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Alternitive Power - Honda 750CC Bike Motor

3K views 31 replies 17 participants last post by  joe_and_jeep 
#1 ·
I was thinking about building a lightweight trailrunner. I have a 750CC Honda street bike motor. 79HP and 13,500 RPM. More than a Sami :D So I figured a Geo Tracker might be a good candidate considering I have a 95 Tracker with a blown motor. Gonna do a lot of weight reduction. Run minimal lift and 31/32s and use it more of a trail go-kart. Something to jump and beat on.

Any ideas on how to hook the bike motor to a car/truck manual trans? I have a 4speed out of a 47 Dodge 1 ton with a healthy granny low and a 1:1 4th gear and I was gonna run that to a divorced NP231 or a NP208. I can make a driveshaft to the t-case easily. Chevy case's are 27spline so I can use a D30/35 axle shaft or an output shaft.

So how would I run the bike motor to the trans? I need to run a regular trans so I have a reverse gear.
 
#4 ·
Yes it can be done and I am planing one. What I would suggest is using a motercycle engine with a shaft out put to a divorced TC not chain. If you do use the chain style you can use a gear box out of a brush hog to change the rotation. Also I would scrape the tracker and go full tube it will makine it much lighter and lower CG. Remember the high rpms gearing is your freind.
 
#5 ·
I'm not too greatly concerned about torque. 13,500 RPM will make up for torque. And I can shift thru the Bike's gears.

Yea, it has a gear box on it.

Yes it can be done and I am planing one. What I would suggest is using a motercycle engine with a shaft out put to a divorced TC not chain. If you do use the chain style you can use a gear box out of a brush hog to change the rotation. Also I would scrape the tracker and go full tube it will makine it much lighter and lower CG. Remember the high rpms gearing is your freind.
I dont have a shaft drive bike engine. I wanna try to get a way to use a chain drive bike motor. That way when I get some extra cash I have more options for a motor swap. Like a GSXR1000 motor.

I was thinking of making a jack-shaft but I think that would offset the motor too much.
 
#7 ·
Rock Ape said:
How about a u joint mount off of the output shaft(where the front sprocket mounts)thats how a legends car is.But then go to a sammy t-case!!!!
like this!!!
http://store.600racing.com/site/pro...7&dept_id=622E1E39-B0D0-791A-65B23BFDCCF3BDC3
That looks like a good idea. I gotta get ahold of them so I can find out if it will fit my motor. I would go straight to the t-case but I am picky and want reverse. So I am gonna go to a 4speed trans and have extra gear reduction if needed plus reverse.
 
#8 ·
Remember most of the gearing of the bike is in the chain and gears. I would run a chain to a box that will put a 90 degree the the direction of the power. this way you could even stack gears like on a drill press and have diferent ratios going in to the tranny. What I am using is the axles tranny and TC from a cherokee and running 35 BFG MTs.

A few thing to keep in mind. There is no way to mount a aultinater, power stering pump,OBA, OBW ect. to the engine. Even if you want to run a couple of high out put lights it will realy tax the charging system and forget a winch. the only way around that I can see is to use a second motor for those to run a altinater and the power sterring pump. I am using a motor off a BIG old chain saw that way if your main engine dies you keep all of your power acceseries. Also remember the motercycle was not ment to be in water so water profing is a must.
 
#9 ·
Remember most of the gearing of the bike is in the chain and gears. I would run a chain to a box that will put a 90 degree the the direction of the power. this way you could even stack gears like on a drill press and have diferent ratios going in to the tranny.
I'm gonna run the yoke adapter to a divorced 4speed trans. I'll have 1st - 5th gear in the bike, 1st - 4th gear in the trans and Hi/Lo in the T-Case. I figure I should have a rediculous low range and a high range too high and everywhere in the middle. Roughly 40 forward gear choices. I'll run a cable shifter to the bike.

A few thing to keep in mind. There is no way to mount a aultinater, power stering pump,OBA, OBW ect. to the engine. Even if you want to run a couple of high out put lights it will realy tax the charging system and forget a winch. the only way around that I can see is to use a second motor for those to run a altinater and the power sterring pump. I am using a motor off a BIG old chain saw that way if your main engine dies you keep all of your power acceseries. Also remember the motercycle was not ment to be in water so water profing is a must.
I'm gonna run a manual steering box. Not too concerned about OBA/OBW. I should have enough power to run adequate lighting. Just run 2 taillights and 2 small headlights. This is not gonna be my main trail rig. I have a YJ that I use for club runs. I want to build this more of a toy. To fawk off with. Use it on the stocker trails. And I have most of these parts in the backyard.

I've ridden the donor bike in some pretty big rainstorms, I'm definately gonna waterproof it better. Maybe run the air intake a little higher.
 
#10 · (Edited)
http://www.pirate4x4.com/forum/attachment.php?attachmentid=213690&stc=1&d=1131385589
this is from a guy in norway. Motorcycle engine with a short driveshaft running an alternator with the diff welded in the FWD tranny t give reverse and a large selection of gears. http://www.pirate4x4.com/forum/showthread.php?t=334588 here is the whole thread. the little sucker seems to move if you watch the videos of it. And it shows a way to mount a regular alternator to run lights and charge a normal size battery. And BTW motorcycle can get wet just fine, I rode my old one through lots of rain and a couple creeks without issues.
 
#11 ·
Turn the motrocycle engine in there sideways and run a chain of the sprocket on the transmission onto one mounted in between your frame rails and then run two driveshafts off of the larger sprocket. I did something like this with little front wheel drive honda engine. I mounted it midengine, turned it sideways and ran two driveshafts of the transaxle and eliminated the need for a transfer case...I don't know if you could do the bike engine that way...but it seems like the most logical idea to me...
 
#12 ·
this has been done..I have seen it (but not seen it wheel:( )

if nobody here chimes in (I am sure sombody knows him - he's from back east somwhere)

I know someone who knows someone.

you can use a 6:1 in the sammi case too..

the one I saw ran a hydropump off of one of the shafts he made (I think it was the tranny input shaft right where the sprocket adapted on)

anyways he ran a orbital off of that..

this guy had a sammi on stretch (slightly) chassis and 33's

dang I wish I knew more..

I think this has alot of potential
 
#15 ·
If you intend on using an automotive transmission, you won't be able to direct drive from the output on the bike motor. You'll need to reverse the rotation between the bike output and trans input. If you drive the T-case directly from the bikes tranny this isn't an issue...but you're still going to want another reduction I'd think.

But lack of reverse would be the suck in that case.
 
#16 ·
Well it works quite well for Einar in the norway thread. I dont see why It wouldnt work here. Just turn the motor or tranny to where it turns the right way. mid engine rear engine or front engine. flip the motor& tranny 180 degrees and itll essentially change the direction it rotates the axles.
 
#20 ·
In the UK theres a big movement to put Bike engines in kit cars. Usually Lotus 7 derived 2 seaters, with 1, or maybe 2 Bike motors(sometimes 2 GSXR1300 Hayabusa motors, 320 bhp....4x4)
Anyway, the bike clutches and transmissions cope fine with the abuse, and several companies make a little gearbox that sits in line with a prop from the bike engine and another prop to the rear diff. This box has foreward and reverse gears in it, and I believe Ive seen ont that had 2 ratios foreward, and also reverse.
The only major probs so far have been oil starvation, since a bike sump aint that deep, can be helped with baffles/winged sumps etc.

Google bike engined kit cars and you'll turn up some info.
 
#21 ·
With the skills some of the people here have, I wouldnt put it past them to be able to make a nice deep sump to hold extra oil with baffles so that it will not starve for oil. And bike engine will take quite a bit of lean and angles especially a sport engine. They lean way over and then get pretty good ammount of angle with the front wheel off. And with the egine turned to run into the tranny itll be sitting to where the most extreme angle will be like its just leaning into a sharp corner.
 
#23 ·
Rat_ranger said:
With the skills some of the people here have, I wouldnt put it past them to be able to make a nice deep sump to hold extra oil with baffles so that it will not starve for oil. And bike engine will take quite a bit of lean and angles especially a sport engine. They lean way over and then get pretty good ammount of angle with the front wheel off. And with the egine turned to run into the tranny itll be sitting to where the most extreme angle will be like its just leaning into a sharp corner.
Depending on the motor some old honda 750s were drysump, and I'm guessing by the HP figures he's not talking about the older SOHC air cooled 750 motor...so its probably a wet sump.

A drysump motor would be great for off-camber situations.
 
#24 · (Edited)
There are aftermarket clutch baskets. If you go with a Suzuki Hyabusa (1300cc) there is the potential for near 200hp and there are lots of after market parts. If you choose a 2000 or earlier motor, you should be able to pick one up fairly cheep. If you try to get a 2002 or newer you will be fighting the SCCA crowd for the motor. We are getting about 185hp from a dry sumped 2005 GSXR1000 motor with 8” slicks. The fuel injection really helps take care of the clutch as you can ease into motion. With a smaller contact patch and lots of gearing, the clutch should be ok. If you get serious, I’ll look up who is making our clutch baskets and the dry sump system.

 
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