Mystery Dowel pins!

Hello XR people! I know I haven't been posting much in here in the last couple of years but my old XR has been pulled out of retirement by my dad who is now retired him self and bored.


Ok so short back story, joined military, left XR at parents house sort of needing work but still rideable. Bought new KTM while still away and the XR continued to live with my dad. Little brother rebuilt a CR250 and now dad decided he really liked riding my old XR and pulled it out of storage. He took it apart do to a possible cam chain knock.


The bike is now apart and he is waiting on parts to come in to get it back together. But he has an extra dowel pin that either of us can not find on a parts schematics. It's size is 10x16mm just like the oil pump dowel pin. But he has two! He does know know where exactly it came from, but it did come out of the engine. I have checked the parts list on bike bandit and RMATV with no luck on finding a second place for this size dowel pin. Any help would be amazing! :ride:

You didn't mention what year or model of XR.

If a 400 then since he took the engine apart to work on the cam chain, check to make sure the extra dowel pin isn't actually the plunger that goes with its companion spring in a small hole under the cam that engages the auto decompress mechanism on the cam. If that pin is omitted on reassembly, the engine won't start.

^^ what he said..

the plunger pin is about 4mm od,nowhere near 10mm,at least on an xr250

Edited by firstplacephoto

There not the locating dowels for the rocker cover?

My screen name is the year and model of the XR. So a 87 XR250R. I will have him take a picture of the extra pin. Maybe it will help. I am currently in Texas and he is back home in California so I can't get hands on with it. Thanks guys

There are pins between the case, cylinder, and head, but I think they're 12mm.


Its that little guy sitting on the gear cover.

Is it possible the previous owner had the engine apart and left that piece floating in the engine?  And bought a replacement dowel because he couldn't find that one?

Yes it is possible. The previous owner was a pretty squared away mechanic but I am pretty sure he was a pot head. He handled all the suspension work for the county I grew up in. All the parts diagrams for the XR I have seen only shows one of these dowel pins. And if it was floating around in there I got super lucky because k put all kinds of hours on that bike for the 5 years I rode it.

I'm like you, I can only see where there is only one dowel that size in that engine.

Is it for the oil cooler line? I seem to recall there being a dowel on the outflow oil line that connects to the side of the case. I don't recall what size it is though.

Edited by XR250rdr

87xr250 did you ever figure out where it went? The same exact thing happened to me and I have looked all over the diagrams and cannot find where it goes either. I would like to know before I put oil in there. I have looked over my manual and every diagram I could find and for the life of me have no clue where it could go but I find it weird you have the same problem. Mine is the exact same size of the oil pump dowel pin. I don't think it's just an extra one since both of is have it. Thanks

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