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Re: T140D or E Single Carb Conversion [Re: Steven A] #778770 07/16/19 4:16 am
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That has more to do with the 750 kit on the long rod motor than the single carb. It's something every Triumph enthusiast should experience at least once. Like Mr. Healy states, once the cc's are up to 750 the head starts to work.
I've had a long rod 750 myself, but with twin carbs and hot cam. The throttle would not tolerate rough treatment....the front end would shoot straight up in the air.
However, having said that, the bike was near unridable because of the vibration. It's something that I began to address in my bikes a few years after I had this one. I know I could build an engine with a 750 kit that would be tolerable now, but then I hadn't discovered the secrets.
Also, the five speed isn't really necessary on these bikes either. They're just a much nicer shifting gearbox than the four speed.
Finally, Bill Getty knows how to build a bike that works. I have a Command built by him in the early 80's that still hasn't had the bottom end or gearbox apart and has been in continuous service since then.
Cheers,
Bill


Bikes
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1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
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Re: T140D or E Single Carb Conversion [Re: HawaiianTiger] #778779 07/16/19 5:42 am
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Originally Posted by HawaiianTiger
That manifold TT showed us just might be the ticket.
Bill


It took a couple of attempts to seal the carbs onto it.


Amateur Loctite enthusiast.
Re: T140D or E Single Carb Conversion [Re: Steven A] #778792 07/16/19 10:51 am
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In 45 years of Triumphs, the nicest one is the parallel intake ports T140D with Mikuni flat slides I ride now...I also had a 67 TR6 than ran very nicely...It's my opinion a dual carb bike tuned properly and with a rider who know how to roll open the throttle properly, gives up nothing to the single carb bike at normal road speeds and is faster at high speeds..And dual carbs just looks better...


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: T140D or E Single Carb Conversion [Re: Steven A] #778843 07/16/19 6:34 pm
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Fastest street Triumph I ever saw was a '66 TR6R with a Routt 750 kit and ONE BIG Mikuni carb.

Even with a lengthened swing arm, that TR6 would pull the front wheel up when the rider hit second AND third gear.

Re: T140D or E Single Carb Conversion [Re: Steven A] #778847 07/16/19 7:05 pm
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This has turned into one of the most interesting and informative threads for quite some time - please keep the carb / heads/ ports stories coming!


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Re: T140D or E Single Carb Conversion [Re: Hillbilly bike] #778855 07/16/19 7:56 pm
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Originally Posted by Hillbilly bike
In 45 years of Triumphs, the nicest one is the parallel intake ports T140D with Mikuni flat slides I ride now...I also had a 67 TR6 than ran very nicely...It's my opinion a dual carb bike tuned properly and with a rider who know how to roll open the throttle properly, gives up nothing to the single carb bike at normal road speeds and is faster at high speeds..And dual carbs just looks better...


i just rode this T140D of tony's a week or so ago. it's fantastic.

don't listen to tony. he complains about bogging. he's way picky. his bike has instant throttle response, absolutely zero hesitation on the slides in normal to enthusiatic throttle openings. it's like a correctly-tuned harley-- open the throttle, boom. it's made me look really hard at the VM mikunis i've used for years, that always seemed so much better. until i rode this machine with correctly-set up TM carburetors.

and there's no reversion in his bike either, at least none that anybody but him could detect.


every day you do not take a chance is a day of your life that you will never get back.
Re: T140D or E Single Carb Conversion [Re: Steven A] #778858 07/16/19 8:16 pm
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The parallel port head is only parallel on the outside, once inside you have the angled ports of the TR7 aiming the intake charge at the spark plugs. The TR7 head in turn is just a TR6 head with a modified casting for the 10th bolt hole, added material to the outside of the inlet entry ports to allow room for machining and threading for the steel carb stubs, (which are parallel) and a chamfered combustion chamber lip to match the larger bore of the 750.


The new TR7 head castings as seen on line appears to be the parallel inlet port head casting with the extra intake material still there but machined for the single carb manifold...might be a good head to have for some custom dual carb mods or a... straightened out port … single carb head for better flow than short stock single carb manifold. I wouldn't mind having one with the KB valves and guides and springs but just wonder about the quality of the valve/guide job? Just thinking about things.


Back to the original poster...it would be fairly easy to weld in a couple of flush aluminum plugs to replace the steel threaded in stubs, line up a stock TR6/7 inlet manifold, drill and tap for the manifold studs or use the stock steel stubs and do as Dmadigan suggested. Nothing at all wrong with a torquey, responsive TR6/7 around town which will usually outpull 99% of the ill tuned Bonnies you're likely to come up against.

Re: T140D or E Single Carb Conversion [Re: Steven A] #778865 07/16/19 9:12 pm
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Quote
Nothing at all wrong with a torquey, responsive TR6/7 around town which will usually outpull 99% of the ill tuned Bonnies you're likely to come up against.


In what imaginary world are there TR7 riders torquily responding around town, “coming up against” 99 Bonnevilles!


Amateur Loctite enthusiast.
Re: T140D or E Single Carb Conversion [Re: Steven A] #778867 07/16/19 9:25 pm
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I'll challange any of you with a single carb 650-750 to a 2000 rpm in high gear roll contest...


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: T140D or E Single Carb Conversion [Re: Steven A] #778877 07/16/19 10:41 pm
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This has been a good thread.

Re: T140D or E Single Carb Conversion [Re: triton thrasher] #778895 07/17/19 1:51 am
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Originally Posted by triton thrasher
[quote]Nothing at all wrong with a torquey, responsive TR6/7 around town which will usually outpull 99% of the ill tuned Bonnies you're likely to come up against.


In what imaginary world are there TR7 riders torquily responding around town, “coming up against” 99 Bonnevilles!
[/quote

Maybe I should have said 'Back in my day' a good stock TR6 could take a not so well tuned, poorly synched twin carb T120 a good percentage of the time...just keep turning corners and stay off the freeway. I used to piss off my buddy on his kawi H1 triple with my basically stock stripped downTR6 TT bike, of course I was geared way down so wouldn't even look at a straightaway but in our then undeveloped but paved neighborhoods I'd out drag him from block to block then just turn a corner.

I just wanted to let Steven A know that there is a lot to be said for a good single carb 650 or 750 Triumph twin, one of the best running Triumphs I rode in the 60's was a TR6 Rickman Metisse scrambler with a Chantland 750 kit,34mm vm mikuni and desert torque cams, can't remember the grind and it did run out of steam on top end but anywhere else just open the throttle and go sideways. Nowadays add a little hotter cam and a flatslide and you'd have a fun streetbike.

Re: T140D or E Single Carb Conversion [Re: MarksterTT] #778916 07/17/19 7:11 am
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[/quote
I just wanted to let Steven A know that there is a lot to be said for a good single carb 650 or 750 Triumph twin, one of the best running Triumphs I rode in the 60's was a TR6 Rickman Metisse scrambler with a Chantland 750 kit,34mm vm mikuni and desert torque cams, can't remember the grind and it did run out of steam on top end but anywhere else just open the throttle and go sideways. Nowadays add a little hotter cam and a flatslide and you'd have a fun streetbike.[/quote]

I appreciate your contribution.

Re: T140D or E Single Carb Conversion [Re: Steven A] #778956 07/17/19 4:40 pm
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...seeing your comments seems that depends on what the rider or user is looking. Seems too that most only use the bikes at barely mid range speed or into town and for few kms, hence the perception that the single carbs are better.
I always admitted that the later Triumphs are the best in functionality for the street use. Not the best looking though. The factory was down but they tried to squeeze all of the design, so disregard all that is somewhat dumb.

Then you have the opinions Tony and Kevin here, that are tuning these bikes since long time and race them, then my opinion that is from a daily rider, strong mid range rpm user and "long" distances user. Then you have the opinion of HT that is wrenching the older stuff and some of these and then you have almost all the factories that made all the big engines with multiple carburetors...

Re: T140D or E Single Carb Conversion [Re: reverb] #778980 07/17/19 10:24 pm
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Originally Posted by reverb
...Seems too that most only use the bikes at barely mid range speed or into town and for few kms, hence the perception that the single carbs are better..



I mostly use my singe carb 750 for fairly high speed (80 - 85mph) cruising for hours on end in France with occasional 100mph+ overtakes. Not exactly 'barely mid range speed or into town stuff. I find it performs excellently and gives great fuel economy too. But if anyone chooses to disbelieve, its no skin off my nose.


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Re: T140D or E Single Carb Conversion [Re: Tigernuts] #778982 07/17/19 10:56 pm
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Originally Posted by Tigernuts
Originally Posted by reverb
...Seems too that most only use the bikes at barely mid range speed or into town and for few kms, hence the perception that the single carbs are better..



I mostly use my singe carb 750 for fairly high speed (80 - 85mph) cruising for hours on end in France with occasional 100mph+ overtakes. Not exactly 'barely mid range speed or into town stuff. I find it performs excellently and gives great fuel economy too. But if anyone chooses to disbelieve, its no skin off my nose.


Ok 100 mph overtakes? That wold be a stock engine with you riding up right?


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: T140D or E Single Carb Conversion [Re: Tigernuts] #778983 07/17/19 11:10 pm
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There is an old "60s" magazine comparison test ... drag race . ( cant seem to find it )
Where they raced a TR6 against a Bonnie .
The Bonnie won the quarter mile by 2/100 of a second ... @ 98mph
Thats a clear win on a drag strip
That amounts to , I think , ... about 28"
On the street , if you need to get to the post office 2/100 of a second faster ... you need 2 carburetors .

On the other hand
TR6's ruled California desert racing in the mid sixties
And scored a major win as late as 1970 ... if there's a desert between you and the post office ... take the TR6

Triumph continued to make the single carb TR7 up till the end of Co-op production
Triumph even won a road rally race
In the Pyrenees in 1981
On a single carbed TR7T
This last small hurrah garnered
The Triumph Co-op some much needed export orders .
... if you're ever in the Pyrenees , ride whatever is offered .





Last edited by quinten; 07/17/19 11:12 pm.
Re: T140D or E Single Carb Conversion [Re: quinten] #778986 07/17/19 11:54 pm
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Originally Posted by quinten
There is an old "60s" magazine comparison test ... drag race . ( cant seem to find it )
Where they raced a TR6 against a Bonnie .
The Bonnie won the quarter mile by 2/100 of a second ... @ 98mph
Thats a clear win on a drag strip
That amounts to , I think , ... about 28"
On the street , if you need to get to the post office 2/100 of a second faster ... you need 2 carburetors .

On the other hand
TR6's ruled California desert racing in the mid sixties
And scored a major win as late as 1970 ... if there's a desert between you and the post office ... take the TR6

Triumph continued to make the single carb TR7 up till the end of Co-op production
Triumph even won a road rally race
In the Pyrenees in 1981
On a single carbed TR7T
This last small hurrah garnered
The Triumph Co-op some much needed export orders .
... if you're ever in the Pyrenees , ride whatever is offered .





.....98 mph in the 1/4 is way faster than any other road tests...Usually low 90's in the low to mid 14's. And every road race and flat tracker with a B engine had dual carbs...I believe Cycle magazine tested a 73 Tiger that ran a 13.6....As did the off road 60's straight pipe on each side single carb 650 when geared low..
Bring them screamin single carb stock bikes over to my place near the beautiful Finger Lakes...Go to Tommy Hillbilly bar for the best hamburger and then we'll do a two lane blacktop contest of speed...Like I said, 2000 rpm in high gear roll to show me how those torque monster bikes perform... wink


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: T140D or E Single Carb Conversion [Re: Steven A] #778987 07/18/19 12:04 am
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What I'm getting from all this is that twin carbs rule, but the Triumph twin carb head sucks. So, if you put twin carbs on a single carb head especially an early small port one, you get the best of both.
Sound about right?
I'd like to do some experimentation myself, but money and time are issues at this point.
It beats all the work you would have to do to make the twin carb head work.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: T140D or E Single Carb Conversion [Re: Steven A] #779025 07/18/19 10:37 am
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It all comes down to how carefully a motor was put together and tuned I think. Back at the factory and now.
I've spent enough time with the Halls to conclude that these are all over the map. Their dyno gets used a lot and they are always willing to test a new tuning strategy, whether theirs or anyone's. 650's with single carbs from mid 20's HP to high 30's and low 40's. Twin carbs from the 20's to around 50.
How fresh is the motor? How are the cams timed? What size carb? Exhaust? Gearing? Even from the factory, I bet no 2 bikes were identical. I've never found any evidence that they dialed in camshafts. How many combinations could that result in?
Bottom line IMO is a careful build and the small details matter.
So, Tony, I have a pretty fair running 650 with 2 carbs. How bout it?

Last edited by Mike Baker; 07/18/19 10:39 am.
Re: T140D or E Single Carb Conversion [Re: Steven A] #779026 07/18/19 11:00 am
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Mike, yeah, it runs pretty fair .....................


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: T140D or E Single Carb Conversion [Re: Hillbilly bike] #779031 07/18/19 11:52 am
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Originally Posted by Hillbilly bike
Ok 100 mph overtakes? That wold be a stock engine with you riding up right?


I didn't say it was a stock engine but that is sitting upright, and it does have a single carb. My point was that single carb head 750s don't have to be slow. I know that if I was to fit a twin carb head (if I did it would be a V head, not an E one), it would increase the top end somewhat but for road use, albeit not hanging around, I can't see the need.


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Re: T140D or E Single Carb Conversion [Re: Tigernuts] #779036 07/18/19 12:39 pm
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An honest 100 mph in an upright position? Naked frame or a fairing? What is done to the engine? I never said a single carb is slow, I said a dual carb can be faster..


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: T140D or E Single Carb Conversion [Re: Hillbilly bike] #779039 07/18/19 1:07 pm
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Well I agree with you on that. It was Reverb, I think, who seemed to imply that single carbs were only good for pottering around slowly (sorry if I misunderstood you on that Reverb). The engine has a 70-9989 exhaust cam, 71-7017 (standard) inlet cam, 9:1 or so compression, T140D exhaust system without any silencer (I recommend this setup - releases a lot of otherwise stifled power), carb jetted to suit. No fairing, 'western' bars and me hanging onto them in my Belstaff coat like a parachute! I've had it over 110 on the clock, but that is a fraction over 100 in reality. I never crouch down for extra speed as that reminds me of kids on mopeds.

I'm building a similar engine but with a twin carb head in racer style. This will have a small (Ducati 900SS style) fairing, clip ons, rearsets etc. It'll be interesting to see how fast that'll go. I reckon well over 120 with the right gearing.


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Re: T140D or E Single Carb Conversion [Re: Steven A] #779348 07/22/19 5:51 am
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Keep the twin carb, buy another bike with a single carb.

Motorcycle Mechanics (and others) used to publish bhp and torque curves for bikes tested, that would provide the answer to "which pulls better at lower revs". As I recall, the single carb Tiger was well regarded by magazine testers in the mid-1970s; suitable testing attire being leather jacket plus fireman's boots with fisherman's socks turned over.

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