Form & Function

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At the risk of being provocative. Which engine makes the better Triton, unit or pre-unit? Logically the later engine has advantages brought on by additional years of development, but if you’re taking a Dominator engine out of a Featherbed frame you’re probably not motivated by logic. I don’t own a Triton. Asking for a friend.
 
I am going to say the Pre Unit looks better visually.
The large bearing Pre Unit bottom end can have a later model one piece crank shaft added and later 9 bolt top end for the best of both worlds.

 
As TW says, pre unit looks a lot better as it fills the frame. Especially when not using a stock primary case cos then you can pretty much space out the engine and box at will. If using a stock primary case, the long ones are better.

This has functional benefits too as the distance twixt engine and box in the featherbed also helps get the best balance between gearbox output sprocket location at the rear (for good chain run, best chain life, etc), and engine position at the front (for handling).

But, unless you’re using after market strong cases etc, the unit design is much stronger both in terms of the crank case and gearbox case.

As to whether the extra strength is required is of course largely dictated by the bikes state of tune and intended use. A mildly tuned road going 650 / 750 used as a ‘classic’ is highly unlikely to need the extra strength.

If using a unit motor, a skilled and careful builder will still get good handling and chain life. If the builder doesn’t possess the design skill, he / she should buy plates from someone like Dave Degens at Dresda.
 
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Thanks TimeWarp and Eddie, I'm trying to influence a friend to find a pre-unit motor for his very nice Triton. It's a tricky business , in the 60's and 70's the unit motors may have offered a meaningful improvement over pre-unit, but viewed on the vastly expanded scale of motorcycle performance in the 60 years since there can't be much between them . I imagine "the look" and mystique of the Triton is what most owners and admirers appreciate. The visual complexity of the pre-unit motors and gearboxes is a big part of that.
T ingermanson's Triton shown recently is a real beauty, right down to the (already noted) Francis Beart inspired color scheme. He's done a great job of updating various features without resorting to jarring anachronisms, well apart from the four piston calipers.
 
As TW says, pre unit looks a lot better as it fills the frame. Especially when not using a stock primary case cos then you can pretty much space out the engine and box at will. If using a stock primary case, the long ones are better.

This has functional benefits too as the distance twixt engine and box in the featherbed also helps get the best balance between gearbox output sprocket location at the rear (for good chain run, best chain life, etc), and engine position at the front (for handling).

But, unless you’re using after market strong cases etc, the unit design is much stronger both in terms of the crank case and gearbox case.

As to whether the extra strength is required is of course largely dictated by the bikes state of tune and intended use. A mildly tuned road going 650 / 750 used as a ‘classic’ is highly unlikely to need the extra strength.

If using a unit motor, a skilled and careful builder will still get good handling and chain life. If the builder doesn’t possess the design skill, he / she should buy plates from someone like Dave Degens at Dresda.
Pre unit is the only proper way to go with a Triton IMO
But I would add to this the motor should have an oil seal conversion on the timing cover with a unit top end as a minimum
After that it's morgo barrels ,5 speed box ,belt drive, decent clutch and on and on
 
Why not build a Commando motor in the Featherbed and keep it all Norton, if done right will be the better option, but of course I do know this is all about Triton's.
Form & Function
 
At the end of the day, both unit and pre unit can be made to work well and look good.

They can also be made to work horribly and look awful !

The only Triumph twins that don’t work in a featherbed are the ‘small’ C range 350 and 500 unit motors, there’s space for three or four of them in a featherbed !

Generally speaking, a Norton engine is a poor engine choice for a featherbed Triton…
 
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