I need to remove the oil pump to replace an oil seal, however can you remove the oil pump without the need to drain the gearbox oil etc?

I'm pretty sure that you can. The ones I have removed are fixed by two screws - just make sure that you use a JIS screwdriver, not Phillips.

There is an oil seal inside the clutch cover to keep gearbox and injection oil separate .

Are you just replacing the seal in the pump behind the plastic priming wheel. Might need a new gasket where the pump mounts but it'll be a pain to scrape off the case if it's well stuck on. Being 'me' ie lazy, & if gasket isn't broken I'd just refit the pump & see how it goes. My memory fades nowadays but I think the pump has a plug in the shaft where the primer wheel is which might leak so double check incase 'that'. But wait there's more lol. Oil can come out the plunger shaft that goes up & down while pumping. Not sure what they have for a seal that side or an Oring on the plunger shaft but others will know?.

Thanks for all the information.

I have just realized what the actual problem is. When I stripped down the oil pump, cleaned all the parts and reassembled the oil pump replacing the oil seals and gaskets etc with a DT1 repair kit. I also removed the internal plug or stopper inside item # 4 = Distributor Shaft 214-13120-00 which I shouldn't have. I went to commission the oil pump the other day and when you turn the nylon starter gear wheel to bleed the air out of the oil line and the pump, oil is coming out of the inside of the hollow distributor shaft with each revolution of the nylon starter wheel.

Is the location of the internal plug or stopper inside the Distributor Shaft critical or can I simply fit a stopper or plug in the front end of the shaft at the nylon geared wheel end to block off the inside of the shaft so oil cannot leak out? I downloaded the pdf manual Yamaha Injection System (Auto-Lube) which shows the internal stopper inside the Distributor Shaft, however no part number for this item is shown.

Need an answer from oil pump expert DEET about that. If you have the one you removed can you make something going by the length of the old one. I wonder--total guess-- could a solid piece of rubber be used, like a short piece cut off a fat oring then pushed in under tension so no chance of moving. By memory the split pin on the plastic wheel goes across the end of it so can't escape.

Hi there, thanks for your comments - sounds a good idea to me making up a rubber plug. I have dropped a note to DEET to get his thoughts on this as well

Thanks Syd

I have not been able to get a comment form DEET about this so would be keen to know from anyone  - Is the location of the internal plug or stopper inside the DT1 250 oil pump Distributor Shaft critical or can I simply make up and fit a stopper or plug in the front end of the shaft at the nylon geared wheel end to block off the inside of the shaft so oil cannot leak out?

The plug is approximately 10mm long. The plug diameter depends on the distributor diameter.
It has to be epoxied in place at the proper depth.

You can send it in to be done if you can't figure it out.
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Thanks for the information which is much appreciated. No problem to sort out and fit a 10mm long plug. Can you advise the depth the plug should be from the nylon starter wheel end of the distributor shaft?