Backfiring & pinging Shooting Star 441.

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Sep 21, 2009
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My 1968 Shooting Star used to backfire a lot on deceleration and I was going to check the timing/points etc but didn't get to it, and than one day I re gapped the plug cuz it was way out of spec & the backfiring almost stopped. So being lazy I never got around to rechecking the points/timing etc. I took it out for a long ride a few days ago & noticed it's pinging a lot under load & backfiring just a little on deceleration. Valve adjustment is good so does this sound like I have the timing a little to advanced ?
 
The backfiring could be a leak in the exhaust, my pinking under load was cured by retarding the timing. I had strobed it but the pinking needed more retard than the std 28 degrees advance. With todays fuel you have to do this sometimes.
 
Remember when they were new you could buy diecent gasoline for them, 95+ octane. With the crap they sell in the US. most of the old bikes will detonate with a agressive throttle hand. I mix aircraft fuel (100 low lead) 50/50 with premium pump gas, it stops pinging (detonation) and helps the exhaust seats last alittle longer. Your decell backfireing is most likely an exhaust leak where the head pipe fits into the head. The way to fix this is to remove the pipe and clean the area in the head where the pipe fits, this must be free of carbon, same with the pipe, use some high temp silicone sealer on the refit and let set over night, the backfireing will disapear. Also make shure the engine mount bolts are tight so the engine dose'nt rattle around in the frame, this is what made the pipe loose to begin with.

Ken G.
 
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