Posted by Ken Sturgeon on April 07, 2002 at 12:46:02:
In Reply to: Lapping Pistons with Lava Soap posted by Ian Easton on April 07, 2002 at 08:19:09:
I've used Lava Soap on my piston valves on my Yamaha 621F. Yamaha valves are notorious for sticking especially when new so when I took it to a repair shop to have a lapping job done, the repair person suggested Lava Soap. He said that this what he used anyway and to save my money if I didn't mind doing it myself. I think that he also just didn't want to do this job anyway since it takes a lot of time and is a bit monotonous. As mentioned in the below posts, it is the pumice in the soap that is the effective ingredient and the other suggestions could work also. I tried toothpaste before, but it wasn't as effective for me. The Solyptol sounds very similar to Lava Soap. Look on the ingredients for pumice or a similar compound. When I used it on my valves, I only used it on the piston itself, and NOT in the piston casing. I used my bare hands applying a good amount on the piston and rubbed it on several times for each valve. BE SURE TO RINCE EACH VALVE THOROUGHLY WITH WARM WATER TO REMOVE ALL SOAP AND PUMICE. I worked for about two hours while watching some TV. I should mention that I had to do two 2 hour sessions to notice any significant difference. I think this mostly had to do with my Yamaha valves. Most other valves don't have as close a tolerence in the piston to casing as Yamaha does, so if your horn is not a Yamaha it hopefully will be more effective with less effort. I hope this helps some. Keep us posted as to your progress.
Ken