porting question

[trippivot]

it is correct to say intake valve size up 1 mm will wake up your bike

difference between gs1100 and gs 1150 stock heads

[Mark M]

it is correct to say intake valve size up 1 mm will wake up your bike

difference between gs1100 and gs 1150 stock heads

The exhaust valves are also bigger on the 1150, IIRC.

Mark

[headsbikesmopars]

GS1100 = 27mm and 23mm .
GS1150 = 28mm and 23mm.

[Mark M]

GS1100 = 27mm and 23mm .
GS1150 = 28mm and 23mm.

Thanks for that. Obviously, old-timers is setting in and I remembered it the other way around...

Mark

[Tarbash 27]

This is the head that Im using for my GS1000 motor build. What are your guys opinions on this. It will have a 1085 wiseco and high lift cams. I got the head like this, Ported on the intake and exhaust.

[BadBillyB]

Well, it is nice looking, but honestly there was too much of the port floor ground away. On a good note, the most critical area is around the valve seat and bowl area. Doesn't look like it was touched. The port can actually be improved by raising the floor. Very little exhaust gas flows along the floor until it reaches the very end of the port. Raising this area increases the velocity of the gases, improving volumetric efficiency (more power)......Heres a pic of the exhaust port on my 1238cc kitted drag motor. The floor was raised with (dont do this on a street motor) JB Weld, and you can see where the exhaust gases were eating away the center of the floor right before the gasket. This is where the flow converges.....Billy

[trippivot]

i'll take a picture of a Dwayne Williams head I have. 2V no pix of 4 V stuff

[trippivot]

,,

[trippivot]

small port gs head started life flowing mid 60s' C.F.M. I and X

this is a great example how much work is needed on the intake side and NOT MUCH necessary on the exhaust side to achieve 89 C.F.M at 0.490" of intake lift - 79 C.F.M. at 0.430" on the exhaust side. stock valve sizes.

opening it way up is not what you are looking at either. never take material off of the floor of the port.

port diameter back and forth from 30 mm to 32 mm and finally to 38 mm at the intake valve. smooth ridge on the roof splitting the guide boss.

[rapidray]

Jeff is right! When I do a BIG GS head I actually put epoxy in the port floor to raise it up & reshape the port to improve port VELOCITY. As far as the only opinion that counts being your own, whoever said that, I've got lots of GOOD head cores for you after you figure out you are making yours good for recycling. Ray.

[gearhead13]

As far as the only opinion that counts being your own, whoever said that, I've got lots of GOOD head cores for you after you figure out you are making yours good for recycling. Ray.

LOL, Ray.
Well, here is the head after i got it back from media blasting. I am in the process of painting it now. Does it look like recycling material??

[rapidray]

Can't tell from this picture, can't see the ports. From what I can see in this picture it looks like a STOCK valve job & there is a LOT to be gained with just a good RADIUSED jalve job. Porting is next to useless without a good valve job. I have seen bigger power gains with a good valve job than with porting. Of course, the guys that do good porting also know to do a good valve job. Ray.

[gearhead13]

I am not looking to do anything radical here, just smoothing out the bumps. I am focusing on the 1/4" (or so) before and after the valve, which I think is the most important part of the port. I have done a fair amount of grinding in these areas already.

[rapidray]

Where's the pictures? Ray.

[renobruce]

From what I can see in this picture it looks like a STOCK valve job & there is a LOT to be gained with just a good RADIUSED jalve job. Porting is next to useless without a good valve job. I have seen bigger power gains with a good valve job than with porting. Of course, the guys that do good porting also know to do a good valve job. Ray.

Ray, by saying a radiused valve job, do you mean the angle of the grind? The guy that did my head said he did a "3-angle grind". Also here's a pic of my porting. When I run my finger on the bottom of the exhaust port, I can feel a bump. It's not a huge bump, but it's there. Is that the way it should be?






Sorry, not trying to hijack, just thought we could all learn a little.