| Author | Message | ||
     Blackhat |
Every now and then I'm getting a backfire into the airbox on my 9R. It's a pretty good pop. It only happens after the bike is good and warmed up, usually when I goose the throttle between downshifts, or from the stop when I goose it prior to letting the clutch out. I took it into the shop when it was 2 months old. They reset the TPS for free, but the problem remains, I've kinda chaulked it up to a Harleyism. When I pull the airbox, there's an oily residue inside the top portion of the box, as well as inside and around the velocity stack. Anyone have this same problem? Is it a Harleyism, or is there something I can go to the dealer with to have them check out. Bikes still under warranty. Any help is appreciated. Blackhat | ||
| Misato |
I think that oil residue is normal, I got it too. mine seemed to stop backfiring after more miles/and a tps reset. | ||
| Kaese |
I have some minor backfires but only backing down the throttle. I have noticed some oily residue on the inside the airbox. My guess is some unburnt fuel due to backfiring. Do you have the Buell racekit on yours? My backfiring doesn't sound as severe as yours. My cause, i'm sure, is the Drummer and the Race ECM. I've heard this is normal for the race kit. Maybe you should have them try the TPS reset again. | ||
| Oconnor |
I have the same thing happen to mine. I can't believe its a problem. I believe that most engines do this. It's just that we can feel it and hear it more because its directly between our legs and right by our stomach. As for the oil... I think its normal. I have seen it on every xb I have seen (only four so far, but atleast its consistant.) | ||
| Blackhat |
Kaese, My bike is stock. I'll start cutting on it once the warranty is up. The backfiring began when the bike was straight out of the box. I'll probably just give it some time and see how it works out like Misato said. It's got about 3500 miles on it now, and doesn't get ridden nearly as much because of Mr Winter. | ||
| Chainsaw |
I've NEVER had a backfire! Stock bike, 9968 miles. I don't really know what's going on. Could it be a timing or cam sensor issue? (wild guess) | ||
| Viros |
My bike did it really loud and multiple times after I washed it once. It also did it really loud when I didnt check my oil and was running low after coming back from a long trip in AZ. Ive also noticed it when I ride it on a cold night, after its been sitting outside collecting water condensation. I got the residue, but the loud pops are what bother me its pretty damn loud and embarrasing when it does do it | ||
| M1combat |
Mine does this too but mostly only off idle at cold temps (I always let it warm up for at least five minutes though so just cold air temps). The thing that I have noticed as a common thread in all of the threads that mention backfires is a low idle. Mine idles just below 1000 and doesn't do it very often. What do yours idle at? | ||
| M1combat |
Mine does this too but mostly only off idle at cold temps (I always let it warm up for at LEAST five minutes though so just cold air temps). The thing that I have noticed as a common thread in all of the threads that mention backfires is a low idle. Mine idles just below 1000 and doesn't do it very often. What do yours idle at? Mines a twelve. | ||
| Oconnor |
mine used to idle at around 650-700 rpm. But just brought it up to 1000-1050ish | ||
| M1combat |
The service manual says 1050-1150 is correct. The adjustment is just inside the left air-scoop and shouldn't affect TPS. Make the adjustment after a full warm up if you plan on it. | ||
| Kaese |
When mine was stock, it never backfired. It was just a slug. Now, with the mods, never backfires at idle. | ||
| Buckinfubba |
the oily residue is very common. Its from the breathers that come out of the heads in to the airbox. on the tuber buells it was alot worse. the new breathers work real well. when you say backfiring, do you mean thru the pipe or thru the throttle body. If it is thru the throttle body that is not normal. If you mean thru the pipe and you have the race ecm and pipe that is fairly common. mine has never backfired thru the throttle body. 14k miles | ||
| Boulderbiker |
Mine will backfire through the intake every once in awhile if I goose the throttle from idle. I'm at elevation 5000ft. I've never had it happen any other time then when I'm at idle and I just tweak the throttle real quick. My idle is at around 1050. | ||
| M1combat |
Oh yeah, I'm at about 5000' as well... I will adjust the idle at some point soon and see if the issue goes away. | ||
| Artesian |
I'm the newbie, only about a week old. Im still trying to stick to the corners in my neighborhood, etc. I was in the driveway meeting friends that pulled up one time- after being warmed up and I backfired, thought a tire popped... Not again since. 2001 M2L 1400 miles idle at 900-1100 (i play with it a lot) at sea level (or under :-) | ||
| Dutchie |
Elevation issue? My stock 9R with 2 500 miles on does it exactly as Boulderbiker explained, blipping real quick at idle. Elevation here is 5 764 feet. Could it be altitude, with the accompanying thinner air, related? Dutchie edited by Dutchie on December 03, 2003 | ||
| M1combat |
Very well could be... I'll make an effort to pay attention to it next time I make a run to Phoenix. | ||
| Blackhat |
Alright, couple things, my idle is right at 1000. Is this low? Altitude is definitely not the issue. I can knock a 5 iron into the Gulf of Mexico. If temperature is an issue, it is definitely a heat related one. It's DAMN HOT here in the south, with high humidity for at least 8 months out of the year. I have to admit that the problem hasn't been as apparent in the last month since the cold began moving in. Maybe mechanical, maybe environmental, don't know. Fubba, this backfire is definitely in the airbox, right under my belly, not within the header pipe or muffler. Bike is stock, minus a K&N filter. But did the same thing with the factory element. Got your info on the oil breathers, I'm taking that to mean the oil residue is a non-issue....... thank you. Blackhat | ||
| Darthane |
Mine has only ever backfired through the throttle body once. Right after I put my home-made plate on it, and that thing was LOUD. I took it home and pulled the airbox cover off to check it and the backfire pressure had cracked the plexiglass plate I'd made! Never done it since, though. -=sigh=- ...more than eight months until I can ride my Firebolt again... Bryan | ||
| Chainsaw |
I don't think it's elevation related either. I live at 5300 feet, and I've taken the 'Bolt over 14,000 feet (Mt. Evans, CO) with no backfires. | ||
| Dutchie |
OK, so not altitude. That leaves temp as an environmental factor. It's summer here and quite warm but I recall it doing the same during our winter (winter temps round 15 deg C, no idea what that is in US speak and too lazy to go to a conversion site). If mechanical - my 9R is going in next week on the 10th for the 2 500 mile service. The head tech at the local HD seems very Buell inclined. I will ask him to have a look and post back. Dutchie | ||
| Steviejay01 |
The oil in the airbox is kinda common so I'm told, my buell dealer told me this could happen, there are butterfly valves in there and now and again they fail (they are 1 way), they are pretty cheap to replace but its the labour thats gonna shaft ya. Only had my bike a day but I asked what the most common problems are. This is one of them so I'm told. | ||
| Buckinfubba |
its not a butterfly valve persay. now the breathers on the xb's have an oil air seperator in them with a filter in the top. The oil film is not a "problem" now if you have a real load of oil in your airbox then that would be a problem | ||
| M1combat |
Alright, so everyone that has this backfire off of idle... What does the bike indicate that it idles at? Mine says JUST under 1000. I have noticed that if I goose it a little at a light and then give it a bit of throttle and let the clutch out, that is the most common time that it happens. Also, if I am rolling along and gear down to first, let the bike slow down (at a streetlight for instance) and when I get to about ten MPH I blip it just a bit so as to match revs it will do it. That's still off idle. | ||
| Chainsaw |
Dutchie: I would have to rule out temperature also. I routinely ride at 0 degrees C and below (I'll ride down in the mid 20's F), I don't think my bike has ever seen more than 112 degrees F. For what it's worth.. | ||
| Cyclonecharlie |
I don't know what makes them backfire(since mine never has),but could it be the water/oil mix that comes out of the breathers and into the intake?It sounds like it only happens at a high vacumn time(around idle)which is when you might draw alot of mist from the breathers.My intake stays dry as I got bored one night and took my breathers out of the intake and ran them out the back end by the tail light.........Later Charlie | ||
| Buckinfubba |
charlie how the hell ya doing ain't seen ya in a while. when ya gonna be stoppin thru again. I got something for ya..... and no it ain't a hug! | ||
| Cyclonecharlie |
Hey Fubba, Two big guys hugging is not a pretty sight. I should be coming thru in a week or two. No give away kittens or puppys please. anything else I'll take.........Later Charlie | ||
| Dutchie |
Well, collected the 9R from HD today. Speaking to the head mechanic when I dropped it off on Wednesday he said he would do the TPS reset thing but he thinks it is because they deliberately set the idle low - allegedly if they set it to spec it hangs because of altitude? Now I did notice it was idling dead on 1 000 before I dropped it off and I haven't really looked at it on the short ride back to the office BUT it did backfire 3 times, which is more often than it used to? Ah well, I'll go and see what they did to the idle. Dutchie | ||
| Dutchie |
OK, just took it home and of course it did not backfire once. I did not do anything different than when I rode it from HD to the office and as I said then it backfired 3 times in about 15 minutes.  Oh yeah, the idle seems to be at the manual specified setting of 1050~1100. It is stinking hot 33 deg C / 91.4 deg F with relative humidity around 45%. I give up. Dutchie |
