TOPIC:

Ya Nads I'm with ya on this point, at least on the intake side for my 650 head I'm using with my 810 kit. If it doesn't work as well as I hope, then I will start again on another 650 head that I have lying around. Last year's porting and polishing job for my 700 Wiseco with Mikuni 24's was much more conservative than what I decided to do today.

My measurements all came in just under2 mm tapered wall thickness at the intake manifold mating surface. This is plenty of room to seal the manifolds for the Mikuni 28's. I will be sealing everything up nice and tight with a thin and even bead of 3-Bond liquid gasket. I ground down the ridges on the 28 boots' head side to give a flat mating surface on the manifold to head area.

I had to enlarge the bolt hole openings on the bigger boots, test mounted them and then blended the boots to the individual intake ports. The transition from boot to intake runner is seamless.

For the exhaust I left it pretty much the same but brought everything up to one step short of a mirror finish. I figure with everything else I have done to get this motor running strong, pushing the envelope a little more agressively on the intake porting would be worth trying.

I also polished the combustion chambers, though not quite as impressively as no name did with his.

Cheers-Colin Firth

'77 Kz 650 Custom - (Miss July on 2006 Kzr Calendar-Last year’s project Wiseco 700) Newest rebuild includes Wiseco 810 kit, Kz750 cams, Kz750 intake valves, 750 GPz springs, Ported head, WG Mikuni 28's, Velocity Stacks, Dyna Ignition and coils, MAC pipe, 14 tooth front sprocket. Returning to original '77 Moon Dust Silver. Goal is to have a stock-looking, ultra-sleeper bike that will tighten up any loose dental fillings off the light and surprise other, bigger bikes.

Post edited by: reborn650, at: 2006/05/14 21:47

Post edited by: reborn650, at: 2006/05/14 22:41

Amen brother

When I was flow benching big block mopar heads, and really getting into what made more HP to the last nth- the way we did it is go to super polish as well- but (and I don't know where this area would be analogous to a Z1 head now) - but on the roof of the port, we made dimples like a golf ball has along the roof with a sharp awl, and it seemed to keep velocities high and CFM remained high. Also- it seemed to keep more fuel atomized rather than some of it following out of suspension- which happens in these huge motors- but I have no idea if this translates into these much smaller ports and scales of size!

Did you do the exhaust as good as the intake? It's important to get the bad stuff out as easy as possible.

Yup Don, I opened up the exhaust ports as well. They received more of a polishing than the intake side. I left a little more of a less finished surface on the intake side to allow for a little more of an abrasive wall surface of the intake mixture.

Cheers-Colin Firth

@donthekawguy
the exhaust looks like the intake.

A friend of me has a tuning shop and builds engines for the German Superbike Challenge.
He`s building race bikes since 25 years and has a lot of experience.
His work looks very different to the heads I make.

I didn`t want to show you a head for the racetrack,this one is made for daily driving and will run very smooth.

It`s a cheap solution to get some extra hp and a nice running bike.

For more power I wouldn`t use a Z1 head ...

@CruisingRam
the ports of some Porsche cars have these "golf ball" dimples too .

On a street motor it's easy to go TOO big on your porting and create flat spots in the lower RPM range. With compression ratios suitable for the street your combustion chambers might not be able to move enough air in the intake ports if there too big. My 650/716 has nice street porting with the intakes matched to my 29mm smoothbores and a nice blend into the valves. The exhausts are opened up to 2mm under the header pipe to help stop the exhaust pulses coming back up the outside of the head pipes. the intakes have a swirl finish with the exhaust sides are polished. My little 716cc has pulled 85 HP on a rear wheel dyno, not bad for a little motor. I'll try to get some pix of my buddies race head. Here's a few pix of my porting.











Post edited by: Mark Wing, at: 2006/05/15 17:41

yup!

Mark Wing wrote:

The exhausts are opened up to 2mm under the header pipe to help stop the exhaust pulses coming back up the outside of the head pipes.

Can you elaborate on how this is done plz? is there a ridge or something I cant see in the pics?

Well you'd measure the inside diameter of your head pipe and transfer the measurement to the exhaust ports and open them up to that. your exhaust has a reverberation or pulse that comes back up the outside of the header while the spent exhaust travels down the middle of the pipe. You can't see much in the un ported port, it was taken of an old extra 650 head I have but if you look closely at the ported exhaust you can see a thin dark line around the edge. It's hard to get the pipe centered up every time but it still works anyway.
Mark

What you are describing to me Mark is port matching?

Mark seems to be talking about anti reversion, the exhaust port is 2mm smaller than the exhaust pipe.
IIRC, it's to prevent pushing exhaust back into the cylinder just prior to the exhaust valve closing due to harmonic impulse. AKA exhaust tuning.