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Discussion Starter · #1 ·
Bike is in stages of disassembly in the garage right now, pieces everywhere but the guts still there for mock-up purposes. Called T&O today to quiz them on some stroker questions. I'd like to swap out my narrow cylinders for some 3 5/8 jugs, and stroke it while i'm in there. T&O said I can go up to 4 1/4 with stock height jugs. I'd really like to do 4 5/8, which needs a jug that is (IIRC) .115 over stock.

Problem is I don't have enough clearance between my boxes and the backbone to go that high. rather than abandoning an expensive idea, what if I had the machine shop mill the same amount off the engine mount perches? there is plenty of meat there, and the castings are plenty strong. would this just introduce strange new problems by moving the engine down? I don't really want to cut and box the backbone to make the space.

Once I get my camera working, I'll start posting some pictures and build plans, and selling the parts I don't need.
 

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It's only 1/8". Before machining the cases, I would double check the frame. It "should" be doable. Worse case scenario, modifying the backbone would be the easiest solution.
 

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Discussion Starter · #6 ·
I think he may be talking about machining the frame mounting bosses on the cases in order to make the engine sit lower in the frame. I don't think that's a good idea.

Bob
Thats exactly what I'm talking about doing. Any reason why its a bad idea.

I'm hesitant to notch the frame, its already been notched some for clearance once. I'm not comfortable enough with my welding skills to notch it myself. I didn't figure the cost involved in milling the bosses down would be that high. the cases look like they'd still have plenty of beef,and it wouldn't cause the engine to hang too low. The skid plate has about 3/4" clearance, so that 1/8" wouldn't cause contact on the bottom, I don't think.

I'm not saying its doable, just that I don't know why I couldn't...
 

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I think you mean 4 1/2" stroke on stock length cylinders? If you have to go through all that extra work why not just leave it at 4 1/2"? With a 3 5/8" bore thats 93 inches isnt it?
 

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Discussion Starter · #8 ·
I think you mean 4 1/2" stroke on stock length cylinders? If you have to go through all that extra work why not just leave it at 4 1/2"? With a 3 5/8" bore thats 93 inches isnt it?
According the guys at T&O, 4 1/4 is the most they can do with stock cylinders. at this point, I have to trust their knowledge, as I don't have personal experience in the matter. 4 1/4 would give me 88ci, while 4 5/8 would give me 96. i didn't want to get greedy
 

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I'm not saying its doable, just that I don't know why I couldn't...
As long as there's enough material on the cases to remove what you need, the only thing that comes to mind might be a very slight mismatch of bolt holes if you have to bolt up an aluminum primary. 1/8" ain't much, so the slight repositioning shouldn't affect exhaust positioning. I can't say exactly why it wouldn't work, and now that you've made me think it through, I have to say it's an option. I'm just skeptical when it comes to deviating from the tried, true and traditional solutions to the problem.

Bob
 

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I have a set of cases that were machined that way, don't do it. The alternator hits the frame. The bike they came out of had 1/8" plates under the mounts (basically undoing it), and the alt. still hit, because of wear between them (apparently they loosen alot easier than unmachined cases). If you want big, just cut and fit everything and go pay a welder a coupla bucks to ensure it's strong, don't mess with your cases, really!
 

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Discussion Starter · #11 ·
As long as there's enough material on the cases to remove what you need, the only thing that comes to mind might be a very slight mismatch of bolt holes if you have to bolt up an aluminum primary. 1/8" ain't much, so the slight repositioning shouldn't affect exhaust positioning. I can't say exactly why it wouldn't work, and now that you've made me think it through, I have to say it's an option. I'm just skeptical when it comes to deviating from the tried, true and traditional solutions to the problem.

Bob
I'm running an open primary, so that shouldn't be a problem

I have a set of cases that were machined that way, don't do it. The alternator hits the frame. The bike they came out of had 1/8" plates under the mounts (basically undoing it), and the alt. still hit, because of wear between them (apparently they loosen alot easier than unmachined cases). If you want big, just cut and fit everything and go pay a welder a coupla bucks to ensure it's strong, don't mess with your cases, really!
I'm running a genny, so the alternator clearance isn't an issue, I'll double check around the engine cases and see if there would be any more potential clearance issues. The other question is if I can find a machine shop willing to do the work.
 

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Well, here's another: belt tension. Another: you can't run an "S" pipe, How about foot brake clearance?, Rear pipe to kicker, I'm sure I could \think of more, AND if you have reasons why none of this matters, just remember that it's permanent. There's no turning back. The frame is the easy and obvious way to clear a stroker motor, and the way you're considering is not a good idea.
 

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3 5/8 bore with 4 1/2 stroke= 93cu
3 5/8 bore with 4 5/8 stroke= 96cu
3 5/8 bore with 4 3/4 stroke= 98cu

Stock stroke on a 80" shovel is 4 1/4" I have 4 1/2 wheels on stock length cylinders, make it a 93" and skip all the extra hassle your figuring. A 93 will more than likely do everything and more your wanting, you would probably get more out of it with some good head work, proper cam selection and setting the deck up tighter than the extra stroke.
 
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