So I'm out putting some miles on my 107" on this nice winter day here in Tampa and slowly I notice she's not as snappy as when I left the garage, and things don't sound all that healthy. FFWD a few miles and she's popin' and fartin' all over. I pull over, thinking it's an exhaust leak or a blown head gasket (like a Cometic would ever let that happen huh?). Things are sounding weird from the rear cylinder, so I pulled the plug cap on the fly and she smooths out but sounds like a muffler-less lawn mower.

Hobble home, tear down, troubleshoot. With the carb removed and plugs in the front cylinder cranks over normal but the rear is making this loud POP somewhere in the cycles with a pronounced puff of air out the intake. Things are going too fast to see where exactly the POP is on the 4-stroke cycles, but it's certainly the rear cylinder.

Start with the pushrods and WTF?!?!?!?!? The exhaust pushrod is about as loose as a hotdog being thrown down a hallway! Crank them down since I'm already at TDC, then get the front cylinder at TDC and reset those pushrods as well and she's back to normal. No more POP on cranking.

I can also confirm my build is 175 psi cranking, but when the CR's are active it's about 95 psi.

Am I supposed to loctite them nuts in place?

 

 

IDK-in 40 years never seen one come loose.
A dab of red won't hurt.
You will have to fire up the propane torch to bust it lose probably someday

 

 

That's the thing, when I go to remove them it'll be a total bitch! The ones I have are Rivera Taperlite. They came in the bike and some horses-*** marred up the threads a bit so for umpteenth time thus far in this build I've powered thru hand wrenching down pushrods. Ice on the cake, these are the only pushrods that are 40 threads per inch! Yea... it takes a while.

Fortunately that was my engine problem. I just got back from filling up the tank and she's right as rain. Valvetrain sounded a lot smoother too.

I think I'm gonna go with the Zippers cut-to-length ones with the Mae West ends. A set of 4 is about $90 and I'll be done with this **** forever! I got a guy at work who I can leverage for the precision machining.

 

Smith Brothers instruction include using red Loctite but, as has been said, it can make re-adjusting difficult. Of course, if adjusted properly the first time, they should not come loose. I started using a "dab" of red as suggested by Ranger73. To minimize the challenging removal/readjusting, I don't apply to the threads but use a toothpick to get that dab of red between the jamb nut and the flat shoulder of the pushrod.

 

The thing I hate the most about these pushrods (and probably any pushrod that uses a 1/2" nut to lock the position) is that it rubs on the front exhaust pushrod tube. That's another reason I wanna go with the custom fixed length ones.

 

I'm also a fan of one piece pushrods.

Smith Brothers will make a set in any length you want for a very reasonable price. Info is on their website

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I had a set to the Rivera's and I did not like the way they fit into the rocker and Lifter. In fact in the area where the top ball goes into the pushrod tube, it started to show signs of fracturing (in the tube) I got rid of them and went with S&S (7/16" nuts). never had an issue. Keep in mind that it takes 3 wrenches to properly tighten an adjustable pushrod....

 

Yup. These take a 5/16" for the adjustment shaft, 7/16" for the pushrod body, and 1/2" for the locknut. If the locknut isn't rotated properly the pushrod tube won't fit on the base.