I just thought I would make a quick post while I was here to help folks out.
I have a stack of Organic gardening magazines from the 70's and early 80's and I used to look at them and wish and think how fun gardening would be if I had 1 of those Troy bilt horse tillers! Wow, I was being flopped around by a old 4 hp Merry tiller.Did a good job but was hard on me
Well,fast forward to 2013 I did some work for a lady who's husband had 1 of the original 1's from the 70's and it was under a tree rusting. He had passed away and I was getting her tractor running so she could bush hog. i did the work for the rusty tiller that she said did not run. The tines are half worn but work fine for me.
I struggled for a while trying to get the 7 hp Tecumseh engine to run and it did but not well and not for long.
I picked up 1 of the 6.5 hp Chinese Honda clones for 20 bucks that needed a carburetor at a tractor show and I did the repairs and put it on the troybilt. Direct bolt on except you will need a 5/16ths bolt for the crankshaft instead of the stock 3/8ths bolt that retains the reverse drum.
It so happens the engine I picked up was a electric start 1 so i built a battery box for the tiller.
I type this to say if your tiller needs a new engine, the 6.5 hp manual start engine you can get at Harbor freight for around a 100 bucks on sale will work wonders and if you are handy with tools you can swap it yourself using a floor jack to support the engines as you remove and replace them.
No need to junk a otherwise good tiller because of a engine.
I am impressed with how quite the engine is and how powerful it is.