May 23, 200521 yr I took my Scorpa out at the weekend and it run lovely. Brought it home, cleaned air filter and filled it up with petrol. It started and run for about 20 seconds and then stopped. Kicked it a few times and it backfired (very loud). Cleaned carb and cleaned plug and put it back together but with no joy. Has anyone got any ideas. Edited May 25, 200521 yr by sy250
May 24, 200521 yr Has it just started doing it? Mine does it quite a lot but it was worse untill I retarded the ignition. It'll backfire after a kick then start.
May 24, 200521 yr Author It has always backfired but not this often. Waiting for the plugs to arrive. If they do not work i think it could be the woodruff key. But what i can't understand is that it run lovely for 3 hours on Sunday????? Started first kick and never backfired.
May 24, 200521 yr The back firing is very much a part of the SY Racing which are the only 250 Scorpas imported into Australia.On my 2004 SY I retarded the timimg back to the Original timing mark settings and had no back firing at all.On the 2002 and 2003 SY Racing the back firing caused the Expansion chamber to split slightly,which then needed to be rewelded.I have found if you over oil your Air Cleaner foam it will enhance the problem.Have now 4 air cleaner elements and replace after a days ride,save the used ones till they all need cleaning..clean them all together and continue the cycle.Let us know how you go when you fit the new plug.Will be very surprised if the woodruff key has come adrift.
May 24, 200521 yr Glad this came up as a topic , thought it was just my bike that did this ,though it starts fine still !, apart from sometimes it seems a little reluctant to start from cold , the symptoms being , if you dont catch it well enough to start on first kick, it then needs the fuel turning off and full throttle ....wrong pilot jet ? too much oil on filter? ...... BTW starts absolutely perfect once warm Cheers Brad .
May 24, 200521 yr Mine does it also once in a while. Ever since I turned the timing up a bit. Interesting yours just began doing it out of the blue.
May 24, 200521 yr Author It has always backfired but never this often. It is only done it about 3 times in 8 months then about 3 times in 5 minutes
May 25, 200521 yr I had 2 Scorpa's, a 2001 and a 2004, and they both backfired every now and again, people used to really s*** themselves when it happened in a queue !!
May 25, 200521 yr i ve had an 03 and now got an 04 sy250 03 backfired every now and again when i used the kill switch 04 does it very rarely i had a word with crosswaites and they said nothing to worry about but check the carb could be a bit of water there ?
May 25, 200521 yr sounds like the timing to me.a mate had a fantic that sheared a woodruff key and that backfired once, ran for a few seconds and refused to start again.due to the fact the woodruff key is important to the timing it would explain why the bike will not run anymore. just a thought, see if it hepls
May 25, 200521 yr Author All fixed. NGK platinum spark plug arrived today from Birkett. Started first kick and run lovely. Very happy.
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