Would you all call this ridiculous??????

[kevin_sine]

I have this cx390 honda laying around collecting dust so I thought I would see if it fit's and.....it does.It has a tapered output shaft but I have access to a crankshaft grinder, a lathe,and a Bridgeport mill.If I could fit a tav this thing would haul some serious ass..

Any imput???????????????????????

 

[gbones]

maybe over kill? get a 5hp B&S, would look better "imo" and it would be cheaper. alot of work and parts would have to be done to get that beast running. but if you have the time and $$$, go for it. DO IT

 

[jeep2003]

Slightly rediculous. But if you think itll be workable id do it. I think id run a clutch to a jackshaft. Lately iv been thinking clutches are better than tc's

 

[gbones]

and not much leg room

 

[Harleys Papa]

Better put some wheelie bars on it

 

[kevin_sine]

I'll save the 13 horse for the next one i do.I have a decent 3.5 briggs that came with this mini but,by the time i fix it up I might as well buy a censure clone.

 

[Dave Morris]

Well, in my opinion it is ridiculous! But don't let that stop you. Its quite a handful.:smile:

 

[5 Horse Fan]

I'd call it "BIG RED":laugh::laugh::laugh:

 

[MikeBear]

Pay up your life insurance, and maybe add any extra disability insurance you may have! :scared: ut:

 

[Oldsalt]

You asked for input so here goes. The input is based upon the fact that you have a lathe and a Bridgeport.

1. It is not necessary to tear down the engine to turn down the tapered shaft to a size that will work for you. I've done this several times and it is easier than it sounds. Remove the fan shroud and what ever else is required so that the starter side of the crank can be chucked by a three jaw or 4 jaw chuck. Put a steady rest on the output shaft and with a capscrew in the threaded end of the shaft center drill it. Remove the steady rest and insert a live center. Remove the spark plug and ground the high tension wire. Immobilize the engine block so that it will not turn. Wire will work! Then machine the output shaft as desired. Use a rather slow RPM and protect the carb intake rrom chips.

2. Clamp the engine on the bed of your mill and useing a pair of vicegrips lock the shaft from turning. That isn't as difficult as it sounds; you can even use wire between the vicegrips and the mill bed or whatever works. A "DA", or simular collet extention will be necessary. Without the extention it's not possibe to reach down with the end mill and key the shaft without the mill's quill diameter interfearing with the engine block.

3. Put that bad boy in the mini! I would consider streaching the frame to get a longer wheel base so that it will have more room for the rear tire and it will not wheelie so easily.

I know a guy that is an experianced trials rider and owns a couple of GAS-GAS trials bikes. With a simular mini, that belonged to his friend, he jumped the throttle to do a wheelie down the block but it simply looped. Tore the heck out of the mini.

 

[george3]

I am sure you need a longer wheel base.

 

[kevin_sine]

You asked for input so here goes. The input is based upon the fact that you have a lathe and a Bridgeport.

1. It is not necessary to tear down the engine to turn down the tapered shaft to a size that will work for you. I've done this several times and it is easier than it sounds. Remove the fan shroud and what ever else is required so that the starter side of the crank can be chucked by a three jaw or 4 jaw chuck. Put a steady rest on the output shaft and with a capscrew in the threaded end of the shaft center drill it. Remove the steady rest and insert a live center. Remove the spark plug and ground the high tension wire. Immobilize the engine block so that it will not turn. Wire will work! Then machine the output shaft as desired. Use a rather slow RPM and protect the carb intake rrom chips.

2. Clamp the engine on the bed of your mill and useing a pair of vicegrips lock the shaft from turning. That isn't as difficult as it sounds; you can even use wire between the vicegrips and the mill bed or whatever works. A "DA", or simular collet extention will be necessary. Without the extention it's not possibe to reach down with the end mill and key the shaft without the mill's quill diameter interfearing with the engine block.

3. Put that bad boy in the mini! I would consider streaching the frame to get a longer wheel base so that it will have more room for the rear tire and it will not wheelie so easily.

I know a guy that is an experianced trials rider and owns a couple of GAS-GAS trials bikes. With a simular mini, that belonged to his friend, he jumped the throttle to do a wheelie down the block but it simply looped. Tore the heck out of the mini.

Great post,thank you.
Looks like I can buy the correct crank online for under $100 too.

 

[gpxsrxracer]

No TAV needed with that engine, it already has enough torque and hp to move that thing with any gearing you throw at it. Get a Noram Cheeta adjustable clutch(gold basket one) and hang on!

More is always better in my opinion so put that bad boy in and lean over the handlebars and hang on!

 

[Old Dinger]

Wow! That reminds me of the 800 pound guy stuck in his bed!:clap:
If it fits, you must commit.:thumbsup:

 

[cxbra]

Nice, too bad the frame is on the small side though.. I always think the big 390's are better suited to a kart (no wheelies, 2 driven wheels on a live axle). Not saying I dont want to see it done :thumbsup:, but your riding position will suffer. Maybe having bmx footpegs on the back axle would be a do-able position :shrug:.

 

[olajoe808]

judge for yourself

stock 6.5hp chinaman, tav db30 with 5.33 gearing. On a careless start up the bike will stand up and run away.

YouTube - DB riding

 

[Oldsalt]

Yes indeed. A 6.5 gives pleanty of performance! Mine is dead stock so I'll leave it that way because a grand daughtor is about ready to ride. But more and more I am starting to look around for a cheap abused db to hop up.

 

[65ShelbyClone]

It is not necessary to tear down the engine to turn down the tapered shaft to a size that will work for you. I've done this several times and it is easier than it sounds. Remove the fan shroud and what ever else is required so that the starter side of the crank can be chucked by a three jaw or 4 jaw chuck. Put a steady rest on the output shaft and with a capscrew in the threaded end of the shaft center drill it. Remove the steady rest and insert a live center. Remove the spark plug and ground the high tension wire. Immobilize the engine block so that it will not turn. Wire will work! Then machine the output shaft as desired. Use a rather slow RPM and protect the carb intake rrom chips.

I will admit that I haven't worked on a GX390, but it may be possible to pull the crank without removing the piston and rod. I think I remember being able to do that on a GX140 and a 1950s iron Briggs.

 

[DMR]

The 390 is not even worth it in my opinion, maybe for a novelty or for fun, but its not practical, Much rather put a hot flathead in it and save 30 lbs, but I guess if you have the engine just layin' around, go for it!:thumbsup:

 

[TeamCheap]

Just do it...........it can always be undone if you want.

I still want to see a MB with a 440 snowmobile engine stuffed in it.ut: