Installing gaskets properly

(6/11/2014) I had two leaks in my bike that I repaired on Sunday: a fuel leak and a primary case oil leak. I actually attempted to fix the fuel tank leak on Saturday but did a really half-assed job and actually made the leak worse. I made the mistake of using the old gasket and sealing screws and failed to notice that the gasket was installed backwards.

Here are some lessons I learned from this experience and previous experiences with gaskets.

Fuel Tank Canopy Gasket

As I wrote in an earlier post, I had my fuel pump, pressure regulator, and filter replaced earlier this year. These are all mounted on a bracket that angles into the fuel tank. By the way, the fuel level sender and float are also located on this assembly. Proper installation of this crazy-looking assembly is very important if you want to avoid altering the way your fuel gauge indicates the fuel level.

This assembly terminates on the top of the tank at what Harley Davidson calls the canopy. The canopy is a metal mounting plate with ten screw holes in it, in addition to two holes for mounting the console and the hole into which you pour gasoline into the tank.

In between the canopy and fuel tank itself, lays the canopy gasket (HD part no. 61402-02. Shown in the photo at the top right of this article.) Note a couple of things about this gasket that I missed the first time I worked with it: (1) it’s tapered, wider at the top than the bottom; and (2) there is a small piece jutting out on one end; that little piece indicates that this end of the gasket faces forward on the bike. This is how you can readily determine how to properly position the gasket. Had I read the maintenance manual more carefully the first time, I might have avoided some work.

Even after I read the manual and understood what to do, I managed to get distracted by something during the installation process and put it on bottom forward. Fortunately, I was proceeding very slowly, double-checking my work before moving on to the next step and caught my mistake right away. I sympathize with mechanics who screw this up.

As soon as I had the gasket in place, I could feel that it was right. It fit perfectly. Next, I hand-tightened the ten new canopy sealing screws (HD part no. 1311D, $1.05 each) into position in the order specified in the manual. These screws are specially designed to seal in a way that prevents gasoline from getting past them and the gasket. Notice in the photo of these screws (right) that they have a piece of plastic around the threads just beneath the head. On many of the old screws, this plastic had become worn or was absent completely. 

I then got out Mike Russo’s inch-pound torque wrench and tightened the screws to approximately 22 in-lbs. (The manual specifies 18-24 in-lbs.) Once tight, I inspected the gasket and could see that it did not bulge anywhere along the perimeter, as the old one did. The fit was snug and I can tell you after filling the tank to the top and then riding for several days that this gasket and its screws are doing the job.

Primary Cover Gasket

This is an expensive gasket (HD part no. 34901-94C), costing me $31.17 plus tax the the local Harley dealership. I knew from experience that if I had oil leaking from the primary chain case at a location other than the drain plug, I would have to replace the gasket. Sometimes, oil will leak at the drain plug if the O-ring has worn out. I knew the bolts were torqued to spec so that left only the gasket as the culprit. Sure enough, after I pulled the gasket, I could see it was worn and damaged at the point the oil was leaking, around the number 1 bolt.

This job took longer than I had anticipated because I forgot that I had to remove the rear shifter lever, left floor board, and loosen the left floor board bracket. It was a straightforward job, but it took a couple of hours.

Be sure to thoroughly clean the surfaces—on the engine case and primary cover—before installing the gasket. Inspect the surfaces for any damage.

Just as in the case of the canopy gasket, the bolts that hold the primary cover and its gasket should be tightened first by hand and then with a torque wrench in the order specified in the manual. In my case, I tightened them to approximately 100 in-lbs. (The manual specifies 84-108 in-lbs.) Coincidentally, there are also ten fasteners in this case. However, unlike the specialty screws, these bolts do not have to be replaced each time you change the gasket. If I could have afforded them, I would have installed new chrome bolts. :-)

With the cover off, we checked the slack on the primary chain and it was still in spec, so we didn’t make any adjustments. Mr. Russo happened to have a spare, new clutch inspection cover gasket in his garage, so I installed that as well. 

I am happy to report that after torquing the drain bolt properly, the oil leak is history.

All that remains now is for me to change the rear tire and my bike will be ready for my June 28 - July 13 ride to Banff (Alberta), Hells Canyon (Oregon), Yellowstone (Monana), etc. 

May spring last forever!

-The Long Rider