Downhill project motorcycle transmission

Ecobogan said:
Mate if that's the only problem then this thing is nearly ready to ride. The chain and sprockets are #25 kart gear at 13/57 good for 30+ hp

Nice work!

You prolly mean 219 cart chain, its good stuff but the high power on a cart is via rpm or the speed of the chain, we are often running more strain than them and the best chains can do about 1000kg -motor itself drives it to 550kg and what you see is from the shock loads/wear etc that happened often over a single weekend.

Try design for 22/96 -same ratio and you will get over 10 times the chain life, i get over 4 months now from that change alone and the longest lasting on dirt are cz o-ring chains.

 
You're right I meant #35 pitch which, as you'd know, is different to 219. This I could only get in set lengths which is why I opted for the 35, and it's slightly heavier duty? Used on hire karts and light buggies I believe.
Some more news.........the motor, controller and throttle just turned up this morning Yeah hah then.
It fits to perfection in the crank case area, will be tight to get all fixings worked out but is doable just need so e case milling.
Pics on that coming directly
Xxx
 
So I got the chain tensioner and idler looking like something tonight. The swingarm needs to be taken out some more for better clearance but it swings through the travel just fine with decent tension. It may need a guide of some description to prevent chain jumpage but we'll see.
Fitting the motor to the cases will happen on the morrow
 

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Doing some backyard milling with something that isn't a mill......chain drilling. Slow and wildly inaccurate but in this particular case it doesn't matter too much, just removing material then cleaning up with a flap wheel on the die grinder. Mounting hole have been drilled through the cases
 

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Looking good so far.
Was wondering if you could do away with the cycle gears and attach pedals and cranks to the engine gearbox using the kick start shaft assembly (some modification needed) :D
 
Maybe I could mate but it's running over time and budget as it is. The closest to changing the cycle gears would be to convert to single speed to save unsprung weight but I'll get it running first. The kickstart part of the cases has been removed and it wouldn't be the place to drive the cranks from anyway, this could get complicated!! It is a pity to double up on the driveline, you're right but this is how she'll stay for the minute. Cheers bloke!
 
Looks good.

When you wire up the motor, remember, the wire pairs are not 1-2, 3-4, 5-6. Wire #1 is paired with wire #6, then wire #2 and #3 are paired and wires #4 and #5 are paired (for Delta).

Matt
 
Thanks Matt, there may be some very small questions when I finally wire it up. Will start off in wye, or star as we seem to call it, until I get a wye/delta switch sorted. Thanks mate and got your PM too, all fine.
 
Rustled up all the bearings and seals today to re condition the gearbox, here she is. The whole ensemble with motor weighs in at about 4.5kg. Next onto the case covers, pressing the clutch gear together, turning the motor drive adapter and that bloody countershaft sprocket
 

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Ecobogan, this is similar to what I would like to do. May I ask some questions?

Do you know the weight of the total unit?
Have you used it yet, did it work, and what about downshifts?

Thanks,

SHiFT
 
No worries. The weight will be nudging 5 kg all told. I haven't run it as yet but it will downshift like any dirt bike. A smaller ie 60-65 cc box would be preferable just finding one was tricky which is why I went for a more common 80. As mentioned some advantages of this set up is that it will handle power increases down the track and ease of water cooling. Am keen to see it going myself
 
Any progress? I'm considering something similar using an aprilia rs125 bottom end as the sprocket drive is on the opposite side. :D
 
A bit of progress, made the countershaft sprocket the other night and pressed the gear that is driven by the motor together also. Going to install the swingarm tensioners and start on the rear brake this weekend. Going to run a 250mm YZ 450 front disc on the back, bolted to and set inwards from the rear sprocket (same stud pattern) the sprocket is about 180mm so the caliper will just clear.
Running an RS125 bottom end will certainly work but even an 80 like mine is on the porky side, a 50-65 would be the go. The RS will have a nice wide ratio box though and a right side drive will obviously allow using the stock rear brake. You won't be running pedals? And will the rear cassette ratchet hub be up for 9+kw bursts if that's what you're planning? Running it off the left is the beefiest option.
I opted for leaving the pedal driveline as is to retain some vague connection to the trek once being a bicycle.
 
From experiance, a freewheel hub will not hold 8kw. Mine (shimano zee 12mm axle DH hub) exploded after about 15h of riding (broken pawls, bearings and FW body)
Nice job on that box ECOBOGAN, I would love to have a ligthweigth 2-3 speed box..
 
One option could be the old Yamaha Mini Enduro 60 or the MX/Enduro 80 from the early to late seventies. Two strokes and four gears.
 
We'll it seems my dirty old bathroom scales have been leading me up the lightweight path. I thought it felt heavy for 4.5kg and the dirty old kitchen scales are telling me she's nudging nearly 7kg, yes you told me so. This will make the bike around the 25kg mark sans batteries and about 33kg with 1150wh's of lipo.
I'm going to do some extensive drilling to shed some weight and there are many places where a few hundred grams could be lost. Still way lighter than a Stealth bomber with more kw!
Currently getting the adapter boss turned up which attaches the drive gear to the motor shaft and seals off the water cooling housing from the oil in the box. Might be ready this week.
On the '70's two stroke motors. I couldn't track down a KTM 65 bottom end for anywhere near a reasonable price and I looked into a few old school 50's and 60's. The wrecker man who lives,breathes and shits these things told me that most jap 50's and 60's share the same bottom ends as the same year 80's. Worth a thought.
 
More pics on the rear brake. Had this YZ450 front brake rotor machined down from 3mm to 1.8mm to fit the Hayes caliper. This was actually quite an easy and almost bolt up solution and only 250mm to clear the sprocket,obviously.
The chain tensioner is a bit of a piss ant little thing that might need revisiting down the track but she's ready to go on.
 

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Ecobogan said:
On the '70's two stroke motors. I couldn't track down a KTM 65 bottom end for anywhere near a reasonable price and I looked into a few old school 50's and 60's. The wrecker man who lives,breathes and shits these things told me that most jap 50's and 60's share the same bottom ends as the same year 80's. Worth a thought.
The cheap chinese dirt bikes might be an option for a cheap bottom end. They would likely be bad quality but its possible they'll handle a good amount of power.
 
Picked up the gear drive boss yesterday as the assembly continues.
Just a quick one, anyone have any charger recommendations? Initially I'll be running 10 ah that being four 22v 5ah lipo's. Obviously something that'll charged as fast as the c rating will allow. These batteries will be 1 c I'm pretty sure. Thinking a Hyperion 1440i or Thunder 1220 or maybe not. Not sure yet
 
I use a Meanwell RSP-1000-48 with a Watt's up meter as a charge display. I set mine at 50.15 volts. It will charge at 1,200 watts. This setup is around $300 depending on the price of the power supply (I scout e-Bay for them).

Most modern Lipos will handle 2C charge rate without any issues at all. I charge my 3 year old lips at 2C, no problem. My wife's 10ah pack gets charged at 24 amps without an issue.

Matt
 
No, still very dead. I did however roll around the yard and do some bouncing of the suspension if that counts. There was a bit of mucking about getting a thread cut onto the astro's case hardened shaft, all sorted out now though. I couldn't get to the machinist's in time so it's all still in his shop ready to roll.... Literally!
What's left(watts left) man I'm funny, is to now fix the mounting plate that the astro bolts to onto the gearbox case I need the gear adapter boss screwed to the motor shaft to centre it in the bearing before tapping any holes. This probably doesn't make massive amounts of sense but will when I get it back and post photos. Also have to shorten the gear lever so the cranks clear it. The cranks actually clear the cases by about 4 microns which is shitloads.
Later on today I'll be mounting the controller and throttle black box and getting my head around the wiring connections etc. how much airflow do these castle creations controllers need? I'd like to mount it in the triangle just above the rare shock mount. Ok airflow there but not as good as on the lower down tube where it'll surely get pounded by rocks and crud.
On the charger...getting my hands on a mean well 48v 1000w is proving tricky, new here they're going out the door for a mega $560. Think I might go for a ready to roll thunder power for $230. Also going to order as many 6s 5ah lipo's as I can afford next week.bike is looking good and hits the scales at 27kg. Give me a week or two, then she will be alive. Oh yes she will
 
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