Head leak on '78 XS650E

[df_252]

I have a '78 650 standard that only has about 4000 miles on it. I haven't tried to start it yet because I want to fix the few problems that it has first. The head gasket has a leak and I'm wondering if retorquing the head to try to stop the leak is safe or advisable. I'm confident that the engine has not been apart since new, so I'm sure that all the gaskets etc. are original. I would (obviously) like to avoid removing the engine from the frame if I can avoid it. Thanks.

 

[5twins]

Yes, re-torque the head. This is a common problem on these bikes and it's caused by the rubber/metal sealing washers Yamaha chose to use under the 4 outside acorn head nuts. They cause those 4 nuts to constantly come loose. They should be replaced with copper or brass washers (soft enough to seal but hard enough to hold the torque). MikesXS sells brass replacements. Copper ones can be had from a Suzuki dealer (all their big fours from the '70s and '80s used them). What aggravates the problem is that Yamaha's original torque value for the 8 large acorn nuts was a bit low @ about 26 ft/lbs. They don't need to loosen much from that to get leaks started. We bump that value up to about 30 ft/lbs. Here's a chart with the revised values .....

 

[5twins]

Since this has probably never been done to your bike, some of the nuts and bolts may be stuck on their threads. This will give a false torque reading (read tight when they may be loose) so loosen each one slightly before tightening. Better yet is to remove each fastener one at a time, clean it, apply anti-seize, then install and torque.

 

[df_252]

Thanks for the quick response and for the good news. I wasn't looking forward to taking the engine apart on an essentially new motorcycle.
Dave

 

[df_252]

Any chance you have a parts number, or size for the Suzuki washers?

 

[5twins]

09168-10017, and as you can see, it's used on tons of different models .....

http://www.partzilla.com/parts/detail/suzuki/SP-09168-10017.html

Here they are installed on my motor .....

 

[gggGary]

5twins gives good advice. probably best to do one at a time, don't loosen all the nuts at once. Be very careful with #11 Do #9 and #10 also. #12 through #15 are cam cover bolts they don't go through the head.

 

[df_252]

Thanks for the help.