Sears Roper Trail Tamer rebuild

cfh

Well-Known Member
#1
A buddy of mine bought a 1970s Sears Roper/Trail Tamer project a while ago, and gave up on it. He bought it because it had the reciprocating motor/rear suspension thing. Also this particular model had front suspension and a Comet 20 torque converter with jackshaft. Also the remote mounted gas tank and disc brake set up. As far as Ropers go, probably as advance as they made. But the project got over his time allotment, and he wasn't going to get it done.

So I took on the project. The biggest problem with the bike was lack of wheels. He had some random 6" front wheel and a 5" rear wheel. They were not original, and I'm not even sure how they would even work. He kind of knew this too, and had bought a pair of Azusa 10" wheels for the bike. Some Ropers did come with 10" wheels, and I am partial to 10" wheel bikes too. So I thought I could make this work.

Another problem was the front suspension. The stock chrome springs were wasted, compressed to nearly nothing, and ready to break. So I used a new pair of standard front fork springs as available from OldMiniBikes (ordered with new cups.) They are longer then the originals, so had to re-mount the lower cups in a new position to make it work (and maintain geometry.)

Another thing I did was to move the rear shock mounts. On original Ropers the shocks are basically vertical. But with the 10" wheels (and the new rear disc brake setup), this was not going to work. So i did a more conventional shock mount position. It increased the swing arm angle a bit, but overall I liked how this looked. And it would enable me to use a DB30 doodlebug style rear disc brake set up a lot easier (more on that later... remember no original rear wheel, so no original rear wheel disc brake rotor.)

Here's the bike mocked up with the Azusa wheel, just to see how it would "sit":

 

cfh

Well-Known Member
#2
Unfortunately I didn't take a lot of pictures during this, so i will fill in with words best i can. Like I said above, the biggest fun was making the wheel hubs for rear sprocket and brake rotor. I like to use a DB30 rear disc brake set up, as those parts are readily available and inexpensive. And overall that brake set up works well. So I got the 60 tooth rear sprocket mounted with a newly made hub. And made a hub for the DB30 brake rotor. The only thing I had to do was mount the disc brake assembly itself to the swing arm. Not too bad, make some special mounts and welded it all up. Was pretty happy with how it worked.

I bought a china Comet20 torque converter and made a new jackshaft. That worked out pretty well. The gas tank had some holes in it, TIG welded them shut. Also was missing one of the tank mount bolts, so welded that up too.

I like my bikes to have fenders, so went through my pile of crap and found some fenders that would work. I did have the original rear fender mount bracket for the Roper, so that was good. The rear fender may be original. The front fender is definitely not (it's a broken in half Speedway fender that I welded back together!) Also made a front fender mount and welded that in place.

Was missing the rear "tail" metal that goes behind the seat. Interestingly Ropers use 1" pipe (instead of 7/8"). Got some 1" pipe and bent it up to make the rear tail assembly. Though originally not welded in place (bolted), I decided welding it was a better idea.

Here's the next level mock up...

 

cfh

Well-Known Member
#3
For the motor I decided to use a fresh snowblower-to-minibike converted Tecumseh HS50 engine in white. I wanted to use a slide carb for this, and a custom bent exhaust. The problem with the side carb is it sat down too low, almost hitting the jackshaft. To fix this, on the original intake manifold, I cut out about an inch, and re-welded the manifold back together. This worked out pretty well. I did have to make a custom cable for the throttle. I usually use a DB30 throttle assembly (work great with slide carbs.) But those only work on 7/8" handle bars, and this was 1". So used a vintage Cherry throttle and make a cable with custom cable end, to work with the slide carb.



On the exhaust I bought some 7/8" stainless steel .065" thick pipe, and custom bent it. Put a 1.5" harley style end on the pip too for a nice custom look.
 

cfh

Well-Known Member
#4
Powder coated the entire frame and gas tank. Note on powder coating gas tanks you have to do some work. Solder melts at about 375 degrees, and powder coating basically goes to that temperature. To compensate (so the tank doesn't fall apart), I tag TIG weld all the seams, so I can't come apart. This has worked well for me.

Also looking at the catalog pictures I could see the bike had original decals. Someone is selling nice decals on ebay, but they weren't quite what I was looking for. So i ended up making mine own. Though not really stock, they look pretty good over the red powder coat.

For the seat all the "usual suspects" were not interested in making it. So I made my own. It's no great creation, but it works well and looks decent. The wife helped out (could not have done it without her.)

Overall I'm pretty happy with how it turned out.



 

cfh

Well-Known Member
#5
By the way, if anyone know what year this bike might be, i would love to hear from ya. I'm guessing 1971? but the only Sear catalog I can find does not have a date.

 
#6
By the way, if anyone know what year this bike might be, i would love to hear from ya. I'm guessing 1971? but the only Sear catalog I can find does not have a date.

I owned the bike on the Left the 5 HP Tangerine Orange 2 Speed Roper, though they (we) (maybe just me ).... did not call them Roper's at the time. I bought it new with cash I had saved for over a year to buy. I think I bought that bike in May of 1969 or maybe 1970. I had it for 3 years or so? before buying a 1972 Suzuki TS90J on December 31st 1971.

That Mini Bike.................... THAT MINI BIKE was more fun when it ran. It was so unreliable at times. But I also did soooo much to it. I also had no understanding of what a 2 speed mini bike was like, but believed it was better that the TAV mini bikes at the time, because the TAV bikes always sounded like they were being " held back " I tore up, tore down, tried a solid instead of the 1speed overrunning sprag clutch sprocket. ( broke the welds on the solid sprocket in less that 10 min) and went back to the sprag clutch sprocket. Cleaned it, repaired it, and got it to work. It was fun though trying to ride it with 2nd speed only......... for a while.

That mini bike taught me a lot. I later went to trade school and came out with a Auto-Diesel - Welding certificate from Nashville Auto Diesel College (Now Lincoln Tech) in 1977 and went to work in the Louisana Oil Marine Propulsion and Oil Field Power generating. Including a stint as a RF Tech, still using the mechanic skills and troubleshooting, I am still turning wrenches and working at a job presently working on Aircraft GSE. A job that I used to work at 31 years ago, and now I am back at.

That mini bike broke a lot, partly due to the fact that I was a mini bike riding animal, could not leave well enough alone, and always had to be making something I rode........ better. I am still like that today.

I pulled the governor our of the Tecumseh, and over the period of 2 years, broke the con rod twice. We patched the block and replaced the rod the first time, the 2nd time she was done.

Also put a set of 4 or 5 inch springs in the front, raked the front end like a mini chopper and slowed the steering a lot. Was it better? No way, but it was the fad at the time, and bottom line was........... I like it.


That mini bike......... THAT MINI BIKE. is part of who I am professionally. It gave me a lot of grief, but gave me a lot of fun. I probably would not have learned about bolt torque, part failure, and would not be where I am today, with out THAT mini Bike.

Thank God, for that Sears Roper Mini Bike.

PS. Thanks by the way for the picture of the 2 bikes. That Picture has brought back a lot of GOOD memories for me.....( Well they are Good NOW! LOL ! )

Dadrider
 
#8
The reason there is / was a fuel shortage in the 70's is well, my buddy's and I burned all the oil reserves up in our mini bikes and motorcycles in the late 60's and early 70's..LOL !

If you pulled that spark arrestor and the long tail pipe off the engine, and turned the bike so that the exhaust bounced off the side of the house and corner of the shed, when you pulled away at full throttle, it would sound like a version of a little harley davidson..........

I also bought a kick starter kit for the Tecumseh for Christmas the 2nd year, because it looked cool. What a mistake for such a hard starting engine, At least mine was.

Also put a windshield on it during the winter months. Well my parents wrangled me to have to do it as the cold air would give me a sinus infection that would keep me out of school for a week. That was 4th or 5th grade, maybe 6th grade do I was 10 or 11 at that time so it would place it as 1969 or 1970

Yeah that Sears mini did have it's advantages, until the winter windshield deal was dropped on me. !
 
#9
Powder coated the entire frame and gas tank. Note on powder coating gas tanks you have to do some work. Solder melts at about 375 degrees, and powder coating basically goes to that temperature. To compensate (so the tank doesn't fall apart), I tag TIG weld all the seams, so I can't come apart. This has worked well for me.

Also looking at the catalog pictures I could see the bike had original decals. Someone is selling nice decals on ebay, but they weren't quite what I was looking for. So i ended up making mine own. Though not really stock, they look pretty good over the red powder coat.

For the seat all the "usual suspects" were not interested in making it. So I made my own. It's no great creation, but it works well and looks decent. The wife helped out (could not have done it without her.)

Overall I'm pretty happy with how it turned out.



Hands down I think your build and preservation, has made a mini that out performed mine on it's best day ! Great looking job.
 
#14
that's really cool! I got a crusty roper I'm going to tear into at some point. this is an inspiration for me to think about which direction to go with the build.

I'd REALLY like to see how you made that DB disc brake setup work (how the rotor mount to the wheel), and how the sprocket mounts to the rear wheel.
 
#15
Nice build cfh. While we're on the subject of sears trail tamers. Was that red two speed model really 5hp or just labeled as such because I have never seen a small frame 5hp tecumseh with a rounded top shroud....other than some sleepers built by some guy in Florida whose name starts with an M.

Small frame hs50 rounded shroud not h50 big block which were rounded.

Somebody lemme know. I've wondered this for years.
 

cfh

Well-Known Member
#16
This is what i figured out about this...

The Sears Trail Tamer model aka Roper (6" wheels 5hp) does look like a small framed HS50, as shown in the spring 1971 Sears catalog. But the Tecumseh HS50 model didn't come out until 1972. But do we really know that as correct? Looking at the picture it's definitely not a big body H50. But also looking at the picture it's not really a picture. It's a colorized drawing. So who knows? It could just be how it's drawn. Or maybe the HS50 came out in 1971. I don't know.

I have heard the first year or two of the HS50 engine did have the 'old style' round blower housing. But personally the oldest HS50 i've seen is 1974 (i have two of them.) And they have square top blower housings (and aluminum flywheels). Note if you look at the spec chart in the 1972 catalog (below), the two top models have torque converters as their '2 speeds'.

Now in the 1972 Sears spring catalog, the model with 10" wheels and 5hp, is shown. Labeled as the "Road and Trail" model. But we don't see the engine side. It also has lights, but a battery box too. So it's probably not a lighted magneto motor. But we can't really tell a lot from that black and white drawing.

I am going to change my red Roper to a black HS50 motor though. It has a white motor, but from the catalog pic, it should be black. But it shows in that chart i should have made my bike orange/yellow, not red. damn

1971 Sears spring catalog, pg 459:


1972 Sears spring catalog, pg 483:
 

markus

Well-Known Member
#17
Nice build cfh. While we're on the subject of sears trail tamers. Was that red two speed model really 5hp or just labeled as such because I have never seen a small frame 5hp tecumseh with a rounded top shroud....other than some sleepers built by some guy in Florida whose name starts with an M.

Small frame hs50 rounded shroud not h50 big block which were rounded.

Somebody lemme know. I've wondered this for years.
That 80717 model shows in the service manual as coming with craftsman model 143.615062 engine which is a medium frame H50 in Tecumseh numbers

There was never a production thin flywheel /small shrouding HS50. Pre-production Tecumseh literature from 1971 shows it as being available for '72 season and shows it with the square shroud.

sincerely,
"M"
 

cfh

Well-Known Member
#18
The Sears catalog pictures are not really pictures, they are colorized drawings. So though they are drawn as HS engines with round housings, as M sez, they really can’t be HS50 motors.

It’s good to know the first few years of HS50 motors never had round blower housings. I always wondered that... would the Hs50 not work with a 32517 flywheel?
 
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