Lapping valves? Advice please.

ali · 05-Feb-2005, 00:37

Hi,

Thinking about lapping the valves on my DD bike while the heads are off. Would I be right in thinking that lapping the valves will see them sitting deeper in the head, thereby throwing the shims out??

If so, is it better to measure the shims, lapp (?) the valves, and then order new shims based on the difference? Forgive me if this makes no sense but my brain's aching as I reach, and go rushing past, the very limits of my technical understanding...

I've another question about how to determine the right base gasket thickness, but it better wait until my head clears!

Cheers,

Ali

skidlids · 05-Feb-2005, 00:55

Will depend on your current valve clearances if they are nearly at maximum then a bit of lapping may just take them to the minimum, depends how much lapping they need. So check your clearances first and note the shim sizes when you take them out.

Kev

nelly · 05-Feb-2005, 00:57

If you're going to lap the valves, strip the heads, clean the carbon out, lap the valves, clean them thoroughly then rebuild them.
Then measure the valve clearances and order you're shims. The lapping will probably alter the clearances. close the openers down and open the closers out.

Base gasket thickness................... measure the squish then alter rthe gasket thickness to get the squish as close to 1mm as possible. Try not to go under that.
Once the gasket is sorted, check the squish and and also piston to valve clearance. About 2mm for the latter. If it's too close you'll need the pockets on the pistons machining.................

Felix · 05-Feb-2005, 01:02

Nelly, you need to get out, mate! Ta, for the pads, BTW.

[Edited on 5-2-2005 by Felix]

antonye · 05-Feb-2005, 01:19

Cheers for the info nelly (as always!) - great help.

ali · 05-Feb-2005, 08:09

Nelly/Skids, many thanks for the info.

DSC: The only place in the world you can get realtime information on lapping valves at 11.30pm on a Friday!!!

Cheers guys,

Ali

nelly · 05-Feb-2005, 10:19

Quote:

Originally posted by Felix
Nelly, you need to get out, mate! Ta, for the pads, BTW.

[Edited on 5-2-2005 by Felix]

I do..........I go and play with Ducati all day

:P

What's really amazing is I wrote that with a bottle of red swishing around in me gut

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode
Postbit Selector
Use Horizontal Postbit

05-Feb-2005, 00:55	#2
skidlids MotoGP God Posts: 18,275 Join Date: Apr 2002 Location: Oxford Mood: Its ONLY a Bike Club Will depend on your current valve clearances if they are nearly at maximum then a bit of lapping may just take them to the minimum, depends how much lapping they need. So check your clearances first and note the shim sizes when you take them out. Kev Reply

05-Feb-2005, 01:02	#4
Felix Registered Forum User Ducati Meccanica Posts: 2,467 Join Date: Dec 2001 Location: North Yorkshire Mood: Is 112 dB loud enough?? What?? Nelly, you need to get out, mate! Ta, for the pads, BTW. [Edited on 5-2-2005 by Felix] Reply

05-Feb-2005, 01:19	#5
antonye Administrator Webteam MotoGP God Bikes: 748S, HM1100S, V4SP, Was: DD-A #111 Posts: 13,084 Join Date: Feb 2002 Location: Back in Essex Mood: Passion Killer Cheers for the info nelly (as always!) - great help. Reply

05-Feb-2005, 08:09	#6
ali Registered Forum User Ducati Meccanica Posts: 2,463 Join Date: May 2004 Location: Guernsey Mood: Damp Nelly/Skids, many thanks for the info. DSC: The only place in the world you can get realtime information on lapping valves at 11.30pm on a Friday!!! Cheers guys, Ali Reply