DragBikeMike
Serious Thumper
Offline
SuzukiSavage.com Rocks!
Posts: 4284
Honolulu
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When I experimented with this jack bolt idea, I was in the middle of preparing and installing my stage II head. I prepped the stage II head for the jack bolt too. Instead of a 3/8-NF jack bolt I set it up for a 5/16-NF and incorporated a steel threaded bushing in the aluminum head (for durability). But I wasn’t ready to try it yet, so I plugged the jack bolt hole and put the idea on the back burner.
At that time, I was concerned about making the cam chain drive too rigid. Although the factory design seems to lock the tensioner in place, that long rear guide is still flexible. Once I put that jack bolt in there, the rear guide becomes rigid. So, when the cylinder grows, the pawl restrains the bottom, the jack bolt restrains the middle, and the pivot bolt restrains the top. It’s not gonna give much. We already have a problem with accelerated chain wear. I wasn’t willing to solidify the system.
Later, I start seeing discussion on the forum about Batman’s complete removal of the tensioner pawl, and then Dave sets his up with no pawl and a stopper to restrict plunger retraction to 1mm.
While I understand that Batman’s system is working fine, I need more control over my valvetrain. The unrestrained plunger setup is fine for a daily driver, but I’m pushing mine past 6.5K on a regular basis, and I’m fixin to bring the valves a whole lot closer to the piston. With the pawl removed, you can watch that plunger stroke in and out a bunch as the engine rotates. Every time the intake lobe goes past the nose, the valve springs take control and drive the cam. That takes the slack out of the rear side of the chain. The pawl is there to prevent the cam from running away. The cam lobe has a deceleration ramp that is intended to gently place the valve on the seat. The deceleration ramp can’t perform its intended function if the rear side of the chain is slack. The chain must hold back the cam as the intake valve is closing.
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