ATC. ATC-90 – Forths.com https://forths.com Family - Friends - Projects Thu, 12 Nov 2020 17:01:31 +0000 en-US hourly 1 https://forths.com/wp-content/uploads/2022/12/cropped-1219225-32x32.png ATC. ATC-90 – Forths.com https://forths.com 32 32 ATC 90 Engine Work https://forths.com/atc-90-engine-work/ Thu, 12 Nov 2020 16:59:15 +0000 https://forths.com/?p=5356 The ATC 90 engine work continued today, focusing on the head. I took the carbon-caked valves to the wire wheel, which made easy work of removing the carbon. While the exhaust valve looked good, the intake valve face was too worn to be used again. A new pair of valves was available online for under $20, so I opted to order them instead of reusing the original pair.

A tiny wire wheel mounted to a rotary tool took care of the carbon removal from the combustion chamber. Gasket mating surfaces were cleaned too. The original exhaust pipe and muffler were long overdue for replacement. A hole in the bottom of the muffler was visible next to an old “temporary” patch. The original exhaust parts will be discarded since the aftermarket exhaust arrived last week.

Once the new valves arrive I will continue to reassemble the engine. Until then, I’ll clean and re-lubricate the chain and throttle cable. I’d like to see the ATC 90 back in good running condition before the snow flies.

  • Intake valve face is too worn to use
  • Rotary tool cleans carbon
  • The holey muffler will be discarded
  • Combustion chamber is cleaned
  • New exhaust is test-fitted
]]> The ol’ ATC Gets a New Carburetor https://forths.com/the-ol-atc-gets-a-new-carburetor/ Sat, 19 Jul 2014 17:07:23 +0000 http://192.168.50.23/wordpress/blog/?p=2635 Our ancient Honda ATC 90 3-wheeler has needed some help for a while.  It hasn’t been run in a few years, mainly due to carburetor issues.  The 36 year old carburetor suffered from a sunken float, flooding the poor machine and dripping gasoline on anybody that attempted to ride it.  My motorbike projects from the past few years took priority, so the poor little ATC sat, neglected – until now.

I ordered a new aftermarket carburetor last week – only $49.  It’s slightly different from the original, and has a slightly larger capacity, but my research suggested that it’s the recommended replacement for the ATC 90.  With the body shell and fuel tank removed, I took the opportunity to clean the machine and replace the air filter.  I also lubricated the chain – something that probably hasn’t ever been done.

This ATC always seemed to lean to one side.  I had always attributed that to the mismatched rear tires, but even after I put new tires on it 4 years ago, it still seemed to lean a bit.  I studied the tires and wheels and it finally hit me – the front wheel is different than the two rear hubs, and they’re in the wrong positions.  The front rim was mounted at the rear right side.  Once I moved the wheels to the correct positions, the ATC sat level for the first time that I could recall.  That should help it steer straight, and it looks much better.

After the fuel tank was cleaned and refilled with fresh gasoline, I connected the fuel lines to the carburetor and switched it on.  I set the choke, pulled the starter rope, and after two tugs, it started.  I adjusted the idle setting, and the bike settled into a nice, relaxed rumble.

I had to re-learn the shift pattern of this machine – neutral is all the way up, and the 4 forward gears are all down from there.  I rode the ATC to the beach for a test drive, and it worked perfectly.  The engine has plenty of power, so the new carburetor did the trick.  Perhaps next on the list is a new aftermarket generic headlight to replace the damaged original.  This loyal little machine deserves it.

 

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