The instrument according to the description does not fit the Xj600 51J (87). However, I found somewhere on the web information that it is a replacement for Yamaha's YM-01245. According to the service manual, such a designation has a gauge for this motorcycle. So I ordered it and it fits.
Operation of this gauge is, contrary to the opinions on the forums, child's play, the key to success is accurate axial installation with the shaft cam and following the service manual. Assembly of the instrument, removal of the valve plate, insertion of a new one, and finally removal of the instrument takes about 5 minutes. On the forums they write that you need to file something or ream the holes - total nonsense! The edge of the head in the place of installation of the gauge is not straight, but runs along a curve, so the gauge adheres to this curve point-wise - it does not matter. Just axial with the cam of the shaft and fits perfectly and the first time.
I recommend using this jig- the forum methods of supporting the valves with a clamp make it difficult to remove the valve plate and risk bending the valve!
I recommend, it fits Xj600 51j.
The key performs its role perfectly . However, it is necessary to catch a little practice.
Adjusting the valves with its help will be simple and quick. One more important thing . The product is durable. Since the date of purchase I have done dozens of engines both in scooters and mopeds running , and continues to work great . I recommend to other buyers .
Stones of good material, they are durable and effective in fastening and unfastening valves. Of the disadvantages that do not affect the use, they are quite heavy, and cause slight discomfort if you fasten the valve with the middle part of the hand.