Underneath the front engine cover on your Honda CX500, GL500, CX650, GL650, GL700, CX400 or GL400 motorcycle are several dowels and O-rings – here’s what you need to look out for and info on replacing them if necessary.
Firstly, there are two locating dowels which fit into the front cover – one should be on either side. We are getting a photo of those.
The oil system behind the front cover has three O-rings, two dowels and an oil metering jet – locations are marked here:
Working our way from left to right across the photo, near to the clutch is the oil metering jet that leads to the gearbox:
Two things about this; someone has previously installed the metering jet in backwards, and the O-ring does not appear to be present. The O-ring had fallen out when the front cover was removed:
The metering jet goes flat face in; it should look like this:
The metering jet on the CX500 and GL500 is part number 11132-415-000, and on the CX650 and GL650 it’s part number 11132-MC7-000. The accompanying O-ring is the same part number for the 500s and 650s: 91303-001-000 or 91306-HB3-003 and is 8×1.7.
Moving along to the next circled area, we have a dowel and O-ring near the primary drive gear:
…and another identical dowel and O-ring on the front of the oil pump, on the right hand side of the image:
These larger dowels are part number 15155-300-000, and it is the same part across the CX500/GL500 and CX650/GL650 models. The O-ring is part number 91301-268-020 (eBay US, eBay AU, eBay UK ). Can’t find your dowels, O-rings or metering jet? Check the matching hole in the front cover in case they are stuck in there instead of on the engine side.
All of these O-rings are essential for maintaining the correct oil pressure in these engines, so it’s a good idea to replace them if there’s any doubt at all. One test for O-ring life is to roll them between your fingers – if you can feel any kind of edge or lip then they should not be used again.
Given that these engines are all over 30 years old and quite a few have not been opened before, or at least probably haven’t been opened for many years, expect to replace them.
It’s a good idea to remove the dowels, O-rings and metering jet and put them in a marked plastic bag while you’re doing a triple bypass or working in the front of the engine – that way they’re not going to be knocked out and disappear into the dark recesses of your workspace. Remember to double check that all are present and that the metering jet is correctly oriented before closing the front cover back up!
If you’re doing the triple or quadruple bypass, click here to go back to the main page.