Author Topic: noisy engine  (Read 252 times)

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Offline down under

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noisy engine
« on: August 03, 2018, 06:19:17 AM »
i have a gtr 350 with only 3000miles on it but the engine is very noisy,i know i can get main bearings from richard,but what ang big end and small end bearings are they available,or could it be wear on the rotary valve discs,its sound terrible,starts up easily enough,any thoughts?

Offline BS Mechanic

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Re: noisy engine
« Reply #1 on: August 03, 2018, 01:18:57 PM »
I find it very difficult to evaluate noise in the 350 because of the dry clutch.  The dry clutch normally makes so much noise with all the plates rattling around it's very hard to tell if there is any unusual engine noise.

If it sounds ok when riding and under load, I generally don't worry.
« Last Edit: August 03, 2018, 01:20:32 PM by BS Mechanic »

Offline OldSwartout

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Re: noisy engine
« Reply #2 on: August 03, 2018, 05:46:49 PM »
A loose nut on the end of the crankshaft, a loose nut on the clutch basket, worn clutch friction plate tabs and a couple other items related to the clutch will make an awful noise and make you think there are bad bearings or excess piston slap.  Check the clutch related items before getting concerned about internal bearings, unless you have good reason to believe there was internal damage. The engine internals should last 50,000+ miles without an issue unless there has been water/rust, lack of oil, etc. As BSmechanic says, if it sounds OK under load and riding, the internals are probably good. If it changes when you pull the clutch lever, it's the clutch or related items for sure.  I rode mine for quite a while with a loose nut holding the the gear on the right end of the crankshaft - sounded like the worst rod bearing failure, but the noise went away under load.
« Last Edit: August 03, 2018, 05:49:03 PM by OldSwartout »
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

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Re: noisy engine
« Reply #3 on: August 03, 2018, 06:28:14 PM »
        350s were never the quietest of engines even when new. Try using a piece of wooden dowel or a long screwdriver to listen to various parts of the engine. Simply place one end on the engine and put your ear to the other end. You may be able to pinpoint where the worst noise is coming from.
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Offline coxy

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Re: noisy engine
« Reply #4 on: August 03, 2018, 06:40:47 PM »
what every one said
where about are you down under 

Offline down under

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Re: noisy engine
« Reply #5 on: August 03, 2018, 06:45:27 PM »
hi Coxy ,i am in sydney(western suburbs)
cheers Greg

Offline bsforever

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Re: noisy engine
« Reply #6 on: August 04, 2018, 01:06:57 AM »
        350s were never the quietest of engines even when new.
        350s were never the quietest of engines even when new. Try using a piece of wooden dowel or a long screwdriver to listen to various parts of the engine. Simply place one end on the engine and put your ear to the other end. You may be able to pinpoint where the worst noise is coming from.
Simply place one end on the engine and put your ear to the other end. You may be able to pinpoint where the worst noise is coming from.
A pipe or even a rubber hose is able to pick up more noise differences and would need to hold up one end right up on your ear for best results, moving the other end until the loudest place it is heard can be pin-pointed. This also works for finding live noisy crickets :)

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Re: noisy engine
« Reply #7 on: August 05, 2018, 08:25:53 AM »
       Would also recommend removing the heads, easily done, and checking the cylinder bores for lifting or peeling of chrome at top  or round ports. This is not uncommon after 50 years. Condensation was the killer.
      You may be lucky, if the bike was stored in dry conditions, my GTO is still running on it's original barrels with good compression. Fact yours starts easily is also a good sign.
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Offline Tom Meadows

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Re: noisy engine
« Reply #8 on: August 05, 2018, 01:56:55 PM »
A traditional mechanic's stethoscope has many advantages over a piece of rubber tubing: Stereo sound with all external sounds blocked out,  the ability to reach down into tiny areas, and pinpoint location.Mine has lasted thirty years.  Fifteen bucks on Amazon:

https://www.amazon.com/Lisle-52500-Mechanics-Stethoscope/dp/B0002SQYSM

tom

 


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