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Oklep
Posted on Tuesday, September 16, 2014 - 04:39 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hi guys.

I have some backfires under deceleration, sometimes it fires into exhaust during cold start, and last ride I noticed that it also sometimes "pops" into muffler even through constant speed.
I also noticed that rarely, when I kill engine with button, there is self ignition for a second.

What do you think it could be?
Lean mixture? Some intake leak?
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Modified4speed
Posted on Tuesday, September 16, 2014 - 07:42 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Cant build a case on this evidence it could be a crap load of things. When was the last time you're carb was cleaned, Do you know how to check for intake leaks, Do you know how to check for a cracked exhaust or Hows you're fuel filter? Use the search function and bring some more evidence please. Start with the easiest first in this case every test is easy if you're performance suffers check fuel filter, boots then carb if not check exhaust mounts then look for cracks. Start with that and you'll have you're answer..
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Cyclonecharlie
Posted on Tuesday, September 16, 2014 - 10:17 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Sounds like your dumping raw fuel into exhaust.Possibly stuck float or trash in needle and seat.
Go through the carb. first and see if that corrects the problem.
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Buellistic
Posted on Wednesday, September 17, 2014 - 06:49 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

EXHAUST HEADER GASKETS ???
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Oklep
Posted on Thursday, September 18, 2014 - 05:01 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thank you guys
I have this bike for few months now, so I dont know when was the last time carb was cleaned. I wanted to do it through winter, but it looks like I need to do it a bit sooner. I dont have fuel filter.

Modified4speed: Is test with WD40 for intake leak, and with oil into cylinder for exhaust leak correct? I am new into buells, so everything is school for me.

Btw: I have hsr42 carb
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Rocket_in_uk
Posted on Thursday, September 18, 2014 - 05:56 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Chances are you've an exhaust leak - thus air gets sucked in on the overrun - makes a bang and a backfire when the additional oxygen lights the wasted gases in the exhaust.

Hold a rag momentarily over the muffler exit to create a seal preventing the exhaust gases escaping whilst the engine's running. You should soon know if exhaust gases are escaping anywhere other than the muffler exit. If gases are escaping, sort it and seal the system before doing anything else.

As for the popping when you switch off with the kill switch. It's likely the wasted spark system igniting the mixture already entered into the cylinder is all.

The bike is being asked to shut down instantly off the kill, which it will do, but on the odd occasion the kill being instant it won't prevent the last spark exiting a discharging coil. If this spark happens upon the unburnt mixture sometimes, it'll bang.

The two conditions you describe are very likely unrelated. It's also very likely the only issue you may have is a slight leaking in the exhaust system.

Have a mechanic do a plug chop. Check the timing. Test ride to check it's not running lean at the top.

Rocket in England
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Modified4speed
Posted on Friday, September 19, 2014 - 05:44 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I second Rocket. I have the same issue currently because I have cracks in my pipes allowing oxygen in and causing decel pop.In my case a new exhaust is in order but if you're lucky you may get away with just replacing the exhaust gaskets.
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Rocket_in_uk
Posted on Saturday, September 20, 2014 - 05:33 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I second Rocket.

Thank you.


Rocket in England
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X1brett
Posted on Saturday, September 20, 2014 - 10:54 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I just had the same symptoms and found a crack in the header near the O2 sensor. ECMSPY revealed 150 AFV {Air Fuel Value}, trying to compensate for a lean reading from the O2 sensor. I also had an intake leak, which couldn't have helped. Do you have ECMSPY to check readings like AFV?
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Oklep
Posted on Sunday, September 21, 2014 - 01:46 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thank you guys, I will look into it but I am away for now.

Rocket, what I should see when I put rug over the exhaust exit? I thought that I need to put a bit of oil through spark plug into engine, so I can see smoke. Can I see with this method also some small leaks?

X1brett: sadly, I have S1, so I dont have any sensors. So I need to find what is wrong with oldschool way :-)
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X1brett
Posted on Sunday, September 21, 2014 - 02:26 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Of course. Sometimes I wish my X1 had a carb. The sensors had me confused for 2 months, until yesterday! I'll leave it to the carb guys to offer advice. You'll get it figured out.
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