It's All In Your Head..

EMS · Post by **EMS** » Tue Nov 27, 2007 2:36 pm

...or so they say. As the engine in the 79 CBX has been tilted to remove the carbs, the valve cover has been removed to inspect all that moves under there, I have decided to go one step further and pull the head in order to have a look inside the heart of the motor. As I have a couple of spare heads AND I made the aquaintance of a real nice gentleman

(FC

) who has vast experience in porting motorcycle heads - he is currently doing the head of my CB1100R - I have asked him if he would like to try his trade on a CBX head. Rather than just bolting a turbo on the bike and ending up with a screaming straight-line 1/4 miler but terrible canyon carver that will be beaten by any 600cc sportbike as soon as the road starts to turn, how about making a serious attempt to improve the natural aspiration capabilities, whith special attention to the outer intakes

It probably has been done before. I know Rick from "Rick's Tricks", way back when, modified heads by machining the intake canal bosses off, rewelding material on and remachining intakes that were all very much the same between the six cylinders. I would not want to go all this way, as I would like to retain the stock carburetor arrangement. And besides, I have other bikes that are faster than my CBXes, no matter how much money I would pour into one of them

alimey4u2 · Post by **alimey4u2** » Tue Nov 27, 2007 4:36 pm

Keep us updated Mike.....

Terry · Post by **Terry** » Tue Nov 27, 2007 4:42 pm

Since you "have other bikes that are faster than my CBXes, no matter how much money I would pour into one of them" I guess this is just an exercise in how much $$ you can spend then eh? I mean, since no amount of head work can make the X beat a 600 thru the twisties, why else would you have the head ported? BTW, with an average rider on a 600, I have had a lot of fun with them in the twisties on my 79...

EMS · Post by **EMS** » Tue Nov 27, 2007 5:41 pm

Terry wrote: " I guess this is just an exercise in how much $$ you can spend then eh? I mean, since no amount of head work can make the X beat a 600 thru the twisties, why else would you have the head ported? BTW, with an average rider on a 600, I have had a lot of fun with them in the twisties on my 79...

That's exactly not what I intent to do, Terry. I just would like to improve the response of the CBX a little. To a level matching the looks. To, let's say, the level of my CB1100R, which was from the same time period.
And as far as the 600s in the twisties are concerned... you'd be surprised how many good riders on 600s there are here in Ohio

Comparing apples and apples, the CBX has little chance.

Dave Hansen · Post by **Dave Hansen** » Wed Nov 28, 2007 12:31 pm

I don't think you'll ever turn a CBX into something that is going to beat a modern sportbike. However a well ported head will make for an engine with better response and smoother running. You can go to far with it though and end up with something that runs like crap at anything other than full throttle.

EMS · Post by **EMS** » Wed Nov 28, 2007 1:57 pm

Dave Hansen wrote:I don't think you'll ever turn a CBX into something that is going to beat a modern sportbike. However a well ported head will make for an engine with better response and smoother running. You can go to far with it though and end up with something that runs like crap at anything other than full throttle.

You nailed it, Dave. Thing is, you need to let someone do the job who knows what he is doing and has the right equipment. A flowbench is an absolute must if you go deep and start removing material. My objective is to achieve exactly what you said: an engine with better response and smoother running.. That's all. I don't feel the need to have the fastest CBX around in order to brag about it in every other post I make.