Quality cylinders
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From: Nunya.
If you are starting with a 114" motor with 4.5" stroke you can easily get 120 ci by boring to 4.125" bore. The stock 114" cylinders come with 4.016" bore. The SE 114" cylinders come with approximately 4.07 bore. I know you can take the SE cylinders out to 4.18" bore and that will give you 123.5 ci with the 4.5" stroke. Whether the stock 114" cylinders can be bored that far I'm not sure. If you increase the bore to 4.25" to get a 124" with 4.375 stroke or 128" with 4.5" stroke, there is an orifice in the heads that needs to be plugged, but it not a big deal to do. I don't think it is necessary to plug it with the 4.18" bore, but I could be mistaken.
Using the stock cam will give you cylinder pressures in the 240 psi range. Stock pressures on the 114" motor are around 225 psi. I don't know if that will present a problem or not.
Using the stock cam will give you cylinder pressures in the 240 psi range. Stock pressures on the 114" motor are around 225 psi. I don't know if that will present a problem or not.
Just have to watch the CR is not too high with the stock cam .
Peace.
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From: Massachusetts
I stayed with the S&S 475 cam and stock heads, Jamie said that combo would work best staying under 11:1 CR.
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So, you did for cam choice. I get that, just wanted to verify. Makes total sense for cylinder pressures, Given the weight of these baggers, your path may just be the right way to go
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From: Massachusetts
Yes, I already had that cam installed and I liked the way it made the bike sound as well as the performance. I did however install a set off S&S hi-lift valve springs when I took the engine apart. I figured it would make life easier if I decided to with a bigger cam on down the road.
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From: Berlin, Germany
Does somebody have further Infos regarding those cylinders? Are they resleeved OEM-Cylinders (like T-Man uses for their 124/128 kits) or are they completely aftermarket?
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From: Nunya.
These are the guys https://suburbanharley.com/Parts-Catalog-M8 they'll answer any questions you have.
Peace.
Peace.
Club Member
Joined: Apr 2016
Posts: 11,598
Likes: 8,427
From: Inland NW
These are the guys https://suburbanharley.com/Parts-Catalog-M8 they'll answer any questions you have.
Peace.
Peace.
At 11.0:1 static compression ratio, the 124" with the S&S 475 cam makes the about same cylinder pressure as the 114" with the stock cam does. I really don't see that it is necessary to go with the lower compression with that cam. These M8's deal with cylinder pressure way better than the TC's ever thought about doing.
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