Does the SX400 headlight fit the RD400 (Glass only)? Is RD400 headlight a sealed Beam?
No, the XS400 headlight is different. The RD is a sealed beam but not a standard 7" , it is a bit smaller. There are the smaller ones available like this https://yambits.co.uk/rd400c-halogen-headlight-conversion-unit-p-53134.html?osCsid=66btf9h36hogspirdbf01qbk07
Quote from: 1976RD400C on February 22, 2021, 09:53:11 AM
No, the XS400 headlight is different. The RD is a sealed beam but not a standard 7" , it is a bit smaller. There are the smaller ones available like this https://yambits.co.uk/rd400c-halogen-headlight-conversion-unit-p-53134.html?osCsid=66btf9h36hogspirdbf01qbk07
That's the correct size unit and a simple conversion kit but unfortunately the wrong light pattern for the US. It will shine directly in the opposing lane. It also isn't made for rims with adjuster screws as used on the RD400.
The headlight unit size is 162mm (6-3/8")
Thank you for the replies. What I thought to be easy to find is getting difficult!. I have the lens in good condition but bulb was bad and I took it out. Maybe have to figure something else, can not find one!. Any suggestions?
Yambits light is for vehicles driving on the opposite side of the road and does not work for use in US.
The stock is sealed, if yours is removable is most likely a H4
Regarding your original question, yes the XS400 (1980-82) uses the same sealed light unit as the RD400.
And as mentioned above if you have a removeable bulb, it's not a stock unit.
Here's a stock unit: https://www.ebay.com/itm/NOS-Yamaha-OEM-Lens-Assembly-1979-RD400-1981-1982-XS400-1A0-84320-61/303675686130
I removed the bulb from mine by bending out the tabs, breaking the bulb and sucking out the glass with a vacuum. For a replacement I used a 45 watt H4 bulb, trimmed the skirt down to fit and laced it in with some fine copper wire. I would have liked to use a lower wattage but couldn't fine one that would fit through the hole. I don't ride at night so I am not sure how well it lights up the road but it works well for a daylight running light.
im going to try to retrofit an incandescent one with these style.
https://www.ebay.com/itm/2pc-HEADLIGHT-BULB-SOCKET-H6M-P15D-25-1-3-WIRE-SCOOTER-ATV-QUAD-ATV-YAMAHA-HONDA-/233535841158
i know not as bright as a halogen or led.. but if its scattering the beam, doesn't matter.
BUT, on my t500 i went to a pre-focused bulb and its way better (more usable) than a halogen or led insert in that lense.
https://www.ebay.com/itm/P15D-3-Bulb-RP30-prefocus-12v-12-volt-45-45-watt-early-Lucas-type-/203166490497