A "REAL" Frankenbuggy

[roysheepdog]

That gives you time to think about every thing,that helpes it come together better in the end a lot of times.

[SYCARMS]

So very true for when we rush to get something done in a hurry mistakes and miscalculations are made. Some times a break in action is the best thing for it gives you time to maybe realise the great idea you have is not so great at all and the origional plan changes. Nice video by the way.

[roysheepdog]

Originally Posted by SYCARMS

So very true for when we rush to get something done in a hurry mistakes and miscalculations are made. Some times a break in action is the best thing for it gives you time to maybe realise the great idea you have is not so great at all and the origional plan changes. Nice video by the way.

My vid.?If so thanks.

[metalstudman1]

This project just got revived with something I got for a small trade last month. I just built a new swing-arm and added a YFM350 off a dead/rusted 91 Yamaha Warrior. Kids just learned how to drive a stick shift and it's proving to be a great project even though it's been setting for so many years and had 4 different engine & swing-arm designs. Pic's and vid's coming soon!

[SYCARMS]

Well low and behold your back!!!

[metalstudman1]

Still enjoying the kids playing in the dirt! Of course I splurge and play too. Here's a glimpse of the Franken buggy in action as my daughter learns how to use a clutch.

[metalstudman1]

Here's some muddy pic's of the newest power-plant and golfcart rack-n-pinion I added since the other rack was for a front steer. Had to add a clutch pedal back in it only a lot beefier.

[metalstudman1]

If anyone is interested- Kid's driving the Franken-buggie and NOT using the clutch to down shift slung the chain so hard it punched a hole in the block of the YFM 350. Thank god it was at the top of the sprocket area about the size of a dime. I don't have any argon right now so I went to Harbor Freight and bought some of there low heat aluminum rods and plugged the hole with my Mapps gas torch. I works as advertised, I tested it prior to the repair on 2 small pieces of sheet aluminum and I couldn't beat it apart. Hopefully I'll get to try out the repair Sunday as we have rain tomorrow.

[metalstudman1]

The repair to the block seems to be holding all it's done is rain, so I decided to move the axle closer to the body-as it turns out all I got was 2" but every inch shorter makes for a tighter turn. I also added some well needed axle spacers and changed out the rotor & caliper as the other one one was aluminum and showing some strange wear. Hopefully tomorrow will be dry and not freezing and I'll get the kid's to give it a beating. Also stepped up to a 44 tooth sprocket from a 39 to help the new clutch operators not burn up the clutch so easily, of course it'll be slower but that's not an issue for us.

[metalstudman1]

Figured I better put up a vid of it in action with the Yamaha Warrior motor:
https://youtu.be/4BqxmjmjRFQ

https://youtu.be/ts33qMIUBE0
We only enjoyed this power plant for a couple of months before a friend of friend came over to play in the dirt on his 4-wheeler. After seeing it in action he handed me $500. for me to pull the motor out to put in one of his toys, I couldn't say "NO" since this engine didn't cost me much.

I have a back-up plan- I have a decent running '79 Kawasaki KZ750 (vertical 2 cylinder), I owned 2 of these back in the 70's and they're solid, reliable HP with strong transmissions. So in the near future you'll be seeing my daughter master the clutch/shifting action with something that has a lot more grunt!
I'll be posting pic's of the KZ750 install soon for anyone that cares to view.

[metalstudman1]

The saga continues

Finally got to get the Franken-buggy back in the shop.I'm taking this CHEAP Craig's list bike(79 'KZ750twin) & giving it another pair of shoes to wear! It's about 50+ hp & 40+ ft.lbs. of torque @ 3,000rpm ,redlines around 7,000+(perfect for a kart IMO).Started last week pulling the motor & fabricating the swingarm for it to rest on.Made some motor mounts,calculated the space needed and realized I could set my Polaris transmission(off a 325 Magnum 2WD) kinda beside the motor by turning it around backwards as I don't think it knows the difference from forward to reverse. This gained about 4"+ of savings in length,it also put the sprocket beside the motor instead of under.Made the slot big enough for a 60+tooth sprocket(starting with a 45t or 8:1 ratio). I managed to get this buggy back to 8' long again by doing this.I then made a transmission/rear engine mount plate with slots for chain adjustments.I'm thinking it should adjust both chains with one movement(I hope).

[metalstudman1]

After reworking the axle position,sprocket location I added re-enforcement sleeves thru the swingarm to hold it in place as solid as I can make it.Made the upper-rear engine/tranny removable mount.Motor has 3 attachment points & tranny has 3 points on it's plate & 3 to the swingarm plate-I'm hoping that's enough!Got the removable shock mount tube in to know where to run the mufflers.I started working on the exhaust piping. The pipe that came with it were rotten on the bottom so I butchered up some other header pipes to make it work.Made everything clear for easy working on the motor.By the way- this motor is HEAVY (174lbs.)I had to use my winch with an overhead pulley to set it.I lucked up as it passed thru my rollcage with 1/2" of clearance. Thinking I'll wrap the pipes later to cover up the stitched pipe work. Got this set of mufflers for $20. w/ a box of other misc. bike parts(bike unknown)

[metalstudman1]

Now let's see if I can get it to run again! Cleaned the carb's, checked the timing(static setting),temp. wired the coil/points and........IT RUNS All good things end. It ran on choke only and would barely rev up w/back firing.Now to trouble shoot- points look OK but condensor is weak (based off volt meter) coil is weak too(I have spares that will work). Ordered a set of points & condenser($35.- way cheaper than a vintage CDI) but will take 2 weeks to get here(bought NOS OEM parts). Then magic happens A friend calls this morning and asks me to get my dolley out to my driveway.He just picked up a 82' KZ750 (4 cylinder) and needs me to unload it here! in the box of parts w/the motor is a set of dual points & condensers.I managed to make a set for mine & fired it up till my order gets here. Still not running right but I'm closer to getting it right. Smoke from the exhaust is probably from me stitching the pipes together & who knows what kind of issues they had from their previous engines.Got to check the transmissions-they work as they should. Still have a lot of little things to do before I can take it for a test run. Crossing my fingers it'll DRIVE out of my buildingin a couple of weeks purring like a kitten.

https://www.youtube.com/watch?v=-yeMvU8mHhw

[SYCARMS]

Gonna be a beast.

[BuggyMaster]

Spectacular! Can’t wait to see it running around!

[metalstudman1]

I got to test drive it on the street ,the only break in the every other day rain,way too muddy to drive on my track especially if it didn't survive the test! No video-no one here to take it for me. It ran for about a 1/4 mile before popping & backfiring when above 3,000rpm,then lost forward (kept jumping out of gear). Had to back up to get it home.First off-44T sprocket is WAY TOO low,got the new points in and seems to be working good & I'm real close on the timing-but didn't solve the popping/backfire issue. One spark plug lean the other rich that's why I'm convinced it's a carb. issue(ordered a complete rebuild kit). Changed the sprocket to a 39T (it's what I have), got the carb's going thru the sonic cleaner again-had to drill out 2 of the jets(previous owners stripped them). Got the shifter adjusted properly for forward.It has a low frequency vibration, so I'm searching for any lose body/chassis parts! So now I wait again for small parts!
If the carb's fix the problem then this motor may stay in it since it has more than enough power/bottom end torque for our needs and I'll finally strip it down soon(warmer days) for a well needed paint job.Hopefully a video soon

[metalstudman1]

It was quite a wait on the carb kit, but quick since it came from Taiwan during a pandemic! The carb kit definitely improved the performance- well worth $13. I'm letting it warm up outside to get my wife to catch a video of it running around our track before it rains again. I know it's still geared way too low just by seeing this video. At least it runs well now-
https://youtu.be/1c7VuCJV4m4

[metalstudman1]

Finally got someone to video a short test run so you can see it does function.I got my wish-I drove it out of the shop & back into the shop and it runs pretty good too! Now to go have some fun in the trails while it's dry.
https://youtu.be/qq1Jgeh2TKo

[SYCARMS]

Kinda looks like a Joyner trooper in the front. Looks and sounds great.

[metalstudman1]

Tom- Thanx-I've never seen a Joyner Trooper in real life to know what it looks like!
Played most of Superbowl Sunday & today as it was mostly rain free-I did snap a chain but grabbed some more used chain and went at it again
I ordered some new #530 & #520 chain w/extra master links now that I know it's viable. Must have a bad valve guide seal/seat as it smokes on the passenger side- but the plug is burning clean/tan,so I can't complain too much for the price,it still runs great. Trying to narrow down the vibrations/rattles-I should have expected rattles as it's all riveted metal body panels. It turns really tight again with the shortening of the wheelbase.I'm going to source out some larger/taller rear wheels/tires to try and get some more top end speed before sprocket changing again, I'm guessing it only goes about 35-40mph. I can easily climb our steep hill (50-60 degrees for 70') in 3rd gear. Right now with the 22" tires I have a 14"+ ground clearance-I guess a couple more inches up won't hurt the center of gravity since it's almost 60" wide. The rear mono shock is too stiff-so some adjusting is needed.Amazing how much light the inexpensive ($21.)4" LED lights put out with very little amp draw- I drove for a couple hours this evening. More video coming as the weather improves & I can get some one to shoot it.
I figured out what the exhaust came off of-"Honda V65" if anyone is interested.
More thrashing on my part to absolutely confirm this power plant & tranny combo is a keeper.

[metalstudman1]

Update- I wrecked the Frankenbuggy last week . I ran over a large piece of quartz that slashed the drivers front tires side wall-it went down immediately and I hit a tree @ about 25-30mph.The impact broke the steering tab off the Polaris strut housing & bent the fender-took almost 2 hrs. to get it home with no steering.Only had it out about 10 times with all the rain, it's been a true FUN-MACHINE . I'll get it fixed soon (waiting on a deal I made on a Polaris 250 Trail blazer chassis to be completed) With warmer/dryer days ahead I'm looking forward to getting some more video for those who care to see it.

[metalstudman1]

Got the strut housing replaced- in the near future I'm going to beef up the A-arm design to provide better protection from impacts. Hopefully I can get some more video before it get's wrecked again!

[metalstudman1]

Well that didn't last long I went to play and trashed the tranny-now we know that a used Polaris 325 gearbox can't handle 80+ hp very long.Possibly a new gearbox would go the distance. This gearbox was WELL used when I got it, then is was coupled to a 400cc motor for awhile and then this motor giving it a serious workout. I'll give some thought to a repair or modification I can afford to resolve the issue.

[BuggyMaster]

I wonder if the trans in a 500 or 700 or something is stronger?

[metalstudman1]

Unfortunately The bigger & newer Polaris ATV's use shaft drives & are much bigger units. I'm going to pull this unit & tear it down to find the issue.It could be just a simple bearing failure. It appears these units could tolerate a lot more HP than recommended as I've repaired/tore down a few, the gears are similar to ones in a car/truck manual transmission and considerably heavier duty than a motorcycle transmission. I'm currently looking for a newer/less hours unit to buy- if anyone has one let me know (older 2WD 250-325 units are the right configuration & chain drives).

[SYCARMS]

You need one out of a Scrambler 500.

[metalstudman1]

I'll check into that- Thanx Tom

[metalstudman1]

I checked out the Scrambler tranny spec's- it's almost the same as the one I'm using! I'm thinking I stripped the lugs on the F/R sliding gear changer (internal).Still have to pull it out & tear it down to confirm.

[SYCARMS]

The gentleman who built the Jolaris I now own said he had a like new 250 325 gearbox but decided on the 500 gearbox after researching and finding it was a heavier duty gearbox and I don't remember if the 250-325 gearbox has hi/low mine is a hi/low.

[metalstudman1]

That's the kind of info I need! My gearbox's don't have High/Low. I do have one that does but don't remember what it came out of-I do know there is a difference in how the F/R change-mine have 3 lugs that interlock like a lovejoy connector without the damping rubbers (I'm thinking I sheared the lugs off)) the other gear case has a star/cloverleaf type gear that goes inside the drive gear. The star/cloverleaf shaped version definitely appears more durable as there's a lot more engagement material to interlock. That's the only difference I've found in the gear cases as the drive gears are about the same in size & thickness. The bearings do interchange!. I'm still searching for a replacement tranny/gearcase.

[SYCARMS]

I would go with the scrambler 500 HO gear box. The guy who built this buggy has really driven it and now I have it and the gear box has been flawless. I have yet to use low gear and he told me he only used it 2-3 times. Now the engine has been bored and stroked to a 610cc @ 65HP on dyno.

[metalstudman1]

Here's an update-
As it turns out the tranny is fine, the adapter for the sprocket to driven shaft broke/sheared. I managed to grind too much material off the end of the sprocket creating a very thin weld.I didn't weld the back side off the sprocket to the shaft so it simply sheared the thin weld and sounded like a stripped gear.I did split the tranny and it's perfect-so it appears that this type transmission is suitable for 50+/- HP. Since I have a mini-lathe now I made a new shaft with a matching tooth sprocket on the motor. I test drove it and it's working like it should.