[gsurya]

Originally Posted by farhadtarapore

I feel silly asking this question after a year, but now that my 4 free services are over, what is the time/kms service interval for a 2015 Thunderbird 500?
Thanks.

3) chrome plating / or at worst silver paint on the rusted portions

You have rusting within an year? Is this on the bike or some add-on accessories? My old LML Vespa had rust only on the exhaust & the chrome protector frame only after a decade.

[farhadtarapore]

Originally Posted by gsurya

You have rusting within an year? Is this on the bike or some add-on accessories? My old LML Vespa had rust only on the exhaust & the chrome protector frame only after a decade.

Yes I have rusting within a year - on the kick lever, bend pipe, the place where the bend-pipe joins the main exhaust (don't know what it's called), those round circles below where the fork starts (top of the front fork), the entire clamp holding the instrument pod is fully rusted.

My bike is completely stock. Nothing added/removed/replaced.

[gsurya]

Originally Posted by farhadtarapore

Yes I have rusting within a year - on the kick lever, bend pipe, the place where the bend-pipe joins the main exhaust (don't know what it's called), those round circles below where the fork starts (top of the front fork), the entire clamp holding the instrument pod is fully rusted.

My bike is completely stock. Nothing added/removed/replaced.

Shocking & unacceptable quality if basic steel components have contamination. You should really complain to RE, this is a manufacturing defect.

[drdeepudev]

Regarding the rust, its not a big surprise. My 2 year old 53000 KM run Thunderbird 350 has rust in the above mentioned areas. May be, the coastal climate aggravates the issue. I stay hardly 800 metres from the sea and the rust is an issue in my 1991 standard 350 too. I believe except regular cleaning, nothing much can be done in that part. We have done electro plating twice for the standard in a gap of around 5 years, and within an year or two, rust sets in. I'm planning to get the bend pipe of the thunderbird, which is stock, chrome plated. Any thing special to be noted? Whether cat con should be removed and is there any special care to be taken while removing that?

Off topic as there is a separate thread for exhausts:
Last day, I changed the exhaust of the thunderbird to Wild boar, without any changes to the carb or air filter. My mechanic was of the opinion that no changes are needed to the carburettor. But, while decelerating im hearing a lot of popping sounds which is part fun and part irritating, especially for my wife. I believe it was there with the stock one too, and the wild boar amplified it. What is the science behind those popping sounds? Is there something to be worried of? I know it is not a total free flow and there is a restriction in the outflow of exhaust gases due to the cat con, but, im curious to know. Also, may be it is in the mind, my low end has taken a hit, but the mid range and top end has improved a bit post the exhaust swap.
Thanks.

[ArizonaJim]

To greatly help in keeping rust away from chrome plating, painted surfaces and even bare steel apply a coating or two of a good automotive wax and buff it to a shiny bright condition.
Do not use the "auto polish" type waxes as they contain abrasives. Instead, look for a wax that is made for clear coat paint.

Auto waxes containing Carnauba wax are among the best.

The wax works by forming a waterproof barrier that will keep moisture and salt away from the metal.
The wax will deteriate over time so it should be reapplied at least every 4 weeks. More often is better and once a week is not too often.

The only place waxes will not work is on the exhaust pipe. It and the silencer get too hot and will turn the wax to carbon.

As for the popping or "backfiring" as we call it here in the US goes, it generally indicates a lean fuel mixture that can harm the engine if the problem isn't addressed.

With the stock silencer on the motorcycle there is quite a bit of backpressure in the exhaust pipe and the cylinder.
The air/fuel ratio in the carburetor is set up by the factory to provide the right amount of fuel under these conditions.

This includes providing a air/fuel ratio that will burn even under the low compression that occurs in the cylinder when the throttle is closed. Typically this happens when you are cruising along and suddenly close the throttle.

When the silencer is replaced with a non-restrictive or "free flowing" unit, the pressure in the exhaust pipe is reduced leaving less total gas in the exhaust pipe and in the cylinder when the throttle is closed.

Because the throttle is closed, the cylinder cannot breath in any more of the air/fuel mixture than it had when the restrictive silencer was installed, so the compression ratio is reduced.

Recall that in order to run an engine needs four things, air, fuel, compression and ignition to burn the fuel.

Now that the cylinder has a reduced compression ratio with the throttle closed, the air/fuel mixture often (not always) won't ignite.
This dumps the raw fuel and air into the exhaust pipe where it accumulates to a point that just the heat from the pipe and silencer is enough to ignite it.

The result? Pop! Pop! Pop.

Interestingly, adding more fuel to the air/fuel mixture causes the fuel to burn even at the low compression ratio so enriching the mixture with the idle mixture adjustment screw can help to reduce the problem.

The story doesn't end there though.

With the less restrictive silencer, under hard acceleration when the throttle is opened the lower pressure left in the cylinder pulls in more of the air/fuel mixture.
This usually increases the engine power under these conditions, although it often reduces the low and mid range power where most of us ride.

In any case, under almost all riding conditions, this increase in airflow causes the air/fuel ratio to lean out if the stock carburetor is still in place.
This lean condition can burn valves.

To correct this, the jets in the carburetor need to be changed to a larger size that will give the correct air/fuel ratio under normal riding and under hard acceleration.
That is why re-jetting the carburetor is almost always needed when a free flowing exhaust is installed.

OK. I can hear you people with fuel injection asking, "What about me?".

Usually, the fuel injector sensors will detect the closed throttle and the computer is often programmed to shut off the fuel supply when this happens.
That results in no back firing if the throttle is completely closed.
If the throttle is "mostly closed" some backfiring can happen, it depends on the programming.

Under normal riding and hard acceleration the inlet manifold pressure sensor treats the lower pressure in the duct from the increase in air flow velocity into the cylinder as a change in altitude and coupling this information with the throttle position sensor, it provides a correct air/fuel ratio to the engine.

This is not to say that removing the silencer is a good idea with a fuel injected engine. There are limits to how much of a correction the fuel injection system can provide.

[varadnerurkar]

Originally Posted by ArizonaJim

Under normal riding and hard acceleration the inlet manifold pressure sensor treats the lower pressure in the duct from the increase in air flow velocity into the cylinder as a change in altitude and coupling this information with the throttle position sensor, it provides a correct air/fuel ratio to the engine.

This is not to say that removing the silencer is a good idea with a fuel injected engine. There are limits to how much of a correction the fuel injection system can provide.

Very well explained. For the first time I understood the problem behind the backfiring. I own a classic 500 and changed my stock silencer to short-bottle. Within a few minutes the back firing started. The people at the service center were unable to determine the problem. Since then I was in the hunt for an answer for this problem. Thank you.

[ZedMae]

Originally Posted by ArizonaJim

----

As for the popping or "backfiring" as we call it here in the US goes, it generally indicates a lean fuel mixture that can harm the engine if the problem isn't addressed.
----
This dumps the raw fuel and air into the exhaust pipe where it accumulates to a point that just the heat from the pipe and silencer is enough to ignite it.

The result? Pop! Pop! Pop.

----

Hi Jim, It is always a pleasure to read your detailed explanations. After reading through this response, had a question. Might sound naive, but just clarifying. If the raw fuel and air can ignite because of the heat from the silencer pipe, wouldn't the same happen in the cylinder itself, which will be equally hot if not more?

[drdeepudev]

Thank you Mr. Jim for the detailed explanation. Now it makes sense about those popping sounds. I was just curious about the exhaust gas levels post the exhaust change. I'm uploading the image of pollution certificate of my Thunderbird 350, the top one being taken on April 2016 and the second one a day after the exhaust change. Both were taken at the same place, with the same machine. He was mentioning about a slight increase in the level of Hydrocarbons post the change, which changed to 1240PPM from 1200PPM. ( Is it because, some unburned fuel is being pumped out through the exhaust?) There is some changes in O2 & Co2 levels too. I know this was not the right way, but I could not wait. What is your opinion?
Thank You

[gsurya]

Originally Posted by drdeepudev

Regarding the rust, its not a big surprise. My 2 year old 53000 KM run Thunderbird 350 has rust in the above mentioned areas. May be, the coastal climate aggravates the issue.

My dad's Ambassador & Premier Padmini had major rusting issues. My Fiat Uno had it to a lesser extent. My LML Vespa had almost none until a decade. After 7+ years there are few rusting spots now on our Chevy Aveo - mainly on the bottom edge of the door etc.

I wonder why people accept rusting on a Royal Enfield, that too in 1 or 2 years as normal? Is it the same with other bikes too?

[drdeepudev]

Originally Posted by gsurya

I wonder why people accept rusting on a Royal Enfield, that too in 1 or 2 years as normal? Is it the same with other bikes too?

I did not say that is normal, but it is a common issue in Enfields. I had replaced the exhaust of the thunderbird under warranty within 8 months of ownership, due to the rust issue. Until and unless more and more people raise issues like this, im sure the company will never change its vendors. But, my rims are alright and there is no visible rust anywhere.

I had owned two Honda unicorns and one Yamaha FZ in the past, and the rust was not an issue. Among cars, I have a Fiat linea and an Alto, which does not have any major rust issue. So, I assume, it is a problem with the quality of material used.

[farhadtarapore]

Originally Posted by gsurya

Shocking & unacceptable quality if basic steel components have contamination. You should really complain to RE, this is a manufacturing defect.

Yes, I have written to RE at your behest. They've asked one Mr. Abhimanyu to look into the matter. Nothing further so far.

Originally Posted by navin_v8

Mate I hope you have the owner's manual, it is clearly mentioned on it that the service interval is 3000 kms or 6 months whichever is earlier.

Will easily set you back by around 25-30K including tyres

Get hard chroming done for better results.

Can be done during your first paid service.

Get the brake pads checked along with the brake assembly(brake piston caliper, master cylinder, etc.). Also check the brake fluid level in the rear brake reservoir. Get this rectified ASAP.

That cost is something I will have to bear.

[ArizonaJim]

Originally Posted by ZedMae

Hi Jim, It is always a pleasure to read your detailed explanations. After reading through this response, had a question. Might sound naive, but just clarifying. If the raw fuel and air can ignite because of the heat from the silencer pipe, wouldn't the same happen in the cylinder itself, which will be equally hot if not more?

To a limited extent, you are correct but remember, the walls of the cylinder have cooling fins and the underside of the piston is constantly getting bathed by a flow of oil from the crankshaft.
Both of these things make the cylinder and piston much cooler than the exhaust pipe.

Originally Posted by drdeepudev

Thank you Mr. Jim for the detailed explanation. Now it makes sense about those popping sounds. I was just curious about the exhaust gas levels post the exhaust change. I'm uploading the image of pollution certificate of my Thunderbird 350, the top one being taken on April 2016 and the second one a day after the exhaust change. Both were taken at the same place, with the same machine. He was mentioning about a slight increase in the level of Hydrocarbons post the change, which changed to 1240PPM from 1200PPM. ( Is it because, some unburned fuel is being pumped out through the exhaust?) There is some changes in O2 & Co2 levels too. I know this was not the right way, but I could not wait. What is your opinion?
Thank You

Yes.
The unburned fuel in the exhaust is the cause of the increase in hydrocarbons.

Likewise, the increase in the oxygen (O2) level from 14.5% to 17.65% is due to it not being consumed by the burning of the fuel.

The decrease in Carbon Monoxide (CO) from 1.98% to 1.88% is also due to the fuel (HC) not being burned. (CO or carbon monoxide is the result of incomplete combustion.)

I'll have to think a while to figure out why the CO2 level increased from 2.14% to 2.15%. At the moment, the only explanation I can think of is, it is showing the variation typical of the machine in measuring the gasses?

[drdeepudev]

Originally Posted by ArizonaJim

Yes.
The unburned fuel in the exhaust is the cause of the increase in hydrocarbons.

Likewise, the increase in the oxygen (O2) level from 14.5% to 17.65% is due to it not being consumed by the burning of the fuel.

?

I guessed so sir. So, does this report give any idea about the air/ fuel mix? Am I running lean? What should be the way forward? Should I revert back to the stock exhaust?

[ArizonaJim]

If your not familiar with your carburetor, ask a mechanic to enrich the idle fuel mixture just a little bit. See if that reduces the popping when you back off of the throttle.

Because your air/fuel mixture may be running lean, remove the spark plug(s) and replace it (them) with new ones. Then ride the motorcycle normally but be sure to ride far enough to heat the engine up. A 1-4 km distance is not enough.

After accumulating 40-50 km. on the new spark plugs, remove them and look at the center electrode and the ceramic insulator that holds it in place.

If the insulator is a light gray or brown color, everything is fine.
If the insulator is white and looks a bit like shiny glass the engine is running lean.
The only way to fix this is to replace the stock jets with slightly larger jets.
(The actual metal jet is not larger. The hole or orifice that regulates the fuel flow thru it is larger.)
I don't have any information for the recommended jet size for a 350 cc engine but a good local mechanic who has worked on Royal Enfield 350's should know exactly what is needed.

[GrayBerry]

Dear All,

I have a 2001 350 Machismo, it comes with the AVL engine.
Recently got it serviced, but have an issue.

The bike starts on choke, however, once I switch off choke the engine stalls.
Things that I checked:
1. Coil and wiring - no issues, in perfect condition.
2. Changed spark plugs multiple times, however, after running the engine for a few minutes, I find it black with lot of oil residue, as it the bike is running on oil instead of petrol.
One of the mechanic said that piston and rings need to be changed, however, I feel there is sufficient compression.
What could be the issue? Have anyone come across this problem? please advice.
Thank you,
Venky