[diwa]

Originally Posted by cogentr

Congrats Diwa, I still have a long way to go (probable delivery in May 2011).. by the way when was your booking done?

Ride safe.

Thank You. I booked it in July.

I am just excited to take the delivery of the bike this evening.

[cogentr]

@ Diwa..Congrats again, enjoy the bike and if help is needed we always have this forum and the gurus to look upto.
Mine is booked in Chennai too, same RE owned outlet in Adyar, what is the total landed cost in Chennai right now (I was told 143K not including accessories)
And please let us know if you see the earlier mentioned 'upgrades' featuring in your bike.

[ricky_1605]

Originally Posted by hexanerax

Contrary to popular belief, Back pressure will affect the compression. There is a phenomenon called valve overlap that uses the principle of inertia to improve engine breathing. Hot exhaust gases are vented out at a high velocity , a lot of the thermal energy getting converted to kinetic energy as it expands into the low pressure exhaust system. The intake valve opens and the exhaust valve also remains open for a small part of the crank rotation ( few degrees) so that the inertia of the hi velocity exhaust gases can be used to create a lower pressure in the cylinder head , pulling in air at a good rate even as the piston moves down in the intake stroke. This is a function of the exhaust gas velocity and a restrictive exhaust can decrease this effect. But conversely , too free an exhaust system and the exhaust gas velocity will decrease and the advantage is lost. Bernoulli's principle at work ( fluid pressure is inversely proportional to velocity of flow ).
The port diam , the valve stem , intake manifold shape , Air filter and so many variables influence the torque characteristics but generally , free flow ( intake and exhaust ) will tend to reduce low end torque and improve high end power. That is why , if the silencer is fully removed , replaced with a stove pipe design( just a length of pipe ) , the vehicle will not even idle well ( due to extremely poor low end torque) but may show impressive gains at full RPM.
More over , higher exhaust gas velocity results in higher temps on the exhaust valve seal , face and stem and may lead to premature failure. A lot of fun can be had by cam re-phasing , adjusting the intake cam to open the intake valve later in the stroke and leaving it open a few degrees past bottom dead center , even to the point where the piston has started rising in the compression stroke.The fast flowing air stream will continue to fill the cylinder , even against the rising piston till the pressure inside is higher than the kinetic energy of the air stream can overcome.

To my understanding what you mean to say is that if a the silencer is removed and the bike is running only with the bend pipe then the performance will be better on high RPMs but may lead to premature failure because of increased temperature on the exhaust valve.

When we change the silencer to a short bottle from a long bottle there is noticeable difference in the performance at lower RPMs. Can you throw some light on this? Also tell us if a free flow is better or the silencer with a perforated sheet, mesh, glass wool?

[nasirkaka]

@ Randhawa:

@Nasir- Will make the price and part list soon of the conversion.

Looking forward to that.


As for the upgrades on the older C5:

19" fromt tyre upgrade on the older C5.
cost seems to high V/S the gains. CANCEL for the time.

Heavier crank upgrade
cost seems to high V/S the gains. CANCEL for the time.

Plastic box in the air-filter box
Would stick to the K&N as of now.

Plastic chain guard
Not required for the current michellin M45

Oil filter cap:
Am planning to upgrade to motul. Not confident of doing the flushing and the change myself, would seek professional help. Oil Filter cap not required at present.

Opps.. Here goes the plan of all the upgrades. :(

SWING ARM BUSH from the CI 350 is the only one which makes sense. Would try and get that done.


@ Hexanerax:
As per your explanation,what i understand is the more free-flow the silencer, the lower the velocity of escaping gases, resulting in LOW low-end torque and vice-versa. While using my goldie i did feel a drop in low end torque. is that the reason? which also means the with a goldie, i should gain torque at higher RPMs. Sigh! never had the courage to test that.

I believe the more the number of bents/twists in the exhaust system, the higher is the back-pressure. So with a short bottle/goldie, which are relatively straighter then the upswept, we should gain high-end torque. So in-effect all this is related to the shifting the torque to the desired RMP band, by playing around with the silencer shape, size, flow, diameter etc.

Now, what i want to ask is, are there any thumb rules for designing the silencer based on our requirement? For eg, lets say, i want to improve the low-end torque on my bike, and i also want a bit louder thump. Therefore, i dont want to use the OEM BAZOOKA, or the UPSWEPT, but would want to use the glass wool type goldie. How do i do it? What should the diameter of the opening at the end of goldie? what should the diameter of the inner perforated baffle in the goldie? how much of glass wool to be filled? Not aure if i am being vague, but i hope u understand what i am trying to ask.

[ricky_1605]

Originally Posted by nasirkaka

As per your explanation,what i understand is the more free-flow the silencer, the lower the velocity of escaping gases, resulting in LOW low-end torque and vice-versa. While using my goldie i did feel a drop in low end torque. is that the reason? which also means the with a goldie, i should gain torque at higher RPMs.

u felt a drop in low end torque? I thought changing to aftermarket silencer like short bottle or goldie will make city driving more comfortable by increasing the low end torque. By low end torque do u mean RPM range from 1500 to 3000 revs?

[nasirkaka]

u felt a drop in low end torque? I thought changing to aftermarket silencer like short bottle or goldie will make city driving more comfortable by increasing the low end torque. By low end torque do u mean RPM range from 1500 to 3000 revs?

Yes, did feel that there was a minor drop in power in the lower RPM range :(

[ricky_1605]

Originally Posted by nasirkaka

Yes, did feel that there was a minor drop in power in the lower RPM range :(

I am thinking of getting the goldie for my 2002 Thunderbird. Can you tell me the difference between glass wool type, perforated sheet (mesh) type and free flow type silencers? Also which one will be better?

[Randhawa]

Exactly what are you expecting from the exhaust?

[ac 427]

Originally Posted by Randhawa

@AC- To get rid of wobble, you will have to follow through certain steps.

1. Get the oil in the forks checked and fill it up to 170ml or 195ml in each fork. 170 if you ride on quite rough roads and 195 if you ride it on smooth roads, it will also take care of front diving on hard braking.
2. Get the front T-cone bearings greased and properly adjusted.
3. Check the rear tyre and rim for run out. Rear tyre on our C5 has some issue with run out from factory and replacing them is only the way out.
4. Replace the standard swing arm bushes with the CI bushes for better stability.
5. Or grease the swing arm bushes and align the swing arm properly.
6. Align the swing arm with top mounts of shock absorber.
7. Loosen up the chassis to engine bolts. Rev the engine and let it idle for 10 seconds. Repeat this step 4 times. On 4th time let it idle for a minute. Tighten the bolts.

That should take care of instability for good. The reason behind all of above steps is because even minor miss adjustment on any of the parts will cause the wobble but we are not sure what is causing it unless you do step by step tune up.

Planning to do all these on saturday. for the help. Will update you.

cheers,
ac

[Puffdamgcdragon]

Fantastic write-up Randhawa. It's good to have profecient people in the forum...

I have a question- I recently sold off my 4,000 kms run, almost brand new LB 500 coz I needed the cash immediately. Now I'm interested in acquiring the Classic 500. ( Actually, am trying to decide between the CBR 250 and the Classic 500)

My question is- how much better does the Classic 500 feel in terms of in-gear acceleration, torque and smoothness as compared to the LB500? I've checked the specs out and it looks formidable, but am more interested in the seat-of- the pants feel. Is it more peppy? Smoother at say, 100-110kmph?
The Lean Burn 500, for all it's torque was not smooth at all in higher speeds- too much vibration and engine noise. It wasn't too quick either and the gearings were real short..

THanks. Keep up the good work.

Puffy.

[nasirkaka]

I am thinking of getting the goldie for my 2002 Thunderbird. Can you tell me the difference between glass wool type, perforated sheet (mesh) type and free flow type silencers? Also which one will be better?

This is been discussed earlier, but for you info here is my understanding.

the original goldie (from BSA GOLDSTAR) silencers would be some 40 odd years old, and almost impossible to find one. What we generally get is goldie replicas. Within these replicas, there are design variations. I have come across 3 main variants of goldie replicas as follows:

1. A conical shaped exhaust with nothing inside. Fully free flow. This one is just looks like a goldstar (loosely) and produces the loudest noise. (read NOISE). typically costs between 700-1000 rs.

2. A goldstar type exhaust which has a perforated sheet metal baffle inside. This perforated sheet metal is is bent like a 4 petal flower (cross section).
This one make loud noise, but is not as loud or irritating as the first one, would roughly cost around 1500-1800 rs.

3. The third variant is made in two parts. The shape is similar to goldstar type, but the rear part of the exhaust is removable.
There is this outer sheet metal tube and inside there is another (lesser dia) perforated sheet metal pipe. Between these two there is provision to fill in the glass-wool and close the end. These type produce good sound (not too loud) and more bass based.
The cost ranges between 2000 to 3500 rs, depending on the city and the maker.

Exactly what are you expecting from the exhaust?

Best of both the world, if possible. Mainly-

1. Good low-end torque (quick acceleration from 0-60), as well as decent breathing at high RPM.
2. pronounced and clear thump and less of the engine clatter.
3. These if possible. Reduced/No popping, no reverse flow of exhaust gases, no golden hue of the bentpipe, no leaks from the joint.

But more important to me is point 1 & 2.

[indian21r]

Originally Posted by ac 427

Planning to do all these on saturday. for the help. Will update you.

cheers,
ac

Hey AC I am also thinking of getting the stability issue sorted out. Where are you planning to get the work done?

[EssYouWe]

Originally Posted by nasirkaka

1. Good low-end torque (quick acceleration from 0-60), as well as decent breathing at high RPM.
2. pronounced and clear thump and less of the engine clatter.
3. These if possible. Reduced/No popping, no reverse flow of exhaust gases, no golden hue of the bentpipe, no leaks from the joint.

But more important to me is point 1 & 2.

1.) Both wouldn't be possible without using Bajaj's Exhaustec :P. Don't go in for a completely free flowing exhaust. You will be left with a shortened bottom end.
2.) The engine clatter can not be affected by the exhaust. You can at best make the exhaust loud enough to drown out the clatter.
3.) Tuned right, this won't happen to any engine.

[hexanerax]

You are correct. A free flow silencer sacrifices low end torque for peak power at high RPM but the intake would also need to have appropriate mods. And the fuel supply will have to be increased by jetting. The science of airflow management is highly technical and modern designers use computational fluid dynamics to check for the airflow rates. Ideally , you would use a less restrictive silencer and tune it , testing at a variety of settings. There is no simple formula. Also remember that the silencer can be tuned for flow at certain ranges of RPM. Even racing engines cannot really have the best of both worlds without complicated resonant exhaust systems and tuned headers. A full free flow silencer is less than ideal for normal use and prolonged hi RPM runs.

On the EFI 500 , the rev limiter will limit your top end no matter what you do to the airflow or the fuel injection. You will need to regear , changing the chain sprocket to a larger one ( front sprocket ) to go faster for a given RPM as compared to stock. But tuning for torque at low end can yield good improvements in pulling and acceleration through the gears.
Also consider that at a speed of 4800 RPM , the 500 is doing 2400 intake strokes/min which corresponds to a pumping rate of 1200 Liters/minute of air. Given the cross sectional area of the intake manifold , you can calculate the velocity of the incoming air stream. The exhaust can be sized based on that figure but you will have to take into account the higher velocity of exhaust gases. As i said , a good job with numbers that are correct and actual dyno results to back up the mods is a tedious and expensive process. A K&N fitted to your bike will rarely give the kind of improvement that people claim to feel with their Butt-Dyno. The physics of IC engines is extremely complex and claims of improvement of more than 15 % should be taken with a lot of salt. Also remember that the quoted 27+ BHP for the EFI 500 is crankshaft output. A couple of BHP will be lost to the alternator and other mechanical devices like the oil pump. The primary chain will account for some more as will the clutch and gearbox. The drive chain and the wheel bearings will sap up some more till you are left with 21 to 23 BHP at the wheel.

[Randhawa]

@Puffy- LB and C5 are a lot apart. You wont find the touring comfort of LB on C5 and you wont find the agility of a cougar in LB compared to C5.

Yes C5 is smoother but the way it delivers the power is quite different compared to LB. One things about C5 is that it performs different at given times. Its like an Italian pedigree bikes. At times it perform like lightning and then sometimes like a bull. All to do with ECU.

You seriously need to ride the new C5 to see how smoothly it can do 100-115 all day long.

I think Navpreet can give you a better comparison as he has a LB500 and test rode a C5.

@Naren- We can't go for a bigger front sprocket on C5. There is no space for it.