Tippie
Hero member
- Location
- Dr?bak, Norway
Not everyone is so fortunate to have a pet Serdi man in their neighbourhood.
Even the best tooling is only as good as it?s operator. I have seen too many heads damaged by people doing valve work that should have admitted they were out of their depth. It is a real problem on shim heads that run out of shim-range as the valves disappear up the hole as the seat gets corrected and re-corrected to get it "true" or because a guide has been fitted askew. On screw tappet heads at least you can screw out some clearance and "only" lose compression and have poorly shaped valve seats and badly angled leverage from the rocker-arms as a result, ha ha!
I always lightly lap in valves by hand to clear the carbon and then check the condition of the surfaces with Bearing Blue. It clearly shows a problem from slightly bent valves or worn seats. Often that is enough to fix a leaking seat as it has simply been a problem from carbon or such. If it needs more and you have a good proven head jobber you can then let him fix it.
True a trick expensive machine will outperform a hand cutter in measured flow but it depends what you are after. A leaking seat is often the cause of poor starting and idling which is a real pain in everyday riding but a few percent of lost power due to the actual shape of the seat is rarely noticeable. A quick lap-in can save you from a lot of headache.
If your suction tool keeps falling off when you are lapping buff the valve smoother and make sure there isn?t oil on the valve causing a suction problem and don?t let the paste get too thick as you work, add a drop of CRC to thin it a bit.
Even the best tooling is only as good as it?s operator. I have seen too many heads damaged by people doing valve work that should have admitted they were out of their depth. It is a real problem on shim heads that run out of shim-range as the valves disappear up the hole as the seat gets corrected and re-corrected to get it "true" or because a guide has been fitted askew. On screw tappet heads at least you can screw out some clearance and "only" lose compression and have poorly shaped valve seats and badly angled leverage from the rocker-arms as a result, ha ha!
I always lightly lap in valves by hand to clear the carbon and then check the condition of the surfaces with Bearing Blue. It clearly shows a problem from slightly bent valves or worn seats. Often that is enough to fix a leaking seat as it has simply been a problem from carbon or such. If it needs more and you have a good proven head jobber you can then let him fix it.
True a trick expensive machine will outperform a hand cutter in measured flow but it depends what you are after. A leaking seat is often the cause of poor starting and idling which is a real pain in everyday riding but a few percent of lost power due to the actual shape of the seat is rarely noticeable. A quick lap-in can save you from a lot of headache.
If your suction tool keeps falling off when you are lapping buff the valve smoother and make sure there isn?t oil on the valve causing a suction problem and don?t let the paste get too thick as you work, add a drop of CRC to thin it a bit.
