I'm real close to starting my RD400 up after restoration. Adjusting the oil pump cable at wide-open was easy, but I am confused about the pump stroke adjustment. I have the RD400C service manual from this site, pictures are grainy. The instructions talk about rotating a plastic starter plate and using a feeler gauage set. My pump is a 1A0, and there is not a plastic starter plate. It looks more like a pump from a mid 80s RZ. Does anyone have instructions on how to adjust the 1A0 pump stroke.
Cheers!
The RD400 Service Manual and the RD400 Autolube Service Manual both state to run the engine and observe where the pump plunger is fully extended and then stop the engine at that point. You should also be able to do this without the engine running by rotating the engine with the kick starter (or remove the plugs and rotate the rear wheel while it's in 5th or 6th).
yam_rd400_pump_adjust.png
Minimum pump stroke should be .20mm-.25mm. There are shims under the nut and flat washer on that pulley shaft.
you can roll the motor over w the kick starter to get it to move. TBH, i have a similar bodied pump on my R5, and thats how i did it. :twocents:
Awe, nice to have knowledge like this to lean on! Thanks.
Update.
I using the 6th gear to turn sparkplugless engine work fine. The gap read about .018. I always have brass shimstock on hand, so I built a shim and now have about .010 gap. That service manual says .008-.010.
I have never dismantled a oil pump, so the function is a bit of a mystery to me.
Question 1. comparing .008 to .010, which one injects more oil, smaller or bigger gap.
I've taken the RD400 for a couple of rides now. I am using the latest Klotz synthetic TC-W3 oil. I am shocked at how smokeless the RD is. Almost scary.
How much of this smokelessness is attributable to the Klotz, and how much to shrinking the shim gap from .018 to .010?
Bigger gap, longer stroke, more oil. Did you check the cable adjustment when at full throttle? Turn and hold throttle full and check if the marks line up.
(https://i.ibb.co/MD2QzwrL/20250430-063338-1.jpg) (https://ibb.co/ynf7zvtJ)
Longer stroke = more oil. That is what I thought. Last night I remeasured the gap. Part of my problem is how I was using the feeler gage. I would slide the gauge up the round ramp to enter the gap. This ramp and gap was well greased and would eaisly accommodate a up to an extra .003 of gauge. Difficult to get a feel for resistance. So, last night, I cleaned the round ramp and the contact washer with brake clean. I put back the OEM combo of shims. This time instead of sliding the gauge in from the ramp, I approached the gap from the side, on the radius. No influence of grease. The measurements I got this way were agout .012-.013. Yamaha in their wisdom used 3 shims, one of which was about .0025. I suspect this was done to provide easy one time adjustment on a well broken in pump. Mine has about 21,000 miles on it. After pulling the .0025 shim out, I am now about .0095 gap. Looks good. Added back a smidge of grease. Test ride today!