2004 88ci Rebuild advice
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2nd Gear
Joined: May 2019
Posts: 6
Likes: 0
From: New Zealand
What do you mean bore the casings? To fit a newer style crank?
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Joined: Apr 2019
Posts: 58
Likes: 12
From: Western New York
Not that. If you need to change out the crank/flywheels assembly then you have an opportunity to to bore the cases where the spigots fit. That leaves room for cylinders.over 4inches go with the longer stroke so you can get to 113, 117 or bigger. Look at Axtel for kits. The best running motor will have similar bore to stroke ratio called "square" or close to it. They are faster reving and more reliable than long stroke motors.
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Joined: Apr 2019
Posts: 58
Likes: 12
From: Western New York
Grand HDF Member
Joined: Nov 2009
Posts: 4,315
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From: Tampa
In my opinion, boring the cases is taking the engine to an unnecessary extreme for a daily rider. I've done two Harley engines with case boring to get mad cubes (88" Sportster and a 106" Evo) and both of them were wicked quick bikes, but their "streetability" fell and made them not very enjoyable bikes to ride for the long run. Not to mention, I'm having the damndest time keeping the 106" Evo from melting pistons.
You can get 110" from the stock Twin Cam cases with the stroker crank and the latest technology of piston/cylinder combinations from many of our forum vendors who build engines for a living. Check them out, you'll have more than enough power and you won't need to send your case away for boring to allow for the larger bore cylinders of anything greater than a 110".
You can get 110" from the stock Twin Cam cases with the stroker crank and the latest technology of piston/cylinder combinations from many of our forum vendors who build engines for a living. Check them out, you'll have more than enough power and you won't need to send your case away for boring to allow for the larger bore cylinders of anything greater than a 110".
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Joined: Sep 2009
Posts: 3,569
Likes: 624
From: deland,florida
In my opinion, boring the cases is taking the engine to an unnecessary extreme for a daily rider. I've done two Harley engines with case boring to get mad cubes (88" Sportster and a 106" Evo) and both of them were wicked quick bikes, but their "streetability" fell and made them not very enjoyable bikes to ride for the long run. Not to mention, I'm having the damndest time keeping the 106" Evo from melting pistons.
You can get 110" from the stock Twin Cam cases with the stroker crank and the latest technology of piston/cylinder combinations from many of our forum vendors who build engines for a living. Check them out, you'll have more than enough power and you won't need to send your case away for boring to allow for the larger bore cylinders of anything greater than a 110".
You can get 110" from the stock Twin Cam cases with the stroker crank and the latest technology of piston/cylinder combinations from many of our forum vendors who build engines for a living. Check them out, you'll have more than enough power and you won't need to send your case away for boring to allow for the larger bore cylinders of anything greater than a 110".
boring the cases or going big inches will have no negative effects on reliability.the way the motor is built will.a small very aggressively built motor will give same problems as a large aggressively build,best way to reliable HP/TQ is a big,mildly built motor.a VERY mild 124" will yield 135+/140+ and have much better reliability & longevity than a smaller motor doing the same HP/TQ
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Joined: Apr 2019
Posts: 58
Likes: 12
From: Western New York
You make some good points Mattbastard. It was mentioned that the Timkin would be a good idea. If that is done is where my suggestion comes in.
I know a guy that had a twisted crank so he did the Timkin upgrade and bored the cases while it was at the shop. This was planned out build.
Here is what he ended up with; 4.375 stroke, 4.125 bore, flat top pistons, 91cc heads with .045" gasket, woods 777 cams, 55mm TBI. = 117 cu\in. Corrected compression works out to about 9.5:1. His HP/TQ numbers are both a bit above the one per cube ratio.
This bike runs as close to a '72 500 cu\in Cadillac as you can get in a TC. Smooth and powerful.
I'm sure 4.375 stroke, 4.0 bore 110 would be a good rummer too and cost less.
I know a guy that had a twisted crank so he did the Timkin upgrade and bored the cases while it was at the shop. This was planned out build.
Here is what he ended up with; 4.375 stroke, 4.125 bore, flat top pistons, 91cc heads with .045" gasket, woods 777 cams, 55mm TBI. = 117 cu\in. Corrected compression works out to about 9.5:1. His HP/TQ numbers are both a bit above the one per cube ratio.
This bike runs as close to a '72 500 cu\in Cadillac as you can get in a TC. Smooth and powerful.
I'm sure 4.375 stroke, 4.0 bore 110 would be a good rummer too and cost less.
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,116
Likes: 7,640
From: Poolville
You make some good points Mattbastard. It was mentioned that the Timkin would be a good idea. If that is done is where my suggestion comes in.
I know a guy that had a twisted crank so he did the Timkin upgrade and bored the cases while it was at the shop. This was planned out build.
Here is what he ended up with; 4.375 stroke, 4.125 bore, flat top pistons, 91cc heads with .045" gasket, woods 777 cams, 55mm TBI. = 117 cu\in. Corrected compression works out to about 9.5:1. His HP/TQ numbers are both a bit above the one per cube ratio.
This bike runs as close to a '72 500 cu\in Cadillac as you can get in a TC. Smooth and powerful.
I'm sure 4.375 stroke, 4.0 bore 110 would be a good rummer too and cost less.
I know a guy that had a twisted crank so he did the Timkin upgrade and bored the cases while it was at the shop. This was planned out build.
Here is what he ended up with; 4.375 stroke, 4.125 bore, flat top pistons, 91cc heads with .045" gasket, woods 777 cams, 55mm TBI. = 117 cu\in. Corrected compression works out to about 9.5:1. His HP/TQ numbers are both a bit above the one per cube ratio.
This bike runs as close to a '72 500 cu\in Cadillac as you can get in a TC. Smooth and powerful.
I'm sure 4.375 stroke, 4.0 bore 110 would be a good rummer too and cost less.
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