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#708157 - 09/12/17 1:34 pm Re: Why is my T140 gutless? [Re: Stein Roger]  
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I remove the chokes a while ago... I was doing well without them, and as some of you suggested, if I'm not too careful, I may engage them by accident. (and I plugged the carb cap)

Regarding the exhaust: I got the bike with aftermarket exhaust pipe, they don't have a balance pipe. I read a little bit everywhere that they do not matter too much. I'll remove the exhaust and give it a try. The reason why I have not done it yet is that I'm afraid that it will require a re-jetting: a ride without muffler, my neighbors will tolerate. Many rides, not so much.

How likely is it that the camshatfts in my engine are not what they are supposed to be? Given that my bike seems to run too rich with standard jetting, and assuming most improvement cams require a richer mixture, I'd say it is very unlikely. Anybody disagrees? I don't have the tools to check the actual timing, I'd rather skip it if mostly uncesessary. By the way the cam was in good shape when I took the cylinders off.

Originally Posted by TR7RVMan
I road my bike today. From idle up bike pulls well. 1500rpm up bike pulls strongly and smoothly. 3500 power is very strong. As rpm increase the power increases. At 4700rpm the power just explodes. A pillion passenger could easily fall off the back. This power boost is known on 750s. To me the 650 doesn't have such a sudden surge yet they still come on the power at about 5000.

Originally Posted by Stein Roger
The T140 wakes up around 5000 rpm (thanks to the inlet cam) and by 6500 it's all over.(thanks to the E3325 shape exhaust cam).

That does not sound like bike at all... yesterday, at ~50 mph, uphill, 4000 rpm (I forgot which gear. 4th?). I opened the throttle and it did not go well. I feel like going to higher rpms would damage the engine. I noticed the hesitation being worse when going uphill. Is it the sign of anything?

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#708160 - 09/12/17 2:15 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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Dave M Offline
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USA

[/quote]
yesterday, at ~50 mph, uphill, 4000 rpm (I forgot which gear. 4th?). I opened the throttle and it did not go well. I feel like going to higher rpms would damage the engine. I noticed the hesitation being worse when going uphill. Is it the sign of anything?

[/quote]

A dying battery will cause electronic ignitions to behave in this manner. Inspect your battery for warping and or wavering voltage readings.
You stated the use of a strobe, retarded timing is a possibility.
Are the spark plugs covered in sooty black? What do the plugs look like?


66 TR6R Trophy
67 T120R Bonneville
68 BMW R60/US
69 T100R Daytona

#708161 - 09/12/17 2:15 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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I'll give you an example of an eye-opening experience that I had a few years ago, and you can decide if it might have some applicability to your situation. I think it might, but I don't insist on it.

I was riding my BSA Firebird 650 down the highway at an easy 60 MPH, throttle barely cracked. It has stock jetting and a stock Firebird exhaust, which is two mufflers and a "birdcage" shield high on the left side of the bike.

Suddenly, the bottom bracket that holds the mufflers in place on the header pipes broke. The exhaust pipe clamps alone were not enough to hold the mufflers onto the headers, and so the mufflers separated from the headers, but stayed on the bike, just swinging from the UPPER bracket that holds the mufflers to the bike.

So the bike is running down the road with only the header pipes as the exhaust; the header pipes end about 18" from the heads, the mufflers were not in the circuit.

The bike would not hold 55 mph on the flat any more; the throttle was halfway to the stop just to try to hold speed. It would not climb a hill without shifting down a gear. In other words, it had become completely "gutless", and had lost about 1/3 of its horsepower, because the carb jetting and the exhaust line were no longer even close to compatible.

When I got to a place where I could bodge up a new bottom exhaust bracket and reattached the mufflers, the bike went back to full performance.

Lannis


OK, I admit it, I'm addicted to brake fluid.

But I can stop any time I want.
#708173 - 09/12/17 3:23 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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Originally Posted by Notthepainter
... the carbs were new when I got it...


Did you verify the needle clip is in the right slot, the needle jet, pilot jet and slide are the right size (and the needle jet has a cross-drilled hole)?

Afterthought: correct voltage coils for your EI?

Steve

Last edited by JubeePrince; 09/12/17 3:24 pm. Reason: afterthought

'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
#708176 - 09/12/17 3:49 pm Re: Why is my T140 gutless? [Re: JubeePrince]  
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Originally Posted by JubeePrince
Originally Posted by Notthepainter
... the carbs were new when I got it...


Did you verify the needle clip is in the right slot, the needle jet, pilot jet and slide are the right size (and the needle jet has a cross-drilled hole)?

Afterthought: correct voltage coils for your EI?

Steve


Yes, I tried to move up the needle jet. No big change, worse if any.

Coils are 6V. I replaced them when I switch to the EI.

Last edited by Notthepainter; 09/12/17 3:51 pm. Reason: coil answer
#708177 - 09/12/17 3:50 pm Re: Why is my T140 gutless? [Re: Lannis]  
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Originally Posted by Lannis
I'll give you an example of an eye-opening experience that I had a few years ago, and you can decide if it might have some applicability to your situation. I think it might, but I don't insist on it.

I was riding my BSA Firebird 650 down the highway at an easy 60 MPH, throttle barely cracked. It has stock jetting and a stock Firebird exhaust, which is two mufflers and a "birdcage" shield high on the left side of the bike.

Suddenly, the bottom bracket that holds the mufflers in place on the header pipes broke. The exhaust pipe clamps alone were not enough to hold the mufflers onto the headers, and so the mufflers separated from the headers, but stayed on the bike, just swinging from the UPPER bracket that holds the mufflers to the bike.

So the bike is running down the road with only the header pipes as the exhaust; the header pipes end about 18" from the heads, the mufflers were not in the circuit.

The bike would not hold 55 mph on the flat any more; the throttle was halfway to the stop just to try to hold speed. It would not climb a hill without shifting down a gear. In other words, it had become completely "gutless", and had lost about 1/3 of its horsepower, because the carb jetting and the exhaust line were no longer even close to compatible.

When I got to a place where I could bodge up a new bottom exhaust bracket and reattached the mufflers, the bike went back to full performance.

Lannis


I totally believe it. That's why I am afraid I won't learn much by testing the bike without mufflers. I'll still do it though, this week end.

#708178 - 09/12/17 3:55 pm Re: Why is my T140 gutless? [Re: Dave M]  
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Originally Posted by Dave M

A dying battery will cause electronic ignitions to behave in this manner. Inspect your battery for warping and or wavering voltage readings.
You stated the use of a strobe, retarded timing is a possibility.
Are the spark plugs covered in sooty black? What do the plugs look like?


I tested the battery (in my driveway, not while running; could it make a difference?)

I can always advance some more the timing, for testing purpose. I don't like to kick start a bike that has too much advance.

The plugs are not sooty black, or even very black. Just greyish. But I only ride the bike in the range of rpms where it feels good ( < 4000 rpms).

Last edited by Notthepainter; 09/12/17 7:48 pm.
#708196 - 09/12/17 7:27 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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So what carbs are on this thing?
78 is a transition year

#708200 - 09/12/17 7:46 pm Re: Why is my T140 gutless? [Re: AngloBike]  
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Originally Posted by AngloBike
So what carbs are on this thing?
78 is a transition year

AMAL 930

#708203 - 09/12/17 8:14 pm Re: Why is my T140 gutless? [Re: Lannis]  
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Originally Posted by Lannis
I'll give you an example of an eye-opening experience that I had a few years ago, and you can decide if it might have some applicability to your situation. I think it might, but I don't insist on it.

I was riding my BSA Firebird 650 down the highway at an easy 60 MPH, throttle barely cracked. It has stock jetting and a stock Firebird exhaust, which is two mufflers and a "birdcage" shield high on the left side of the bike.

Suddenly, the bottom bracket that holds the mufflers in place on the header pipes broke. The exhaust pipe clamps alone were not enough to hold the mufflers onto the headers, and so the mufflers separated from the headers, but stayed on the bike, just swinging from the UPPER bracket that holds the mufflers to the bike.

So the bike is running down the road with only the header pipes as the exhaust; the header pipes end about 18" from the heads, the mufflers were not in the circuit.

The bike would not hold 55 mph on the flat any more; the throttle was halfway to the stop just to try to hold speed. It would not climb a hill without shifting down a gear. In other words, it had become completely "gutless", and had lost about 1/3 of its horsepower, because the carb jetting and the exhaust line were no longer even close to compatible.

When I got to a place where I could bodge up a new bottom exhaust bracket and reattached the mufflers, the bike went back to full performance.

Lannis



<y experience was the exact opposite! My ,76 T140 wasn't much faster than my A10 (this was in 1978) and I was a bit fed up with it being so slow. One day I fell off it and the bike slid into the kerb right-hand silencer end first, concertina-ing the silencer and breaking it off the downpipe. I couldn;t find a way of re-attaching it, so I took the left one off and left them both under a hedge. The ride home was a revelation. It felt as if a supercharger had suddenly been fitted. It would go faster in third than it used to go in 5th, and get there in half the time.

So, just saying what my experience of ditching the silencers was, and what has led my decisions on exhausts on every bike ever since. Yes, I did have to re-jet to suit after I got home, and the carb changes were actually quite significant. I used the trial & error / plug chop method until I got it right. It went even better then!

Please do let us know your own experience when you try yours without silencers.


If anything other than a blank space is visible here, something's wrong.
#708204 - 09/12/17 8:34 pm Re: Why is my T140 gutless? [Re: TR7RVMan]  
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Originally Posted by TR7RVMan


I road my bike today. From idle up bike pulls well. 1500rpm up bike pulls strongly and smoothly. 3500 power is very strong. As rpm increase the power increases. At 4700rpm the power just explodes. A pillion passenger could easily fall off the back. This power boost is known on 750s. To me the 650 doesn't have such a sudden surge yet they still come on the power at about 5000.

Don



Explosive? are we talking about 45 hp Triumphs grin


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
#708269 - 09/13/17 4:07 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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Hi Hillbilly, That is for a 45 hp motor... In the lower gears the 5000 is very well felt. Still they are not slugs.

Of course the modern sport bike, that explosive!
Don


1973 Tiger 750
#708270 - 09/13/17 4:15 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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Hi notthepainter, In your original post you stated exhaust was stock with emgo mufflers. I took that as repro stock emgo mufflers I have on my bike. They replicated the original muffler. (visually anyway, internals are different)

I and 1 fellow I know used stock type Emgo with no performance problems whatsoever.

Now your bike has aftermarket exhaust with no crossover pipe? Emgo makes many non stock type mufflers. That changes things.

So exactly what exhaust & mufflers do you have?

Things are not adding up.

Messing around with carb mixture before you mark grip & know where slide is at the time motor is bad, is doing it the hard way. You must know what part of carb is in effect while bike is acting up.
Don


1973 Tiger 750
#708287 - 09/13/17 6:49 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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My 78 Bonneville was the only brand new bike I ever bought. Mine had the Mark II carbs. A few months after I bought it I put Dunstalls on it, drilled the air boxes (still had the filters, just made more passages to get air to them) and rejetted. It was thought to be one of the fastest T140s in the area. A year or two later, I got tired of the noise and put the stock mufflers back on. Interestingly enough, the jetting didn't change and the bike was still a very fast Bonneville. It did an indicated 105 mph, two up for 45 minutes on a fast run (I was 50 lbs lighter, but my wife was 140 lbs at the time). I sold it, it passed through several owners, but it is still around and is still considered to be one of the faster T140s around.
If you are convinced that your cam timing is ok (see my previous posts), and taking it around the block with the mufflers off doesn't make a difference (you won't hurt anything running it for 5-10 minutes), try taking the air boxes and filters off. By the way have you tried lifting the carb needles?

Ed from NJ

#708314 - 09/13/17 11:00 pm Re: Why is my T140 gutless? [Re: TR7RVMan]  
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Originally Posted by TR7RVMan
Hi notthepainter, In your original post you stated exhaust was stock with emgo mufflers. I took that as repro stock emgo mufflers I have on my bike. They replicated the original muffler. (visually anyway, internals are different)

I and 1 fellow I know used stock type Emgo with no performance problems whatsoever.

Now your bike has aftermarket exhaust with no crossover pipe? Emgo makes many non stock type mufflers. That changes things.

So exactly what exhaust & mufflers do you have?

Things are not adding up.

Messing around with carb mixture before you mark grip & know where slide is at the time motor is bad, is doing it the hard way. You must know what part of carb is in effect while bike is acting up.
Don

You're right. I meant to say that my mufflers were (repro) stock. The exhaust tubes, not sure what they are, but not stock.
Sorry for the confusion.

#708330 - 09/14/17 12:36 am Re: Why is my T140 gutless? [Re: Notthepainter]  
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It's too bad that factory didn't make their 750 with just a big bore kit. (they did, but only a few bikes in 1970 per racing rules)

The way these two 750's make power has to be experienced to be believed. They are radically different.

According to the urban legend going around at the time, it was said that Triumph intentionally de-tuned the 750 because of 5 speed gearbox breakages. Then once the gearbox was sorted, they never re-tuned the motor. That would be typical Triumph, in my opinion.

Don't know if this is true or not......

Soooo....I would be inclined to change a T140 into a long stroke 750 if it was my bike. Not sure how to go about doing that, but that would make a plebeian motorcycle rather fun. Or just fit a 650 motor with a big bore kit......Late four speed 'boxes are great, too. Don't need no stinking 5 speed anyway.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
#708347 - 09/14/17 2:36 am Re: Why is my T140 gutless? [Re: Notthepainter]  
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Originally Posted by Notthepainter

I totally believe it. That's why I am afraid I won't learn much by testing the bike without mufflers. I'll still do it though, this week end.


you have to try it and see, because other things can make it work, or not work.

[Linked Image]

^^^ this motor has lots of things changed, but the bike goes way over 100 mph on just open pipes, and four inches either way make a 4 mph reduction in top speed.


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708359 - 09/14/17 8:07 am Re: Why is my T140 gutless? [Re: Notthepainter]  
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3 times now I have discovered that increasing the needle jet size provided good results. Try installing a pair of 107 needle jets and see what happens. And double check that you have the correct needles. There are about 3 different needles.
I noticed that nobody has mentioned this. My theory is that the original jetting was arrived at in the '60s...about 50 years ago when gas was different. Perhaps the current air/fuel ratio requirement is different today.

#708365 - 09/14/17 10:37 am Re: Why is my T140 gutless? [Re: HawaiianTiger]  
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Originally Posted by HawaiianTiger
It's too bad that factory didn't make their 750 with just a big bore kit. (they did, but only a few bikes in 1970 per racing rules)

The way these two 750's make power has to be experienced to be believed. They are radically different.

According to the urban legend going around at the time, it was said that Triumph intentionally de-tuned the 750 because of 5 speed gearbox breakages. Then once the gearbox was sorted, they never re-tuned the motor. That would be typical Triumph, in my opinion.

Don't know if this is true or not......

Soooo....I would be inclined to change a T140 into a long stroke 750 if it was my bike. Not sure how to go about doing that, but that would make a plebeian motorcycle rather fun. Or just fit a 650 motor with a big bore kit......Late four speed 'boxes are great, too. Don't need no stinking 5 speed anyway.

Cheers,
Bill



The urban legend is not true.. You need to read Vintage Bike grin ..It was done to avoid problems with the main bearings available at that time...
I got money that says if you build a 750 long or short rod street motor with the same cams ,compression,head,etc, a rider would be unable to notice any difference...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
#708373 - 09/14/17 12:07 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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They do have a different feel. The long rod motors seem to last longer too.
Pistons and rings seem to last longer.

The NUP style roller was available at the time T140's came out.
Triumph decided to stick with a ball race.
May have been cost driven but i don't think so as they still used that very expensive drive side bearing rather than going metric.

Last edited by NickL; 09/14/17 12:10 pm.


#708379 - 09/14/17 12:43 pm Re: Why is my T140 gutless? [Re: NickL]  
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Running from demons in WNY
The theory is, on two engines identical except for rod length...The longer rod engine makes a bit more top end power, the short rod a bit more low end....This is well known to auto tuners and should also apply to bike engines.
This is from Vintage Bike gathered info from those who were there at the time...
Quote
At first glance it seems strange that Triumph engineers deliberately mismatched intake and exhaust cams in the T140. While the Intake cam is quite “sporty” the exhaust cam is very mild indeed. By doing this Triumph may have avoided some warranty problems by de-tuning the engine, as there wasn’t much chance of accidentally overloading the engine. These days we can fit better main bearings. The more adventurous can tuftride a crankshaft, so it’s less likely to break if we start playing in the upper rpm limits. We can safely have more torque available where we want it.


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
#708398 - 09/14/17 2:11 pm Re: Why is my T140 gutless? [Re: NickL]  
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Originally Posted by NickL
The NUP style roller was available at the time T140's came out.
Triumph decided to stick with a ball race.
May have been cost driven but i don't think so as they still used that very expensive drive side bearing rather than going metric.


I didn't know the NUP roller bearing was available back then - is this a fact?

I had a '76 T140 which suffered massive timing side main bearing failure. The cage fell apart, allowing the balls to wander wherever they wanted. They stayed within the inner & outer races, but must have varied between roughly correctly spaced and all bunched together, allowing the crank to jump about so much it broke the oil seal housing in the timing cover, and stopped itself before I killed it by jumping out of mesh with the idler pinion, losing the valve timing! When I pulled it apart, the balls looked like black gravel and the inner race was blue.

The problem with those bearing was that they had spot welded cages. Riveted cage versions are - apparently - much more robust. I'd never use one of any kind, now the double lipped rollers are readily obtainable. Triumph's approach of de-tuning the engine instead of fixing the weakness seems almost incredible. But so is a lot of the history of the British bike industry.

Last edited by Tigernuts; 09/14/17 2:12 pm. Reason: Typos

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#708428 - 09/14/17 6:22 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
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So, Triumph waited until the Four valve motor to try to get more power out of them even though they upgraded the main bearings? I remember the ads in those days. They tended to downplay outright performance and up play classic styling and handling when it was clear that any bike coming out of another factory could just run away from a Triumph.

At half the price......I ended up with a string of middleweight Japanese bikes in those days simply because I couldn't afford the new Triumphs, even though I wanted one. For my Triumph needs, I settled for basket case bikes from which I built high performance classic street machines.

So now I'm concerned for my friend's '76 T140. It still has low miles on it, but we were considering 650 cams. Maybe a change of bearings to go along with that?

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
#708432 - 09/14/17 7:05 pm Re: Why is my T140 gutless? [Re: Hillbilly bike]  
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Hi Bill,

Originally Posted by Hillbilly bike
Originally Posted by HawaiianTiger
According to the urban legend going around at the time, it was said that Triumph intentionally de-tuned the 750 because of 5 speed gearbox breakages.

The urban legend is not true..

Can't be true if you think about it - Small Heath put the same 5-speed in the triples and they (could) make wa-aa-ay more power than Meriden boneshakers ... cool

Regards,

#708444 - 09/14/17 7:37 pm Re: Why is my T140 gutless? [Re: Notthepainter]  
Joined: Jul 2012
Posts: 1,426
AngloBike Online content
BritBike Forum member
AngloBike  Online Content
BritBike Forum member

Joined: Jul 2012
Posts: 1,426
UK Berks
I wouldn't add "hot" cams to a 750 without doing the bearings . You are there anyway.
It's generally accepted that a half race cam on a t140 is safer with a three piece bearing

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