T140 Crankshaft Balance - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 9 (permalink) Old 11-18-2012, 09:18 PM Thread Starter
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T140 Crankshaft Balance

Completed on a Sunnen DCB-750 operated by an expert.
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post #2 of 9 (permalink) Old 11-18-2012, 09:53 PM
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Interesting that they added 3 gms/cylinder for oil.
The 74% spec from Triumph was with a dry crankshaft.There would certainly be more than 6 gms of oil normally in the sludge trap,probably more than 20 gms.

It looks as though it would have been balanced closer to 65%,when it left the factory.It's not unusual to find that,yet the engines still run smooth.

A higher balance factor decreases vertical imbalance and increases horizontal imbalance,but the imbalance loading on the crank increases.Overall smoothness and comfort to the rider doesn't seem to change.
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post #3 of 9 (permalink) Old 11-18-2012, 10:23 PM Thread Starter
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Crank Balance

Understand that. I believed that going this far it would be a good idea to have the crank balanced, not ever having riden the bike (Barn find) I guess I will never know wether or not an improvement has been made.
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post #4 of 9 (permalink) Old 11-22-2012, 09:42 AM
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I would assume you will be ballancing the rods and pistons also, or that was a waste of time and money?
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post #5 of 9 (permalink) Old 11-22-2012, 01:15 PM Thread Starter
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Balancing

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Originally Posted by wolfwolf View Post
I would assume you will be ballancing the rods and pistons also, or that was a waste of time and money?
And I would assume that you read the above attachments?

Last edited by lovecuba; 11-22-2012 at 01:15 PM. Reason: Spelling?
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post #6 of 9 (permalink) Old 11-23-2012, 06:47 AM
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I was refering to EACH piston. I see that all parts were weighed and used to ballance the crank, but did you also make each piston and rod weigh the same?
Im not trying to be a smartass here, really just courious.
I usuall just throw the motor together and hope for the best!
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post #7 of 9 (permalink) Old 11-23-2012, 01:48 PM
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Quote:
Originally Posted by wolfwolf View Post
I usuall just throw the motor together and hope for the best!
In a way I wish I had done that now. My engine is heading for a couple of grand now. I guess it'll run amazingly but how much better I'm not really sure!

Would have cost £200 if I had done a basic job on it!
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post #8 of 9 (permalink) Old 11-24-2012, 08:34 AM
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yep, once you start down the road with the best of everything its hard to draw the line where to stop.
Untill your pockets are empty!
Good luck with the build.
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post #9 of 9 (permalink) Old 11-25-2012, 06:08 PM Thread Starter
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Dynamic Balance

Quote:
Originally Posted by wolfwolf View Post
I was refering to EACH piston. I see that all parts were weighed and used to ballance the crank, but did you also make each piston and rod weigh the same?
Im not trying to be a smartass here, really just courious.
I usuall just throw the motor together and hope for the best!
I guess, given that the balance was undertaken by an expert (not Me) the job has been done correctly. Time will tell!
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