In frame Predator fricton drive build

Here's what I came up with for exhaust system. Still need to work on clamps some, and paint it.

Has a nice mellow tone, much quiter than the stock muffler, Has a nice motorbike sound.

I tried it without the muffler and it was LOUD but beautiful. Runs WAY better too, I saw 40 MPH rather quickly. Wind it up good and let off and get that funky statacco sound.




Don't wanna bug the neighbors or cops, so I put the muffler back on.

Better try a test hole with that hole saw. My experience sometimes they make the hole oversized. You can dress the OD of the teeth by lightly turning the bit against the side of bench grinder wheel and testing again.

If yer drilling aluminum, the bits gonna clog with aluminum, you have to stop frequently and knock the buildup off with a screwdriver.

The best thing i have found to prevent aluminum buildup and cool the bit is plain ole Windex, works incredibly well .

OK, Now that the exhaust is behind me, I could hear the noisy rockers real good, so I decided to check them.

The exhaust rocker was way loose. There is a compresson release bump in this cam, just before TDC and that is where the valve clearance was set by some chinaman.

I wanted quiet so I set the valves to the very minimun noted in the engine manual.

It was then very hard to start. The compression bump was kicking in too much, ang there wan't quite enough compresson for easy reliable starts.

So I re-set them to the max recomended in the manual, and now it starts easily again.

I don't fell comfortable with cams with bumps near tdc on compresson stroke. I feel like it's gotta reduce performance some. If I ever have it out, Im gonna take it down some.

The valve adjustment hardware is very sturdy and well machined. Takes a 14mm and 10mm wrenches

Yes, I plan on adding a guard and other refinements after I finish tweaking things. Haven't had any trouble with pantsleg, though it is hazardous without a guard.

My engine runs very smooth with very little vibration at any rpm. I wouldn't bother with rubber in the mount.

Ok, here's an update on the Predator in frame fricton drive. I have over 100 miles on the odometer now. No problems at all. no noticable tire wear. very smooth and quiet. Did I say Fast? Seen a scary 38 mph many times. NO MESSY, FUSSY CHAIN LOL, Luvs to cruise 30-35 mph

This concept works well , the large dia roller is way more efficent than the usual small dia ones. And these lil motors just look right with the cyl foreward.

I am going to change it some by adding my freshly made 3.5 " knurled roller and a Maxtorque clutch on the engine, instead of the 3" clutch/roller on the jackshaft now. Here's my new roller.

Hi all, I've done some more r&d with the In frame fricton drive.
I installed the 3.5" knurled roller and a 4" jackshaft pulley. The roller is depressed into the tire 3/16".
I decided to try a manual belt clutch with a cable operated idler before I forked out the bux for a Maxtorque bearing clutch. I would be more in touch with roller slippage this way too. There is WAY less pedaling drag with the belt clutch and large roller than with the bushing clutch that I removed.

When I got it running, it was raining, so I got to try out wet performance.
The roller hardly slipped at all at first. but after about 10 miles, and the fresh burrs of the knurls wore down, i could detect a little slippage when i hit wet spots while accellerating.

Had no trouble pulling the steepest hills wet, didn't have to be too carefull with the throttle, with the efficency of the large roller.

Was geared a little tall, it still wanted to do about 38, but had trouble taking off from a dead stop. Lotta belt squealing while slipping it for speed enough to completely engage it without getting jerky power pulses or killing the engine.

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Still need to tweak it some . A slightly wider belt, and maybe a 4.5" pulley to drop the revs some to cruise at 30mph.

This drive train is very quiet. Never realised how much noise a chain makes.

I think that the larger rollers is the secret to a good, efficent fricton drive that doesn"t slip much or wear the tires so fast.
I can't wait to try a grinding wheel. With the large OD that equals less slippage, it may not wear the tires too bad dry, and grab real good wet.
Tires are cheap and easy anyways.

Dry use should be awesome with the 3.5" steel knurled roller though.

Sorry about the random spacing of the pix, :~)

I forgot to mention something that baffeled me a while.

All the threaded holes around the pto are 5/16" SAE fine thread. All else is metric. Took me several trips to hdw store to figure it out LOL. Go figure.

I went with the large roller for performance and efficency, not for gearing.
I am using the cheap pullies for now . They don't explode, they crack at thr keyway sometimes from the engine pulses. I think EZM, Stanton and others have used them successfully.
I am now using a 5" pulley on the jackshaft. It tops out at about 32mph. With the 4" pulley and the 3.5 roller it topped out at 38 mph.
Think I will try a 4.5" pulley to get a comfortable cruise rpm at 30mph

.My engine is not the 79cc It's the 99cc version



I had to severly modify the air filter adaptor to make it work. I bored out the inside some on the lathe, and shaved off about 1/4" from the face, to make it thinner so the original carb studs would be long enough.

Then I sawed notches from the stud holes of the adaptor so it would straddle the studs.

I had to ust flangeless nuts to bolt it on instead of thr original flanged ones. The flange nuts interfere with the air filter's socket.

I had to notch the rubber stop flange inside the airfilter a little , filled the adaptor notches with RTV. After curing, I clamped the filter on.

The exhaust pipe is 3/4" conduit. I packed the original exhaust manifold with sand and angle iron scraps on each end and used a torch to heat and bend it about 10 more deg. Also took some 3/8 rod with rounded and bent ends, and heated the manifold and worked some of the flatness out of the manifold bend ,from the inside.

I then sawed off the flange, and used a bench grinder, dial calipers and file to round and dress the manifold to fit snugly inside the conduit.
A standard 1/2" hotdog muffler fits snugly in the pipe, held on with a crossdrilled hole and a wire pin.

I have been looking at grinding wheels listed on E-bay. Never knew that there was so many types and sizes.
I'm lookin for a 2" wide by 3.5 dia. might use something narrower and stack them.

Hey RC, Thanks for the reply and the muffler ideas.

There's not that much power loss with the muffler, got more power than needed anyway. But that strait pipe sure sounds good.

I have an Kubota belt on there now. it rides way down in the pullies. A Napa belt will ride at the top edge of the pullies. Prolly take more abuse than the narrower belt too.

An adjustable roller in in the works, with a jackscrew and knob for control. just gotta work out the details.