- Joined
- May 12, 2011
- Messages
- 89
Those must be replaced, you do not want to be sucking any little bits of rubber into your carbs.
Help Needed - Sputtering and Backfiring(2016)
- Thread starter spartanman
- Start date
- Status
SwissCommando
VIP MEMBER
- Joined
- Jun 19, 2022
- Messages
- 31
I note that there are other posts on the subject...
SwissCommando
VIP MEMBER
- Joined
- Jun 19, 2022
- Messages
- 31
Part of Wikipedia's description of Persig's Novel: 'Zen and the Art of Motorcycle Maintenance' (1974). I was 22 at the time.
In the book, the narrator describes the "romantic" approach to life of his friend, John Sutherland, who chooses not to learn how to maintain his expensive new motorcycle. John simply hopes for the best with his bike, and when problems do occur he often becomes frustrated and is forced to rely on professional mechanics to repair it. In contrast, the "classical" narrator has an older motorcycle which he is usually able to diagnose and repair himself through the use of rational problem-solving skills.
In an example of the classical approach, the narrator explains that one must pay continual attention: when the narrator and his friends come into Miles City, Montana he notices the engine running roughly, a possible indication that the fuel/air mixture is too rich. The next day he is thinking of this as he is going through his ritual to adjust the jets on his motorcycle's carburetor. During the adjustment, he notes that both spark plugs are black, confirming a rich mixture. He recognizes that the higher elevation is causing the engine to run rich. The narrator rectifies this by installing new jets and adjusting the valves, and the engine runs well again.
With this, the book details two types of personalities: those who are interested mostly in gestalt—romantic viewpoints focused on being in the moment, and not on rational analysis—and those who seek to know details, understand inner workings, and master mechanics—viewpoints with application of rational analysis, vis-a-vis motorcycle maintenance.
I think I have spent most of my life being the former (romantic) and late in life, I am discovering the later (rational). I've got a ways to go...
In the book, the narrator describes the "romantic" approach to life of his friend, John Sutherland, who chooses not to learn how to maintain his expensive new motorcycle. John simply hopes for the best with his bike, and when problems do occur he often becomes frustrated and is forced to rely on professional mechanics to repair it. In contrast, the "classical" narrator has an older motorcycle which he is usually able to diagnose and repair himself through the use of rational problem-solving skills.
In an example of the classical approach, the narrator explains that one must pay continual attention: when the narrator and his friends come into Miles City, Montana he notices the engine running roughly, a possible indication that the fuel/air mixture is too rich. The next day he is thinking of this as he is going through his ritual to adjust the jets on his motorcycle's carburetor. During the adjustment, he notes that both spark plugs are black, confirming a rich mixture. He recognizes that the higher elevation is causing the engine to run rich. The narrator rectifies this by installing new jets and adjusting the valves, and the engine runs well again.
With this, the book details two types of personalities: those who are interested mostly in gestalt—romantic viewpoints focused on being in the moment, and not on rational analysis—and those who seek to know details, understand inner workings, and master mechanics—viewpoints with application of rational analysis, vis-a-vis motorcycle maintenance.
I think I have spent most of my life being the former (romantic) and late in life, I am discovering the later (rational). I've got a ways to go...
Tornado
VIP MEMBER
- Joined
- Dec 5, 2017
- Messages
- 4,863
When I started riding (only 8 years ago at 50 yrs old!!), I met a rider of similar age and with the same bike (both modern Triumph Bonnevilles). I've always been a tinkerer with mechanical things and was always fussing with my bike (tire pressures, checking oil, lube abd adjusting cables etc etc) while my friend had no clue on any of this, just wanted to ride. Later when I got the Commando, a whole new level of mechanical involvement was needed. My friend started getting interested in owning a vintage bike. I advised him unless he was willing to give up on professional mechanics and take up the commitment of doing his own work, it would be a disappointing experience. He got a KTM 1200 as his second bike and last I heard he was doing cross continent trips on it.
Later read Zen and it fully captures my experience of the two types of riders.
Tornado
VIP MEMBER
- Joined
- Dec 5, 2017
- Messages
- 4,863
Regarding riding at altitude, I regularly take my Norton from sea level up past the snow line of our local mountains. Jetting is standard spec as described for an 850. I find no major issues once up above the snow, other than a little idle behaviour change. So I doubt your issue is due to improper jetting (assuming you have the standard setup, need to confirm that once carbs apart).
If you are loosing acceleration above 3500 rpm as described, it could be an unwinding main jet or an air leak. I had a jet unwind and bike would suddenly stutter and misfire above 1/4 to 1/2 throttle opening (more informative to know where on throttle roll the issue happens as this tells you what jet on the carb is involved; rpm does not provide this info). I've also had a. Carb flange bolt come off while riding, making for a large air leak at the manifold. Behaviour was sudden inability to increase speed when applying more throttle. Engine kept running as other carb was fine, but trying to accelerate, bike was only a 420 cc.
If you are loosing acceleration above 3500 rpm as described, it could be an unwinding main jet or an air leak. I had a jet unwind and bike would suddenly stutter and misfire above 1/4 to 1/2 throttle opening (more informative to know where on throttle roll the issue happens as this tells you what jet on the carb is involved; rpm does not provide this info). I've also had a. Carb flange bolt come off while riding, making for a large air leak at the manifold. Behaviour was sudden inability to increase speed when applying more throttle. Engine kept running as other carb was fine, but trying to accelerate, bike was only a 420 cc.
- Joined
- Jun 30, 2012
- Messages
- 14,004
If most of the riding you do on public roads is not done using full throttle, the metering of the fuel is done by the needles and needle jets. If the needle jets are the correct size, at sea level the clips on the needles should be on the centre grooves. The needles are tapered - if you raise them by moving the clips down, you richen the mixture. As you increase your altitude above sea level, you have less oxygen, so you might need to lower the needles. It is common for the main jets to be too rich - if you really fang the bike and want to go faster, you might lean the main jets off. But when you do that, you risk burning pistons or valves. As you raise and lower the needles, the rate of change of taper on the needle affects how much moving the clips changes the mixture. Most Commandos probably have quick taper needles.
- Joined
- Feb 10, 2009
- Messages
- 2,972
I used to refer my colleagues in the Quality department to that book.
It’s about a guy who thought so much about “quality,” that he went nuts.
- Joined
- Jun 30, 2012
- Messages
- 14,004
Rich mixture usually only makes the motor a bit sluggish, unless it is extreme. But the jetting only has to be the slightest bit lean to cause a cough. With experience, you should always know when your jetting is too lean. I usually lower the needles until I get the cough, then raise them one notch. If you do that with a two-stroke, you might cough out a crank.
- Joined
- Mar 7, 2020
- Messages
- 3,156
The title seemed a bit highbrow for us 'erberts with grease under our fingernails!! We did had no choice regarding maintenance (two wheels or four) 'cos the cheap cr*p we were riding/driving was near/past it's expiry date :-(
Sort of thing you might leave lying around if there was a bit of posh totty you wanted to impress
- Joined
- Jun 30, 2012
- Messages
- 14,004
I have worked as a signatory of the National Association of Testing Authorities for 40 years. I have also brought one medium sized engineering company through to ISO9000 certification. I am not nuts - just different.
In any venture, there are four major risk areas - quality, safety, environment and security - which must be balanced and managed. Quality is about repeat business.
The reason I am a scientist and not a medical doctor, is my association with motorcycles. When I should have been studying, I was building racing motorcycles. In my year 12 at high school, out of 300 boys, 90 became medical doctors and I was smarter then many of them. I was never money-motivated. I have probably had a happier life.
Last edited:
- Joined
- Feb 10, 2009
- Messages
- 2,972
I didn’t say you went nuts!
- Status
Similar threads
- Locked
