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bravenrace
bravenrace PowerDork
6/25/12 7:39 a.m.

Part one - Putting a chain drive bike engine on an off road kart. The current engine and rear axle mount to a swing arm frame just behind the seats. This has caused problems for the engine when driving the kart aggressively on rough terrain, as the engine sees all the shock loading that the tires do.
So I'd like to mount the engine rigidly to the frame and then fab up an IRS for the rear, or short of that, use a swing arm just for the axle.
The latter idea I know how to do. But I've seen rear diffs with half shafts on other off road vehicles and Formula SAE cars. I just don't know where they come from. Is there a GRM way of doing this, possibly by buying a used piece of RV equipment to use parts from, or??? The engine will have about 60hp and 5 gears.

Part Two - After reading posts here (damn you!), I now have this urge to build the bike that the engine is on now instead of doing the kart. It's a Honda CB650 Four. It's in bad shape, but the engine does run. Seems like a good bike to strip down to bare bones just to have some kicks. If I did this, I also have a Yamaha 400 2 cylinder engine that I could then put on the kart, or I could get another engine altogether.
So have at it. What should I do, and how should I do it?

44Dwarf
44Dwarf SuperDork
6/25/12 7:56 a.m.

Why not mount engine sideways add drive shaft coupler on counter-shaft instead of a sprocket then use short drive shaft to some IRS say Subaru unit. There plentifully and should hold up just fine heck their even LSD unit out there.

http://hawkmachine.com/

bravenrace
bravenrace PowerDork
6/25/12 8:39 a.m.

I've considered that also. Are there any factors to consider when looking at mounting an air cooled inline 4 in a fore-aft position? Cooling? Carburetion?
Are there standard ways of adding a drive shaft coupler, and what exactly do you define as a drive shaft coupler? A u-joint yoke?
And I assume you are talking about a rear diff out of a Subaru car?
I like this idea in general, but could use any more details you or anyone could provide.

fasted58
fasted58 UltraDork
6/25/12 9:35 a.m.

paging Kevlarcorolla

Grtechguy
Grtechguy PowerDork
6/25/12 10:04 a.m.

check these guys out: http://www.xtc-motorsports.com/mini.htm

(I went to H.S. with their son).

This minibuggy is a motorcycle engined device with IRS. incredibly quick and nimble

44Dwarf
44Dwarf SuperDork
6/25/12 10:57 a.m.

Well you'd need to duct air to flow over the cooling fins. In Dwarfs when i ran a air /oil cooled motor we'd normally jet the Cly against the fire wall one size (2.5 or 5 depending on how big the stock jet was) bigger so if it had say a 135 we'd toss in a 137.5 or a 140 as 2.5 are not alway available. Standard drive shaft coupler replaces the sprocket and has Spicer PTO/Ranger 4 bolt pattern for a slip yoke like in a 4x4 truck.

http://hawkmachine.com/Parts.htm#20 one up from the bottom.

Yes rear dif out of a Subaru should be easily and cheaply sourced i believe 3:90 and 4:10 were available in the early days i have no idea what is out there now for ratios.

Woody
Woody UltimaDork
6/25/12 12:17 p.m.

When I had the old Formula Ford chassis that I was thinking about dropping a bike engine into, I found a crapton of cheap used ATV rears on eBay.

BAMF
BAMF Reader
6/25/12 12:36 p.m.
bravenrace wrote: I've considered that also. Are there any factors to consider when looking at mounting an air cooled inline 4 in a fore-aft position? Cooling?

You'd almost certainly need a duct/shroud of some kind, and a cooling fan of some sort (maybe just an electric one for low speed & idling) to accompany it would also be wise.

eebasist
eebasist Reader
6/26/12 10:07 a.m.

www.minibuggy.net has a ton of good info. Remember that you will need to compensate for the increase in diff ratios as you go add a diff to an existing engine....you may find you can only do 30mph

sobe_death
sobe_death Reader
6/26/12 3:31 p.m.

4 wheeler diff, anyone?

Do you need differential action, or will a spool work? We used one from a Polaris outlaw for our Mini Baja that worked quite well. You wouldn't even have to convert it to shaft drive.

bravenrace
bravenrace PowerDork
6/26/12 7:14 p.m.

Hey, I like that idea! What kind of power were you putting through it? Do you think it would handle 60hp? Know any good sources (other than the usual) for used ATV parts?

sobe_death
sobe_death Reader
6/27/12 5:10 a.m.

We were running a 10hp Briggs through a gear reduction box, but the Outlaw uses a 52hp single. Don't know about sources for parts though, as we had a factory sponsor supplying us with the parts and we had fabricated our own trailing arm suspension for it.

bravenrace
bravenrace PowerDork
6/27/12 5:41 a.m.

In reply to sobe_death:

Thanks. The problem I see with running a driveshaft is packaging. I'd have to extend the wheelbase more than I'd like, and shift linkage would be just a little more complicated. The chain drive would also allow me easier drive ratio changes. Craigs list here I come....

bravenrace
bravenrace PowerDork
6/28/12 10:14 a.m.

Man, I've been scouring CL and Ebay for any kind of chain drive diff, and haven't come up with anything. Anyone have any suggestions?
Seems like most ATV's use shaft drive and aren't IRS. Is this correct? I don't know much about them.

sobe_death
sobe_death Reader
6/28/12 4:13 p.m.

Yeah, many will use a shaft drive. Many are also not IRS, aside from the big "utility style" 4-wheelers.

I wonder if there is an ATV-equivalent to car-part.com?

RXBeetle
RXBeetle Reader
6/30/12 9:20 p.m.

Honda Foreman Rubicon cam and pawl diff. It's tiny, simple, light cheap and it just takes a couple sleeves with confines for some lip seals to allow it to run out in the open. We ran 75 hp to some hoosiers with one on our FSAE car with no issues other than the digital operation, open to full lock can be a bit unnerving. The diff cups are rzeppa style so you can make your own custom length axles by sleeving the ATV axles for low power applications or have some custom axles splined up (not cheap) http://i22.photobucket.com/albums/b309/duwem/DrivetrainSmall.jpg http://www.powersportsplus.com/parts/detail/honda/HP-42400-HN0-671.html?gclid=CKbi67-097ACFYcBQAodjyd1Fg

bravenrace
bravenrace PowerDork
7/2/12 5:55 a.m.

Okay, so looking at the link you posted, what does that include, and what do I need to add? Is that a complete diff? Chain drive?
I don't think I really need a diff (versus a spool), but it wouldn't hurt either as long as it was limited slip. My only real motivation for using IRS is to keep the engine mounted to the main frame of the machine versus the swing arm. I suppose I could also achieve that with a solid axle, but it seems like it would be more complicated, possibly more troublesome, and maybe not worth the effort.

Woody
Woody UltimaDork
7/2/12 7:40 a.m.

Here's what I would do:

I would find a derelict Honda ATV to use for parts. Then I would park the two side by side for a visual comparison. At this point, I would most likely come to the conclusion that I'd probably be better off just fixing up the Honda and abandoning the other idea altogether.

I'm not suggesting that this is the way you should approach the problem, but I suspect that this is the way it would happen in my garage.

fasted58
fasted58 UltraDork
7/2/12 8:07 a.m.

Chain driven diff, lsd or drive tube (spool) can be done. D/SR guys been doin' this forever. Lotta fab and machine work tho w/ chassis mods, adapting diff, axles, hub carriers, suspension links etc. Sounds like it'd be a good project.

bravenrace
bravenrace PowerDork
7/2/12 9:25 a.m.

In reply to fasted58:

D/SR?

fasted58
fasted58 UltraDork
7/2/12 11:43 a.m.

D Sports Racer

you'd be looking at building like this: diff or lsd w/ sprocket flange, carrier brgs, disc brake flanges, cv drive flanges etc

bravenrace
bravenrace PowerDork
7/2/12 12:44 p.m.

In reply to fasted58:

Thanks. Where do you find these kinds of parts?

motomoron
motomoron Dork
7/2/12 2:52 p.m.

Sports Racer Diffs

Quaife makes a helical, torque-sensing diff in a configuration for chain drive cars. I've got one in my Radical. They're reliable and work very well, and they cost a freakin' fortune. $1300 for a bare diff, I believe.

bravenrace
bravenrace PowerDork
7/2/12 3:44 p.m.

In reply to motomoron:

Yikes! The Honda diff is sounding better and better.

bravenrace
bravenrace PowerDork
7/2/12 3:45 p.m.
Woody wrote: Here's what I would do: I would find a derelict Honda ATV to use for parts. Then I would park the two side by side for a visual comparison. At this point, I would most likely come to the conclusion that I'd probably be better off just fixing up the Honda and abandoning the other idea altogether. I'm not suggesting that this is the way you should approach the problem, but I suspect that this is the way it would happen in my garage.

Would be my approach also if I wanted an ATV, but I want a fast off road kart.

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