Topic: Porting the honda head...........from the shop of Jerry Branch

[Jim F]

This is interesting reading for all of you who thinks that sticking a dremel in the intake ports
is porting.

Well I am guilty of that too

enjoy

Big Jim

http://members.tripod.com/cb750k2/Technical/porting/Porting_the_Honda_Head.htm

[Jim F]

Just bought a head the was ported but have no idea what the flow characteristics are

going to send it to a shop that has the equipment to check the intakes and the exhausts

hope there is room for improvement

hope its not ruined either

fingers crossed

will keep everyone posted

Jim

[RRRToolSolutions]

Jim, that article inspired me to get my head ported when I did the 836 build last year. I was very surprised at how restrictive the stock ports were. I also realized that if a stock motor couldn't breath and make any power above 7,500 rpm - a modified one with larger displacement, cam, and stock carbs wasn't going to do it. I have said all along that the porting on my bike is the single biggest reason it has impressed everyone who's been on it. It is what drove me to spending a small fortune on the Carillos rods - the engine is in an entirely different class of power when compared to other "hopped-up" bikes I'd ridden and the rpm limits are moved way beyond that of stock where the factory rods give up. Adding a cam or carbs, or displacement is something you'll notice slightly - it's there and it sounds good and you feel better - but porting (correctly) is like coming into a high school game with a major league pitcher. This article is a very good place to start for your next build plan.

I would not build a bike with power in mind without starting with the head.

Gordon

[MRieck]

 That's a tease Gordon...you're only showing the exhaust ports.

[RRRToolSolutions]

Ok Mike, just for you --

Before and after --

[matchanu]

Cha Ching!!!

[Jim F]

Gordon

Did you get the final flow numbers?

If so can you share them?

thanks

Jim

[RRRToolSolutions]

Sorry Jim, those aren't available. Here is a link to the porting company that did these for me. The senior porting specialist, Bobby did mine. He does nothing but porting 5 and 6 days a week and has for 20 years. They do Harley and metric bikes, automobiles, blower motors - you name it. They've recently won several circle track awards for engine building. It is high dollar, but in the overall scheme, it is the "best bang for the buck" I've ever spent. If done correctly - it can change the entire character of the engine and have you thinking "rods, man rods". I don't pretend to know what works. Clements uses flowbenches and have perfected the flow patterns down to an art. This little 836 was pulling the front off the ground at 7,500/8,000 just under power with stock gearing. I put a Dyna 2000 on her to control the rpms - it was just coming on too when the limiter makes the stutter. With these new Carillos and heavy studs, I intend to see where the ports quit passing air.

http://www.homestead.com/HouseOfPower2/5.html

Mike Rieck has shown some nice pics of his portwork and he's right here.

Better yet - maybe you should stay away from having it ground. It will cause you to spend even more money on stuf like Kibble-White springs, stainless valves, titanium retainers, bronze guides, CR carbs, humongus K&N filters.......

It is contageous..

[gregwaits]

Question....what does he charge for a porting job on SOHC heads? Shipping?

[RRRToolSolutions]

Greg, for a 2 valve head they get $175 per cylinder. That includes the labor for the port work and valve angles - parts are extra. If you're going wild plan on $70 for the springs, $240 for the valves, $200 for the titanium retainers, $100 for the bronze guides - you can have $1,500 in a head real easy. Porting is forever. It never wears out, it works with a small cam, a big cam and it will live up to many upgrades as you progress. There is a happy medium where if the ports are made very large for nothing but high-rpm filling- then you will lose your velocity and suffer poor volumetric efficiency in the low/mid ranges. Quite simply the holes are so big, that the mixture moves slowly at low rpm and stops flowing when the piston reaches TBC. In a high-velocity port, the mixture keeps stuffing the cylinder even as the piston rounds TBC because of the speed of the flow.

Think about what a new Kerker or a set of Wiseco pistons and pins with boring, a set of bigger carbs will cost you - all of these are about the price of a ported head. The porting is my choice for the biggest bang.

You guys need to give Mike a call and work out something with him. He's done several here and everyone has been happy. I had Bobby do mine because we've ridden together and I've known him for years. He was in high school with my best friend, so it was like "all in the family". No, I did not pay that much for mine, but I wasn't supposed to.. 

Gordon

[Jim F]

Yes it is very expensive but your right Gordon

Its the biggest bang for the buck

I am planing a head job for the 2 valve GS 750/840 and its going to be around $2000.00
750 for the porting job, plus new valves, springs, under the bucket shims (the older GS motors use shim over the buckets and they can spit
out when you float a valve) installing the head and doing dyno runs and re-jetting the carbs
but There is a %18 to 22% in poser increase so its well worth it

Thanks for all the info Gordon

Jim