head porting

kpier998 wrote:

kpier998 wrote:

Last one:

I think this is a GS850 head. I don't know if the intake was originally round or not. If so, what do you think was the reason for the new shape - kind of D shaped near the bottom but only slightly so.

I can't comment on whether this is a good design, or if it just looks good...

What do you guys think that have done some porting?

It also looks like there is a ridge on top leading all the way from the outside edge of the intake to the valve guide. Is that a standard design for performance or is this unusual?

kpier998 wrote:

kpier998 wrote:

Last one:

I think this is a GS850 head. I don't know if the intake was originally round or not. If so, what do you think was the reason for the new shape - kind of D shaped near the bottom but only slightly so.

I can't comment on whether this is a good design, or if it just looks good...

What do you guys think that have done some porting?

as i said before i got the idea from late 60s bigblock chevy high performance heads and just tweaked it to make it work.my reasoning was the top of port(long side)needed extra velocity to catch up with short side of turn.theres more to it than that but im not good at explaining techno stuff,maybe timebomb or larry can be more specific.all i can say is it worked for me

How much more hp can we gain with a ported head?

A Lot. A ported head is where the power is. A set of cams or big valves are useless if you don't have the ports to move that air. The best thing is to look at Larry Cavanaugh's web sight. He is the "Head Master" he is the Guru of head porting, the Jetai Master of the flow bench.
www.flowbenchtech.com/porting/CRH/kz-data.htm

Is it true that 28 pumpers actually work better than 29 smoothies? I heard it from a kawboy. P

saxjonz wrote:

Is it true that 28 pumpers actually work better than 29 smoothies? I heard it from a kawboy. P

Don't swap with him. :ohmy:

Keep the smoothies. :laugh:

Again...define better

The 28's with pumps were a nice street carb for what they were. I've never known anyone who was disapointed after tossing them for 29 smoothbores though...

Well Larry, I never even used them on my bike because I had the smoothies. But I remember you talking about the 29 keihins. You remember talking to me about this stuff of course? It was a while back. I live in Chicago and wanted to send you my engine to do but at the time was just waiting to save up enough to send it?
I have experienced now from two people and they tell me that these keihin carbs are MUCH easier to setup and are designed much better. In that same conversation I was told that the 29's are really hard to set up and that the 28s performed just as good and maybe even better. But that the keihins and smoothies were no comparison at all. I remember you had mentioned them to me briefly but as all the talk about the smoothies I just thought those were the way to go period. The keihins are more expensive to get but they can be mated to J boots with the little adapters and that leads to even better breathing as you can port the head out to mate to the j boots. I don't really know that much about it really so would appreciate the feedback from someone who does really know what he's talking about.
Well about the earlier phone conversations...
I bought another kz to ride while I was going to slowly restore my 79 but somehow my monies and efforts have gone in to the new bike and has depleted my funds for the 79. Now that I have a daily rider I want to go wild with the 79.
I definitely want for you to work on the head at the very least for sure. I just have to get my money together again. I saw your work on OMR's bike and must admit I like the whole vibe that is going on. He did a really great job on his bike in my opinion and saved the stuff like the head for the professionals. Putting something together following instructions is one thing but re-engineering something to make it MUCH better than stock is a daunting task. I just want to make sure that the money I spend on the 79 is going to be well worth it and the best decision for a nasty spirited street ride. I don't want to drag race it but I do want to take it out in the evening or on weekends and just spank the crap outta the other bikes that think it's just a dinosaur. I want them to redefine that word as dyno saur. Would be a bike that I would just ride for traffic free or relatively short jaunts nothing much over 100 but up to that speed just be beastly fast. I have ridden newer 1000s and haven't been all that impressed with the advances in modern tech over my dinosaur. Let me just say that after 100-120 is just too fast I did 188 and was just about scared about jail time forget about dying because I knew I wouldn't feel a thing after. I didn't like the feeling of riding just 40 miles and even at that speed I got off the bike to put gas in and felt like one of Jerry's kids trying to open up the gas tank and just knew that my future children had been severely abused by my seating position. The old bikes handle just fine and are comfortable to boot. Why mess with the perfect street ride?

I have both and was told that the 29's were not much if at all better than the 28's with pumpers. I never even bothered to find out. I just swapped out the 29's on my 79 for the 28's and those are in a corner of my garage collecting dust. So it wasn't a question of swapping anything just a statement that was made to me concerning the keihin's and smoothbore carbs. I like my smoothbores MUCH MUCH MUCH better than the 26's I had on my 79 so much so that I stole them off the bike and put them on the 80 just as soon as I got it. Can't go wrong with that idea. I just wondered about the 28's. I guess the real test would be to put them on and find out how it feels but that would just be crazy.
Patton wrote:

saxjonz wrote:

Is it true that 28 pumpers actually work better than 29 smoothies? I heard it from a kawboy. P

Don't swap with him. :ohmy:

Keep the smoothies. :laugh:

saxjonz wrote:

Is it true that 28 pumpers actually work better than 29 smoothies? I heard it from a kawboy. P

I do not think that is true, but that being said, the 28pumpers will have a much better transition on a stock engine, and the 29s will have a better top end. The 28s have a throat sweep area of 616mm/sq where the 29s have a throat sweep of 660.5mm/sq. you will always have more air in the 29s. But if you were to put on a set of BS34 CV carbs from something like a 81-82 CSR or LTD than they have a sweep area of 735mm/sq that would be like putting on a very friendly set of 31.5 mm smoothies. This properly set up this will give you a very good transition and a VERY GOOD top end.

Thanks for the info otakar.

Short of fuel injection, I would take a set of Mikuni BS34 or BS36 CV carburetors over smooth bores or any other mechanical for the street any day. The best part is that for about $500 or so, you can get them, all set up for your bike.