XL600 - Does Anyone Know What This Part Is?

Hello everyone,


These forums have been of great help to me over the last few months, and I find myself now in a situation that demands I ask the more experienced for help.


My XL600 recently started spraying oil out the engine for the first time. It would appear that there's some kind of plug missing that I've never noticed before. I haven't crashed or dropped it since I got it (the scratches have been there since my purchase).


Does anyone know what part is supposed to go into that hole, and where I can find it (if it's something that I can replace myself)?

xl600 engine1.JPG

xl600 engine2.JPG

On my XL there is just an alum plug in there. Nothing sticks out and I can't remember if it holds anything inside.

I believe it was an access port to drill a hole to the center inside of the cover, the plug may be stuck inside.

Edited by jjktmrider

Does the plug look like it can be removed with any household tool?


On a schematic of the left crank case cover it doesn't list any specific part that goes there, so I'm thinking I'm out of luck as far as getting it replaced goes, which is a shame because I love this bike. If it's a removable part however, a junkyard might be able to supply me with one.



I'll go and investigate a little further.It looks to be just a plug of sort pressed in to seal the hole and not a replacement part or even anything critical, it just has to stop the oil from coming out. I'll make sure but I think even some rubber slug pounded in will work, the factory just has it aluminum,. will go investigate right now. 

Thank you for going to the trouble mate, I really appreciate it. Suddenly excited to get this girl back on the road.

what year ?

It is plastic. I can't tell how deep it goes without taking the cover off but it is in my '83 XL and '87 XL motors so it isn't a certain year thing. I would assume the XR's have it too. What is needed is any plug that's made to fit in a 12mm hole, probably needs to be 8mm long or so, you should be able to look down in your open hole and see how deep it is before hitting a cross hole or lip ect..

This is similar to what is needed and may work but there are probably better options, plus it doesn't need to be a "T' shape.




Even some hard rubber slug 12mm od will work, it doesn't do anything but plug a hole.



Here's a whole cover, not cheap, not expensive




Yep XR's have it also, here's a nice NOS, $$$$


Edited by jjktmrider



the crankcase is vented ( no psi or vacuum)  so it just needs to keep splashing/ flung   oil in and dirt out

I see rubber tapered plugs for sal at the local parts store that should be fine

I'm running an '87 XL as well.


Zimman, I had no idea the crank case was vented, that's a huge relief. I had driven a good 8 miles before I realized the plug was gone and was wondering if I'd done any damage to the engine.


jjktmrider, thank you for the great information. I'm going to stop by the hardware store tomorrow and see if I can't find any ~12mm slugs. Also I'm assuming I'll need something a little more heat resistant, I think the engine gets upwards of 200 degrees, yea?

A well nut may also work, I think most hardwares have them & lowes & Home depots. http://fasteners.oemfast.com/viewitems/pop-well-nuts/pop-well-nut-threaded-inserts

But the warm oil may soften it. Is the hole round or "D" shaped? In your pic, it looks round. If round, you should be able to find a metal freeze plug to beat in hole. Dorman products make them, & some auto stores have them. Any carbruator rebuild shops around you? They also might have some aluminum plug slugs. here is the dorman file http://www.dormanproducts.com/catalog/hardware2006/127-130_Sec8_Part1.pdf

  But to use the metal freeze plugs, usually there is a small lip or shoulder for plug to stop against, before concave is smashed.

12 mm is a tad under 1/2"?? cut a piece of wood dowel, ( 1/16" short and fill top with epoxy.)

It's a round hole, and that's a good suggestion. I had another idea as well that I was going to implement. Back when I changed the stator, I used a thin layer of silicone cement in place of gasket sealant when putting the gasket and engine case back on. I figured I could use a short threaded bolt that's just thinner than 12 mm and seal the hole with silicone as well. It stands up to the heat well and is pretty sturdy, and I have plenty on hand so it wont demand any extra cash out of pocket.


I'll let you guys know how it worked out after it's set and I run the bike tomorrow.

Make sure your not plugging a side hole , I don't know if there is an oil passage under there or what that drilled hole does down in there. It goes to the front of the flywheel. Keep the plug somewhat short.

Sweet success. Turns out I was out of the cement, only had silicone grease, so I went with bork's suggestion of the wood + epoxy. Worked like a charm.


Thanks a million guys, one more bike on the road again.

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