12-3 Trigger Wheel Design

[BW250]

So Dontz and Matt have been very helpful in letting me know what my trigger wheel needs are, and it sounds like I'm going with a 12-3 on the cam (this is for a single cylinder 250cc Yamaha 4 stroke).

I will be using a VR sensor and can draw up whatever I need in AutoDesk, but I have a few questions before I get started

1. Is trigger wheel diameter important?
2. Is tooth depth important?
3. How thick does the wheel need to be?
4. What are my spacing limitations from the wheel to the sensor?

I have thought about just buying this wheel

12-1 trigger wheel.png (27.43 KiB) Viewed 2939 times

(http://pe-ltd.com/trigger-wheels.html) and cutting two more teeth off. Would that work?

Also using this sensor http://www.autohausaz.com/pn/0261210229.

Thanks for the help.

[dontz125]

The width, thickness and gap are all items found on the sensor data sheet. They are fairly standard, but there are variation from sensor to sensor.

Looking at that trigger wheel, my first question is - how will you prevent it from slipping on the shaft?

[BW250]

I would most likely end up key-holing it similarly to the camshaft sprocket. Depending on what wheel to sensor clearances I need I may have to just use one of those as a pattern and draw up one that fits my needs better dimentionally. However, I suppose if I needed to reduce the size I could always just shorten the teeth on that particular wheel. That would probably be the better route in the long run.

[Matt Cramer]

Not sure the code supports 3 missing teeth - I would use 2 instead.

[dontz125]

Are you sure? I acknowledge all the example are -1 or -2, but there's nothing to say there's a limit. TS doesn't seem to have a restriction.

The old MS1 was restricted to -1 or -2 ...

[BW250]

So I am about to buy the above trigger wheel, but I still don't know how many teeth to cut off... Also, I have been reading on Hall vs. VR sensors, and can't seem to find if one would definitively work better for my application. Any input?