Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: 400 Cafe Racer on March 26, 2025, 09:05:31 PM
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Hi Guys,
I had a Kit from DS to overhaul the 50 year old petrol tap and also ordered their "O" rings for the seal between the tap body and the rotating handle. It was suggested that 2 would be necessary as 1 would not always seal !!
After carefully cleaning all parts before rebuilding I measured:-
1. the outer seal face of the rotating handle - then the inner seal face of the tap body.
2. the O/D and I/D and cross section of the OLD seal
3. the O/D and I/D and cross section of the NEW seal
Because the sealing faces are the inner and outer circumferences the cross section or thickness is vital to prevent leakage.
Measuring the DS seals they are undersize in thickness to make a seal and actually leave a clearance gap for petrol to leak through, so putting 2 in as was suggested is an incorrect solution.
Having spent a couple of hours on ebay I found a supplier of VITON O rings ( much better for unleaded) with a sizing very close to the original Honda size. Priced at £5.49 for 10) - great price.
Only a single O ring was used, assembled with a very thin smear general purpose grease to ease assembly when dry, and tested overnight with petrol in the tank, before refitting to the bike. It has now stood for 4 days with a 3/4 full tank and the sealing is bone dry.
I hope it may help others on the forum with same problem, I have posted below the name - details - and size Code BS018
This was purchased on their Ebay website
sealsuppliesUK
Imperial Viton Rubber FKM O Ring Seals 1.78mm Cross Section
BS018 - 18.77mm ID x 1.78mm C/S
Regards
Dennis
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Great tip I'll save that size for future reference.
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thanks for sharing