Suzuk-E

1987 Suzuki RM125 Conversion - Part 1 ...

Nov 2008

Notice: This page is image intensive and even longer than most on theworkshop.ca, so you may need to take an extended lunch-hour...

As you browse the three images below, you'll notice that it is an early 1980's Kawasaki KLT250 not an RM125 as the page title implies... The KLT was originally going to be the featured conversion project, but I just didn't care for it's ridability, beyond some minor work it was revived and was a viable machine that had enough value that I was able to parley it into the Suzuki (which is by far the superior conversion platform).

After draining the 2 year-old sludge laden fuel, dis-assembling and cleaning the carb & fuel-pump, the electrical harness to the ignition switch and starter line needed to be replaced.

The leaky head gasket was about to be replaced when the Suzuki became available...

Since this machine was running and the RM125 was missing it's head & cylinder the trade seemed like a fair deal to both of us...

What a fuckin' weapon!!!

The original Dirt-E bike (featured Nov/Dec 2007) has been an overwhelming success, and has found a new home with some close family friends, specifically their 13 year-old son that was the most enthusiastic test rider by far.

The Suzuk-E is a much taller bike with superior suspension, brakes and lighter construction, not to mention that the rubber front and back is near brand new.

It took a few months for life to settle down to the point that it could be rolled into the shop and start the conversion process.

This is one of the best parts of doing a project like this, dis-assembling a fairly good piece of machinery and getting a sense of how much thought went into it's original design, what parts you can leverage to your benefit, and what will need to be changed...

The original Dirt-E Bike did have some short comings, specifically low-end torque to climb some of the steeper hills around the farm, as well as needing a bit more top-end on flats where it was limited to 24km/h. 

To address these issues, the hope is to re-use the 6-speed transmission from the 125cc motor and install a slightly larger(1200Watts vs 750Watts) MY1020 permanent magnet DC motor. 

With the motor removed, it sat on the table for half a day as I freaked about taking it apart and screwing it up such that I couldn't put it back together.

Eventually I resolved to just rip into the job, but was re-assured by having found the exploded view diagrams of the transmission and casings.

The diagrams are listed below and were sourced from www.bikebandit.com , when ever I need diagrams or parts, Bike Bandit is my #1 source.

Here is the clutch-side of the casings with the basket and kick-start already removed.

This is what I wanted to avoid...

As the halves split apart, I heard several pieces fall off inside the casing before it was separated enough that I could see inside and their original positioning.

Note: for the RM series motors, remove the gear shifter, and bearing retainers on the clutch side of the casing...

Roll the casings on the out-put sprocket side and separate the casings with the clutch side facing-up and the entire internal drive train should remain assembled in the lower casing.

My sincere thanks to the entire Black Lodge Hunt camp, the Turners, and the Cruise's who so generously lost the sum of $114.90 in Canadian Tire money to me in poker over the year...

For international readers Canadian Tire is a retail institution in Canada, to the point that they actually have their own currency. Everybody has a pile of this paper rolled into a wad on a desk some where in their house as it takes years to accumulate enough to purchase anything substantial when the largest denomination is $2.00

Worse still is the stigmata that attaches to anybody that clogs a check-out line for 20 minutes as the clerk has to sift through $287.45 of the stuff dumped out of a grocery bag onto the counter while 3 of the 5 people in line have to have a piss in the worst possible way.

To that end, rather than developing an unhealthy and potentially ruinous gambling habit, our family and friends use CT as the denomination of choice.

This was a good year for me, and by extension theworkshop.ca as I picked up a nice set of metric sockets, a fresh bandsaw blade just to cut the casings and several other misc consumables that go into the projects featured on this site...

The new blade was like the proverbial "Hot Knife thru butter".

Note: there are a few alignment pegs that have to be removed and re-inserted to get the castings to lay flat on the bandsaw table, otherwise the casting will bind and possibly snap the blade...

Although this is a low-end 9" wood working bandsaw, with a fresh 14 tooth per inch blade it can cut non-ferrous metals of various thickness quite well provided that you don't apply too aggressive a feed rate.

With both case halves cut, cleaned and air blown of any metallic particles from the process, the drive train is re-assembled with the diagrams at hand as a reference.

There are 3 (three) shifter forks that are actuated by the slots machined into the shift barrel located below the drive train.

In this image I was able rotate the input shaft (clutch drive) through all six gears including neutral, while advancing the shifting barrel manually.

The images below are the full-size "GIF's" I used, right click and select "Save-As" or "Print" for a local copy, again these were sourced from www.bikebandit.com 

There is an inherent issue with the execution of the transmission on this project, in that it was originally designed to be bathed in oil with numerous passage ways to the "Wet-Clutch" that is now just open spacing.

For this phase I hope to be able to do the initial testing of the transmission and determine ratios, loads and speeds by simply spraying down the drive train with a spray type lithium or similar foam based lubricant via the access holes on the clutch side.

Ultimately the gear-box will be returned to it's intended configuration of an Oil-Bath but it will require fabricating a flat cover for the clutch-side, and closing-up the cavern that was created when the motor was cut away... 

To the right is the remains of the actual clutch basket, as it has been cut and drilled to accommodate a 38 tooth sprocket that will be driven by the MY1020 motor.

The 750Watt MY1020-Z3 motor featured in last years build was successfully re-wound and modified to handle 48V at 40Amps for 100's of Km's this past summer...

So the plan this year is to take the 1200 Watt Version and hop-it-up to handle 48V @ 75Amps peak, again through a full armature rewind, brush-plate upgrade and active cooling.

If this can be done, less electrical and mechanical losses, the motor will be hitting 2.4 to 3.6Kw of energy input or 3 1/4 to 4 3/4HP...

The masking tape applied to the rear wheel and input sprocket serve as relative indicators to determine the input to output ratios of the 6 gears available via the gear-box.

By advancing the input sprocket thru the range of gears and recording that value for a single revolution of the rear wheel the ratio's were recorded.

Initially I got side-tracked counting the teeth of the gears, number of splines the gears slid along and the mating gear it was meshing into, when it occurred to me that the Clutch-basket input and the rear wheel were really all that was important... 

Hopefully the chart below renders on your screen readably (1024 x 768 res if not)...

This is a copy of the spread sheet that I created to determine the primary drive sprocket size that will be mounted on the MY1020 motor. The equations on the sheet allow a single change of either sprocket size or wheel diameter and the associate speeds are updated (that's what spread sheets do best). No guarantee that the equations are correct (see Disclaimer)

Also of note is that the motor speed is only being calculated to a conservative 3,000 RPM, while the rewind will hopefully take it somewhere above 4,000 RPM and below "Grenade-Point" about 6,000 RPM...

The image to the left is the sprocket template for a 10 tooth sprocket per the calculations above.

As theworkshop.ca is located behind God's back and the very thought of leaving the farm puts me in a cold sweat, I've found that I can design and fabricate a simple mechanical fixture like a sprocket faster than it can be procured from an outside source at a fraction of the cost. 

Also as a side benefit each sprocket is easier and faster to make than the last one so project modifications don't seem like such a hassle...

(these are the types of skills that will be of value when the hoax of fiat currency is exposed as  the abstraction of reality that it is...)

The template is glued onto an appropriate piece of stock, each point is punched twice, first with a very sharp punch for accurate placement...

...and again with a slightly blunter punch to establish a good seat for the pilot holes.

All pilot holes are drilled with a sharp 1/8th" bit...

The chain roller "Hobbs" are drilled out to 1/32nd" larger than the roller dia. size for smooth and slop free movement.

The tops of the teeth are actually the lower portion of the exterior ring of 1/8th" holes.

The teeth are cut by eye with an angle grinder and the teeth are shaped on a bench grinder...

As inefficient and time consuming as the above may sound, from the moment I settled on the final tooth count to the part shown the left is about 3 hours, and I can just barely see what I'm doing... So once you have your templates made I would guess that most folks could crank out a sprocket in an hour or less.

This is the present motor mount and sprocket config affixed to the gear-box. 

Both the motor and the mount are all that is left of the electric recumbent trike project that was eventually scrapped out due to an inherently flawed frame design... 

I'm just glad I finally cut my losses on that project as it was a time-sink that knew no bounds.

The mount will likely have to be revised in the future as it lacks any chain tensioning provisions and is pretty crude for making fine adjustments for alignment.

As shown above the alignment was honed in by hanging a small 12V 7.5Ah battery directly off the motor leads and pushing it around until the chain ran true.

The cells shown here are sponsored by the Baran-Harper Group located in Markham Ont, a sincere thanks!

These are identical to the 17Ah Portalac's that were used in the Fortress 2000 and Dirt-E conversions.

The controller is a PicOx Ver 1.02C controller  that is tuned down to 20Amp current limiting and calibrated against an analog current meter in line with the motor.

The mains power is switched via a 35Amp switch and a manual pre-charge resistor (housed) in the black project box as well as a 30Amp thermal breaker incase there is smoke or something goes awry.

This is how the Suzuk-E sits for now...

The battery, controller, motor and PC  are finally all wired properly and I can slam the juice to the motor and rip through all 6 gears up & down without a clutch by just easing the throttle between transitions. 

There are some concerns about the over-all slop in the total drive-train (motor shaft to rear wheel), and the horrendous volume of the sound screaming off this set-up that will hopefully be addressed in the next installment.

Similarly the next steps are to install a speedometer onto the rear wheel, a tach onto the motor shaft and see how close the spread sheet above is to the measured No-Load reality.

Provided there are no show stoppers above, then it will be onto some frame cutting and battery mounting hardware.

And predictably this is the view out the back door of theworkshop.ca in the last week of November, so I see months ahead of me that can be spent bringing this project to it's fullest potential.

(Just added - a week after initial posting!!!)

theworkshop.ca has gone "Video", I say this like it's a big deal... But it has take 2 (two) years to do what most 14 year olds have been doing with their cell phones within minutes of receiving them...

The link below is to the progress of this project so far.

http://www.youtube.com/watch?v=L1mSELOrJTg

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