Oil pump wear and 'O' rings

[Laverda Dave]

Following an eventful afternoon in the man cave standing over the parts washer today (having to use the last of my annual leave and I've decided on a self catering holiday in the garage....)..... I decided to strip the oil pump for a clean and inspection.
First thing of note was the amount of 'O' rings present  . Having previously ordered all the required 'o' rings as shown in the parts book I was a bit surprised to discover there are three additional 'o' rings present within the oil pump itself that are not shown in the parts manual, Oh dear ! I toyed with re-using them but like everything on this engine somebody has been inside it before me and they have done what I was planning on doing,turning them around! I cant do that as they are not 'o' in shape any more but very flat where they have been squeezed down, several times it appears.
Does anyone know what size 'O' rings I should order and where I can get them? The parts manual does not list them so I'm a bit stuck, I'm sure my local Honda emporium will not stock them unless I can provide a part number. I can measure the diameter but not the thickness as they really are flat! The 'O' rings I am after are for the gearbox rotor (photo attached) and the main chamber oil seal (the one with the rotor shaft in the photo). Being an oil pump were pressure is everything I don't want to re-fit the old ones and potentially suffering a leak and loss of pressure. I have the other seals all brand new and ready to fit.
On inspection of the pump I checked for wear on the main rotor housing body, it appears to be scored (see photo) although I couldn't detect any discernible 'ridges' in the body with my finger nail although the housing is so small it is difficult to get a finger in there to test it!  Has anyone stripped a pump down before and is this type of wear common and is it acceptable? If not is there any way a repair can be undertaken as new pumps are slightly scarce at the moment!
Finally, I mentioned at the beginning of this post that somebody has already been inside this engine, this is confirmend as the main pump rotors (inner and outer) are punch marked and the punch marks should both be on the top face, they weren't the inner rotor punch mark was face down.  Looking at the attached photo, is the wear on the rotors acceptable?
Any advice would be welcome as always and despite the setbacks, shocks and horrors I'm actually enjoying the rebuild .
Regards
Dave

[Bryanj]

Can't tell you the sizes for a 400 pump, you will have to use a vernier and measure. O rings are sized on the inside diameter and the thickness, DO NOT be tempted to one size up on thickness as that will increase the end float on the rotor and markedly drop the pressure.

The rotating parts are incredibly robust and will pump at a very high percentage of new with incredible scoring

[Dave_Canada]

Check this out:

http://forums.sohc4.net/index.php/topic,83694.0.html

[AshimotoK0]

From the 'Land of the Rising Yen 


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[Laverda Dave]

Chaps, you have been amazingly helpful, what a great forum this is .
I have ordered some o rings from Mayday seals (still not arrived yet, ordered early last week.....) although these are not the exact same size as those on the link posted by Dave_Canada for the larger diameters.  For safety's sake I will order the two larger o rings from the Yamiya site as these are genuine Honda and as BryanJ detailed on an earlier post, don't go oversize as this will reduce the pump pressure. I just hope don't have to wait months for the delivery from Japan otherwise I will just have to push the bike to wherever I want to go
I will order three sets, one for the bike I am currently building, one for the spare pump I inherited with the box of spares that came with it and is in reasonable condition when I took it apart and one for the pump I fitted to my original 400/4 rebuild I completed in 1992 and has only done 2k since    as this bike has always suffered from incontinence in the oil pump area despite the pump being brand new at the time.

Dave