Author Topic: 500cc OEM piston weight  (Read 2260 times)

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Tarnand

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on: November 22, 2018, 04:45:43 am
Would anyone know what is the the weight of an OEM piston for 500cc IB?  I know it varies from one to another but that is their nature.  I found some info in the archives but not about OEM.  Thanks.
2005 KS (ex ES) Bullet 500cc
1994 FLSTC
1983 FXRS


ace.cafe

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Reply #1 on: November 22, 2018, 04:49:33 am
514g including pin.
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Tarnand

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Reply #2 on: November 22, 2018, 04:59:46 am
Thank you Ace.  Rings are about 12g so that would be 526, right?
2005 KS (ex ES) Bullet 500cc
1994 FLSTC
1983 FXRS


ace.cafe

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Reply #3 on: November 22, 2018, 01:54:31 pm
I haven't weighed oem rings, but they are trash. So is the piston.

Are you rebalancing or something?
« Last Edit: November 22, 2018, 04:19:50 pm by ace.cafe »
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Tarnand

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Reply #4 on: November 22, 2018, 09:05:16 pm
Engine vibrations are nuisance.   So I am actually thinking of getting deeper into the subject and started gathering information.
2005 KS (ex ES) Bullet 500cc
1994 FLSTC
1983 FXRS


ace.cafe

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Reply #5 on: November 22, 2018, 10:32:15 pm
Engine vibrations are nuisance.   So I am actually thinking of getting deeper into the subject and started gathering information.
The majority of the vibrations are typically from an out-of-true crank. True the crank up <.002" run out . Or <.001" if you can.
Smoothness is improved by lessening reciprocating mass. The lighter the piston, the better.
You don't need to do any adjustments to the flywheel balance.

Our forged 87mm 9:1 piston weighs ~472g including pin. If you can get the piston weight down around there, Or less if it is a 84mm, it will be fine. We don't change the flywheel balance.

Our Fireball builds run smooth as silk., and that's what we do to them.
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Tarnand

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Reply #6 on: November 25, 2018, 07:00:42 pm
Recently I replaced the OEM alloy conrod and bush with Hitchcock's set of steel conrod and roller bearing.  The thing is that the motorcycle while being on a center stand starts traveling backwards when approaching 2000 rpm.  My reasoning is that the additional weight disturbed the crankshaft balance.  Truing was done by someone I know and trust and the readings were .0005 on one shaft and .0015 on the other.  I contacted Hitchcock regarding a set of flywheels they sell and they assured me that these flywheels were made specifically for that particular, aforementioned conrod-bearing set.  They also mentioned that such crank would is balanced to work with an OEM piston.  I also asked them about weight of such piston but they did not give me this info stating only that "their weight varies".  This is why I posted this question on this forum.

http://accessories.hitchcocksmotorcycles.com/accessory-shop/Flywheels-crankshaft/11402

2005 KS (ex ES) Bullet 500cc
1994 FLSTC
1983 FXRS


ace.cafe

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Reply #7 on: November 25, 2018, 07:56:17 pm
We have not seen that problem.

If the truing is as you report, that should be fine.

We have used steel con rod and roller bearing with various brands and weights of pistons, without having that kind of problem.

My first thought when faced with vibration of that magnitude is to check the headsteady to see if it is loose or broken.
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Tarnand

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Reply #8 on: November 25, 2018, 10:10:53 pm
My first thought when faced with vibration of that magnitude is to check the headsteady to see if it is loose or broken.
I went to the garage and found out the headsteady indeed was quite loose.  Right now the tank is not on the bike but I will try to see sometime during the week if tightening it changes anything.  Thank you.

P.S. Earlier you pointed out poor quality of the OEM rings.  Woud you be able to recommend any right source and brand for replacement hopefully in the USA?
Thank you.
« Last Edit: November 26, 2018, 01:43:18 am by Tarnand »
2005 KS (ex ES) Bullet 500cc
1994 FLSTC
1983 FXRS


ace.cafe

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Reply #9 on: November 26, 2018, 01:36:43 pm
I went to the garage and found out the headsteady indeed was quite loose.  Right now the tank is not on the bike but I will try to see sometime during the week if tightening it changes anything.  Thank you.

P.S. Earlier you pointed out poor quality of the OEM rings.  Woud you be able to recommend any right source and brand for replacement hopefully in the USA?
Thank you.

You can contact Total Seal piston ring company and they will allow you to send your piston to them and they will fit a good set of rings on it.

The worst OEM  ring is the one-piece oil ring. Get a decent 3-piece modern type oil ring.
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