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Discussion Starter · #1 ·
Hello Everyone,

I am new here, here are some pictures of my current build. Frame is 175cc Honda and front is girder fork. I am thinking to swap a 400cc V engine in it.

Pls share your expert opinion.
 

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I'd love to find a girder fork for my latest 250 project.

No expert opinions on that one though. Insert typical replies about rear suspension travel and front end geometry just to get things started I guess?

Oh, yeah, welcome to the forum and stuff like that too.
 

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Discussion Starter · #7 ·
I am still confused to go for vtwin 400 or 250.. As I have both engine's available at the moment. And this is my first project...
 

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Discussion Starter · #8 ·
Front end is off from an early 40s triumph 3hw.

I know it's going to be a testing / long project.. Will be sharing updates here.
 

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Desmo already mentioned it but there will be a few things that will be reoccurring as a theme here.
The main question is the end result you want. Is this going to be a rider to put genuine miles on or is it more for shows and showing off?

Nothing wrong with either as long as you are under no illusions on what you are building or trying to pass it off as.

Practically speaking though from what i can see:

You're rear tyre will contact that rear loop in operation. Think about how you are going to solve that and how the solution may effect geometry.

The front forks are a very neat bit of history but aren't as good as the ones that would have came with the bike originally. Essentially a downgrade in performance.

The engine swap in theory is obviously doable. But then you are increasing the horse power through a chassis with downgraded breaking and suspension. Which is sub optimal.
 

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If you can find one, go with any Suzuki or Yamaha or even Bultaco 250cc single cylinder 2-stroke engine and it might even be made to work. Given a whole bunch of other new parts including some kind of spring and shock for the antique front forks.
 

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The engine swap in theory is obviously doable. But then you are increasing the horse power through a chassis with downgraded breaking and suspension. Which is sub optimal.
What if he is thinking Briggs&Stratton V-twin engine with no transmission included, because I suspect that is the case.
 

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Have you ever fixed a motor, or at the very least kept something old working?
 

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Would you go with belt drive gas engine
or gas powered electric drive
or gas powered hydraulic drive ?
I'm thinking gas/electric sounds doable if the gas engine is a little power generator.

He doesn't have much there for brakes so it best be light and slow moving.
 

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Discussion Starter · #15 ·
Really appreciate all the information. I understand we need to upgrade brake's.. Maybe disc.

All the weight will be on girders due to riding position so might do some customization on it too.

Will now be swapped with an inline 2 cylinder motor instead of Vtwin.

Hopfully will start working on it from next week, as few small bits remaining for my current triumph t20S.
 

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250 should bolt into the frame. That front end looks like something that might rot from the inside, might want to do some careful inspection. A failure at any speed would not be fun.
 

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Tiger Cub makes for a very nice competitive vintage class trials bike engine. I'd make a second chassis for that engine and swap it out to race it, but that's just me, if I had a working cub engine. The rest of the machine is marginal but still valuable for collectors & builders.
The Honda parts look beyond rough and I rode bikes with 1940's brakes and suspension, they don't do much by modern standards. The proposed bike could never be made street legal with the mismatched front end in most countries, unless the VIN is already plated and on the road, then you might get away with almost anything for a while or until you crash it and your insurance company goes nuts on you for modifying the motorcycle.
 
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