Recommendation for cutting valve seats

3 replies to this topic
  • Pooley

Posted July 26, 2014 - 06:37 PM


With the help of TrailriderJoe, we tore down my 01WR426 today to troubleshoot a hard starting/non-starting issue.  This bike has somewhere between 13,000 - 15,000 miles of singletrack since I bought the bike new in 2001.  The valves had never been adjusted to this point.  Unfortunately with my current feeler gauges, I cannot actually measure the middle intake valve because the feeler doesn't fit between the casting, so that particular valve clearance had not been measured recently.  The other 4 valves clearances are still within specs, 0.10 mm for the intakes (0.10-0.15 mm spec), and 0.20 mm for the exhausts (0.20-0.25 mm spec).  What we found to be the culprit of low/no compression was the center intake valve that had hammered the valve seat, leaking compression and now it definitely needs to be recut.  


Is there a well respected shop that folks use to cut valve seats?  I know Myler's is the one-and-only for repairing radiators, is there a similar shop for doing head work?  I am in Michigan, so someone local would be a bonus, but I can ship out the head wherever needed.  I definitely want to have someone who knows what they are doing, and will do a quality job versus a some hack who is just cheap.


I would assume at this point I should do all 5 valves and seats just for the sake of being thorough.  I am not decided yet on SS versus the titanium valves, but I know cost is a big difference.  I am inclined to go with OEM titanium just because that is what the bike was actually designed for, and they did last for 13.5 years at roughly 1,000+ miles of singletrack a year.  


Any recommendations for shops?


I was reading old posts and it appears that the center intake is typically a culprit for valve failures, wearing first or whatever valve problem exists.  Is there a specific reason the center intake valve is the first to go?  



  • stevethe

Posted July 27, 2014 - 06:05 AM

#2 these guys are well known and respected for cylinder plating. I'm sure they wont mess up a valve job.

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  • grayracer513

Posted July 27, 2014 - 10:55 AM

#3 these guys are well known and respected for cylinder plating. I'm sure they wont mess up a valve job.

If I lived in Michigan, that's where I'd go unless I could get a good local recommendation.

If you take a pair of decent ordinary scissors, you can trim the sides of a feeler gauge blade to fit the center intake.

If I owned a 426, I would rebuild it using the stainless valves and springs from the 2000 model (or the 400; same parts). Significant savings without a significant performance hit, and probably even more durable.

  • Pooley

Posted July 27, 2014 - 01:20 PM


Thanks for the secondary recommendation for Millenium, Grayracer.  A second set of feeler gauges is now in my toolbox, waiting some trimming like you described.


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