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Discussion Starter #1
bought an old triumph pre-unit hard tail chop a while ago and went about taking it apart and restoring it,now im having a hard time identifying the engine components, the engine number is 21 H 3925 and the inner primary is stamped T 1601. the engine was a 650 but ive fitted a morgo 750 kit and electronic ignition. i need to get a primary chain but cant find the right one for it,it takes a simplex chain which doesnt make sense to any suppliers ive asked,they all say it should be a duplex..
any help please?
 

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A simplex primary chain is probably 3/8 inch pitch. I bought mine a year or two ago at the local Yamaha dealer; I think it's Japanese, don't remember the brand, but it has EK428 stamped on every link.

T1601 on the inner primary is a part number.

Cheers,
Neil.
 

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Discussion Starter #5
yup,going by the engine number its a 3ta from around 1958 (not a 1962 t120 as i was told...) . only thing is they had a duplex primary chain..so the primarys off something else again.. do the 3ta's have the same crank as a 650?just wondering if it can handle the 750 kit now...
 

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. do the 3ta's have the same crank as a 650? just wondering if it can handle the 750 kit now...
No, do not think the 3TA has the same crank or bearings as a 650. Wisdom was that a 3TA could be taken to 500cc but not beyond. Even a 650 bottom end needs to be in top condition to take 750cc.
 

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Discussion Starter #7
unless the only remaining bit of the 3ta is the casing and theres a 650 crank in it..possible? werent the 3ta's unit construction?
 

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Discussion Starter #9
id say youre right, makes it even harder to know what it is though,unless it really is a '62 t120.. and the primary's off somethin else..
 

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Discussion Starter #11
yep,thats probably whats goin on here. panic averted:) gonna look into the chain loctitekid suggested,fingers crossed..
 

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All pre-units used simplex chain, the duplex did not arrive until the advent of the unit motor. I suspect it is a re-stamp. All 3TA engines are unit construction from '57, so if it is pre-unit it is no 3TA! The single chain is no big deal, you should be able to get it about anywhere. I used to buy Diamond branded by the roll at machinery supply houses. Haven't tried for a while though!
Robbie
 

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Discussion Starter #14
ok,im going to order a simplex chain thats for the t120 and t110, i dont suppose theres much difference in the size of the primary and length of the chain..
thanks!
 

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ok,im going to order a simplex chain thats for the t120 and t110, i dont suppose theres much difference in the size of the primary and length of the chain..
thanks!
I ordered the 'correct' endless chain for my 59 pre unit only to find I had to remove a couple links and add a master link! At least it was too long rather than too short,now most of my chain is purchased at a local industrial supply company. If you have a sample they can measure the pich etc. & match it. Same for drive chains & bearins'
 
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