Pops or "burps" through AC on startup??
#1
06-18-2015, 11:49 PM
Pops or "burps" through AC on startup??
I have a 2008 SG that has fairly recently started "kicking back" or "backfiring" through the air cleaner on startup? It is accompanied with a nasty grinding sound from the starter area as well as a puff of smoke from the AC. It does this at random though, not all the time. I may start it 10 times and it never do it. Then it may do it 3 times in a row. It doesnt matter if its a cold start or a hot start, it is prone to do it from either scenario. I had the bike for a year and a half and it never done it, not even once. Now, its fairly common? I have thoroughly cleaned the AC and installed new plugs but that didnt help at all. The bike does have a 103 kit,cams etc. But, like I said, it never done this for the first year and a half that I owned the bike (approx 3500 miles worth of riding) and now its doing it. So, something has changed somewhere?? Any ideas guys? Thanks in advance 
#2
06-19-2015, 05:29 AM
Seasoned HDF Member
Stuff that causes that:
1. Huge amounts of spark advance - not common though
2. Weak battery - have it tested
3. Starter clutch going bad or weak starter - grinding is usually an indication of that
4. Worn Ring gear and/or starter gear - which will be obvious if you pull the primary cover.
As the bike is starting (very first combustion you feel/hear as the bike is turning over) is there a huge clap or clang of metal sound coming from the primary? Almost a "ka-pow" sound.
If so, your compensator is probably in need of replacement. A weak comp can ruin the starter clutch over time because it causes pulses of primary chain slack which pulses the load over the starter.
Then there is 5. High compression and the need for ACRs etc but since your bike ran for a 1.5 years without any problem it's probably not that.
ACRs are always a good idea on a 103 but won't fix the problem your having presently. Just help eliminate it in the future.
1. Huge amounts of spark advance - not common though
2. Weak battery - have it tested
3. Starter clutch going bad or weak starter - grinding is usually an indication of that
4. Worn Ring gear and/or starter gear - which will be obvious if you pull the primary cover.
As the bike is starting (very first combustion you feel/hear as the bike is turning over) is there a huge clap or clang of metal sound coming from the primary? Almost a "ka-pow" sound.
If so, your compensator is probably in need of replacement. A weak comp can ruin the starter clutch over time because it causes pulses of primary chain slack which pulses the load over the starter.
Then there is 5. High compression and the need for ACRs etc but since your bike ran for a 1.5 years without any problem it's probably not that.
ACRs are always a good idea on a 103 but won't fix the problem your having presently. Just help eliminate it in the future.
Last edited by lp; 06-19-2015 at 05:39 AM.
#3
06-19-2015, 06:53 AM
Ultimate HDF Member
#4
06-19-2015, 07:15 AM
I have a 2008 SG that has fairly recently started "kicking back" or "backfiring" through the air cleaner on startup? It is accompanied with a nasty grinding sound from the starter area as well as a puff of smoke from the AC. It does this at random though, not all the time. I may start it 10 times and it never do it. Then it may do it 3 times in a row. It doesnt matter if its a cold start or a hot start, it is prone to do it from either scenario. I had the bike for a year and a half and it never done it, not even once. Now, its fairly common? I have thoroughly cleaned the AC and installed new plugs but that didnt help at all. The bike does have a 103 kit,cams etc. But, like I said, it never done this for the first year and a half that I owned the bike (approx 3500 miles worth of riding) and now its doing it. So, something has changed somewhere?? Any ideas guys? Thanks in advance
#5
06-19-2015, 07:16 AM
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Stuff that causes that:
1. Huge amounts of spark advance - not common though
2. Weak battery - have it tested
3. Starter clutch going bad or weak starter - grinding is usually an indication of that
4. Worn Ring gear and/or starter gear - which will be obvious if you pull the primary cover.
As the bike is starting (very first combustion you feel/hear as the bike is turning over) is there a huge clap or clang of metal sound coming from the primary? Almost a "ka-pow" sound.
If so, your compensator is probably in need of replacement. A weak comp can ruin the starter clutch over time because it causes pulses of primary chain slack which pulses the load over the starter.
Then there is 5. High compression and the need for ACRs etc but since your bike ran for a 1.5 years without any problem it's probably not that.
ACRs are always a good idea on a 103 but won't fix the problem your having presently. Just help eliminate it in the future.
1. Huge amounts of spark advance - not common though
2. Weak battery - have it tested
3. Starter clutch going bad or weak starter - grinding is usually an indication of that
4. Worn Ring gear and/or starter gear - which will be obvious if you pull the primary cover.
As the bike is starting (very first combustion you feel/hear as the bike is turning over) is there a huge clap or clang of metal sound coming from the primary? Almost a "ka-pow" sound.
If so, your compensator is probably in need of replacement. A weak comp can ruin the starter clutch over time because it causes pulses of primary chain slack which pulses the load over the starter.
Then there is 5. High compression and the need for ACRs etc but since your bike ran for a 1.5 years without any problem it's probably not that.
ACRs are always a good idea on a 103 but won't fix the problem your having presently. Just help eliminate it in the future.
LP pretty much hit the head on the nail!!!
Start with the little stuff first or the least expensive stuff.
YB
#6
06-19-2015, 11:17 AM
first thing I would check is the battery and the battery cable (make sure that they are tight and clean)...don't just replace the battery..take it out and have it load tested...if it is weak the bike won't turn over real fast for the first revolution or so and if it fires during that time it can over power the battery and backfire, and that causes all the other noises...if that doesn't help come back and we can dig deeper...
#7
06-19-2015, 12:52 PM
Ultimate HDF Member
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#8
06-19-2015, 04:56 PM
Stuff that causes that:
1. Huge amounts of spark advance - not common though
2. Weak battery - have it tested
3. Starter clutch going bad or weak starter - grinding is usually an indication of that
4. Worn Ring gear and/or starter gear - which will be obvious if you pull the primary cover.
As the bike is starting (very first combustion you feel/hear as the bike is turning over) is there a huge clap or clang of metal sound coming from the primary? Almost a "ka-pow" sound.
If so, your compensator is probably in need of replacement. A weak comp can ruin the starter clutch over time because it causes pulses of primary chain slack which pulses the load over the starter.
Then there is 5. High compression and the need for ACRs etc but since your bike ran for a 1.5 years without any problem it's probably not that.
ACRs are always a good idea on a 103 but won't fix the problem your having presently. Just help eliminate it in the future.
1. Huge amounts of spark advance - not common though
2. Weak battery - have it tested
3. Starter clutch going bad or weak starter - grinding is usually an indication of that
4. Worn Ring gear and/or starter gear - which will be obvious if you pull the primary cover.
As the bike is starting (very first combustion you feel/hear as the bike is turning over) is there a huge clap or clang of metal sound coming from the primary? Almost a "ka-pow" sound.
If so, your compensator is probably in need of replacement. A weak comp can ruin the starter clutch over time because it causes pulses of primary chain slack which pulses the load over the starter.
Then there is 5. High compression and the need for ACRs etc but since your bike ran for a 1.5 years without any problem it's probably not that.
ACRs are always a good idea on a 103 but won't fix the problem your having presently. Just help eliminate it in the future.
1) I don't think its spark advance either due to the 1.5 yrs and miles on the bike with zero issues
2) I replaced the battery roughly a year ago and the engines spins over faster now than it did with the old battery, but I can easily enough take it out and have it tested somewhere. I assume a local auto parts store can check this for me.
3) I never hear a grinding sound or anything odd at all on normal start ups. The only time its sounds crappy is on that "ka pow" start up.
4) If I pull that primary cover to inspect these gears, I assume I am just looking for damage on the gears? Which you stated is pretty obvious?
5) Seems that this issue is pointing towards a mechanical issue and not an electrical or ignition issue? Is there a way to check or test this compensator and/or starter clutch? Like maybe kill the ignition and fuel source and let the starter spin the motor time after time to see if it "kick out" or grinds?? Thanks so much guys!!
#10
06-19-2015, 07:32 PM
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