Archive for 2013
Variator Weights and CVT issues - Part II
This is an update of this post: 1986 Yamaha XC125 Riva - Variator Weights and CVT issues
So I took everything apart and found this:
Notice the tear in the rubber: no good. Essentially, the primary sheave housing, which incorporates the weights I was hoping to replace, had burst at the seams. Taking it apart revealed that a few plastic sliders, which allow a plate to be pushed in and out by the weights inside the assembly, had burst into little pieces and torn the rubber seal. The seal is there because there is an unusually large amount of grease housed inside the sheave. Apparently, Yamaha is the only manufacturer that uses this type of 'wet' assembly, where all other manufacturers use a dry assembly.
Kahuna Powersports has recently decided to no longer be a Yamaha dealer, and so my neighbourhood parts supplier had suddenly become Snowcity Cycle Marine, which is much further away from me. Either way, I ordered my sliders from them, and the primary sheave cap was ordered from a kind gentleman (peteyb5) off of the Riva Riders forums. It was serendipitous, because we had been communicating regarding other parts, and he had listed off a few things that he had in stock, but I had no use for at the time. The light bulb went off in my head when I saw the torn sheave cap, and surely enough, he had mentioned that very part. He was kind of enough to sell and ship to me from the States at a considerable discount.
The grease that is packed into the sheave is something from Yamaha, known as Ultramatic grease. No one knows exactly what it is, but most people have good luck with other high-temp, waterproof greases. I opted for the Lucas X-tra Heavy Duty Grease, which met those requirements, for repacking.
I'm happy to say, that after receiving all the necessary parts, I've reassembled the scoot's variator with new weights, grease and cap, and then installed the new belt. The scooter is on its 350th kilometer right now with the new setup, and it's running great.
In all honesty, the top speed still isn't what it used to be, and I'll chock it up to engine wear at this point. When I have more leisure time on my hands (not to mention more disposable income), I'll keep the scoot alive by boring out the cylinder head and purchasing the OEM oversize piston and piston ring set. That'll liven everything up.
At this point, keeping the Riva alive has become a hobby on its own, and it's no longer about the necessity of transport. I want to keep her going, maybe to one day give it to my little sister.
crockTweet now also controls my 'Flower Pot Smoker' project.
A few posts ago, I described my attempt at building a PID controller for my Crock Pot to try my hand at Sous Vide cooking. It worked great, and in the process I made a PID controller that is an entirely separate unit and thus amenable to any later projects.
There's this excellent smoker on the market called the Big Green Egg, which is as expense as it is awesome. Its expense is enough for me to seek an alternative, which I found in Alton Brown's flower pot smoker, and some detailed instructions provided by another blogger. Two large 16" pots, a single burner and a day later I came up with this:
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| Single Salton portable burner, which I modified by removing the hotplate and dremelling the outer perimeter to fit the base of the pot. |
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| The burner itself then fit nicely into the base of the pot, which itself was seated into the burner's base. A single bolt which held the burner in place was extended to hold the whole thing together. |
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| Here are the holes I measured out and drilled in the pot to accommodate the burner's leads. The entire assembly is otherwise in tact and plugs directly into my crockTweet PID box, seen here on the right. |
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| Here is the whole thing assembled. The temperature probe is inserted at the top, and measures the dome temperature. crockTweet PID regulates the whole setup to reach and maintain my preset temperature for the duration of the time I set it for. |
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| Smoked sausages! |
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| Whole chicken before. |
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| Whole smoked chicken after. |
1986 Yamaha XC125 Riva - Variator Weights and CVT issues
So the little green scooter is starting to show its age. It's nearing 30 years old with ~35,000km on the road: a critical mileage where a lot of parts need to be attended to. I've noticed that although my acceleration has been steady, the top speed of my scoot has decreased drastically. In previous years, I was able to get up to 95kmph, but now I'm happy to see the speedometer creep past 79kmph.
A little bit of quality control shows that the weights are manufactured quite well, and they should fit the bill nicely. We would expect 6 x 9gram weights to weigh in at 54 grams. I used a sensitive scale and indeed: six of them weighed in at 54.0670 grams. The height tended to be slightly larger than 12mm and the width slightly less than 18mm, but we're talking 10ths of a mm here: not an issue.
A little research has shown that there are typically two culprits for this type of issue. Aside from regular engine wear, the scooter's continuously variable transmission has a few parts that require replacement to improve performance. A lot of how this nifty transmission system works can be found at this excellent forum post: "CVT Principles - How it works, how to improve it."
Essentially the belt and variator weights need to be replaced. The principles of how they operate can be seen here:
As the weights wear and are no longer their appropriate weight, they can't push the clutch housing to its highest position, therefore preventing the belt from reaching its highest gear and reaching its top speed. The belt itself is also worn enough that it can no longer achieve this.
Easy enough, replace the belt and the weights and we're all set, right? Except that the scooter is almost 30 years old. And as you can see on the Riva Riders Yahoo Group, there's a lot of discussion about the dwindling state of parts available for these great machines.
The weights in the XC125 from '86 to '01 measure 18x12mm and weigh 9.5grams. I found suitable aftermarket replacement at Chinese Motorcycle Parts Online (part RW147) where they carry 18x12mm 9gram weights. Slightly lighter weights will still sacrifice top speed for acceleration, but these will still substantially improve my top speed over the worn out weights I currently use. The weights are shipped from the UK, and I received them here in Canada within a week of ordering them.
The belt that I need to replace is a Yamaha part number 50W-17641-00-00. The OEM belts are available, but retail for $150 here in Canada from Yamaha dealers. Too much for a simple v-belt. There is an aftermarket supply for these belts through the Gates Worldwide, a belt manufacturer. They run the Gates' Boost Belt Programme which lists part number 9802-21205 as the direct replacement for the Yamaha part number. It costs 20 Euro (~30CAD)! Gates hasn't been helpful when I called and emailed them numerous times to obtain more information and see if I can order it from them. I found a dealer in Madrid, Spain, who has been trying to sell me the belt, but requires me to wire him the money, something that costs as much as the shipping and part together. Other options are being pursued.
The other issue is that there are not standard belt measurements available for this part. Most of the measurements are hearsay and unconfirmed. The other issue is that aftermarket manufacturers who list sizes (length, width and angle of belt) tend to list these figures in a non-standardized way. It's not conducive to finding an appropriate replacement. The hearsay numbers for the Yamaha OEM belt floating around are that it is 940mmx19mmx9.5mm with a 28 degree V. Again, this is unconfirmed. Dayco in Australia produces belts that are of a similar size (part 8231K), but it is unknown if this actually fits, as it does not cross-reference with the Yamaha part number, but instead is listed for a SYM HD200. Dayco has been kind enough to offer sending me a sample so I may test it out. We'll see what happens.
Updates to come!
@crockTweet: Programmable Arduino-Powered PID Sous Vide Slow Cooker
I purchased a very simple slow cooker ($20 at duty free!) a few months ago, which has four settings: High, Low, Keep Warm, and Off.
Most dishes prepared in the slow cooker will cook from 4-8 hours, depending on the setting used. There are a few issues though:
- There is no true control of the cooking temperature.
- There is no automated way to switch from one setting to another (e.g. 8-hours of cooking on 'High' followed by 3-hours of 'Keep Warm').
Some more advanced models of slow cookers allow for automated switching of settings, but have no way of notifying me of these things.
Enter Arduino: an electronics prototyping system that allows the user to interface with the real world through sensors and react to this information based on scenarios coded onto the board through a programming interface.
In the case of the slow cooker, I wanted to use the Arduino to allow me to:
- Detect and control the temperature inside the slow cooker based on preset values.
- Control the amount of time the slow cooker spends at a selected temperature.
- Allow for a multi-step cooking (e.g. 8-hours of cooking on 'High', 4-hours of 'Low', 2-hours of 'Keep Warm').
- Tweet the progress (e.g. When the a new process starts or finishes).
I made a quick video of my progress as of last week:
I just finished coding everything, and I theoretically have the ability to do everything I want, except for Tweeting (still waiting for the network interface to arrive in the mail). The nice thing is that this system will work with any slow cooker, as it required no modification of the slow-cooker itself. I will be controlling its on/off state through a solid-state relay controlled by the Arduino, thereby controlling its temperature.
I will be testing everything out tomorrow morning.
Here's my Arduino code:
There is still tuning of the PID parameters to do once I hook everything up, but once that's done, I will post more.
Currently the list of items required for the project (aside from the slow cooker):
- Arduino UNO Board
- LCD 20x2 Display
- DS18B20 Temperature Sensor
- 20K POT
- SPST Buttons
- Breadboard
- Assorted Resistors
- Assorted Wires
Stuff to read about:
