103 upgrade. Worth it?
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Joined: Nov 2007
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From: SW Oklahoma
Cruiser
Joined: Dec 2008
Posts: 146
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From: Boise Idaho
After reading all the great posts about how to do a cam swamp I am planning to take on that project. Now I am thinking about doing the 103 since I will already have the top off to get the pushrods out.
Would I be crazy to try to swap pistons and jugs myself? The manual shows a special tool to get the circlips out but other than that is there anything about the 103 kit that I should be weary of trying?
I am cheap but also mostly just like the satisfaction of working on the bike. Anyone in Boise area have a bearing puller they want to lend or rent when I get ready to do this?
Would I be crazy to try to swap pistons and jugs myself? The manual shows a special tool to get the circlips out but other than that is there anything about the 103 kit that I should be weary of trying?
I am cheap but also mostly just like the satisfaction of working on the bike. Anyone in Boise area have a bearing puller they want to lend or rent when I get ready to do this?
Outstanding HDF Member
Joined: Jul 2007
Posts: 3,341
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From: Woodinville, WA
Personally I'd go with the ACRs if you are going to build up the compression as the previous poster with the 10.5 CR was suggesting. I'd hope a self respecting dealership would have the tool and if they don't it should be on them to get one! With ACRs you can just forget about it which is kinda handy if you're anything like me. At the same time I wouldn't increase the compression if I were you. I have a 2001 Fatboy that I did the equivalent build on and while it's a great bar hopper I don't consider it highly reliable and now with the mileage I have on that build I'm starting to worry about the bottom end - which I probably wouldn't be if I'd left the compression alone. It all depends on what you're after though. Good luck!
Last edited by davessworks; Mar 5, 2010 at 11:39 AM.
Road Warrior
Joined: Jun 2007
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From: Here
That special circlip tool is as easy (easy is a relative word of course) as a pick that you probably already have to get them out. Then a flat blade screwdriver and strong thumbs to put the new ones back in.
Outstanding HDF Member
Joined: Jul 2007
Posts: 3,341
Likes: 9
From: Woodinville, WA
After reading all the great posts about how to do a cam swamp I am planning to take on that project. Now I am thinking about doing the 103 since I will already have the top off to get the pushrods out.
Would I be crazy to try to swap pistons and jugs myself? The manual shows a special tool to get the circlips out but other than that is there anything about the 103 kit that I should be weary of trying?
I am cheap but also mostly just like the satisfaction of working on the bike. Anyone in Boise area have a bearing puller they want to lend or rent when I get ready to do this?
Would I be crazy to try to swap pistons and jugs myself? The manual shows a special tool to get the circlips out but other than that is there anything about the 103 kit that I should be weary of trying?
I am cheap but also mostly just like the satisfaction of working on the bike. Anyone in Boise area have a bearing puller they want to lend or rent when I get ready to do this?
Ultimate HDF Member
Joined: Aug 2008
Posts: 5,413
Likes: 17
From: eastern oklahoma
in reference to automatic vs. manual compression releases. the automatic compression releases require an overlay harness which plugs into your main wiring loom. not a big deal, but where the compression releases are, means they're very hard to get to if you need to service them. the manual compression releases on the other hand, are right next to your spark plugs, so if you need to service them or have to replace them, it's as easy as swapping spark plugs. i know that the automatic ones, are in the top of the motor under the rocker covers if i'm not mistaken, meaning you'd have to tear the top end of your motor apart to get to them. with manual compression releases, it becomes second nature to push down on them when starting the motor. besides it's cool to have something to do while the yellow light goes out letting you know that your motor is ready to start. i hope this is helpful information.. the kit i did has only been out a few weeks or a month if that... to do it again, with those 259E cams, is a no brainer. loads of torque, and the torque continues to climb from 87 ft lbs at 1800 rpm's to 5500 or so. no peak where it drops off, and better yet, no dip when it's at 2,000 rpm's like many cams. linear torque which increases throughout the band rocks. it just pulls like a pissed off gorilla from idle to redline, as does the horsepower line on the dyno sheet. i'm very impressed. you can find it in harleys site, it's part number 27544-10. it's in the supplimental screamin eagle catalog which just came out. one more suggestion, while you're in the primary changing out the clutch spring for a heavier one, the screamin eagle compensator makes a real difference, as the stock one seems to be a weak link in the drivetrain.
I did the Stage II kit 103 w/ 255 cams with the Vance & Hines Pro Pipe Hi-Output and SE A/C and SERT. Had them put the MCR's in, hopefully get the bike next week. Bought the damn thing new on the 2-6-10, don't even have it home yet..
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Ultimate HDF Member
Joined: Feb 2007
Posts: 7,663
Likes: 7
From: Northeast Ohio
Huh? You have to pull the engine to go to 110" so the cases can be bored to accept the larger cyls. 107" is the upper limit without case boring. And the cost is nowhere near the same as you can easily double the labor charge plus the boring cost and extra gaskets, et.
If you are cooking the oil, the engine is running too damn hot and needs retuned or may have other problems. There are many 113", 117", 120" and 124" engines built up from the HD cases. I built mine, and have 35,000 miles on it and just pulled it down to check all items. Nothing worn so I just threw in new gaskets and put it back together. I know of many others with similar experiences. A well thought out large displacement engine that is not "overbuilt", meaning for race applications will last a long , long time without issues. And, I built the HQ 120 for about $3k less thatn the Jims and it will also out perform any Jims out of the crate.
I am not sure if your original question meant you were just going to do the big bore and nothing else? If so, the gains are not all that appreciable, but you will notice a difference. You asked, what else might you do:
Heads - have them reworked by a pro
Pistons - bump the compresin up to 10.0:1 or 10.5:1 depending on cam selection
Cams - Go with a midrange cam and the increase power will pull the bike along in the lower rpm and will really shine higher in the rpm range.
If you are truly thinking about going further than just the HD big bore kit, take a look at other aftermarket kits and builds. I prefer Headquarters, but there are many others and you end results using aftermarket kits will far outshine an all HD build. Check Headquarters, ProTwin, Hillside, GMR, T-Man, all have websites,
Never hurts to expand your horizons !
bringing it out to 110 has three drawbacks. actually four. 1=gotta split the cases, expensive. 2=cylinder studs are dangerously close to the bore, as are the drainback holes, and "coking" can occur, meaning that the oil can cook while it's draining back down the drainback holes. 3=you can get a 103" to run strong, reliably, and for much less money than splitting the cases. 4=i'd think that the 110 would be so near the cost of a jims 120" motor which is designed with thicker cases, and wider cylinder stud spacing, built for the "too big" of a bore for the mechanical limits of the cases harley makes.
Thanks for the awesome advice guys! Keep it coming!
Yeah, I'm running a H-D SE ventillator breather and V&H dresser duals with monster ovals, so I don't need the breather and pipes in the kit.
I'm at almost 4k on the odometer so I'm thinking that when I take it in for my 5k service it would be a good time to bump it up to 103.
Any other mods you really recommend while I'm having it done?
Yeah, I'm running a H-D SE ventillator breather and V&H dresser duals with monster ovals, so I don't need the breather and pipes in the kit.
I'm at almost 4k on the odometer so I'm thinking that when I take it in for my 5k service it would be a good time to bump it up to 103.
Any other mods you really recommend while I'm having it done?
Heads - have them reworked by a pro
Pistons - bump the compresin up to 10.0:1 or 10.5:1 depending on cam selection
Cams - Go with a midrange cam and the increase power will pull the bike along in the lower rpm and will really shine higher in the rpm range.
If you are truly thinking about going further than just the HD big bore kit, take a look at other aftermarket kits and builds. I prefer Headquarters, but there are many others and you end results using aftermarket kits will far outshine an all HD build. Check Headquarters, ProTwin, Hillside, GMR, T-Man, all have websites,
Never hurts to expand your horizons !
Thread Starter
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Road Master
Joined: Feb 2010
Posts: 850
Likes: 8
From: Tennessee
i'm thinking of going with a gearset and cams from S&S. If I go with the 510 I would stay at 96 CI and just maybe do a port & polish. OR I could go to the next bigger S&S cams (with gearset) in addition to bumping it up to 103. Hmmm.... Decisions, decisions...