briggs ez-spin

oldfatguy

Active Member
#1
stellar mini bike h60 tecumseh :: briggs001.mp4 video by oldfatguy - Photobucket

A Lot of guys have asked about cutting the ez spin off the exhaust lobe of the cam and it it really makes a difference . Here is a short video of my 3hp briggs running.In addition to the cam modification it also has a milled head and is ported and eye browed. I had to replace the plastic pull starter spool today because it broke from the compression. This engine will start cold on the first or second pull every time. So here is proof that a few simple modifications do make a difference over stock.
 

Neck

Growing up is optional
#2
Couldn't the same thing be done by grinding a little off the exhaust lifter and opening up the clearance?
 
#4
Back in 1974 I had a Tec powered rotary mower, found the bump on the cam lobe figured it was a factory defect and ground it off.

What a huge difference it made in idle quality and power!!
 

oldfatguy

Active Member
#5
Back in 1974 I had a Tec powered rotary mower, found the bump on the cam lobe figured it was a factory defect and ground it off.

What a huge difference it made in idle quality and power!!
I just cut the cam on an hs35 that seemed to have low compression . When I checked it the exhaust valve was staying off it's seat for almost 2/3 of the compression stroke. After cutting the cam and changing the head gasket there was a nice increase in compression because the valve now is closed for the full compression stroke. The h60 on my Arco had the compression release removed, it has so much compression that I can almost lift the bike with the pull start but it starts easy usually on the first pull. In fact all the engines that I have removed the ez spin from start on the first pull.
 

oldfatguy

Active Member
#6


The ez spin lobe starts at the center of the round part of the exhaust lobe and continues around to the base of where the actual exhaust lobe begins. It only takes a few minutes the way I do them in the lathe. The part that gets cut is from the tip of the cutter to where the actual exhaust lobe begins.
 
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#10
I know this is an old thread I’m digging up but I’m wanting to do the same thing, remove the ez spin lobe from the cam.
Looking at the photo above I’m having trouble wrapping my head around how the cam is turned by the lathe without the tooling striking the cam lobe. Can anyone explain what I’m missing here? Thanks in advance
 
#11
I used a dremel as a tool post grinder and the ez spin is on the base circle so with the cam chucked in the lathe I set the grindstone almost touching the base circle and by hand turn it to hit the little bump and grind it off to the level of the rest of the base circle.
 

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Doc1976

Active Member
#13
I used a dremel as a tool post grinder and the ez spin is on the base circle so with the cam chucked in the lathe I set the grindstone almost touching the base circle and by hand turn it to hit the little bump and grind it off to the level of the rest of the base circle.
So you're not using the lathe under power, just rotating by hand to grind the little bump off? I'm going to try this soon.
 
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