Planet Minis

84z50r

if i was too port my z50r head how much more power would it have and how should i protect the value seats?

Z124R

Porting the head on its own won't necessarily release a great deal of extra power. The real gains are had with headwork if a big bore kit, cam, big carb and freeflow exhaust are used together.

I've ported many heads over the years and normally remove the guides. I recut the valve seats after new (normally bronze) guides are fitted.

Here's one I did earlier.

http://www.carwardraceeng.btinternet.co.uk/70head.htm

If you don't want to remove the guides you just have to be carefull.

Chris

birddogg

What he said. You can get the big bore kits that come with a much better head that what you have. The stockers have limitations. I cleaned up the stock head on my XR then upgraded later and wondered why I wasted my time.

kane

ya I ported my stock head and it works good but porting alone won't do much. The stock valves really limit performance. Find yourself an e22 head instead and enjoy the extra power.

kane

how did the bike run with those huge ports? What size did you put them at?

Z124R

Kane

The head was a large valve 70 (24mm inlet valve). The port was opened out to 24mm at the manifold face to match the inlet manifold. The exhaust port was opened out to the gasket size. The head flowed 20% more than standard on the bench and runs really well on a 106cc bottom end with a modified cam and semi flatslide carb. No dyno numbers are available yet but you know when the feel is right.

Chris

XR8TED

How can you take full adavntage of a bigbire kit if the head is not done by adding a big bore kit you are adding more displacement. More displacement means you are drawing more air into the cylinder. any engine is a airpump the more air you can fill the cylinder with the more fuel you add and the more power it will make.. The best way to procet the seats is to get stock valves grinder them down on a valve grinder so the is very little margin on the edge of the valve and do the chamber with the junk valves in..

Dave @ XMS race engine's

XR8TED

Its hard to give an exact power number on porting...

84z50r

z124r:what did you use to port it,Die grinder or deremal,and what grinding stone,and how would i fit new vale guides

XR8TED

www.ruffstuff.com

Z124R

I use carbide burrs at low speed for the bulk removal and finish off with fast abrasive flap wheels in a Dremel style tool.

I have a press to insert the new guides, the seats are then finished with Neways cutters.

Chris