Author Topic: knocking  (Read 2951 times)

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Offline coxy

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knocking
« on: November 05, 2016, 08:08:10 PM »
hey guys I was riding the gtr up a slight grade when I heard a slight knocking which grew louder and I felt it through the frame .I am thinking the worst of a dropped crank bearing .it only does it under load .
when I put it on the centre stand and ran it the chain jumps around a bit and I don't hear any knocking going through the gears.
so then I think it could be something else or at least hope it is . any in put would be appreciated thanks

Offline OldSwartout

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Re: knocking
« Reply #1 on: November 05, 2016, 08:35:28 PM »
Check the front sprocket for missing or severely worn teeth.  Also check to make certain the output shaft doesn't have any radial play or roughness when you spin it in neutral.
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

Offline hardy

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Re: knocking
« Reply #2 on: November 05, 2016, 09:46:54 PM »
hopefully it was just a bad batch of fuel causing some pre-detonation or pinging.  Another cause of this could be your static timing?


Offline coxy

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Re: knocking
« Reply #3 on: November 05, 2016, 10:53:56 PM »
thanks Karl I am just about to check that and fingers crossed that's all it is .there is now oil drops as well coming from that area .
thanks hardy I wish it was just a batch of bad fuel 

Offline coxy

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Re: knocking
« Reply #4 on: November 06, 2016, 12:01:24 AM »
Karl
there is a lot of sideway movement on the front sprocket to the extent that it has worn the outer casing thanks I will strip it all down next weekend thanks

Offline rwgibbon

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Re: knocking
« Reply #5 on: November 06, 2016, 11:06:04 AM »
Check the motor mounts and the frame brackets at the rear of the motor
where it connects to the frame.

You may find the rear connection brackets cracked or broken.

That could cause the movement.

Randy

Offline coxy

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Re: knocking
« Reply #6 on: November 06, 2016, 02:41:27 PM »
randy I will be doing that as well .when the bike was first restored I had the upper frame bracket welded ,taking the sprocket cover off it fouled on the frame as if the motor had dropped .thanks

Offline coxy

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Re: knocking
« Reply #7 on: November 14, 2016, 10:17:39 PM »
hey guys
I stripped it down to take a look .there are no cracks on the engine mounts .
the motor has defiantly moved. the dust cover is worn by the chain and the little shim for the clutch push rod has broken in two and fallen out .there is no up and down movement on the drive shaft .there is a about 1mm play side to side . 


 

Offline OldSwartout

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Re: knocking
« Reply #8 on: November 15, 2016, 08:40:35 AM »
There shouldn't be more than a few thousands movement in and out (assuming that's what you meant by side to side).  If there is, either the bearing is failing or the snapring that locates the output ball bearing into the crankcase isn't doing it's job, missing, groove broken from crankcase or bearing, etc.  If the shaft can move in and out. the gears on the shaft aren't properly located and as they move back and forth, the shift dogs will bump against each other or teeth will bump against gears on the input shaft causing the knocking.
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

Offline coxy

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Re: knocking
« Reply #9 on: November 15, 2016, 01:39:24 PM »
thanks Karl
all pretty nasty . on the bright side it could be worse thanks 

Online BRT-GTR

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Re: knocking
« Reply #10 on: November 15, 2016, 04:13:22 PM »
                      A few thoughts and questions :-   There could be more than one issue at play here and obviously,we are not familiar with your bike or what work has been done on it over the years. :-

        What is the condition of the chain and sprockets.  Could the noise have been the chain trying to climb off the front sprocket due to misalignment or play? Is the rear wheel sprocket in line with the front sprocket.      I have a front sprocket that a member gave me. When cleaned, it looks brand new on one side with perfect teeth but shows serious wear on the teeth sides on the reverse suggesting it was running well out of line so it can happen.   While I think of it, Guys, is there a right or wrong way to install the sprocket. The splines are slightly dished on one side for some reason. Was that to remove production burrs or facilitate fitting ? Any thoughts ?

        You say you think the motor has dropped and/or the motor has moved. Assuming all mounting bolts are tight, What is the condition of all 6 rubber motor mounts, particularly the lower and front ones. In my experience the front rubbers fail first and play a large part in resisting engine twist due to the pull of the chain. The engine sits directly on the lower mounts so any fault there may allow the engine to drop. Try carefully levering the engine with a length of wood to see if you detect any serious movement.
     Now I'm grasping at straws and  unlikely issues. Are the rear motor mount plates fitted the right way up, I'm not even sure they can be fitted the wrong way but would tend to lower the motor if reversed. On my only complete bike, the top, rear corner of the plates, where they bolt to the frame, is a right angle. The bottom corner is less than a right angle. Can anyone confirm this.

     I'm baffled by the 'little shim for the clutch push rod', what is this ?  Photo ?

     As well as the obvious oil seals in the sprocket chamber also check for hairline cracks in the gear indicator switch cover for the oil leak.                             Brian




« Last Edit: November 15, 2016, 05:06:45 PM by BRT-GTR »
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Offline coxy

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Re: knocking
« Reply #11 on: November 19, 2016, 01:14:20 AM »
the little shim(my apologies ) I think its a oil seal for the clutch push rod . its defiantly bearings . cheers 

 


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