Bridgestone Motorcycle Parts Discussion Board
Bridgestone Tech Talk => 175 & 200 Talk => Topic started by: Sye on February 03, 2017, 11:44:11 AM
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I know that it's always difficult to disgnose something that makes a noise but I will try and explain what's happening.
I rebuilt the engine but didn't replace the crank bearings as they seemed fine. There was no discernable play on the conrod big ends or small ends. I replaced the wrist pin and small end cages just in case.
Started the bike this afternoon and it runs beautifully, ticks over and purrs like a kitten but...
I have a metallic knocking noise from the left hand cylinder. It's hard to describe but it's a ticking noise that sounds very much like tapping sheet metal with a spanner. I have switched everything off and will lift the head tomorrow and see if there's anything obvious but wondered if anyone had an idea what it might be or come across this before?
In fact, it sounds like a tappet that's too loose? I know it doesn't have any but that's exactly what it sounds like.
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this happened to me once and I hope its the same thing for your sake
I heard a metallic tapping as I was riding I looked for the noise and it was coming from the left cylinder it turned out to be the key ring tag from genes auto tapping against the fin
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this happened to me once and I hope its the same thing for your sake
I heard a metallic tapping as I was riding I looked for the noise and it was coming from the left cylinder it turned out to be the key ring tag from genes auto tapping against the fin
I wish Coxy, this is a 175 Hurricane and the key is in the side panel :-(
I'm going to pull the heads and cylinders tomorrow and find out more... Fingers crossed?
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good luck
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Sye, Hopefully, it will just be piston slap, even with an assumed new piston. annoying but harmless.
Only other things I can think of are, Piston hitting head gasket or a broken ring (hope not). Brian.
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Does it make the same sound when you kick it over with the spark plug out?
If it does it may be a bad top or bottom needle bearing.
Randy
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Jugs off this morning, pistons out, oil pump out and left hand disc valve and everything looks just fine. No witness marks, looseness of pins or bearings and no signs of anything damaged or broken?
Putting it back together now as I'm stumped as to what it could be? The only thing I can think of is the piston that is located in the oil pump may be too dry and it may go when it fills up and purges any air.
Other than that I'm scratching my head....
Just to let others know, it's a 90 minute job to remove the pots and pistons with the engine in the frame. I removed the studs and just slid them off. An hour in and the cylinders and heads are back on. Just the exhaust, tank and bits and bobs to go.
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I remember my KH400 making a ticking noise on over run from the day I bought it, years later when I replaced the piston rings, chamfered the ports, new gaskets etc and everything checked out fine it was still there and never gave a problem.
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Thanks Lee, it's back together now and exactly the same. I've checked everything and it's spot on so whatever it is can't be serious, I hope. Time will tell but it does run very nicely.
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Sye, i have learned a method of pin-pointing where a certain noise comes from although it is not very high tech----- it will tell you where the tick is. You could invest in a stethascope, but there is a cheaper method, using a pipe a foot or two in length ,putting one end of the pipe ( to listen )directly and holding close to you ear and the other end to locate while moving the pipe around the area where the noise is coming from the louder it is, is the location then and could posibly tell a bit more of what it is that is making it. Atleast it could tell you if the noise is more towards the top of the cylinder or towards the bottom. Hope this can help you in a possible diagnoses??? Good luck :-) bsforever
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Sye,
Have just fired up my GTO for the first time and guess what - a metallic pinging noise on the left cylinder. Engine had been rebuilt in the US before I bought. Like you I pulled the head off to find approx 4-6 thou movement at the top of the new piston which could make a noise much like you describe - not much I can do about that. Also pulled the barrel to find everything OK. However, when reassembling, I centred the barrel and head on the studs to ensure nothing was touching the right cylinder. The engine now sounds much better, so is this the answer?, Try slipping a piece of thin card between the cylinders to see if they are contacting. Worth a try.
Brian.