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Post by wiggy on May 31, 2014 19:25:55 GMT 1
i have this strange noise on the engine only when its hot
i cant for the life of me work out what it is
i have eliminated the following though
stator nut catching casing
clutch adjuster nut ( changed clutch casing still making same noise)
impeller bearing
i have recently redone pv bushes with new seals etc noise seems to come from around exhaust area
thanks for any ideas im really baffled
video is 1.18 min
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on May 31, 2014 20:21:12 GMT 1
Like Headcoats Said It Sounds Like A Blow Job. PV Seals In The Right Way Round? Base Gaskets? Or Head Gasket Blowing
(Although It Would Have To Get Past The Water Jacket So Unlikely Unless The Header Tank Is Also FillingUp?)
It Sounds On The Same Freqency As The Crank/Water Pump, Let Us Know What You Find As It Is A Strange One
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Post by ianr4863 on May 31, 2014 20:32:48 GMT 1
Sounds just like my 4LO did when a reed valve failed .
Have you checked them ?
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Post by Delbert on May 31, 2014 21:22:28 GMT 1
Worn idle gear rattling on the back of clutch basket ??
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Post by wiggy on Jun 1, 2014 9:56:26 GMT 1
thanks for the input guys
the noise is obviously happening when the something is expanding on the engine
doesnt do it when cold or when its stood warm for about 10 mins
the air leak sound like a good possibility although the expansion bottle isnt blowing so i dont think its the head gasket
even though i havent used genuine (which i normally do)
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Post by yamark on Jun 2, 2014 16:50:39 GMT 1
Have you lost your pet budgie?
Try to locate the noise with an insulated screwdriver ,the type where the metal goes through the handle. Put it to your ear holding the handle. Might find the source.
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db8888
Thrash Merchant
Posts: 329
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Post by db8888 on Jun 2, 2014 18:38:29 GMT 1
Hi I have heard a sound close to this and the problem was the centre lab seal moving from side to side on the crank try re torqueing the 8 lower crankcase bolts first
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begbie
Drag-strip hero
Posts: 249 
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Post by begbie on Jun 2, 2014 19:06:03 GMT 1
To check for air leaks put some soapy waster in a spray bottle and spray on suspect areas while running or better still do a leak down test.
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Post by 4l04ever on Jun 2, 2014 22:24:48 GMT 1
Hi Wiggy
I am just getting my bits and bobs sorted for doing leak down testing. Should be doing mine this weekend if all the parts arrive :-) If you want to borrow the kit once I have done mine, let me know.
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Post by wiggy on Jun 3, 2014 19:05:38 GMT 1
Hi Wiggy I am just getting my bits and bobs sorted for doing leak down testing. Should be doing mine this weekend if all the parts arrive :-) If you want to borrow the kit once I have done mine, let me know. thanks for the offer rob i will do and i will be in touch if i need it  and thanks to everyone else for the input and ideas i have a couple more things to try |
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Post by steeley on Jun 3, 2014 19:46:44 GMT 1
interesting what db8888 said about lab seal chirping .I remember a mate building a 350 ypvs engine for a chap ,rebuilt crank ect .the bike after running in wouldn't go very fast and it made a noise .the owner of the bike ended up machining o ring groves on the lab seal .there was a batch made that were slightly under size on the o/d.oh my mate span the engine up with an air gun in the finish to try and isolate the noise.
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Post by wiggy on Jun 15, 2014 15:33:27 GMT 1
Found it  my fault for being impatient it was the exhaust gaskets when i rebuilt the top end i hadnt got any paper gaskets(couldnt wait for them to arrive) so i used old ones bonded together with instant gasket after reading some replies it got me thinking about air blowing so i used new gaskets which had arrived 2 days after the rebuild also sealed with high temp silicone job done |
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Post by steeley on Jun 15, 2014 17:50:42 GMT 1
another one sorted ready for the better weather.
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