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Discussion Starter · #1 ·
Just starting a triumph build, long and low stance. I am new to triumphs, but very into restoring/kustom motorcycles. Looking for some info on engine choices for my 1956 triumph frame. I'v been searching around, and it sounds like my best bet would be a TR6 engine. I need something with good power, big bore is looking good. Any and all input will be appreciated.
 

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TR6 is unit construction, the '56 frame is for a preunit construction engine and transmission. Which '56 frame do you have?
 

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Discussion Starter · #3 ·
Umm.. I might have to check the numbers again. I thought it came up as a 1956 TR6 thunderbird 650. Could that be right? I'll go check the numbers right now, and post.
 

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If it's a pre-unit frame, it's not supposed to have a model designation on it- just numbers. If it does, someone messed with it. You should only see model prefix on unit frames. On 50's and later Triumphs, the motor should have the same numbers as the frame, but with a model prefix (i.e. motor number TR6 020611, and frame number 020611).

Thunderbirds models were slower than the other 650 models because they had low compression and skimpy cams, but were easy to start and reliable. The Trophy 650 (TR6) had more power and only one carb to deal with. The Tiger 110 had a similar or same motor as the TR6 depending on the year, but was more of a touring model. The Bonneville was the dual carb, fastest model, but you'll spend big bucks on a pre-unit T120 motor because the Triton guys like them. You can easily take any other 650 model and install cams, high-comp pistons, and a dual carb head and make it go like a Bonnie. You're better off with the mid-50's and later big-bearing cases and a one-piece unit crank.
 

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Throttle, you're in West Michigan, if I were you. I'd talk to Kevin at PT Customs in Burnips Michigan. He knows more about English bikes than anyone I know in the area. And, he has 4 barns/outbuildings full of English parts, including pre-unit engine and gear boxes.
 

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I had a 55 t110, this is the engine the racers would change the head on to accomidate dual carbs, the factory picked up on this and created the Bonneville. It was a kick as engine, that supposedly would do 110 MPH even with the single Carb. I think that was a stretch, but mine would hit 90. Easy to work on, though the mag dyno was pain to get sorted out.
 

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I had a 55 t110, this is the engine the racers would change the head on to accomidate dual carbs, the factory picked up on this and created the Bonneville. It was a kick as engine, that supposedly would do 110 MPH even with the single Carb. I think that was a stretch, but mine would hit 90. Easy to work on, though the mag dyno was pain to get sorted out.
Yup- my '55 T110 with the original 5-fin iron head screams, but I think it would lose steam around 100mph. It's got dual 376/40 Monoblocs mounted on early Webco dual carb adapters, a Joe Hunt mag, and the cams do not sound stock. I'm dying to crack those cases open and see what's in there.
 

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...all the pre units 500 and 650 are:
the old 6/1 model, the 5T, T100, TR5, 6T, TR6, T110, T120

-The TR6 is the Trophy 650
the TR5 is the Trophy 500
 

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I think I have a set of 1956 T110 650 cases I would let go if you want a set that are the same year as the frame (not that it matters really). PM me if you are interested. Any set of big bearing 650 cases would be fine to use, and should be easy to come by on ebay, swap meets or craigslist.

-Shaggy
 

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Tr6 Pre unit manufactured 1955/62, was originally a 650 version of the 500 trophy, basically a single carb version of the bonnie. easy fix putting twin carb head on, but if you don't set the twin carbs up right (can be tricky) theres not much in it and alot less hassle with one carb to set, but two look a hole lot better
 
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