Donor Gearboxes

[husaberg]

for joining the cranks
this is the Harley Aemacchi 250RR they had a 350 version at 74HP, not sure what the 500 crank looked like.
note how they joined the cranks.

[el chupacabra]

That’s pretty simple. I’ve seen something very similar on a speedway setup for 2x Cr250s mated together.

The only difference is that mine also shares a gear as part of the coupling. I think a press fit should be ok and I’ll probably use a tool like this to remove it, like the ones you use to take the roller bearings off a KTM crank.

[husaberg]

Hi what are the pics of? the speedway cr250x2?

here is the yankee 500 made out of 2x 250cc Ossa's by Ossa usa or something.

[el chupacabra]

Pretty much exactly what I’m doing minus the huge chain and it’ll spin the other way. I wonder how reliable the setup was.

[Grumph]

Pretty much exactly what I’m doing minus the huge chain and it’ll spin the other way. I wonder how reliable the setup was.

Pretty sure the dirt version did several 3 day trials and may even have done a 6 day. Good way to test how tough it was.

[el chupacabra]

We will see how it goes. on another note I am about to add a front engine mount, does anyone have any thought on through bolts vs threading the engine on each side individually?

I'm always a little worried about inducing stress into a trellis chassis via tightening the engine mounts. I think one side will have a fixed spacer and the other will use an expanding spacer like a Yamaha R6. So the frame doesn't squeeze onto the engine. I can't help but think 6 steps ahead of where I currently am.

[Grumph]

Not keen at all on engine mounts threaded into cases. Not good practise IMO. Far too much chance of fretting and cracking IMO.

[jato]

Being a bike designed to race - reliability closely followed by light weight . you can design a subtle amount of flex into the hangers for the top engine mounts. robust "doweling" of the cases is assisted by all those main bearings so i'm sure you wont have CB 900 troubles.

[el chupacabra]

Here's what I've come up with, 10mm straight through, directly in-between the main studs.


Also does anyone have any engine weights on hand for comparison?

So far the Crankcases (17.811kg) and Cassette (1.32Kg) weigh a combined 19.1Kg without cylinders/pistons/cranks and I know the gearbox weighs about 6.5Kg minus the clutch.

[jato]

hmmm that through bolt with its washers and nut is just on .25 kg . versus 60grams for a pair of 35mm m10x1,25 into helicoils,

[el chupacabra]

I'm not too sure if you're being sarcastic or not haha. An RG500 is apparently 55kg and an RGV250 is around 32kg. Hopefully I land somewhere in between there.

[jato]

Just weighed my TZ 250 (L spec) engine 27.1 kg (no carbs or ignition stator) around 70hp . if you were to add 6kg for another pair of cranks and another 3kg for cylinders (it already has a layshaft) then you could say just under 40kg would be ok but 35kg should be achievable being your engine has 85cc parts.

[husaberg]

i have one if you want to see it in the flesh but they are a disposable item on any BMW ask at a specialist and they will find one for you'

I found a rather interesting variable speed electric water pump.
I even have a couple here now thanks to a benefactor
Its used on all manner of BMW's as the primary water pump.

The specs are 2kgs and 125 liters /minute.


It needs a controller to operate in variable speed mode but I am pretty sure something could be bodged up with a 555 circuit and a piggy back. Or an Arduino circuit.
http://www.nomad.ee/micros/pwm555.html

or
https://www.maximintegrated.com/en/a...ex.mvp/id/3530
http://www.reichelt.de/ICs-MAX-1000-...40&LANGUAGE=EN



http://www.tecomotive.com/download/manual_tinyCWA.pdf
The manual for this controller gives out the important specs

if you go to the original post you will see the the pics.

[husaberg]

I've started chipping away at the design again and I am contemplating whether to integrate the lay shaft into the cassette plate or not and what bearing i should use on the clutch side, ball bearing or cylindrical roller. . .
I am thinking with the lay shaft I will have a single key way for each gear and it will be secured with a single nut on each. The shaft is looking fairly chunky, but I don't want it to flex. Any feedback on keeping the lay shaft separate or integrated would be welcome.

Also I'm thinking long and hard about how to install said shaft as it won't pass straight into the cases. The only way I can see it working is if the non clutch side of the shaft bearing is installed last, maybe I can put it in a small housing like this.

Attachment 353065Attachment 353066Attachment 353067

had you considered inserting the cassette from the countershaft side a lot of bikes did this. it simplifies the casting as well.


also in there is the patton version 1 joiner

[husaberg]

if you were going to make the gears and couplers would it be easier to just maker the center of a flying web. You mentioned a flying web early on.
Still use the rest of the parts?


Like the JBB