Backfiring... - Star Motorcycle Forums: Star Raider, V-Max, V-Star, Road-Star Forum
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post #1 of 14 (permalink) Old 02-16-2013, 10:13 PM Thread Starter
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Backfiring...

Shifting from 1st to 2nd and from 2nd to 3rd, my Liner backfires if I let up on the throttle between shifts. If I keep the revs up a little while shifting, I can avoid it. To my experience, backfiring is indicative of an overly rich mixture, but the bike has a Roadhouse slip on installed, which I would think would lean out the a/f mixture, if anything. Popping could be the result of a lean mixture, but this is definitely backfiring.
I read somewhere that the efi on these engines is in a closed loop, except for idle or lower revs, where it goes into an open loop. Would this possibly be the cause of the backfiring, and if so, what can I do to correct it? Would going back to the stock exhaust help this situation?

'06 Black Cherry Roadliner
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post #2 of 14 (permalink) Old 02-17-2013, 10:13 AM
Fig
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Backfiring...

I have been having a similar issue and it was getting worse .. It happens as well for me when I do a hard deceleration ( often coming off the off ramp ) and then roll the throttle a bit to get going. I have a set of cobra longs installed.

Here is what I did to 'try' to solve it and turned out to be an interesting thing.

I just had a Power commander installed, the tuning was going great and the fuel ratio was getting dialed right in but suddenly about mid tune between 10% and 20% throttle the bike would go super rich. Not all the time but it would do it run after run then stop. The charts are a mess you can really see the spike at those times..

The shop thought it was either the Throttle sensor or another one ( fuel or air ? forget at the moment) What I can say is with the power commander in it happens allot less but it is still happening and I'd love to know why.

I'm hoping to get it to the dealer as it's still new but naturally I'm expecting them to blame the new computer. Never dealt with the local shop, hoping they surprise me.

If I discover something I'll post but hopefully someone here has some history and solutions or advice to this .


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2009 Roadliner Midnight
Cobra Speedster Longs
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post #3 of 14 (permalink) Old 02-17-2013, 05:03 PM
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If it is the exhaust, it is after fire. Back fire is from the intake...........Check all of your exhaust connections and make sure they are tight and not leaking, they could let in air from a vacuum pull and cause the hot gasses to ignite.
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post #4 of 14 (permalink) Old 02-17-2013, 10:19 PM Thread Starter
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Pulled the Roadhouse slip-ons and reinstalled the stock exhaust. Still get the 'afterfire', but, of course, it is much more muted. The only other engine mod the PO had done to the bike (to my knowledge) is a K&N air filter, which I doubt would cause this problem. Checked the ex pipe to head connections and they are tight. Don't think they were ever taken off either. Maybe I'll try doing the CO adjustment listed on LinerWiki and see if that helps. Off tomorrow to see if I can find a local shop that is willing to put a CT on the rear for me. Maybe just disconnecting the battery and letting the ECU readapt back to the stock exhaust might do the trick...

'06 Black Cherry Roadliner
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post #5 of 14 (permalink) Old 02-17-2013, 10:21 PM Thread Starter
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Quote:
Originally Posted by Fig View Post
I have been having a similar issue and it was getting worse .. It happens as well for me when I do a hard deceleration ( often coming off the off ramp ) and then roll the throttle a bit to get going. I have a set of cobra longs installed.

Here is what I did to 'try' to solve it and turned out to be an interesting thing.

I just had a Power commander installed, the tuning was going great and the fuel ratio was getting dialed right in but suddenly about mid tune between 10% and 20% throttle the bike would go super rich. Not all the time but it would do it run after run then stop. The charts are a mess you can really see the spike at those times..

The shop thought it was either the Throttle sensor or another one ( fuel or air ? forget at the moment) What I can say is with the power commander in it happens allot less but it is still happening and I'd love to know why.

I'm hoping to get it to the dealer as it's still new but naturally I'm expecting them to blame the new computer. Never dealt with the local shop, hoping they surprise me.

If I discover something I'll post but hopefully someone here has some history and solutions or advice to this .


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Thanks for the input, Fig. Definitely share if you figure this thing out.

'06 Black Cherry Roadliner
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post #6 of 14 (permalink) Old 02-18-2013, 08:45 AM Thread Starter
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In trying to narrow this afterfiring thing down I realized that I didn't have the problem until after I removed and reinstalled the fairing to put the risers on. Part of that process was opening up the headlight to free up the wiring in there for the extra length needed. In doing that I naturally had to take off the top plate with slider cover and disconnecting the air temp sensor. I know I hooked the sensor back up, but if that had come loose again while putting the bars in their new position I would guess it would throw things off a bit. Could that also cause the afterfire problem I'm having?

'06 Black Cherry Roadliner
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post #7 of 14 (permalink) Old 02-18-2013, 01:26 PM
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I have the Cobra Speedster Longs on my sled along with their F1-2000 fuel unit. I have a contact over at Cobra and he told me the best setting for this setup is 1,3,2
I also use a K&N Air Filter and my bike runs fantastic.
Once you have it all figured out your bike will do the same.
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post #8 of 14 (permalink) Old 02-19-2013, 02:49 PM Thread Starter
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I went back to the stock slip on and reset the ecu and my afterfire noises are all but gone. Still a little popping if I get on it hard from 1st to 2nd and 2nd to 3rd, but that seems to be the nature of the beast.

'06 Black Cherry Roadliner
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post #9 of 14 (permalink) Old 02-19-2013, 02:50 PM
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I ran all last year with a Roadhouse and had persistent popping even after replacing gaskets, adding a Cobra Autotuner, getting a new exhaust clamp and doing the CO mod. I finally removed about 99% of the popping recently. How did I do it? I switched to a D&D exhaust.

Might not be the answer for you since you already switched back to the stock muffler.

As to your idea of it maybe being the sensor, if that connection is not good it will throw up an error code on your odometer display.

Have you pulled your plugs to see if you are really running rich or maybe even too lean? From a number of people I trust, I have been told that you can get popping like you describe from either running too lean OR too rich. Once you know if you are running either way, you can take the steps needed to balance everything out. The key is to look at those plugs.

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post #10 of 14 (permalink) Old 02-19-2013, 03:33 PM Thread Starter
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I was glad to switch back to the stock muffler, Matt, as I love a nice, low rumble but I'm not a fan of obnoxiously loud pipes. After taking the bike for a rear tire this morning, I am satisfied with the sound of the stockers and will leave them on for now.
No error messages on the display, so the air temp sensor connection is good.
I'll pull the plugs when I next have the tank off but I'm happy with the way she runs now. I believe disconnecting the battery to reset the ecu this morning helped out quite a bit.
Thanks for the feedback.

'06 Black Cherry Roadliner
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