DIY porting and valve reseating

[royster81]

just how much work are we talking here,i was thinking of smoothing out the inlet/outlet ports a bit and reseating the valves as it's something i have never done but am interested in doing

and say i do get it all done,what sort of benefits ,both performance bhp wise and running wise,am i going to get over a set of heads that haven't been touched

i'm not looking to skim heads as this is going to be heading towards a road bike

[Marb]

It took me the good part of a whole weekend to remove, clean, reseat, and replace 16 valves. The reseating is a b***h. Specially the last part, the polishing.

See HERE (bottom of first page) for the pics of the reseating.

I had the head skimmed too (didn't port it) and had a 4bhp increase afterwards (also fully overhauled the carbs) so it isnt purely the valves. The biggest diff is the smoothness of the ride. She's alot quieter, feels better, and picks up much faster. Also high in the revs she feels happier.

Thinking of doing some light porting this winter, have a very long how-to,. unfortuantly it's in dutch

[CMSMJ1]

good arrows Rhory..

I am waiting for my local shop to stock a valve spring compressor and I am also going to be lapping the valves in and dremelling/wet/dry the ports to take away the casting imperfections.

Methinks it would be good if you lived around the corner so we could sup tea and compare tactics!

@ Marb - did you take the valve stem seals out when you dishwashered that head?

[Marb]

Yup. removed the valves, dishwashed the head. Then did the reseating/laping.

If you don't want to wait for the valve spring compressor, you can make your own for about 7euros.






That was prototype 1. After having to do it alot for friends and such i improved on the design:

[MexicanGringo]

Are you going to replace the exisiting valve springs and piston rings while ur at it?

[Marb]

Me? Yes indeed. These are pics of off my 600 engine. It'll get:

- FZR400 race cams with stiffer valve springs
- Skimmed and ported head
- New piston rings
- Krank/rods out of a 3000km bike
- Lighter flywheel with an FZR400 alternator.
- FZR400RRSP gearbox (for that beautiful extremely long 1st gear)
- Will be running a modified FZR400 CDI (modified the rev limiter)
- Dyno'd Stage 3 carbs.
- And ofcourse all new bearings/seals/gaskets, etc, etc)

And then stuffing it all into a FZR400...

But that wasnt the point of this thread i believe.

[alexibrow]

Me? Yes indeed. These are pics of off my 600 engine. It'll get:

- FZR400 race cams with stiffer valve springs
- Skimmed and ported head
- New piston rings
- Krank/rods out of a 3000km bike
- Lighter flywheel with an FZR400 alternator.
- FZR400RRSP gearbox (for that beautiful extremely long 1st gear)
- Will be running a modified FZR400 CDI (modified the rev limiter)
- And ofcourse all new bearings/seals/gaskets, etc, etc)

And a Dynojet kit?

[Marb]

Seems that you quoted me, just before i editted the post. But yes, Dyno Stage3 kits.

[alexibrow]

Phew!

[Neosophist]

I've done it before, didn't notice any difference.

Marb seems to have changed several things at once, valve clearances, carb overhaul etc so the effect on the valve seats alone is difficult to measure.

The engine I helped work on was out of an NC27, I think there the same as the CBR400? Had been fully serviced and was running mint before it anyways.

All I can say is,m depends on the current state of your valves etc. apart from some valve grinding paste, gaskets and a valve spring compressor it's not going to cost a hole load of money to try (unless you break somethign!)

you'll have to report back with how it works on the vfr engine if you try it.