1983 Triumph T140W 750 TSS; 8 valves & electric start!
- Thread starter CarlS
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Mike, they look great. 
Very good.
Sea Dog
Well-Known Member
Have been reading how the exhaust header balance pipe on the TSS causes flat mid range power. When the tuners and racers modified them in the 80's, they found that the same diameter headers with out the balance pipe, improved mid range power. I thought that an experiment could be easily achieved by using a half inch bolt with flat washers and nuts. The washers are a snug fit with the inside of the balance pipe and spaced out to rest against the sleeve of the header pipe.
Experimental blank
Fitting to balance pipe
In position
Have not been able to test on the road as it is hosing down with rain. Will have to wait until tomorrow.
However, upon starting the engine the following was noted.
1. The Dunstall mufflers really have a bark to them now.
2. The air pulse out of each muffler is much more defined and stronger.
3. The engine quickly settled to a reliable idle.
When the dry season returns, I will find out what the experiment reveals.......had to do something in the shed while it is raining.
Experimental blank
Fitting to balance pipe
In position
Have not been able to test on the road as it is hosing down with rain. Will have to wait until tomorrow.
However, upon starting the engine the following was noted.
1. The Dunstall mufflers really have a bark to them now.
2. The air pulse out of each muffler is much more defined and stronger.
3. The engine quickly settled to a reliable idle.
When the dry season returns, I will find out what the experiment reveals.......had to do something in the shed while it is raining.
Well be sure to let us know as this is an interesting mod
A very interesting and well thought out mod. Do let us know how it performs on the road.
Do let us know how it performs on the road.
Sea Dog
Well-Known Member
The rain has abated for the day and I had a few errands to run in town. Town is about a 20 mile run and usually I take the longer circuitous route when biking it. Got to squeeze as much riding as I can every time I fire up the TSS.
Well the enjoyment factor has taken a surge forward with the exhaust modification. Replacing the flat power under 4000 rpm, is a more purposeful edge, lifting to more urgent power at 3700. This equates to 100 kph (open road speed limit over here), which gives the bike plenty of punch just by twisting the throttle when passing. Around town the engine now pulls stronger and cleaner from any revs and the idle is very reliable and consistent. All noticeable improvements after fitting the balance pipe blank. Singularly, none of the improvements are outstanding, however the sum total is a modest step forward. The engine is running better than ever and I feel there is little need or scope to change anything more. Possibly replacing the Bing carburettors with Mikuni's would further enhance the power, however this is taking the bike further from standard than I want to go. If I want more power, then I just have to sling a leg over the Tiger and a whole new world opens up. I can get down and dirty! :y93:
To sum up, I changed 3 things to get the 8 valve engine running sweetly.
1. Lowered the compression
2. Fitted freer flowing mufflers
3. Blocked off the exhaust header balance pipe.
The TSS is now a viable every day ride and a real pleasure to cover miles on.
Oh nearly forgot. The twist grip opening assist spring I fitted ages ago, adds immeasurably to the riding pleasure.
Well the enjoyment factor has taken a surge forward with the exhaust modification. Replacing the flat power under 4000 rpm, is a more purposeful edge, lifting to more urgent power at 3700. This equates to 100 kph (open road speed limit over here), which gives the bike plenty of punch just by twisting the throttle when passing. Around town the engine now pulls stronger and cleaner from any revs and the idle is very reliable and consistent. All noticeable improvements after fitting the balance pipe blank. Singularly, none of the improvements are outstanding, however the sum total is a modest step forward. The engine is running better than ever and I feel there is little need or scope to change anything more. Possibly replacing the Bing carburettors with Mikuni's would further enhance the power, however this is taking the bike further from standard than I want to go. If I want more power, then I just have to sling a leg over the Tiger and a whole new world opens up. I can get down and dirty! :y93:
To sum up, I changed 3 things to get the 8 valve engine running sweetly.
1. Lowered the compression
2. Fitted freer flowing mufflers
3. Blocked off the exhaust header balance pipe.
The TSS is now a viable every day ride and a real pleasure to cover miles on.
Oh nearly forgot. The twist grip opening assist spring I fitted ages ago, adds immeasurably to the riding pleasure.
mikechev
Member
That balance pipe mod is yet another great TSS "development" tip SD.. i'm off to find some big nuts,bolts and washer so i can keep up with the dog...
Saw these on Ebay and thought of you SD... and they are actually in Brisbane...
Rings arrived yesterday and barrels off to get honed today, running out of time to get the TSS to the Bike show at the weekend but we will try.
Cheers
Mike
Saw these on Ebay and thought of you SD... and they are actually in Brisbane...
Rings arrived yesterday and barrels off to get honed today, running out of time to get the TSS to the Bike show at the weekend but we will try.
Cheers
Mike
Sea Dog
Well-Known Member
Thanks Mike.
I'll put a bid in and see where it takes me.
You will be burning the midnight oil to get your bike ready for the show. Good luck!
I have a week and a half before our bike show, so will have to get the polishing rag and tooth brush out real soon. Difficult to stop riding it though.
When making the balance pipe blank, make sure it's a tight fit length wise and the inside diameter of the pipe. My first attempt was a little short by 0.5mm in length and rattled. Made the engine sound very ordinary.
Great that you got a lot out of doing these small mods the way you did. I would also think twice about moding it too far out from what it should be and losing the original feel of the bike
Very nice to hear. Sounds like you have done very well.
Sea Dog
Well-Known Member
Good question.
The short answer is, a balanced system is quieter than a non balanced system with the same mufflers.
The velocity of the gasses from a balanced system is reduced with each exhaust stroke as there is twice the volume with two mufflers and two exits. The reduced velocity equates to less pressure and therefore reduced noise.
From my recent experiment of blocking off the balance pipe, there is an increase in noise as each exhaust stroke has only one muffler to expand into, which retains greater residual pressure and therefore the gas exit velocity from the single muffler is greater. This is clearly evident when you feel the exhaust gas pressure with the palms of your hands.
Hope this helps.
Excellent reply, Bryce.
It does, but can you quantify the difference? For instance in terms of the volume settings on your stereo? Or any other familiar comparison ( you can speak to each other standing next to my T140 when it's running, but you'ld really have to shout next to the TSS. Any help is muchappreciated - sorry to be a nuisance.
