A guy that is porting cylinder heads for motorcycles has approached me. He is saying that a street porting, which will be about 300 dollars, will increase both top-end power by a minimum of 10% and the torque will be increased over the whole rpm range. And also if the bike wheelies in first, it will do it in second to after the headwork. This is to be with stock cams and exhaust. He has ported a few track machines before, and the owners appear to be happy.

Any one has experiences in this and knows if it is possible, or if I should I stop dreaming and turn the offer down?

 

Sounds like a great way to toss $300 out the window, but hey I could be wrong. What about trading the '97 Bird in on a Busa or zx-12r? Fuel injection + 25 hp. Or are you talking about you're Gixxer?

 

It’s the Bird. I don’t want a Busa or a ZX12 even though they are great, I'm happy with the Bird and just want to get the very best out of it both engine and suspension wise since its worth keeping for long. The same porting-guy tuned a Bird to 185 RWHP, isn't that what everybody need [&:] Well, except for the head work, that included new camshafts, raised compression and a full exhaust, and of course the tuning. The Bird engine is a sturdy beast that can handle a huge amount of power with stock engine components. There was a limited series of specially prepared Birds about year -99, having the same power figures or more, and with improved chassie components. There are also turbo applications where the first turbo level (street version) is 240 RWHP, with stock engine components. This Bird engine appears to be designed for a good horse-kick

 

I've read different things about this subject and what it all comes down to is experience - you are entering the world of black art and what works in one scenario may not be so great in another. I've even heard that if you get the porting wrong you can lose HP - that there is a good thing from the gas/air mixture getting a good 'mix' on it's way in (by friction on the port walls) so who knows.

On this subject I occasionally hang around www.cb1100f.net and there is a real bunch of knowledgeable guys there. After a while you get the news that vacuum carbs are pants and mechanical slide carbs are the way to go. I've read from somebody who clearly knew about stuff (respect matt@psb - departed) that you can expect an extra 10-15% hp through a set of properly set up slide carbs. So - anyone fooled about with carbs on the CBR1K?

 

Holy crap - i'm a Senior Member!

 

Thanks for the link to cb1100f.net, a lot of interesting information there.

 

Hey:

From my own experience, porting, cams, and bore kit are the most important ways to real (non supercharged)
(no NOS) horsepower usefull thru the ranges, with porting being the one that is most noticed without anything else being
done. $300 is not a bad price as in my cbr1kf I spent $800 USD on the head prior to getting the thermal coatings. That was
just porting and comp valve job with me supplying all the new valve train parts. I would say that would be money
well spent if they knew the way around a flow bench to get positive results. The bike was alot smoother thru the rev
range and for a few months was the only mods I had done with a V&H pipe, idv K&Ns, and Factory jet kit.
It had great instant throttle response as everything seemed to work together very well. Then the coated bore kit,
lightened crank, and rods was ready and was put in. I got lots more mid range grunt and even more instant accelleration
very street friendly still, but better than stock by alot. Next was the V&H igniton, advance, dyna coils and taylor wires,
With the only thing I noticed was it started instantly in the 2nd advance curve setting. Then the big lift web cams were
installed with 39mm flatside carbs this moved the powerband way up above 6,000 rpm and the bike was not as street
friendly as before, but the bike ran the best times at the drags mid to low tens in various wx like this. I also took it like
this to a road race track day and it worked pretty good, and stayed this way for over 5 years. I have since added new
bodywork, an Ohlins shock, xx forks and swingarm, with a 5lb NEX NOS kit and have not rode it since I did not get it done,
prior to other commitments taking me out of the country for awhile.

Alot of people claim to get big results from porting but very few get great results, due to the time it takes to get it right,
and with some heads getting trashed along the way. If you know for a fact he can port heads, go for it, as long as you know
you won't be one of the trial and error heads. From what I have seen and experienced if done right porting has no down side,
just be prepared to spend some more money getting the most out of it.

Dub

 

You've done an impressive upgrade. Thanks for the clear and extensive information. The head porting guy has no flow bench and just a very few number of references, I feel I'll better pass this time. In case the head has to be lifted by other reasons, I can do the port matching to intake runners, cleaning, remove any cast remaining, and smooth out possible stair-steps between ports and valve seats by myself. My Bird delivers a serous amount of power as is with the new slipons, and it’s far safer to leave it as is than taking any risk by getting help from a trainee in the porting business. Thanks again.

Edit - This link shows the porting basic that anyone can do and will have some good impact on the performance. http://www.sa-motorsports.com/diyport.shtm

 

Hey:

Here some info you might interested in http://www.mototuneusa.com/think_fast.htm. Give you info on DIY porting.

Dub

 

Thanks, I haveseen and read that info. And yes, Motoman appears to know what he is doing and the high velocity porting is very interesting. Here are some pics on ongoing work with my replacement head to the Bird.



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