Whizzer/Cruzzer Motors - Mushroom Lifters Problems


Well-Known Member
Local time
11:54 PM
Nov 14, 2018
So Cal
Howzit Everyone,
Over 14 years I've noticed a couple problems with mushroom lifters in the Whizzer and the new Cruzzer motors.
It all starts at the Taiwan factory when the case was cast.
The case area around the lifter boar bottom is uneven and high on some motors.
This is not a problem when using regular straight lifters
Switching to mushroom lifters this is where I have found problems.
Whizzer/Cruzer motors were designed to be used with regular straight lifters.
Mushroom lifters was an after thought by Whizzer USA. Mushroom Lifters are an upgrade.

Problem #1
Mushroom bottoms out against bottom of lifter boar case area.
This will cause cam and mushroom to wear early and uneven.
I noticed this when I was turning a new motor over by hand and I could feel extra resistance when the intake valve was open.
When I inspected the motor I found that the intake mushroom lifter was bottoming out against the bottom of the lifter boar case area.

The Fix
Remove the intake mushroom lifter and grind the case area around the bottom of the lifter boar. Remove high spots. (See pictures)
Check the lifter by turning the cam to make sure the mushroom dose not contact the case. Now Fixed.
Another Fix - (shave) reduce the height of the mushroom so it dose not contact case.

Problem #2
Exhaust Mushroom Lifter edge hits cam bearing edge.
This can cause the exhaust valve not to close all the way.
I noticed this When a new motor warmed up. It would miss a beat and loose power.
This was very confusing because when I inspected the motor and valve train everything looked fine.
I was turning the motor over by hand and the exhaust valve stayed open very slightly. I taped on it by hand and it popped down.
I tried to make the motor do it again but it would not. I figured thermal expansion might have something to do with it
I inspected the exhaust valve and mushroom lifter.
I noticed the mushroom edge looked like it as rubbing on the top of the cam bearing edge.
I checked to see if the cam bearing was fully seated it was. The cam bearing sticks out from the case about .025"
I now needed to check and see if the mushroom edge was rubbing on the cam bearing edge
I pressed on the mushroom with my finger while turning and moving the mushroom lifter up and down.
I watched the bottom of the mushroom hit the top of the cam bearing edge.
This is what was causing the motor to miss a beat and loose power.
When the motor warmed up thermal expansion caused the mushroom to hit the cam bearing edge sometimes keeping the exhaust valve open.

The Fix
Remove mushroom lifter and reduce the DIA. of the mushroom .010"
How to reduce the mushroom DIA.
Put the Lifter in a drill motor and spin the mushroom against a file reduce .010" Measure with Mic. or Caliper.
Do not over heat the mushroom or it can ruin the temper of the metal. Use oil and take your time.
Install mushroom lifter and check with feeler gauge for a Min. of .005" clearance mushroom edge to cam bearing edge. Now Fixed

I've had both of these problems on new Whizzer/Cruzzer motors See pictures

I'm not saying that all Whizzer/Cruzzer motors will have these problems.
I'm suggesting to check all new motors with mushroom lifters or when switching to mushroom lifters.

Taiwan - Specifications - Close Enough is Good Enough

New Cruzzer motors all come with regular straight lifters now.

I hope this Info can help someone.
ALOHA Wrench


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Thought this might be worth mentioning since it shows up in the pictures.
Notice the LH vent chanber vent ports in the pictures.
Notice the bottom vent port is blocked with casting slag. Picture 1
The bottom vent port is used for oil return from the LH vent chamber.
I removed the casting slag and opened up the bottom vent port. Picture 2
I suggest To check all Whizzer/Cruzzer motors LH vent chamber ports and remove any casting slag.

Sorry, 2nd picture is up side down and the pointer in the 2nd picture is pointing at the wrong (top) vent port.
But you can see in the 2nd picture the bottom vent port is now open.

Taiwan - Specifications - Close Enough is Good Enough


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