O-rings are important, and Japanese motorcycles seem to depend on them heavily. During my years working for others, each time I did a maintenance service on a GL1000 I unbolted the intake manifolds and replaced their all-important o-rings. Ever since then I have had the part number (91301-371-005) etched into my brain and include these o-rings in the shipment of carbs back to my customers today. Another critical o-ring point are the two very thin wall o-rings under the aircut valve. I usually glue them to the valve as I know most folks remove the valve during carb reinstall and I want to make it not easy to lose the o-rings.

But the most important o-rings in GL1000 carburetors are those on the push-in primary and secondary main jets. I replace these on every rebuild. The jets are a slip fit into their cast aluminum towers. These o-rings are extremely hard to find, however, and the ones in rebuild kits are incorrectly-sized, meaning they tear when the jet is installed. The size issue is because, as is usual with Honda, the o-rings are very odd incremental sizes, 3.2mm x 1.1 (primary main) and 4.2mm x 1.1 (secondary main), to be exact. As I say, pretty unique. And none of the half-dozen o-ring houses have them. However, one company imports these from Japan, and though they don't sell to the public there are a few retail outlets, the best being Cycle Recycle in Indiana, who has them for just $1 each. Look for Cycle Recycle part numbers OR-4604 and OR-4609.