Don't touch the exhaust

[Fred]

Do not touch the exhaust Do not change the dia from 1/14 to 2 inch your bike will never run right again. 8 years i have played with this and you can do what you like to your carbs to cure your exhaust choice.

There is forces you do not know going on up your pipe. if you have 2 inch straights you bike runs crap --no --- don't try to tell me other wise it does not run right, you only think it does. I'lle bet your bike pops, hesitates in town traffic and stumbles at cruise. Maybe you cant feel it because you twist open the throttle to full and of course it then pulls like a train,--that is not running well.

Ille bet your fuel filters have fuel in it, the reversion you will get from 2 inch is so bad it knocks air and fuel right back through the exhaust and across to the inlet wetting your filters and pooling fuel in the carb mouth.

1 1/4 pipes keeps the gas speed up and over the speed that can allow thermal and sonic shock to revert less.

Many exhaust diam calculators on the internet,---all of them will calculate 1 1/4 remember it per cylinder so its 700cc not 1400cc.

Next we will talk about the cross over, Not as critical but necessary. Go to the Ducati showroom or suzuki or any twin engine and look. It may not look like it has but get on your knees and look --you will find it.

Multi cylinders always have a collector as does a chevy V8 unless its a drag that only needs full power full throttle running.

[YoDude]

Curious minds want to know!

Yo-

[Fred]

Im afraid you dont understand. Its got nothing to do with the mixture your burning, I tried to explain it is the exit of the gasses coming back to fight the flow of the gases going in by something called reversion that includes sonic and thermal shock. Showing your plugs has got nothing to do with it.
Its ok showing your tounge to the doctor if your feeling down but not much good after you've broken a leg.

That is another one of the symptoms-- constant need to make AF adjustments and a very small movement is critical.

With manufacturer stock exhaust the AF screws where blanked because constant adjustment should not be necessary.

You can not adjust the carbs to fix a wrong exhaust.

[Fred]

Well you are making break thoughs in mechanical engineering. Ide like to lean more about reversion correcting baffles.

I hope Suzuki is listeneing in as Im sure they would like to know how to increase power with dogs bollocks thunder bastards exhausts baffles ( something like that).

In such a competative market all they have to do is change the exhaust.

I wonder why they use 1/14 pipes. does anyone know.?

I tell you what,---- rev your bike up hard --right hard, one big twist up to full throttle then let the throttle snap back to idle.

It will stall.

Take off your filters and you will have fuel in the carb mouth.

[Fred]

Im very pleased you are happy with how your bike runs , some of us require then to run properly.

However as this is a open forum perhaps you would not mind if others discussed reversion.

[YoDude]

Hmmm.....So Fred, you're saying Keith has a problem with reversion if he's not having any problems with his bike?

Is that kind of like saying you don't know what you're talking about, just because you may not know what reversion is? Or is it more of a situation of, I know what it is, but because I've never bothered to discuss it with anyone, it doesn't bother me?

Or, is it something else?

Yo-

[Fred]

We all have problems with reversion YO--even you and me. We have all had it since the piston was invented. Ever wondered how an engine can breath at such speed,---well it has a great deal of difficulty doing so but we get along with it. Year by year better pipes and cams and manifolds get a little bit better and engines get more powerful.

In the early days of automobile engines huge capacities were used to get a mere 25 HP Why was that do you think.

I want to discuss it not its existence

Don't worry Its my fault. Wrong forum. This forum is dead. I have tried!!

AMIMI IRTE Mech E F tech yes I know what im talking about.

Shall we discuss what car wax do you use?

[BRONX INTRUDER]

[Lechy]

Poor fellah does not understand the Intruders at all. The series were sold to the American market in a state of de-tune so as to not compete favorably with Harley Davidson. Whilst the 700/750's came off the production line in a pretty much optimal state, the 1400 did not. 1400's can be opened up by improving the breathing on both sides of the pot. The baby brother does not benefit from any tweaking. Due to government emission laws all Intruders were set lean on the idle circuit and do benefit from a slightly richer mixture.
He is correct however by implying that a certain amount of back pressure in the exhaust system is required due to valve timing overlap.
If these bikes were designed as fine tuned machines I would also agree about the need to have a fully balanced exhaust system, but they are not, they are low tech design and do not require such considerations. Hell, they will run on the cheapest gas available and still out perform most bikes in their class.
[emoji41]

[Fred]

Letchy letchy letcy do you really think Suzuki designed a totally radical 1400 to look like a Harley and sound like a Harley that can wipe the floor with a Harley just to----not compete. What are you drinking.

A 1400 does not improve with tampering with mixture nor will it run better with a 2 inch exhaust.

Old wives tales kept going by old wives.

Do you know what a placebo is? well when you just spent close on 500 dollars on an exhaust system you'de better believe it runs better, wether it does or not.

Now for the techinical bit ( letchy can leave the room) A single cylinder is an air pump the duration and overlap is critical for reversion --hell all this stuff is on the internet fer fcks sake why an I explaining it to dumb ASSES.

[YoDude]

Intruders are awesome!

Yo-

[Lechy]

Fred is always right and always in denial.
[emoji41]

[JPJ61]

I agree with what Fred is saying. More noise does not equal more power! I want to improve the state of tune of my engine without the noise.

[jonnycando]

I agree with what Fred is saying. More noise does not equal more power! I want to improve the state of tune of my engine without the noise.

Then put an emissions sniffer up the tailpipe, and adjust the idle mixture for just lean of stoichiometric, and then redo the main jet for best mix at say, 3000 rpm. You are still going to be compromised elsewhere. You can make a happy medium that is not altogether perfect, but the bike runs happily, or you can create perfection that exists only in a narrow range. Same could be said of any pipes you run....you can get the engine running OK, but perfection will exist in only one spot. The bigger the pipe the higher you have to rev to find that sweet spot.

[YoDude]

I agree with what Fred is saying. More noise does not equal more power! I want to improve the state of tune of my engine without the noise.

No one here was saying a noisier bike had more power. I know mine has more power, not a lot more, but enough that I can tell it by how it pulls. Sorry, I can't prove it, you'll just have to trust me on that.

Yo-

[Fred]

The emission sniffer does not sniff performance.

Why oh why do you guys fit 2 inch pipes then fit baffles and lolipops trying to get back pressure. The perfect size is 1.1/4 inch as per any exhaust diam calculator you will find on the internet and fitted as stock, Exhaust gas exit must be kept above 350 feet per second or shock reversion will come back through the cylinder.

Try blowing a smoke ring into a bucket.

No engine needs back pressure, in fact a lot of time and trouble goes into making heads and exhaust that do not, but you guys are making break through in technology.

And another thing main jets do nothing unless you are pulling a caravan uphill in 3rd gear at full throttle, I can think of any other way you could get a main jet to come in to use with a big bike like the 1400.

The fuel going in is limited by the needle and jet when this reaches its limit then the main jet ( metering jet) has the final say.

The ridiculous obsession with main jets being able to cure exhaust problems is rife here. You fit huge diam exhaust then expect to fix it with jetting.

It does not work like that, the 1400 is already tuned with high duration overlap cams you cant just keep adding bits for HP.

Ive never seen a motorcycle brochure that sells a basic model and all performance bits and pieces can be bought later. Performance is in deep in the cylinder head and piston design not a big noisy exhaust pipe.

[jonnycando]

Reduce back pressure appreciably and you move the torque capability higher in the rev range. Put a dual exhaust on a 2bbl engine that is tuned mildly and it will go completely to sleep on you. Until you get it going way fast and then it might act like it has something. Find a way to let more air in at lower speeds and you retune it to work with the reduced backpressure....actually you reintroduced the back pressure by letting more air in. But if the fuel system can't supply enough fuel at to make good use of that air, you now have a lean condition.....now have to let more fuel in. Yes, you are totally rethinking the engine at every change you make, and it may not be for the best; but you can make it somewhere close to right if you keep fiddling. Or else leave it the way the factory made it.

[Fred]

Volumetric efficiency, thats all you got to remember, getting as much air through as possible = HP how the hell restricting it helps is totally nuts .

Thats why big carbs , quad barrel on your American engines with dual plane manifolds for torque and turbos and blowers that force more air in with high efficiency headers--- not big headers. So your idea is restrict it?

Check out the exhaust diam cal on the internet a Chev 350 should be 1 /1/4 inch. Thats because exhaust gasses must reach 350 ft per second. Its not easy -- no one says it was.

[Fred]

Reduce back pressure appreciably and you move the torque capability higher in the rev range. Put a dual exhaust on a 2bbl engine that is tuned mildly and it will go completely to sleep on you. Until you get it going way fast and then it might act like it has something. Find a way to let more air in at lower speeds and you retune it to work with the reduced backpressure....actually you reintroduced the back pressure by letting more air in. But if the fuel system can't supply enough fuel at to make good use of that air, you now have a lean condition.....now have to let more fuel in. Yes, you are totally rethinking the engine at every change you make, and it may not be for the best; but you can make it somewhere close to right if you keep fiddling. Or else leave it the way the factory made it.

Yes--- you ever seen the RR Merlin engine and the US Allison made under RR license,-- you see the exhaust, they are less than 1 foot long. Mind you reversion was not understood in those days but those engines ran very rarely under 80% so it was OK.

A good Idle and handling in traffic was not a consideration neither is the dragster with pipes of similar length but HP way up on the top of the scale.

[Fred]

I agree with what Fred is saying. More noise does not equal more power! I want to improve the state of tune of my engine without the noise.

No one here was saying a noisier bike had more power. I know mine has more power, not a lot more, but enough that I can tell it by how it pulls. Sorry, I can't prove it, you'll just have to trust me on that.

Yo-

And no one argues with that if you use your bike as a get away vehicle thats fine. You would get more power if you totaly removed the air cleaners and sawed the pipe off at around 29 to 33 inch making zero back pressure.

However it would be a dog in the street.

Why don't you google reversion on you tube.

There is fantastic footage of air coming OUT of the carbs on a running engine when reversion is full on. Dont just sit there Oh no no no its not---- mine is OK.

Wise up