NX 650 head = xr650l head

15 replies to this topic
  • amdderik

Posted February 21, 2006 - 12:37 PM


Will a 88 nx650 cylinder head work for a 2000 xr650l?
Most of the stuff that I saw suggests that they are mostly the same.

Derik Harris

  • martinfan30

Posted February 21, 2006 - 07:23 PM


from all ive read, it is an identical engine.

  • amdderik

Posted February 21, 2006 - 07:32 PM


Good stuff because I just bought a head off of ebay that said it was for an 88 nx650, so I will report back soon.

  • wr450fyamaha

Posted February 21, 2006 - 07:42 PM


it looks the same from the outside.....but that doesnt mean much. its a gamble


Posted February 22, 2006 - 08:40 AM


I would guess the head is the same. I know the cylinders are different. NX had a nikasil bore and I don't think it had any air injection ports. Also the countershafts must be different because they take a different sprocket. Maybe they beefed it up for the "L".

  • Motosprtman

Posted February 22, 2006 - 12:26 PM


Remember that when the XR650L first come on the scene in 1993, it was Honda's result of having observed Scott Summers having stuffed an NX650 motor into and XR600 frame.

The rest is of the story is that so far the XR650L is into a 13 year long run - second only to the XL run of 15 years.

Bottom line is that I would think the NX head will work, given the head stud pattern is the same. I betcha it is.

The CRF's are now the new technology and once sorted out they will also be a long run, probably into my rest home years....

  • amdderik

Posted February 22, 2006 - 07:46 PM


Well I bought the head off of ebay, it arrived today. The heads match up perfectly, but there is a small gash in the middle cam journal. What do you guys think, I know its hard to determine since you can't feel it over the Internet but should I chance it or send it out to xr onlys to have them line bore it for 120 bucks. Do you guys think I will loose oil pressure from this gash?

Posted Image

  • Motosprtman

Posted February 23, 2006 - 06:03 AM


Ouch Looks deep. I would think that it may need to be line bored.

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  • martinfan30

Posted February 23, 2006 - 07:06 AM


that must be why it was on ebay. that mark will f*** up your new cam. have a shop check it out to see if it can first be reused, then linhe bored. good luck bro!

  • amdderik

Posted February 23, 2006 - 12:07 PM


Do you guys know of any shops, other than xr only, that will do this job? I took it to a couple of machine shops... they all said that they can not do it because there is not a straight shot to the cam journal.
I know XR only will do it but it is $120.
Any suggestions?

Have any of your local machine shops been able to line bore these heads?

  • dorkpunch

Posted February 23, 2006 - 12:18 PM


you might loose a little bit of oil pressure because the gash goes clear to the outside edge. as long as its not right on the orifice where the oil comes out you should be okay. actually, this is an old trick on the xls- machine a small slot in the journal on the orifice so that the oil would cover the entire surface- just dont machine it all the way to the edge or the oil will squirt out the side instead of coating the cam journal. wow, did that make any sense?

  • amdderik

Posted February 26, 2006 - 03:21 PM


According to the machinest at the machine shop the gash will not be a problem. YES!
This means that I will have all of the parts to put the bike back together by the middle of next week.
Thanks for all of the help

  • amdderik

Posted March 04, 2006 - 11:35 PM


The bike runs GREAT!
Yes the 88 NX650 head works without a doubt.

I love this bike!


Posted March 05, 2006 - 05:07 AM


Did you do anything to the head before the install-port work/chamber polish/ valve or spring replacement? :thumbsup:

  • amdderik

Posted March 05, 2006 - 10:10 PM


All of the valves were in good shape, so I just had the machine shop resurface the head.
But I also had the cylinder bored over to accept a 101mm Wiseco piston.
Sweet now the bike is done with the initial break in period.

  • goblin127

Posted March 06, 2006 - 06:04 AM


Good news, and one for the archives.

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