Ever wonder how much difference a port job makes?

[callison]

There would obiously be a piont where you are restricting the flow if you went too small.

 

Absolutely. If the EPA were to have it's way, the port would be so small you couldn't flow anything through it, thereby stopping the engine and all possibility of pollution!

 

It should be interesting to watch the details of the Breva 1100 unfold. There are two injectors per head and stepper motors are mentioned in the specs, but no mention of where. The only application for stepper motors I know of for motorcycles have to do with exhaust systems as in the new Buell adaptive muffler. This, to me, means that the intake ports have the stepper motors. This would be a logical application. There are two injectors, one small and one large, just like the primary and secondary ports on multi-barrel carbs. At low rpms, the stepper motor would mask the large injector and it's port runner to keep intake charge velocity high and improve combustion efficiency and reduce pollution. At higher rpms, the ECU would tell the stepper motors to unmask the large injector in response to engine demands. As the current engine is configured, at low rpms, the charge velocity is quite slow, which is a bad thing.

 

Your Ducati guy could be right, but the evidence doesn't support his statement. A correctly ported Guzzi runs better than a stock one. Guzzi engines also have a terrible squish band that contribute to their inefficiency, so changing the pistons also helps. As does a cam, a bore job, a stroker crank... Look, it's an antiquidated, push-rod engine (not as antique as a Harley though), or as Mike Rich puts it - "An overgrown lawn mower engine". It should respond to the same kind of backyard, shade tree mechanic engine modifications as any stock car race engine. Speed is not just measured in units of distance per unit of time but also in cubic yards of money invested. Ducati's are already optomised so heavily from the factory (and priced accordingly) that there is little benefit for them in addtional porting etc. unless they're actually going racing. That may have affected your Ducati buddies evaluation a bit. Guzzi's obviously aren't in the same class, so there should be more latitude for improvement.

[dlaing]

Look, it's an antiquidated, push-rod engine (not as antique as a Harley though), or as Mike Rich puts it - "An overgrown lawn mower engine".

But it is also one of the few 90+ crank HP aircooled twin valve twin cylindered production engines, period.

[Guest captain nemo]

Yes, and antiquated or not antiquated, it still depends greately on the skill of the rider. The Guzzi is more than an HP rating or its individual parts. It has attained something greater than its parts. And this is what makes it a very ridable machine - and a dominate road machine in the hands of a skilled rider. Graphs and specs do not exactly translate in the real world. Most reviews are meaningless. They will review a motorcycle without even setting up the suspension or understanding how it works. Meaningless horse hockey.

 

I was out riding tonight and saluted by kids on high powered Hondas - why???? Because the Guzz has the power of magic. It always performs greater than what is expected by the statisticians.

[dlaing]

Very Well said!

Sometimes I wonder if I would have been content with an 850 Lemans, but I love my bike and always dream of an even higher HP statistic.

The porting seems like an expensive route to that end, but the valve job is eventually a necessity and well worth the money to have done right.

And while the valves are done, it seems to make sense to do the porting....