Engine size change
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Joined: Jan 2023
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From: Ca
Engine size change
Hello everyone.
I recently purchased a 1988 FLSTC, it's got a 1340cc Evolution.
Come to find out the original owner had it bored out 10% and had bigger valves put in. He doesn't remember the size of the new valves.
So my new questions are, does boring out the cylinders 10% mean each cylinder or 5% each one, and what would that change the engine size to?
Then, what size valves would have to be installed?
And would boring out the cylinders mean bigger pistons?
I know, it's a mess.
Any help would be great.
Thanks, Bob
I recently purchased a 1988 FLSTC, it's got a 1340cc Evolution.
Come to find out the original owner had it bored out 10% and had bigger valves put in. He doesn't remember the size of the new valves.
So my new questions are, does boring out the cylinders 10% mean each cylinder or 5% each one, and what would that change the engine size to?
Then, what size valves would have to be installed?
And would boring out the cylinders mean bigger pistons?
I know, it's a mess.
Any help would be great.
Thanks, Bob
Seasoned HDF Member
Joined: Aug 2007
Posts: 21,753
Likes: 17,620
From: Driftless Area
He probably meant .010". Bigger valves aren't necessary for that. 1.840" intake and 1.615" exhaust is stock.
Be interesting to know what cam it has.
New pistons and rings...yes. That would put it around 83.3 ci.
Be interesting to know what cam it has.
New pistons and rings...yes. That would put it around 83.3 ci.
Seasoned HDF Member
Joined: May 2008
Posts: 21,216
Likes: 12,810
From: South Carolina
Take what the previous owner said about the engine with a healthy dose of skepticism..
The only way to know what you have is to disassemble and inspect.
Is the bike in running condition?
The only way to know what you have is to disassemble and inspect.
Is the bike in running condition?
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,168
Likes: 7,676
From: Poolville
Agree with Dan... Enjoy it and ride it or take it apart.. You can also do a compression test and then pull and identify the cam, it's one way of figuring out what you have in the motor.. Also most commonly when people put bigger valves in the head, go stage 2 or whatever for the evos it's usually a 1.90/1.63 Or they just leave the exhaust valve alone..
.
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Stellar HDF Member
Joined: Apr 2016
Posts: 3,339
Likes: 2,127
From: Masshole
Previous seller probably said 10 over, which is not 10%. It means the cylinders were bored 0.10 over stock size which is common with a top end refresh. It is not done for performance. It also does not significantly change your engine size, it does a bit, but not much. Valves in the heads, only way to find out is tear it apart and measure them.
Seasoned HDF Member
Joined: Oct 2019
Posts: 10,881
Likes: 7,510
From: OH
Hello everyone.
I recently purchased a 1988 FLSTC, it's got a 1340cc Evolution.
Come to find out the original owner had it bored out 10% and had bigger valves put in. He doesn't remember the size of the new valves.
So my new questions are, does boring out the cylinders 10% mean each cylinder or 5% each one, and what would that change the engine size to?
Then, what size valves would have to be installed?
And would boring out the cylinders mean bigger pistons?
I know, it's a mess.
Any help would be great.
Thanks, Bob
I recently purchased a 1988 FLSTC, it's got a 1340cc Evolution.
Come to find out the original owner had it bored out 10% and had bigger valves put in. He doesn't remember the size of the new valves.
So my new questions are, does boring out the cylinders 10% mean each cylinder or 5% each one, and what would that change the engine size to?
Then, what size valves would have to be installed?
And would boring out the cylinders mean bigger pistons?
I know, it's a mess.
Any help would be great.
Thanks, Bob
Are you hoping for different responses by asking a second time ?
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