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Old 06-10-2013, 12:10 PM   #76
bmweuro OP
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Quote:
Originally Posted by Hiatt View Post
Chris,

Since you are not sure where or what it is, try using one of those stethoscopes with the long rod on the end. You can hear much better with that than anything else. It might at least help you narrow down the search.

JH
Quote:
Originally Posted by Stan_R80/7 View Post
Here is where I got the NGK BP6ES cross references to a Bosch W5DC: http://www.sparkplug-crossreference.com/

Upon closer examination of that site, it shows both the W5DC and W6DC cross reference to the BP6ES. So, it looks like you need to examine the current plugs used to choose one heat range cooler. Higher numbers refer to colder heat range for NGK and Bosch it is vice versa (i.e. lower numbers). For my airhead ('78 R80/7), the Bosch plug is W5DC. However, if you are currently using a W6DC then going with a W5DC (which is one number cooler) may help. Good luck!
Jeff I would like to try the stethoscope but I can only reproduce the noise under load while riding it.

Stan I am running the W5DC's and it made a big difference in how the bike ran and the plugs finally have some color to them.
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Old 06-10-2013, 12:33 PM   #77
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I doubt if plug choice would have anything to do with the knock
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Old 06-10-2013, 01:21 PM   #78
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Originally Posted by bmweuro View Post
Jeff I would like to try the stethoscope but I can only reproduce the noise under load while riding it.

Stan I am running the W5DC's and it made a big difference in how the bike ran and the plugs finally have some color to them.
Chris,

Have someone else ride it and you sit in the hack and try the stethescope. Odd that it is only under load and still in the motor....did you check the end play on the crank?

I assume since you checked the rods, it is a deep knock?..

That 9.5 piston is not hitting the head is it? I had a set of cyls that had been cut down and did not realize it until I installed them. As it got hot, things grew enough for the pistons to touch the head. It makes a knock.

Just thinking out loud....

JH
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Old 06-10-2013, 02:29 PM   #79
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Originally Posted by Hiatt View Post
Chris,

Have someone else ride it and you sit in the hack and try the stethescope. Odd that it is only under load and still in the motor....did you check the end play on the crank?

I assume since you checked the rods, it is a deep knock?..

That 9.5 piston is not hitting the head is it? I had a set of cyls that had been cut down and did not realize it until I installed them. As it got hot, things grew enough for the pistons to touch the head. It makes a knock.

Just thinking out loud....

JH
The is a Grauer built motor with new everything that sat for nearly 10 years. I thought is might be a rod bearing so I did big and little ends even though they were fine.
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Old 06-14-2013, 12:51 PM   #80
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I was looking up deep oil pan sumps and ran across this thread about a strange engine knock - thought it might be worth throwing this notion into the mix: http://www.advrider.com/forums/showt...errerid=235409
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Old 06-15-2013, 08:08 AM   #81
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Originally Posted by Stan_R80/7 View Post
I was looking up deep oil pan sumps and ran across this thread about a strange engine knock - thought it might be worth throwing this notion into the mix: http://www.advrider.com/forums/showt...errerid=235409
Thanks for that. That was an issue on many of the 81-84 models.

I got a stethoscope and determined it was on the left side so I pulled it apart again and everything was in spec and I still have the noise. I have an idea of what it might be after talking with my friend Bob that built the motor over 10 years ago.
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Old 06-15-2013, 10:29 AM   #82
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Originally Posted by bmweuro View Post
Jeff I would like to try the stethoscope but I can only reproduce the noise under load while riding it.
Befriend someone with a Dyno. ;)

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Old 06-15-2013, 10:46 AM   #83
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Befriend someone with a Dyno. ;)

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Good idea Bill. I have removed the sidecar which would make that a lot easier and I do have a friend with a dyno.
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Old 06-18-2013, 06:03 AM   #84
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Originally Posted by bmweuro View Post
Thanks for that. That was an issue on many of the 81-84 models.

I got a stethoscope and determined it was on the left side so I pulled it apart again and everything was in spec and I still have the noise. I have an idea of what it might be after talking with my friend Bob that built the motor over 10 years ago.
Fill us in. What did you figure out?..

JH
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Old 06-18-2013, 07:13 AM   #85
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Glad I found this thread, sort of. My 77 r100 is doing the same exact thing after a high rev pull through a tunnel. Lots of good insight here, even if I do hope that it isn't a bearing, I have a funny feeling it is...
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Old 07-03-2013, 10:30 AM   #86
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Problem solved. It seem to be a combination of things. Once I got a stethoscope I could here a noise in the carburetor like the slide was rattling. I replaced the carburetors with another set of 40mm Bings and the noise mostly went away. Secondly I rejetted the carbs to a European R100GS spec, retarded the timing and now I have no strange knocks at all.
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Old 07-03-2013, 10:43 AM   #87
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Originally Posted by bmweuro View Post
Problem solved. It seem to be a combination of things. Once I got a stethoscope I could here a noise in the carburetor like the slide was rattling. I replaced the carburetors with another set of 40mm Bings and the noise mostly went away. Secondly I rejetted the carbs to a European R100GS spec, retarded the timing and now I have no strange knocks at all.
Actually your dipstick rattles against the inside of the case. I think you'll need the scope to hear it though.

Spending some time with the scope listing to this and that (valves, timing chain, transmission, rear drive, instruments, etc.) can be very useful. You gt a feel for what it all sounds like when it's running well. Then go around at the same spots come tune-up day and give a listen again and see what has changed and might warrant further attention. I mention 'tune up day' simply because you are getting greasy and irate anyway.

[Did I propose you use a stethoscope on the problem back on post #3 about 2 months ago???]

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Old 07-03-2013, 03:59 PM   #88
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My 40mm rh bing did the same thing a couple of years ago but I could tell straight away where the noise was coming from.
A few drops of oil on the slide stopped the noise. It's never been back.
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Old 07-03-2013, 04:18 PM   #89
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My 40mm rh bing did the same thing a couple of years ago but I could tell straight away where the noise was coming from.
A few drops of oil on the slide stopped the noise. It's never been back.
Good to know. Thx
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Old 07-04-2013, 07:51 PM   #90
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Chris,,never saw if this was a new build or if you had some miles on the engine?
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