45" bobber build

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45" bobber build


Post by longjon » Fri May 13, 2005 6:12 am

Been around harleys for years but just aquired a clean 52 45engine my question might make some of you cringe but isit possible to mate this engine with big twin trans and primary if it was going into a custom built frame?? ...i know you can with the big flatties???

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Re: 45" bobber build


Post by junker » Fri May 13, 2005 4:06 pm

not sure about that .but the old british bsa trannys will fit in with out modifing the old frame so you can go back to stock.i was always told by my mentor if you have a welder and a grinder anything is possable.but you dont want to cut uo anything you cant get just anywhere.just want to ride.

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Re: 45" bobber build


Post by warpony » Sat May 14, 2005 3:05 am

your right about the old limy stuff, but with a little help,you can fit an old 55 side valve 4 speed ,but you need to match up a left side 74,80 rear wheel . this takes a lot of shimming, new bearings to make if work. due to axle sizes.. but if you do the math on sprockets, then you can get at least 15 more mphs top end easly. research the old 45 racers. i own a 45, bored 40 over. took 60 mils off heads, relieved valev access. runing 32 front sprk. but still a three speed. not fast. but its class. later

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Re: 45" bobber build


Post by Jack_Hester » Mon May 16, 2005 11:02 am

LJ -

I'm planning to mate a 45 engine to a 40's vintage BT 4-speed that I have, all in a custom built frame for LSR. With the 4-speed, I will have an almost limitless selection of gear ratios, tranny sprockets, and mated to a later wheel hub, wheel sprockets. Makes for all kinds of ratios to get the most out of the 45. I just installed my frame jig on a new table that a good friend built for me:


Hope to start at least around Summer.



Re: 45" bobber build


Post by Gene » Mon May 23, 2005 4:45 am

I just discovered this forum and this was the first thread I read, since I'm about to aquire a 45 basket case, and I was interested in the same thing. I was going to refer you to Jack, but I should have known he was already here.

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Re: 45" bobber build


Post by junker » Mon May 23, 2005 2:34 pm

Welcome gene,what kind of 45 are you building solo or servicar?

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Re: 45" bobber build


Post by 45brit » Wed May 25, 2005 7:12 am

you can do it but why bother? the BT trans is far too big and heavy. Use a BSA A10 or M20 transmission for better results, less work and keep the stock frame. Google "BSA M20 Enigman Victory Library" for a whole load of information on this

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