[89katana750]

The V&H pipes are completley rusted on the outside so I would have to do some serious sanding before I can get the slip on.

[The CyberPoet]

The reason I am concerned about the richness is because the info I gathered was that I had to rejet. I didn't know that it would sputter/misfire etc. if it was too rich/lean. I don't think I have much of a problem anymore but I am still going to see with the gas analyzer.

There's a cheaper way to tell -- buy a couple sets of plugs. Pull the new ones in 500 miles and look at them. Compare them to a spark plug chart, and you'll see based on the build-up and appearance whether the bike is running rich/lean/spot-on.

Unless, of course, you've got money to burn. Then, by all means, get the exhaust analyzer... make sure you bring it to the rally, and pass it around after you've used it... I'll pay shipping both ways to borrow it for a weekend

Cheers
=-= The CyberPeot

[The CyberPoet]

The V&H pipes are completley rusted on the outside so I would have to do some serious sanding before I can get the slip on.

Don't both sanding them -- send them out to be jetcoated (i.e. powdercoated with ceramic-aluminum) if you want to use them again... The powdercoater will sandblast them first, and they'd never rust again... plus they'll run cooler and look pretty

Cheers
=-= The CyberPoet

[89katana750]

I wasn't going to buy the gas analyzer.

I was going to ask a mechanic politely to use it 8)

[ThAzKat]

It funny how you mentioned the spark plugs being old. They are actually very old. 12,000km old . Don't worry I bought new ones.

The reason I am concerned about the richness is because the info I gathered was that I had to rejet. I didn't know that it would sputter/misfire etc. if it was too rich/lean. I don't think I have much of a problem anymore but I am still going to see with the gas analyzer.

THAZKAT, what do you mean about the backpressure? what does that feel like?

you don't feel back pressure, I think Cyber has a great definition for back pressure. A stock system has the most pressure. A wide open system has next to no back pressure.

[The CyberPoet]

THAZKAT, what do you mean about the backpressure? what does that feel like?

you don't feel back pressure, I think Cyber has a great definition for back pressure. A stock system has the most pressure. A wide open system has next to no back pressure.

OK, here goes...

The higher the back-pressure in the exhaust at the exhaust valves, the more torque the engine will make at low RPM's, as the valves stay closed longer, re-close faster and hold tighter, resulting in less leak-down and better loading of the inbound fuel-air charge (and more piston movement from the detonation).
The lower the back-pressure on the exhaust valves, the more HP the engine will want to make at high RPM's, as the less the engine has to fight to push out the exhaust under load, and the outbound exhaust (at high speed) will help pull a larger amount of fresh fuel-air mix in (the reason for valve-timing overlap -- aka why the intake valve opens before the exhaust valve closes). The speed of the inbound charge is also critical in accomplishing the maximum compression ratio for an engine, and the faster the exhaust leaves, the more vacuum it creates in the cylinder to pull in the fresh charge... Once that inbound charge is moving at high-speed into the cylinder & the exhaust valve closes, the intake valve can stay open even after the cylinder starts moving upwards, and still be adding more fuel-air mix, because the inbound-speed is so high, it defeats the force of the piston rising for a short while. This maximizes how much fuel-air mix is shoved in and results in the highest compression ratio possible on that engine.
Professional world cup race bikes have virtually no back-pressure, but also have their idle set around 3 to 4k RPM to get any power at all at the bottom end.

In a best-of-both-worlds scenario, you'd have high back pressures at low RPM's and virtually no back pressure at high RPM's; many bikes use a valve in the exhaust system to acheive this, by regulating the back pressure (Yamaha's EX-UP valve was one of the first examples of this technology; many modern race-rep spot bikes use a solenoid-controlled regulator flap to do accomplish this, in older bikes it was often accomplished using a spring-flap).

So there's the trade-off. More power down low, or more power up top... Different cam grinds are also designed to work into this equation as well, changing the duration, lift and overlap of the valves (i.e. - how long they're open, how far they open, and how long the exhaust is still open after the intake valve starts opening). The primary difference between the Bandit engine and the Kat engine is a cam difference in which the Bandit gets more low-end torque while the Kat gets more high-RPM power.

Cheers
=-= The CyberPoet

[ThAzKat]

I was waiting for you Marc, I knew you had the definition.

[89katana750]

That would explain why I have not much low end, because of the gsxr cams giving me less back pressure and more top end.