Motorcycle Fastener Tightening Sequence

The topic today is a relatively basic one, but also one that is very important for working on motorcycles in general – “motorcycle fastener tightening sequence.”  That sounds fancy, but motorcycle fastener tightening sequence is a fundamental principal when it comes to wrenching; and possibly something you wouldn’t realize unless explicitly told.  So, here we go:

Motorcycle parts, particularly larger components, are more-often-than-not attached via multiple fasteners.  Think about it; when was the last time you removed or attached a decent sized part on your beloved motorcycle and it only involved a single nut or bolt?  Never.

My real life example is that I reattached “Cal’s” carburetor yesterday, and it involved four independent bolts.  Motorcycle fastener tightening sequence definitely came into play.

On top of that, lots of larger engine components are separated from their immediate neighbors with a gasket.  The gasket issues makes this particular discussion even more relevant.

The rookie mistake we are here to discuss and help you avoid is over-tightening one fastener, while an adjacent fastener is completely loose or loose.  Visualize a square with a bolt at each corner.  The bolts surrounding the square should be tightened a little bit at a time in a crisscrossing pattern.  No corner should be fully torqued with another still far from reaching its final torque.

There are three main reasons motorcycle fastener tightening sequence is critical.

1) Tightening one bolt fully while leaving others loose will dramatically impact the final load on each bolt and could possible result in a fastener breaking during the tightening process.  The goal is for each bolt to provide the same fastening force and bring the surfaces together firmly and cleanly.  Tightening bolts incrementally applying a little more force to each in a crisscross pattern will minimize weird interactions (sometimes called bolt cross-talk).

2) Additionally, sequential tightening will ensure gaskets between parts experience equal compression on all sides minimizing the potential for subsequent leakage.  This is critical after pouring all your time and effort into a rebuild.

3) Finally, due to tight space constraints on a motorcycles, sometimes parts won’t line up for all fasteners if one is over-tightened first.  The gradual, incremental tightening is actually required to get things to line up properly and come together cleanly.

So that is motorcycle fastener tightening sequence in a nutshell; bet you loved that.  It is super critical, so I figured it best to cover it for those out there who may not realize its importance.

Please forgive any typos as I wrote this blog post from my cell phone.

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