Speedometer max for my Yamaha

[ScubaCap]

Here is my design idea!
I am the owner of a Yamaha YZ motorcycle. This is a dirt bike (for those who do not know) and I use it for enduro trail rides, cross country etc. This means that half of the bike is full of mud and the other half is still inside mud J

I want to make an electronic km counter with the following features
-km counter
-rpm counter (the engine is a 2 stroke engine)
-max speed log
-distance counter
-time keeping with memories

I want to use a PIC and a nice 128X64 graphic display with blue pixels.

The hard work is the speed pickup. It must be very durable, absolutely water proof, it must be able to absorb hard vibrations and always keep in mind that it will work in mud.

I have come up with an idea using a magnetic pickup (like the bicycles) with a permanent magnet attached to the wheel and a magnetic pickup attached somewhere on the rear.

[kam]

Welcome to the club ScubaCap!
I also have a motorcycle, not that dirty but I do some trail rides. It is a Yamaha TTR 600.
Once I was thinking of an electronic km meter. I came up  with the following idea. A magnetic or capacitance pickup attached to the back side of the suspension, near the wheel center, from the break side (right side). The break disc will be changed with a self made break disc. This disc will have 6 or 8 holes concentric holes right at the position that during a whole turn of the wheel, the pickup will be able to get all 8 holes.
This is a very good and quite precise method that you can test. Capacitance pickups are made in various dimensions and sizes and can be very easily protected from mud and water as they do not really need to have any mechanical contact with the subject. I know that they are used in various applications for ships so they must be very reliable and vibration proof. I do not have really test it but I believe it will do the job.

[ScubaCap]

Kam this is a very good idea but why not using the permanent magnet instead?
I have seen it on bicycles and they work very good. And I mean mountain bikes, not road.

[kam]

Well scuba, there are some very serious reasons that it will not work. First of all, the new bicycles are for sure made to go very fast but hey, it’s just a bicycle. So the counters are made to have good reading from 0 to 100 (!!!!!! What a bicycle) kms for example. You need to have good readings over 160Km (or maybe more)
Then it is the magnet pickup. It is just a lousy metallic contact that the magnet will actuate if it is near by it. But if you get it on your hands and start moving it very fast left and right, you will get some speed readings that are caused from the vibrations. Thus, if you put it on your bike and ride on road with stones, you may get a reading like 300km/h ! This will not be true of course.
To increase the quality of readings, you need to split the wheel to as many points as possible. Using one magnet, you divide the circle by 1. Using 2, you divide it by two, getting a better reading. But because you have to do with mechanical contacts, you cannot have many magnets (for better accuracy) because if you run fast and you have for example 3 magnets, the contacts will not have time to go from on to off and then back on as the wheel will rotate really fast on 80 or 100 or 120km/h. So, no accuracy.
Finally, I must admit that I have test it on my bike and, man, is it a failure or what! On road you may get some readings up to 100km/p. Up to 120-130 you have a great error (according to another bike that was riding near by me). After 130Km/h this gadget pops! It shows 60, 100, 5, 200, 100 all numbers! Forget it.

[ScubaCap]

Wow so bad? Do I have to make mechanical parts my self?

[kam]

Good results require good design. Poor design leads to poor results. 

[Erkeli]

Wow so bad? Do I have to make mechanical parts my self?

Hey not yourself. Try a machinery with lathe or something. 

[kostas]

And this makes the design more interesting. You must think of everything and also mechanical parts.

I love it. Drawing 2D's for the metalwork lathe! If you need any help i may help you if i can.

[kam]

Actually it is not that hard.

The holes and diameters for a disk break is standard. You will need to measure nothing. You will just ask someone to make a disk break (with the appropriate material of course). If he is a bike custom maker, he will know the numbers for making a good disk. Let him decide as he may know better. You will only ask him to drill or cut 6 or 8 holes or slots in the middle of the disk for your capacitance pickup.

I checked some of them and found that they can switch up to 500 Hz and that's far more than you need. Also they can have great accuracy and hopefully they can be absolutely water/mud proof. I think you have a solution here! 

[ScubaCap]

It looks like it's gonna cost more than i expected but it's gonna be also better than i expected!

Well Kam! I am not really that good to mechanics. Which TTR do you have? The TTR600 that i know (2002 and up) have exactly the same wheel center back with my YZ.
You can recognize it by a ring that has to align the transmission gear on the back left side with the front gear. This spacer ring (that is unique) is about 4mm thickness and internal diameter same as gear and external like 8mm bigger. Is this same?
If it is, i think that we will have the same disc break also. If you could give me some help and some ideas i would appreciate it.

Also, how can we add a photo? I click on image but i only get some img tags. Where can i upload an image?

[kam]

An image. You cannot actually upload an image to PCB Heaven. I do not have any space yet for image uploading and i yet do not know if there will be any in the future. The img tag that appears presupposes that you have an image somewhere on the net an image upload. Then you can put the URL of the image and it will appear here.

You can upload an image for example on a free space server and use the url provided to show it here

[ScubaCap]

Kam is this the rear tire of your bike?

[tpone]

    lol   

What kind of tire is that! 

[kam]

Yes it looks like the rear of my bike. It might be absolutely the same.

[Mosquito]

As i see it can also measure these slots that exists on the break

Why not?