Rayjay wrote:
Big Boy, I have read about those grooves some time ago. That is a mod to the underside of the head/combustion chamber area. I will read that an maybe incorporate it into my mod. Thanks!

Doc, I don't want to put JB Weld in and have it do a melt down. I know that the intake side of the head will run much cooler due to the fuel/air mixture cooling off the ports and the mod to make high velocity exhaust ports uses an aluminum welding process.

I had thought about getting an infrared thermometer myself, but if you have one and would like to help me out, I'd appreciate it very much. You would have to ride to get her hot and then take the temp while still running on the side of the road. If you could take temp at both sides of the head: Intake and Exhaust areas maybe between the fins??

Let me know and thanks.


I have one you can get them at harbor freight for about 30 dollars. Oh if you are wondering about accuracy It worked and read the same temp as 5 of our 7500 thermal imager and was a lot lighter on light ballast calls and humpin hose IMHO

Yeah, as I said yesterday, since you're doing it with extra parts it's an interesting experiment. But, my 2 cents says it won't make more top end power.

If you notice on the guy's web page, he's dealing with crotch rockets. Fact is, today's sport bikes are so far beyond most riders' abilities that an increase in low and mid range power is going to feel like a true performance increase to the average guy. Heck, it probably is an increase for street use.

But our bikes aren't short on mid range power, they gasp at top end, and opening up the ports would tend to help this. The fact that porting our manifolds increases performance proves it: forget velocity, we need flow!

But hey, it will be interesting to see which theory is correct. You can be our Myth Buster!

I agree midstar07

Just to add to the velocity theory,here we are changing the air cleaner soooo there is no restriction ,port the manifold to allow better air flow,change the carby to a bigger one for more air flow and then reduce the inlet just before the valve so the air can go in faster ,me thinks not.If this theroy was to be so efficient then sureley GM,Ford,Chrysler,Toyota,etc etc would be useing it, John

After spending hours & hours over the years porting small block Chevy heads & UNshrouding valves for better flow, to get more h.p., I'm sorry, I just can't accept that SHROUDING the valves will give better flow. It may give more velocity but it'll reduce the volume of fuel/air mixture. Increased volume of fuel/air mixture is what provides the power increase. Also, by adding material in front of the valve will reduce the swirl effect in the center of the combustion chamber causing a less efficient combustion effect. As example, a Hemi-head design chamber is much more efficient because the valves are centered in the chambers with the spark plug located between them. This causes the mixture to swirl more in the center of the chamber & when the plug fires the combustion is more complete. Not to mention, I don't think I want anything added to the inside of my combustion chambers that has the remotest chance of dislodging & wrecking not only the head but blowing whole engine as well, especially when my legs are in close proximity to the block. And as far as grinding a slot across the head to improve the flame front, it's not necessary on the Roadie as we already have 2 spark plugs located on each side of the head which takes care of that. My .02.

If this theroy was to be so efficient then sureley GM,Ford,Chrysler,Toyota,etc etc would be useing it
I don't think so. Do you remember reading about smokey Yunick's ceramic engine about 30 years ago? It disappeared after Chrysler engineers checked it out.

The purpose of grooving is not supplanted by two spark plugs (I think). I don't think that grooving can be done in the Roadie combustion chambers, since they are domed across the entire piston head region. If you check out some of the photos BigBoy linked to, you will see that they appear to be all high compression heads.

Flow bench porting is not "real world." Engine dynamics determine what helps and what does not. If you read several of mototuneusa's articles, he presents evidence that it works, albeit it may be only on high revving engines. He provides dyno charts and race winning as evidence.

Again, I was very intrigued with the concept and wanted to TRY it on my scoot. But I don't want to blow it up in the process. That's why I'm asking for help on engine head temps.

If I could email motoman and ask questions, I would. His email does not go through. Either he is dead or found something better to do...

Does anyone know the melting point of aluminum such as we have in Roadie heads?

BTW - I will look to dyno my scoot before and after I do this mod...if I go forward with it.

Well said stinger

I think time is the deciding factor here, If you move 1600 cc's of mix (in my case) thru the engine in 1 second, the mix may not be moving fast enough to atomize properly, if you move it thru in 1/10 of a second it will be atomized just fine...so at a slower rate, the smaller port may be a plus,,IMHO, anywho, if you do this, let us know the outcome..I think you'll find that for normal riding, it's not needed, if your drag racing then go for it...