Topic: Internal O Rings For CB400F (and CB350F) Oil Pump

[RickB]

Hi,

I have documented this in my project thread, but I thought I'd list it here as I had a difficult time finding them.

The oil pump on the 1975-78 CB400F (and presumably the CB350F) is sold as a complete unit and therefore, is not meant to be pulled apart and rebuilt. As such, the Honda parts fiche or any of the manuals I've checked do not list the diameters or part numbers for the internal rubber o-rings. This makes servicing the oil pump difficult.

I have compiled a list of the correct o-rings and part numbers where applicable. I'm listing them here in case anyone is looking for them.

http://www.cmsnl.com/honda-cb400f-australia_model14644/partslist/E01-3.html


1: 41123516000 63mm x 2.5mm (part# 219 on the above linked fiche).
2: 91302-377-000 15mm x 2.5mm (part# 286/287 on the above linked fiche)
3 & 4: 91302044010 (superseded by 91302044013) 6.9mm x 1.5mm (part# 285 on the above linked fiche).
5. 91302-377-000 15mm x 2.5mm (part# 286/287 on the above linked fiche)
6. No part number as Honda don't sell it. However this is a 40mm x 2mm o-ring.



Rick.

[Jp from Oz]

Thanks champ, will definitely keep this in mind when I get to this point.

[camshaft1991]

Wow, this is great! You're my money savior! 

[eastyork1977]

Some of Honda part numbers in the microfiche are listed but incorrect, I remember having to fish through my O-rings to find a pump cover and two other seals even though I received the OEM Honda O-rings new in package. Your measurements seem right, that's what I had to do.

I did a post on rebuilding this pump not too long ago.

[camshaft1991]

I'm about to order some of these in bulk. I can find numbers 2, 5, and 6 in bulk but definitely not the others. If anyone reads this I have a question on dimensions. Numbers 3 and 4 are 6.9mm x 1.5, but the closest thing I found to that in bulk was 7.0x1.5. Would one tenth of a millimeter be a substantial difference for an O-ring? Let me know, I'm going to buy the other two regardless. I might make semi rebuild kits later.

[eastyork1977]

7 is close but why not just get the OEM Honda orings. Found my shop post for 400F oil pump:

http://forums.sohc4.net/index.php/topic,137234.msg1548625.html#msg1548625

[camshaft1991]

Eastyork77,
In RickB's list of the internal O-rings for for the oil pump he stated that number 6, from what he listed, does not have a part number. Even though number 6, the 40mm x 2mm o-ring, is not listed, it is a common o-ring to get a hold of. If I were to place an order for a pack them I thought about getting some of the other o-rings while I was at it.

I read your previous post about the oil pump. So you got different measurements from RickB?
Listed o rings below (some of the listed rings in fiche were not correct)

Passage seals:

91302-044-013

91301-MY9-003 (17.5 x 2.5 used)

At case seal:

41123-516-000 (91302-250-010 fit)

At cover:

91309-286-000 (31 x 2.5 fit, listed seemed huge)


Or, did he measure the inside diameter and you measured the outside diameter of the o-rings. I feel like I'm going to have to do some measurements of my old o-rings. I worried doing it myself because I can tell that they are no longer tubular and are compressed a little. Also, what do o-ring dimensions go by primarily? Is it the external or internal diameter?

[eastyork1977]

External diameter and thickness are the specs. Unless its oil galley seals, which have 3 dimensions in the specifications.

I'm not disputing RickB's measurements if you read carefully. I'm sure his measurements are accurate.

What I found was the HONDA parts fiche IS NOT CORRECT in some cases especially with regards to the pump cover. There is a hard to find number for that cover, otherwise unlisted, but it is not correct. CB550 oil pump cover seal is not listed either, but available.

The oil pump back in the '70s was listed as one whole item to be replaced in most cases. The errors in the fiche were never corrected, you can make your own mind up as to why.

I happen to be very fortunate and have almost every NOS Honda oil seal at my disposal so finding the correct orings is often about a 10-15 process when I'm at the shop

Feel free to drop me a PM if you have any other specifics.

Cheers