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Hi everyone,

I have a 2009 Speedmaster and am looking at removing the tach (as it is starting to fail) and replace it with the cover that usually comes with the America.
Furthermore, I wanted to remove the idiot lights from their housing and use the holes to add switches to operate (aux lights, garage opener, etc)
That being said, I was hoping to see if the instrument clusters from a Bonneville or Thruxton will work on the Speedmaster as long as I have appropriate mounting systems/brackets.
Has anyone made a conversion like this?

Thanks
 

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If you have a mechanical speedo driven by a cable to the front wheel then any mechanical speedo from a Bonneville will work Haven't a clue if you have an electronic speedo. As for the tach, ditto, plus Bonnevilles have a different firing order so that may affect things. FYI Scramblers have the same firing order as your Speedy.
 

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How can another 2 cylinder motor have a different firing order?

:dunno Is it 1-2 or 2-1? :dunno
 

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(It was kind of tongue-in-cheek)
But the firing order is still 1-2
 

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(It was kind of tongue-in-cheek)
But the firing order is still 1-2
I thought it was 2-1, 2, 1-2, 1, 2 but then I used to be a roadie back in the 70's. (Also tongue in cheek, life is too short otherwise)
When I bought the mini tach to go in my headlamp bucket it seemed the ones for V twins were different to other twins, but I needed a V twin one because of the "firing order". Best part of 10 years ago and my brain is a bit foggy these days so don't take it as gospel.
There's probably somebody on one of these forums that has put T100 or Thruxton gauges on a Scrambler so if they work properly that would answer the question.
 

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The taco realistically is only there for looks. As it is out of your line of sight and useless as a reference gauge, as you need to look away from the road to check it.
 

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True there are 2 different firing engines in the Bonneville. I don't think that will effect your tachometer though. Tachometers usually just look at #1 cylinder. They DO need to know how many cylinders however. (Four rotations of the engine equals two cylinders). I am 90% sure a tachometer from a 270° engine with work on a 360° engine and the other way round as well. If you have a EFI bike, I would stick with an EFI tach to be on the safe side. ...J.D.
 

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Don't need to know anything other than if the engine uses wasted spark technology, which the Bonny does. Each cylinder 'fires' every revolution. The 360 engine has only one coil (because it can), and the 270 has of course two. So select a tacho where one pulse equals one revolution. Harleys are the same so they are very common.

As far as interchangeability between 270 and 360, I'd be pretty confident the OEM tach takes its pulses from just one cylinder on the 270, so no problem.

Cheers.
 

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Good point Nick: I had forgotten about the wasted spark thing. 360° engines use it, but 270° engines use two seperate coils and the cylinders only fire once each, independent of each other. ...J.D.
 

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Without being pedantic the 270 also employs wasted spark technology. There are reams of discussions on the subject in other posts. I only want to clarify this to suggest why a tacho 'should' be interchangeable between the two.

Cheers.
 
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