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 my old gasser did that to. worth checking
May 25, 200521 yr since i siad about the plug , my bike wouldnt fire up today tried and tried weak spark and its the plug gone NGK must be lacking in quality lol James
May 26, 200521 yr Good to hear sy250, Yamaha reliability shows again.....All you doubters . a spark plug and the smile returns.
May 26, 200521 yr my old gasser did that to. worth checking Thats fine , but lets not forget we are talkin about a real engine here !!
May 26, 200521 yr If it backfires too many times here is what happens. er... hmmm ,ok how can one stop it happening then ?
May 30, 200521 yr If it backfires too many times here is what happens. (picture of split exhaust) It sure does, as I found out this weekend. Fortunately, I was able to bend it back shut for the day, but it will still ultimately need to be welded. I have found that the backfire happens in two different cases. The first, which is totally avoidable, is if you let off the kill button too soon; before the engine has COMPLETELY stopped. The second is when starting, and it seems that it's most likely to happen if you give it a half-hearted kick, which I usually do since the bike starts so easily. After mine split this weekend, I was careful to give it very solid kick every time, and it didn't do it again. Of course, one afternoon isn't enough time to say for sure that it won't still do it, but at least it might be less often.
May 30, 200521 yr Bought my SY with a split mid box (it had split in the exact same place as the pic before!!), mine was starting to go around the outlet neck too..... had it all welded up...never thought it was down to the missfiring though........valid point I guess. Mine does it now and again, if it does not go second kick it will normally back fire...my guess is unburnt petrol getting in the exhaust system whilst trying to kick it up. Not too much of a problem at the moment though.
May 31, 200521 yr BruceInAl is on the money with his examples of backfires. I use a platinum plug, they're tops and last for ages. Just changed mine after the SSDT and to be honest it could have stayed in longer.
May 31, 200521 yr There's a new one in, just saying that the old one looked ok. Its yours if you want it? Save you a few penny's there John!
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