If you have specific questions, I can probably answer them. On tig welders, a foot pedal is essential when welding small short welds, difficult to weld steels like stainless or high carbon and medium carbon steels that are thin, like under an eighth of an inch. For general pipe welding roots and such, scratch start is fine.

For tig welding on a motorcycle frame, get several sizes of welding rod, here in the states, 1/16, 3/32 and 1/8 rod would probably cover your welding needs in a 70 s3 steel rod.

1/16, 3/32, and 1/8 tungstens, I use lanthanated at home.

If I was in the market for a tig welder, and I am for home use, look at the Everlast tig welders.

I have had both the lift start and the scratch start tig welder from harbor freight, I kept the scratch start and returned the lift start. I use the scratch start for mostly stick welding, but welded my muffler on the savage with it using tig, nice little welder. For tig welding the scratch start would not be good for those with little experiance. I was unable to tig with the lift start model, well i could, it was just a pain in the as!