A rebuild to trail running Heathkit Hilltopper...

#1
Over the last three yeas I've been rebuilding a Heathkit Hilltopper solely for riding in my mountains,not for show.
From a rolling frame to operational has been an interesting journey that while it was fun to do it had very frustrating times as well.
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I bought it here in the desert of NM where rust is not an issue,however dry rot is. I had no engine as the original had seized up and was thrown away by the original owner!
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While I wanted to put an 8 HP engine on the mini,none would fit without cutting the frame. 6 HP Briggs or Tecumseh engines are not to be found here in NM.
I did have a non-running 5 HP Tecumseh engine that I spent many a week end rebuilding and installing onto the Hilltopper frame. While the engine ran very well, it was gutless at my 7,000-10,000 foot ASL riding area. The only thing the engine torque through the centrifugal clutch
did do is destroy the original rear tire. The sidewalls were so badly cracked the tire had to be replaced.
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Both brakes were worn off the shoes completely.Both head and tail lights were smashed beyond repair. The front forks had to be rebuilt and the rear shocks were in bad shape and needed welding. I did photo essays on most of these repairs.
Even with all the mechanical and electrical repairs needed the rear tire replacement was the hardest to complete. The original tire size is no longer made in 4-ply. Only 2-ply which will not hold up where I ride. Many times I will be miles away from the trailer riding in the mountains with no cell service. Not a place to deal with a flat or blown tire.
I found a tire that was a true 4-ply and made for off-road running on a Quad. Getting it to my home was a real task as the delivery driver kept stealing the tires being sent. I was able to video the "delivery" and the driver was fired and I finely got my tire delivered.
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With the advice from a couple of members here I was able to mount a 7" wide tire on an 8" wide rim. I was very leery of doing this but as it worked out, the tire is rock solid ( pun intended) on the trails I ride on. Not a hint of slipping. Traction is 1st rate over rocks,boulders,rotten granite and sand/mud.
I put on a Greyhound 6.5 HP engine and tricked it out a little for high altitude riding and added an alternator to run my new head light and LED tail light.
I also installed a torque converter which really allows the rider to control power to the rear wheel much smoother than the centrifugal clutch did.
The handlebars were supposed to fold,which hadn't for many decades. Carbon steel bolts had be used in the aluminum castings and corroded badly. I found a fellow who had the original "wing-nut" type bolts and they work very well.
I did have to make and install a heat shield for the exhaust. Since the original Tecumseh exhaust was at a different angle than the Greyhound engine,burning my left calf was a problem. After five minutes of riding the heat was unbearable. Now it is no longer a problem.
The Heathkit Hilltopper rides the trails again and for the last year of so has racked up some serious mileage climbing the mountain trails. The ride is very comfortable with my only complaint that the foot pegs are too far back and too low to the ground. I did put some "Easy-Rider pegs" on the front crash guards but, they change the center of gravity where it can be dangerous on some trails.
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It has been an interesting three years or so. But I have to tell you I really like this mini bike on my trails.
 

mustangfrank

Well-Known Member
#2
Dig it, a Hilltopper is on my bucket list.

Surprised an 8-10hp Tecumseh HM engine wouldn't fit, every bike I've had that ran an H50 could take an HM.
 
#4
I could not get the 8 HP engine to clear the jack-shaft with the intake and exhaust manifolds. My engine would have to be lifted and hits the upper frame tubing. I tried for a long time to shoe-horn it in.
The Greyhound engine is putting out 7 HP now and will pull the mini up to 30 MPH on a flat road. A plus is I'm getting great gas mileage with the Greyhound engine. With one gallon of gas I can ride off road 30 miles which I have done.
 

mustangfrank

Well-Known Member
#5
I could not get the 8 HP engine to clear the jack-shaft with the intake and exhaust manifolds. My engine would have to be lifted and hits the upper frame tubing. I tried for a long time to shoe-horn it in.
The Greyhound engine is putting out 7 HP now and will pull the mini up to 30 MPH on a flat road. A plus is I'm getting great gas mileage with the Greyhound engine. With one gallon of gas I can ride off road 30 miles which I have done.
That makes sense, I had to switch to the Power Sport carb mount (direct to intake port) to clear on a similar jackshaft frame. That long low sideways carb intake most of the HMs had takes up too much space.
 

copyman

Well-Known Member
#6
Great build. Nice job. Most of my experience is with the Hilltopper. They are "adult" size bikes. Have two, one is 99% correct the other 80%. Both original rebuilt engines. Heathkits are very rare bike and looked for over a year for parts. Finally found the original white button kill switch to make the one bike 99% correct, it would be 100% but has a new throttle cable.

I just bought a Heathkit Boonie bike so going to be selling one of the Hilltoppers. Not sure which one I will sell at this point.
 

toomanytoys

Well-Known Member
#7
I want to do a tillotson hilltoppper build! The old H50 runs great but my coleman build runs away from it all over. Its definitely not as punchy or powerful. But there is something to he said for the sound of a tecumseh plugging down the road!

Those sunf power 2 are an amazing tire for a minibike! I am in love with the set of my coleman. They have so much traction it turned it into a whole different animal off road.

The almost correct one I have is too nice to jack around with. One just popped up on Craigslist for a grand but I'm not paying that much

This is mine after 9 years of work (obviously not constant just do a little and then walk away for a year lol). Bought off of a member here in 2011. It was complete only needed restored to its former glory. And the price was more than reasonable.

My dad rides it just about daily. It's one of the few bikes he can ride with his back problems.

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#8
That is really nice. mine has been "rattle-canned" black,but I ride the bike hard so the nice gold paint would be all scratched-up by now.
I like how they ran the gas line to the engine.
 

toomanytoys

Well-Known Member
#9
That is really nice. mine has been "rattle-canned" black,but I ride the bike hard so the nice gold paint would be all scratched-up by now.
I like how they ran the gas line to the engine.
Dad puts around the back roads and pavement. Not sure with him mostly using it but I doubt it's seen a trail since it was completed last year.

That's how the build manual shows the fuel line going. Should be the original H50 on it. Has the lighting coil and all.
 
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