Valve seat cutting DIY

[UK Pete]

I will be buying a set of valve seat cutters to enable me to do my own valve seats 3 angle job, i have decided on going DIY as i have 4 heads to do on various bikes and recon i will save money as well as getting more job satisfaction, i was quoted 75 + vat to put in guides and the face the valve seats , i was supplying the guides, then  postage  there and back insured £40
So i would certainly save money, and when finished be able to sell the cutters if i wanted
Does anyone have any advise before i  take the plunge,  i have read up on it and also watched video's it all looks quite easy,
Hears how i see it  , clean carbon and crap away from the base of the old guide in head, heat up head press out old guide, press in new guide while still hot, cut valve seat , ream new guide, lap in valve  job done
Pete

[Tomb]

Strictly speaking you should always recut seats when fitting new guides, I've done it on my old Triumph 500 head but used only one cutter, your 3 different angled cutters is the correct method, you'll need the right size arbour for the cutters to fit on that fit into your guides.

For knocking out and refitting the guides you'll need a guide drift that with front spigot that fits into the guide and outside diameter thats slightly smaller than the guide outside diameter.

Apologies in advance as you probably know all this already 

And do pics

[Bryanj]

Ream guide before cutting, and you will need the Honda reamer to do the guides as it's an odd size.

Also I found that the seats are so hard you need the powered grindstone type as the metal blunts the steel cutter type very quickly

[Tomb]

My cutter is tungsten carbide, I thought they would all be

[UKROBK7]

The guides need to be reamed before cutting the seats.  The honda reamer is about £45 + vat.  I found an unused 6.61mm reamer on ebay for £5.  The Honda spec is 6.6 - 6.62 when new so this falls nicely into the band but I will ream a trial hole first.  The 6.6mm ones I found were all used ones and I was uncertain of the condition of the edges.  If you use a reamer without the built in guide spigot you may need to make a guide to ensure the reamer is aligned correctly.

Let us know how you get on Pete as I really need to consider doing my seats as well.

rob

[K2-K6]

Sounds like some really good advice you've picked up from the others here.

The F2 my friend owns had the head redone (new guides etc) under warranty and he took the head to them for the work and then rebuilt the motor himself.

They cut the seats with an air powered tool with non metal cutters as far as I remember.

Having a proper sized spigot to locate the grinder will enhance the life of the guides because as the valve is pulled back into the seat it will centralise itself to the seat. If that is off from the guide you'll get a sideways load imposed into the tip of the guide/stem.

I also recall that the original three angle seat spec was good practice for flow in that as the valve starts to lift or close to the seat then with a thin contact seal the same size valve simply flows better than having a wider seat. The assumption is that they were after more flow at high rpm with this (the bigger valves give this anyway) but I think it's more to maintain flow at lower rpm when the valve will simply be at that stage for longer.

Someone else who had an F2 and just did a staright single broad cut on them didn't like the change from standard in engine running, so I guess it's valid.

[Greg H]

With a 3 angle valve job you should get better flow particularly at small valve openings provided the flow isn't spoiled by having too wide a valve seat . I used to do mine to 40thou . 

[UK Pete]

I have got my valve seat cutters , and i am doing a gpz550 head with them at the moment, i have fitted new guides, reamed them, and started on the exhaust valve seats, what i have noticed is that Kawasaki only made a 45 o angle cut as standard so i am recutting with 30, 45, and 60,   all i can say is this is so easy the cutters are terrific they only need a few turns and the job is done, i will try and get some before and after pictures , if all goes well then thats another feather in the cap, and less expense in future when rebuilding my engines
Pete

[UK Pete]

Ok here are the pictures first picture shows the original 1 angle seat 45 degrees, the rest are my freshly recut seats

[hairygit]

You do realise that you will have to have the valves machined to those angles to do any good?

[UK Pete]

No,
 the valves are 45 degree same as the seating cut, the other angles just help smooth the flow when the valve is open, and also they are used to get the required seat width
Pete

[UK Pete]

Thanks oddjob, do you want to sell your Honda Reamer,?
Pete

[Yoshi823]

Instead of using OEM cast iron valve guides I made some out of ally-bronze for my 750/823 special. I then bought a 6.6mm reamer from Pillar Engineering in Croydon (which I still have). Worked a treat.

As for the valve seats, it was recommended by Phil Manzano to cut the 30 & 60/70 angles, then to cut the 45 for the required seat width of 1.2mm on the exhaust (for best heat transfer) & 1.0mm for the inlets. The secret was to not cut too deep as this would recede the valve too far into the head.

There's a bloke called Phil Lovett in Biggin Hill that does engine work. He did the valve seats for my Honda XL250SA restoration job quite a few years ago when I replaced the valves & guides on that engine. I think that he had a Serdi seat cutter...did a good job as well....