How often to change spark plug?

[tt6389]

A straight pipe such as you are talking about will probably cause the bike to lose power. Every pulse of exhaust from the engine generates a pulse wave that travels down the pipe. When it reaches a restriction, a bend, or the end of the pipe, a reflected wave is sent back up the exhaust pipe.

 

Properly designed, the reflected wave low pressure point reaches the exhaust port at the same time the valve opens and this helps scavenge exhasut gases. Not done properly and the high pressure pulse reaches the valve when it opens, reducing scavening and causing poorer performance.

 

A straight pipe, properly cut to the right length will provide maximum scavenging at exactly one RPM level. Therefore, pipe design usually makes allowances to get the best scavenging across a range of RPM's.

 

------------------------------

 

Thanks again for the rich informations. While researching on exhaust systems, I found this website which promotes this brand of exhaust. It declares their endcan do not need re-jet , no baffles which can restrict peak power output. No restrictor tubes. It seems to be the ideal design. They even explain the scientific theory behind.

 

It makes me think if I were to buy a secondhand endcan or silencer such as Yoshimura or Micron, I have to find out which ones is closer to the above "perfect" design.

 

Btw, Yoshimura & Micron silencers are the most commonly available silencers in the 2nd hand markets. I would need to research their website whether they have the above specifications.

 

Can you kindly explain what is a baffled silencer, what is re-jeting & why is it necessary & what is restrictor tubes? Will really appreciates. Tnanks.

 

-----------------------------

 

Quoted from http://www.jbracing.co.uk/quill_exhausts_t3.cfm?ProdID=31&category=6 -->

 

Why fit Quill T3?

Unique design.

Nothing to fit

Nothing to remove

No need to re-jet

No need to re-fuel

Race can performance

Conforms to BSAU

Lighter than factory fitted standard exhausts

Quality race can sound after 4500rpm

No Police OR MOT problems.

Unconditional Lifetime Warranty

Available in Stainless Steel, Carbon, Titanium and Anodised Titanium

Quill T3 Technical Information

 

Dilemma: “Do I choose Race-Can or BSAU approved Can?”

 

Race Can

Advantages..........Enables peak power output - Low Weight - Distinct exhaust note. Disadvantages......Noisy & erratic at low speed - Not legal on the road.

 

Baffled Silencer

Advantages..........Quiet & smooth at low speed - Legal on the road

Disadvantages......Inhibits peak power output - Muffled exhaust note - Weight penalty

 

Solution.............. The Quill T3 Silencer!

 

The ONLY Road Legal Silencer with Race Can Performance...The Quill T3 is the only exhaust that delivers it all!

 

MORE Power On the Road - No restrictor tube to fit!…. MORE Power On The Track - No restrictor to remove! - No need to adjust jets for road or track! Legal, with no compromise! - Conforms to BSAU regulations, thus ending the traditional choice of race or baffled silencer.

 

The Science Behind the Art

Gas mass flow rates through the exhaust change as a direct function of the engine speed, so the functional characteristics of the silencer are determined by the rpm of the engine. At lower engine speeds, the T3 is designed to function as a 'combination' (reactive/absorptive) silencer.

 

At higher rpm (higher gas mass flow rates), pressure build-up in the rear chamber shortens and straightens the apparent gas path. This promotes optimum engine breathing. In practical terms this typically means that from upwards of 4000-5000 rpm* the silencer will perform in a similar manner to a straight-through race pipe.

* Please note that this figure will vary between engine types due to differences in design and cylinder capacity.

[tt6389]

i think i am going off topic here. Other people may not be aware of the enriching discussion about exhaust system inside ; and missed it. They thot its just about spark plugs...

[Strong Eagle]

------------------------------

 

Thanks again for the rich informations. While researching on exhaust systems, I found this website which promotes this brand of exhaust. It declares their endcan do not need re-jet , no baffles which can restrict peak power output. No restrictor tubes. It seems to be the ideal design. They even explain the scientific theory behind.

 

It makes me think if I were to buy a secondhand endcan or silencer such as Yoshimura or Micron, I have to find out which ones is closer to the above "perfect" design.

 

Btw, Yoshimura & Micron silencers are the most commonly available silencers in the 2nd hand markets. I would need to research their website whether they have the above specifications.

 

Can you kindly explain what is a baffled silencer, what is re-jeting & why is it necessary & what is restrictor tubes? Will really appreciates. Tnanks.

 

 

Baffles go inside the muffler/silencer, across it, like walls with holes in them. They kill sound by redirecting the air flow around corners.

 

A restrictor tube is a smaller diameter plug/pipe that is stuffed in the end of your exhaust to reduce sound volume.

 

Re-jetting means changing out the carburator main jets to allow more fuel to flow for a given amount of air. Sometimes this is done because the pipe is truly more efficient and you get more power out of the eninge which of course means that you need more petrol.

 

Just as often though, you need to re-ject with pipes because they create flat spots in the power band. So, you pour more petrol into the engine to make up for it.

 

I cannot comment on the cans you mentioned, except to say that they seem typcial in that the improvement in HP is in the high RPM end of things. If you look at the dyno charts on their website, you see HP improvements starting at about 90 kph (they don't list RPM's).

 

Getting more HP in the high end almost always means a tradeoff. Stock bikes are built as a compromise of smooth power across the RPM band, meeting sound requirements, and fuel economy.

 

Most people who put performance pipes on find that the low end RPM's power suffers and/or fuel economy goes down. You really have to think about how often you will ride in the high RPM band to determine if such a change is justified for you.

[snowparang]

------------------------------

Btw, Yoshimura & Micron silencers are the most commonly available silencers in the 2nd hand markets. I would need to research their website whether they have the above specifications.

In my opinion, most end can replacement do not offer a markedly hp gain. Most are enamoured by the 'sound' produced, not the real power increase. I don't deny a bassier, louder exhaust does make my bike 'sound' faster! But it may not be really faster or more powerful.

 

As for making the engine breath easier, it's not as simple as that. Else all racing bikes will have open pod intakes and exhaust that open directly to the air.

 

Still, if you're really keen to get more power, most bikes will have a full system followed by an ECU remap to obtain the greatest potential offered by the exhaust upgrade.

 

 

 

Back on spark plugs though, the service manual on my VFR says replace every 12000 km.

[tt6389]

In my opinion, most end can replacement do not offer a markedly hp gain. Most are enamoured by the 'sound' produced, not the real power increase. I don't deny a bassier, louder exhaust does make my bike 'sound' faster! But it may not be really faster or more powerful.

 

As for making the engine breath easier, it's not as simple as that. Else all racing bikes will have open pod intakes and exhaust that open directly to the air.

 

Still, if you're really keen to get more power, most bikes will have a full system followed by an ECU remap to obtain the greatest potential offered by the exhaust upgrade.

 

 

 

Back on spark plugs though, the service manual on my VFR says replace every 12000 km.

 

I often read from SBF riders who describe their legal Yoshimura exhaust silencer as "straight through" type. In the Yoshi website, i also confirmed it is mentioned that way. I have no idea what it means but my guess is that it doesn't have a baffle to redirect the gas flow - the gases flow straight thru.

 

The full system Yoshimura includes both exhaust silencer & the 4 to 1 stainless steel header. The reason why full system gives a more dramatic power increase is because there is no catalytic converter within the headers to impede tha gas flow during high rpm. Hence, it is more "straight through" than the stock header. But the trade off is the exhaust emission often fails LTA test. Again I heard this from other riders; i dunno how true this is. But if this is true, then there's no way I will go for full system at all.

 

What I heard from other riders is changing the exhaust silencer alone only gives marginal horse power increase. Only full system can give more dramatic power increase.

 

[roseonfire]

wats d purpose of spark plug? :/

[tt6389]

wats d purpose of spark plug? :/

its for igniting the fuel/air mixture during the compression stage of a 4 stroke engine.

[revenge]

every month, coz 2 stroke bike very eassy foul the spark plug

[KeraKing]

every month, coz 2 stroke bike very eassy foul the spark plug

 

bro u riding sp?

from experience sp no need to change often.

maybe ur carb need retune?

[LongLifeBikers]

yoz...my cb400 can't start suddenly, i think it may be cos of the spark plug. is there anyway i can start for the last time for me to ride to servicing? quite headache now..

[Darkness19]

the best is aft 3000km

[D]

Sori to add in and ask something, wat abt engine oil? every 5000km?

[stinkybutt]

wen i was werking at mac,i usually clock 4000km/mnth. every month change da engine oil n da spark plug. u usually haf to look at da engine oil's colour. if its black,its time for u to change.

[Darkness19]

usually engine oil u will change it with ur spark plug,3000km-5000km will be gd:thumb:

[Am hoppus]

Yep true. change engine oil together with spark plug is a recommended laa. but for me if still can start the bike, i rather stay it that way.

[reconn]

Depends on which type of sparkplugs u use. A good Iridium sparkplugs lifespan can go slightly longer usage compare to normal plugs..

[Darkness19]

yup good Iridium sparkplugs lifespan is longer then normal sparkplugs

[Strong Eagle]

wen i was werking at mac,i usually clock 4000km/mnth. every month change da engine oil n da spark plug. u usually haf to look at da engine oil's colour. if its black,its time for u to change.

 

Just because the oil is black does not mean it is not doing its job. The black is caused by carbon in the oil and does not affect oil performance.

 

If you are using a synthetic oil there is no reason why you should have to change your oil any more often than at least 10,000 km. New cars that come equipped with synthetic oil recommend 15,000 mile oil changes... that's 24,000 km.

 

Bike gear boxes do chew oil up more but a synthetic is still good for between 10,000 and 15,000 km.

[snowparang]

Just because the oil is black does not mean it is not doing its job. The black is caused by carbon in the oil and does not affect oil performance.

 

If you are using a synthetic oil there is no reason why you should have to change your oil any more often than at least 10,000 km. New cars that come equipped with synthetic oil recommend 15,000 mile oil changes... that's 24,000 km.

 

Bike gear boxes do chew oil up more but a synthetic is still good for between 10,000 and 15,000 km.

Shouldn't we take into account that bikes rev about 2-3 times higher than car engines, and hence the change interval for oil changes to be reduced? Because even though a car and bike has both travelled 10,000km, the bike engine has rotated/worked about 3 times as much!

[LPMS]

I normally change & replance my plugs like every 6 months. Am using NGK plugs.

[ponnusj]

Replace them once a year is okay. Hardly see any deposits in 4 stroke bikes.

[azr123]

I find mods are hard to justify by bangs per bucks for street riding. Usually, the changes can only be noticed for a while until you are used to it. The positive feeling will quickly fade and you will end up wanting more. The next thing you know, you have spent a lot.

[Hydher]

Follow the manual

 

Honda steed 6000km

Honda shadow 12 000 km.

 

Ngk iridium 0.6mm tip 50 000 km

DENSO iridium 0.4mm tip 30 000km.

As their website reccomends.