Oil pressure/decompressor question

3 replies to this topic
  • 94xr650lguy

Posted April 04, 2008 - 04:23 PM


Hello all, new guy here with my first post. I just finished rebuilding my XR650l. I took it down to splitting the cases to replace the countershaft, and now that its back together and in the frame, I spent a good while turning the engine over with a wrench and also spun the engine over for a while with the electric starter and no oil showed in the oil filter cavity. Does it just take a while for oil pressure to build after a completer rebuild? Also, I removed my decompressor from the cam because I suspected it was not working and only making noise. Has anyone else done this? I'm wondering if that may have been a mistake.


  • XR650L_Dave

Posted April 05, 2008 - 04:53 PM


You need to prime the oil pump on these beasties.

You need to either pull the clutch cover off and fill the pump, or one fellow was able to use a little compressed air into the resevoir to gently force some oil into the pump.

Hey, I wonder if you could tip the bike over to the right and full the sump via the check-plug on the left-hand case?

I think there may also be an oil passage in the cam that needs to be plugged or restricted if you pull the decompressor- not 100% on that, but I recall it being discussed.


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  • asf

Posted April 05, 2008 - 05:12 PM


I filled up a syringe with oil, and ran a piece of clear tube from the syringe to the oil feed line, and pumped it full of oil until I saw it come out the filter assembly. You can find a hand pump or syringe from the auto store for about $3.

Most say theirs primed no problem, but none of the other tricks worked for me. It should pick up after 30 seconds of running, but that's a risky proposition to me.

For all I know I was going to be that 1/100 that siezed a piston on the first ride...

  • 94xr650lguy

Posted April 06, 2008 - 08:16 AM


Thanks for the replies guys. I did tip it over side to side for a bit and that seemed to do the trick. I had a good amount of assembly lube on everything so I was'nt too worried about pressure at initial start-up. I checked it after about 30 seconds and everything was good :thumbsup: . I was concerned that the electric start would'nt have enough oomph to spin a fresh motor without the auto-decompressor, but it cranked right up. Yup, I did plug that exposed oil hloe on the cam, no need in letting lube just spray around for nuthin'. Looks like it's (FINALLY) time to ride.

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