Finishing touches on a 35 year old project

Augiedoggie

Augiedoggie

Well-Known Member
#1
#1
I had hoped to finish my sons vintage Atlas custom mini bike to bring it to Oley this past spring but other projects and hobbies consumed too much time to complete. I did attend event, but walked around instead of riding proud. Bike has been unused for 5-7 years and shouldn't take much effort to get running, but I wanted to finish the build as I originally intended. Bike had a few items that were not finished to my satisfaction. Rear shocks were uneven and forks were a bit short and made steering a bit too fast. Will also need fuel system cleaned and old hardened fuel hoses replaced. The home brewed exhaust pipe need a few tweaks to secure it better than originally mounted and a new supertrapp open end cap has to be fabricated. Most of the parts were chromed when bike was originally built and welding would burn off the chrome so I have to be a bit more creative with fabrication now. When I built this bike many years ago I had only a torch and angle grinder and electric drill. I'm currently tooled up for much better work, but I still want the bike to reflect the period it was built. My son also insists the bike be kept as we planned and built it as one of our many
"Father/son" projects.
He also insists on keeping the vintage Hijacker decal on the engine fan shroud... 20240821_064108.jpg 20240821_064116.jpg
 
B

bruces

Active Member
#2
#2
Years ago ,I loved watching American Chopper ,No interest in the choppers ,but I loved that those guys were building custom choppers with $60.00 Dewalt angle grinders and a mig welder .Of course they ended up with the latest and greatest ,but they were using virtually nothing when the show first started .Nothing wrong with your grinder and torch ,use what you have and build what you can .
 
Augiedoggie

Augiedoggie

Well-Known Member
#3
#3
Recent covid vacation allowed a bit of shop time to piddle around on my sons mini bike project. Exhaust had issues due to poor engineering(me) and fell apart. Original configuration was used with supertrapp and quiet insert and resonator option. Very restrictive,but needed for our former residential riding area(vacant lot near our home)
He currently lives in rural area and has no noise concerns so an open end cap was fabricated from aluminum and internal quiet insert was replaced with oversize insert. Should sound a bit more rowdy now.
Removed swing arm and cut off shock mounts and fabricated new mounts and currently machining correctly sized spacers. I'm hoping to deliver bike to him before cold winter weather. Still have a fair amount of work to do. Never enough spare time available. 20241011_074144.jpg
 
Augiedoggie

Augiedoggie

Well-Known Member
#5
#5
Supertrapp mounting was rickety and muffler fell off years ago when he was riding it in the woods at his previous residence. He was digging the open exhaust sound and didn't want the muffler installed with closed end cap. I haven't started it yet, but it should sound okay now. I don't like short open pipes. Don't want to risk a warped exhaust valve. Those motors would pop their valve seats when put away hot. Always crank motor to compression stroke when shutdown to allow exhaust valve to seat and transfer heat
 
Augiedoggie

Augiedoggie

Well-Known Member
#6
#6
I have been working on my sons vintage Atlas restomod as time allows. I have been picking away at a healthy handful of items that were just bugging me. Bike was a 2 year project back in the 1980s and I was super busy with work related stuff back then. By the time I had this little monster finished my boy was riding an XR75 Honda and a CR80 Honda, so mini bike was running but never really completed to my satisfaction. My son enjoyed riding the mini bike around the yard but it ended up parked for quite a few years when he got married and started a family. Bike was parked in unheated shed for awhile and has a bit of rust on the chrome but he still treasures it like a jewel. He refused to allow me to clean the bike while I was working on it. He claims he wants it exactly as he rode it as a young boy. Just got it running again today pictures and details soon
 
Augiedoggie

Augiedoggie

Well-Known Member
#7
#7
Made improvements to exhaust retention. Original configuration was rigid mounted and rattled itself apart and required constant attention. Current setup is using rubber mounting to allow movement with engine torque. I welded muffler retention stud and safety wired end cap nut to home brewed muffler cap. Spring retainers and clamps hold exhaust joint tight but will allow for thermal expansion without being too rigid 20250226_152841.jpg
 
Augiedoggie

Augiedoggie

Well-Known Member
#11
#11
Recent work to the bike was more detail and fine tuning the original build. Project started as a fast and safe mini bike that would smoke any competition in the neighborhood. Motor was built to kart racing specs minus the alcohol fuel. My experience with methanol in my racing machinery was enough reason to use race fuel specs. Didn't want the extra maintenence. As it was built with super high compression and race cam and valvetrain it is still a chore to start. Motor was overkill, but I don't build losers so it was as good as I could afford at the time. Horstman Racing supplied go fast goodies. My shop did port and airflow testing and engine balancing. Original setup used tillotson carburetor but I later fabricated an intake to adapt a Honda CL175 carburetor. Minor rejetting has it running good.
 
Augiedoggie

Augiedoggie

Well-Known Member
#12
#12
Since I started this project nearly 40 years ago I forgot many of the little details from when it was first built. I had the starter clutch off recently and realized I had previously installed an offset flywheel key. Didn't exactly remember why I had done it and closer examination found I had used 6° retard key evidently to soften power for my young novice rider son. Forgot all about it and motor ran strong so had no reason to fuss about it. Got to thinking this thing is always a bitch to start and figured it couldn't hurt to restore original timing. Offset key is much more prone to breakage and why not install full size stock key? Worked much better than I would have thought. Little bastard starts like a stock motor and pulls like a freight train. Made a huge difference. Lofts the front wheel easily now. Could be a bit to snotty for the grandkids but my son is going to love it. Thing was always a beast, but this was really impressive change for power delivery. 20250228_120926.jpg
 
White Gas

White Gas

Member
#15
#15
bruces said:
Years ago ,I loved watching American Chopper ,No interest in the choppers ,but I loved that those guys were building custom choppers with $60.00 Dewalt angle grinders and a mig welder .Of course they ended up with the latest and greatest ,but they were using virtually nothing when the show first started .Nothing wrong with your grinder and torch ,use what you have and build what you can .
Click to expand...
”Use what you have and build what you can”… very profound, I’m honestly considering this to be placed on my tombstone.
 
Augiedoggie

Augiedoggie

Well-Known Member
#16
#16
A few pictures taken this morning before delivering bike to my son. Bike was probably in my possession for 5 or 10 years for storage and renovation. My boy was living in suburban area for awhile without large enough yard and space to ride, so there was no urgency to get er running. He now lives in country mountain setting with many acres of yard to ride his mini. Watching him rip around the yard today was very rewarding for me. He is thrilled to have his dream bike back in his garage ready to rage again. 20250309_100210.jpg 20250309_100159.jpg
 

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