From:	kevin flanagan	e-mail:	indgaco@ptd.net
Subject:	RE: Oil Pressure Guage -	Date:	Wed Mar 5 09:40:37 2008
Response to:	1978

Hi Folks, Although I'm no engineer on the oil gauge process's, I believe the restrictor screw in the US gauge is to limit surge fluxuation from the engine to keep the reading steady, (prevent needle bouncing). If you examine many US gauges they have a stop pin to prevent springing of the bourdon tube. It will rise to a set pressure then hit the pin to prevent further travel. I doubt you will hurt these gauges if the restrictor screw is not present as there is a large overload factor in the bourdon tube. Believe me, they withstand a lot of pressure, as I have pressure loaded them to over 150 lbs. with no problems. You may notice some needle bounce or quick movement in the needle upon revving the motor if the restrictor screw is missing. There are adjustments you can do to adjust pressure comparison to a standard gauge, but, many times these gauges are not accurate across the board. I will usually set pressure adjustment to the range in which they usually run (e.g.-20 -50 lbs.) I have found that an inaccurate gauge can be brought back to original specs by first soaking the mechanism in a carb cleaning solution for a couple days,(make sure the face is removed, or it will be!) I then put the mechanism in an ultrasound machine to break up any residual oil residue left in the bourdon tube. I have had almost 100% success on bringing back there accuracy. Just a note on removing the face rivets from the mechanism body. Be careful not to use a standard twist drill as you have a 60% chance of having it break off in the brass body, at that point you are S.O.O.L.(for anyone who does not know the abbreviation, Email me!) The only drill to use is a spade drill sharpened for brass drilling. Once a drill is broken off in the mechanism it is extremely difficult to remove it. Leave the drill chuck slightly loose as to allow the spade drill to spin free if it jams. Or better yet, send it to me to rebuild and save yourself the aggravation! I do complete rebuilds on the US gauges. If anyone has any questions I can help with on oil gauges or ammeters, Email me. Kevin F. ----- ORIGINAL MESSAGE FOLLOWS ----- Howdy Chaps, An Indian 4 interloper from the AMCA/Virtual Indian (peterg440)within your midst here. Dave Hennessey, saw your oil guage notes under Miscellanous Stuff and mention of an "adjustment" screw. Though Kevin Flannagan's way more qualified than I to comment on its function. In a fit of over overpreparation for Bike Week, assembled a spare guage for my 441 last evening and that scew is actually like a small carb jet. So, my thinking is that it is there to protect against the same water hammer effect you are subjected to in your home when operating solenoid valve equiped appliances (washing machine) in your water system that behoove one to fit a damper valve. In this case, you'd be protecting this fragile device from trashing it's linkage on cold start up with the onrush of oil and dampening it's return to its peg stop when cutting the throttle. Cheerio, Peter 1950 Vincent Rapide - A Red Rapide Experience - http://www.patwilliamsracing.com/vincent