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T140V tuning? #142031 05/27/08 3:41 pm
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Spondoody Offline OP
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Hi Have a T140V 1973. Like the simplicity of the bike and compared to my old 850 Commando it is nimbler. I just miss the extra torque of the Norton and wonder if fitting the 650 cam and a gas flow is worthwhile or not. Phoned 2 UK firms and got different opinions. One said the head is not far off its limit re gas flowing and the cam would make a difference, other said it would pull my arms off which I doubt..
Thanks

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Re: T140V tuning? #142032 05/27/08 4:05 pm
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Blapper Offline
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Fitting the late T120 cams on the T140 gives the best bang per buck, but the commando is quick. Don't forget the gearing too - the Combat with the 19T gearbox sprocket is buzzy as heck but VERY fast off the line.

Blapper redwine

Re: T140V tuning? #142033 05/27/08 4:45 pm
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RF Whatley Offline
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Spud Duty -
Some thoughts....
The largest increase in engine power is gained from the shape of the intake track and the combustion chamber. In this area, the Norton Commando head is one of the wonders of the universe. Most modern bikes don't even breath as well as a stock Norton. In order to even attempt to get this quality breathing on a Triumph you should start with a later model head with the parallel intake ports, ala 1979. Even then, the shape of the Triumph combustion chamber is far from perfect.

Obviously, a huge increase in power is gained by exchanging the 1973 ex camshaft for something like a 1970 650cc ex camshaft. So why did the factory just not do this? The reason is that the bottom end can't accept the added power. Remember that this entire lower unit started life as a 500cc.

And too remember that on a Triumph the camshafts are the last parts to come out of the disassembled engine. Are you sure you want to completely disassemble your engine at the beginning of riding season, miss a large portion of the season, and face other unknown repair charges just to swap a cam? If you don't have a spare 1000 quid laying around, then the answer is probably 'No'.


These issues have been covered here before and a SEARCH might help you with more info. It's also always good to remember that you don't get something for nothing. Engine building is a 2-edged sword, usually equating to something like "more power = shorter engine life".

:bigt:


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA
Re: T140V tuning? #142034 05/27/08 6:18 pm
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dale karger Offline
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he might not want to tear down during riding season but i will be splitting the cases in a few weeks. i am interested in spicing up my engine ...just a tad, nothing too radical. so info on hotter cams, carbs, minor head work are things i need to research.


76 T140V
79 Honda CB 650
79 Yamaha 175 Enduro
68 Chevy Impala Convert
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Re: T140V tuning? #142035 05/27/08 7:10 pm
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Blapper Offline
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Hey Dale,

My choice was just to beef up the main bearings and fit late T120 inlet and exhaust. The std inlet and late T120 exhaust will give more poke up top, but the 3134 gives a stronger mid which is what I want.

Personally, I think after that, and bearing in mind that you still want a reliable engine, it is the law of diminishing returns (cost and labour wise) IMHO.

Blapper redwine

Re: T140V tuning? #142036 05/27/08 7:28 pm
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Spondoody Offline OP
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Thanks guys. I think that has confirmed what I probably knew. I have jsut been out for a ride and it is a very nice bike. I will wait till the end of the season and then decide on the cams.

Have a Lightweight Landrover to finish first....
Cheers

Re: T140V tuning? #142037 05/28/08 9:42 pm
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Peter Jones Offline
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Hehe, Landrovers are as addictive as Triumphs

Re: T140V tuning? #142038 05/28/08 11:39 pm
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dale karger Offline
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Thanks Blapper,

i want a little more guts mid range and top end. thats why i was looking at get it to breathe a little better.


76 T140V
79 Honda CB 650
79 Yamaha 175 Enduro
68 Chevy Impala Convert
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Re: T140V tuning? #142039 05/28/08 11:55 pm
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John Healy Offline
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There is a flow bench manufacturer that mentions in their instruction manual Norton heads specifically. They suggest using one as an example of what can be achieved. There is more horsepower to be lost than gained when an in experienced enthusiasts tries to improve a Norton head.

IMHO unless you have had a lot of experience porting a T140 head you would be better served replacing the valves with standard diameter Black Diamond units, BD or Rowe USA valve guides and doing a three angle valve job and leaving the ports alone. There is a lot of available extra flow, and HP, reworking the area in and around the valve seat. It is something that can be done in a short amount of time, doesn't cost an awful lot and you will want to do this when you do you cams anyway.

I would also get a new set of STOCK valve springs and stronger push rods (don't be afraid if they are heavier than stock). Alloy Tech make a nice set. You might as well get the low cam lift you paid for and it is almost free HP. The stock springs will conrol the valves at the rpm's you will be turning on the street (7,500) and won't eat up some of the HP you are looking for. If the stock springs serve you now, and you are not floating valves and missing shifts I would stay away from heavier valve springs with he stock cam. You can always put them in later when you install that 'big" cam.
Just my opinion...


Re: T140V tuning? #142040 05/29/08 12:08 am
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dale karger Offline
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john,
quote from another thread
_____________________________________________
I am working on a head for a customer right now that someone had installed larger valves into and on the flow bench did not flow 1 cfm more than a head with the stock valves installed because they failed to match the port to the valve. Once the port was matched to the valve the air flow went up 20 cfm measures at 10"of water at three valve lifts so that he will realize a real benefit across the whole rpm range.
____________________________________________


that (quote above ) and some of the experiences i have had with automobile engines is why i was considering porting. what kind of work around the valve seats are you talking specifically about? I used to do valve jobs ( 2 and 3 angle ) for cars so familiar with that but alas... sold the equipment years ago.


76 T140V
79 Honda CB 650
79 Yamaha 175 Enduro
68 Chevy Impala Convert
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Re: T140V tuning? #142041 05/29/08 6:23 am
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Blapper Offline
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Hey Dale,

The advice I got for both mid and top improvement was to leave the Spitfire profile inlet in there and add the late T120 exhaust. Main bearing beef-up necessary of course.

I ran that set-up years ago and it was quick!

Blapper redwine


Moderated by  John Healy 

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