the backfire.

Doesn't happen when the throttle slams shut, just going thru 4k, whatever gear. As far as the map goes, I really am at a loss when it comes to reading that and all those numbers. This is my first fuel injected bike, so I don't quite know how to synch and adjust it. I do have a manual and now that I have completed my move from NC to MS and have a garage I can dig deeper into it.
If you or some one else can help me better understand the map and how to read it, that would be greatly appreciated.

Thanks
Scott

Will · 08-21-2012, 12:59 PM

The manual won't tell you anything about how to retune the injection mapping. The factory would prefer you didn't do that. So, it's a single loud bang?

Sagarra · 08-22-2012, 03:23 AM

Yeah Will, one single loud pop, and a flash (I just started working third shift and have noticed it in my mirror). Say I am in 4th gear come down thru 4k, pop, downshift to 3rd and the rpm comes down thru 4k again pop. I have just started to pull the clutch in and coast and hand brake to a stop instead of engine braking. I don't slam the throttle shut either, I gently roll it back and it will still do it. Always on decel and always at 4k.

john bell · 08-22-2012, 03:48 AM

oh yes, throttle cable snapped about half way down i just pulled it out of the insulation...ordered another used one from england had it in about 10 days and stuck it on myself....not difficult....did not end up with any extra pieces!!

Will · 08-22-2012, 11:52 AM

Quote:

Originally Posted by john bell

oh yes, throttle cable snapped about half way down i just pulled it out of the insulation...ordered another used one from england had it in about 10 days and stuck it on myself....not difficult....did not end up with any extra pieces!!

Not sure what this post is all about.

You can get a bike to backfire by rapidly cycling the motor on and off. What that does is allow unburned fuel to go through the motor. When the motor goes back on, then the unburned mixture in the exhaust ignites with a satisfying bang. I used to do that in tunnels for fun. I'm sure it was very, very bad for the bike, but my TT600 was a nearly indestructible cockroach anyway. In your case, you are not being an irresponsible twit like I was, but my guess is something similar is happening right at 4K. There must be some kind of interruption in the spark right about there which is allowing a rich mixture to get through the motor and into the exhaust. Since it's popping in the exhaust instead of blowing back into the airbox, it probably is just mixture igniting in the exhaust, so I wouldn't expect it to be a problem for the motor.

Has the bike been remapped in any way?

Sagarra · 08-23-2012, 12:48 AM

I did the ECU Tune on it and mapped it for an aftermarket exhaust. It has an M2 exhaust on it. I don't know if the p/o had done that as well, but when I picked the bike up in January and rode it back to NC, I remember it doing the popping then as well. I did the ECu tune just a couple months ago.

Will · 08-26-2012, 05:45 PM

Well, then it's a complete mystery. I don't know what would cause something like that.