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  1. #1
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    Default 45 flathead rebuild cost/ideas

    I've been building a little cut down 45 flathead and just found a motor from a guy outta state for a good price(and he threw a trans in for free!). I wanna do some hopping up on the motor, but am not very experienced and only really know of getting a bigger(wla) manifold, port the heads, bigger valves and heavy duty springs, maybe lighten the flywheel. I don't want a racer, just a 45 with a little more pep.

    I am thinking about sending it to Steve Lemay, but am unsure if I can get away with doing more at home, or if I should just have him do it all. Ive never rebuilt anything and am not sure what to expect, or how I can possibly save a little cash. I got the 45 to have a more hands on bike, but also don't wanna lose my head on it cause I wanna get it going and am busy working on everything else for it. But I want a really solid bike when I'm done.

    Any thoughts appreciated.

  2. #2

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    big valves are modified 235 (or 216 cant remember)chevy intake 6 cylinder. Or get bolt in oversize ones to your specs from Ferrarea (spelling) Also ironhead sportster lifters are lighter then the solid 2 hole 45 ones and are a bolt in but ya gotta change the adjuster screw from cupped to flat top. Leineweber can regrind your cams or you can buy egg lobes from enfield racing, price about the same except with the eggs you gotta grind old lobe off and get new lobe pressed on and timed and welded. Eggs by them selves and the Leineweber regrind both about 600 bucks, K model pistons pop up but you gotta releive the head. Also head fitment is critical with bigger valves you can slam the head down and now it wont turn over. Valve hitting edge of the head.
    Last edited by flatman; 04-19-2022 at 9:29 PM.

  3. #3

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    At the very least get the flywheel / rod assembly rebuilt balanced and trued by somebody that knows how to do it. Light weight valve spring collars (or scallop stock ones) and heavier springs enfield sells and am sure others (cycle mos?)do also. 45 books from Victory are good reading. Also the Jerry Branch kr artical at the beauty of speed web site. Rumor has it the newer repop wldr cams tolerances are a wee bit to big. By the time you get the 4th cam in it dont fit. Just a rumor I had heard. Got a set when they first came out years ago and no problems bolted right in.
    Last edited by flatman; 04-19-2022 at 9:18 PM.

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    Thank you so much flatman. I have the victory book, but always getting a second opinion on everything. I'm glad you mention the "at very least, get someone to balance flywheel/rods...". I'm trying to justify sending it to someone else, so the balancing seems like a good reason to.

    From what I've heard from all the old timers is that just about every 45 was treated like absolute shit since nobody thought anything of them. The guy I'm getting the motor from is saying he got it on a trade and it's been sitting around for years, so I figure it's smart to assume the worst..?

  5. #5

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    bought a 45 about 10 years ago that was rebuilt (arent they all) by the hottest shoe to ever live. Did not run at the time only needed a battery. Sound familiar? I knew it was toast when I got it and that the guy was full of shit. Got home fired it up and started knocking like a cop at your door at 2 am. Took it apart. Heads were relieved. I thought we got a good one maybe. Took lower end apart and the crank pin was so worn out at the rollers it let the rod piston assembly go up about an extra 1/8 inch. The head was not flycut it was the piston banging on the head. And looked like it had been for some while. Also remember all big twin flathead harleys and indian chiefs are 80 inchers. LOL Also have purchased several NOS crankpins, after removing the cosmoline they were rusty and unusuable. Beware and careful.
    Last edited by flatman; 04-19-2022 at 11:05 PM.

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    I would absolutely encourage experimentation, but the tools required to do the job right make the entry fee to rebuilding harleys at home pretty steep.

    You have the Victory stuff. Check out the "Tatro Machine" channel on youtube. He does a lot with the 45 and has a real love for it. Also, the factory service manual. That will tell you right off how much rebuilding you really want to do yourself, and how much you want to sublet to someone else. There's a couple of people on this forum who have commercial shops that can probably do anything you don't want, or can't afford, to do yourself.

    I think that, at a minimum, you need some measuring tools before you do or rebuild anything and you need to be able to measure down into tenths. Cheaper ones from Amazon or somewhere are fine (This sort of thing has come a long, long way in the last decade or so.), but unless you can accurately measure something, you can't determine what needs to be done to it.. If it it out of spec, or by how much? Rebuilder endeavors really begin with measurements, so you need a mic set and a dial bore gauge. Even if you just want to have the machine work done by someone else, you can't double check their work or do proper assembly without them.




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    Is there any modifications to watch out for? Sounds like a weird question but I keep reading that stroker motors decrease engine life by a bit. I don't understand why they would, maybe just the rings life I would think I figure there's always something to learn, so does anyone have an opinion on what a nice hotrod job would include. The victory book lists alot of stuff and I also don't wanna spend a ton on the motor...some, yes, but it's not a racer.... Looking for a decent hot runner where I'm not doing everything I can for every little bit of power. Much appreciated so far on the replies

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    Piston speed at the same rpm with longer stroke is higher the old short hand formula is Maximum Piston Speed (fpm)=((Stroke x ?)/12)x RPM., plus the added heat, plus the added side thrust on the piston, plus the need for a shorter piston, plus the naturally higher compression! That said all the flatties I ride are strokers except the race bike and the class breaks for vintage salt racers would make my Scout run against Triumphs Nortons etc. If I rode a Hardly 45 it would be stroked with a medium cam.
    Dusty

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    Here is a fairly simple look at the changes from added stroke. https://www.enginebuildermag.com/201...04%2C333%20fpm.
    Dusty

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    Wow, thanks Dave. That was a good read.

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