TM40 pumper carb.  Good bit of kit.  Have put lots of them on large Japanese singles over the years.  Lots of jet info on line for them.  You'll want to come down a long way on the accelerator pump jet in an application like that or it'll bog when you open the throttle.  Any sort of stationary application imho you want to remove the accelerator pump linkage altogether as a trial

I wonder if maybe the higher voltage related to higher RPMs?  Original 5/1 at 600 and later 6/1 at 650?

Or maybe that's just dumbass layman-doesn't-understand-electrical-generation thinking?

If you had a precision-cut, dowel-and-pin type fit, bolt-together construction imho that would be more do-able

Imagine a structure that basically hung on three sections:

Two vertical side-pates with cutouts and threaded holes to take TRB crank, cam etc bearings - maybe ex M12?  And a horizontal top section, relatively small in cross-section so it wouldn't have to be too heavy, with re-inforced areas where the barrel/head tie-down studs thread in and where it abuts/is fastened to the vertical pieces

After all, the rotational loads are balanced, and the power output is only a handful of kW, and, while there's a lot of torque - there's not a LOT of torque

Think, for example, how light the alloy case of a 200 BHP, 13,000 RPM Yamaha R1 or GSX-R1000 is - it's not about material mass, it's about understanding the loads & applying good engineering design principles

People like to play with the carb adjustments when the saw won't run or won't rev cleanly or won't rev properly - it seldom turns out well - often you inherit a saw that has been so tinkered-with that it won't run even with good spark & compression

Based on my experience, here are some thoughts

(1)  Empty all the old gas out of the tank, put in a wee bit of new clean gas and shake it around to give it a flush then tip that out too

(2) Get a bit of bent wire and fish out the fuel filter and blow it clean with compressed air then fill the tank with fresh 2-stroke mix - maybe 25:1 or 32:1 with that old saw?  If it should be 40:1 a bit extra won't hurt short-term.  Use good quality 2-stroke oil such as Husqvarna or Motul - something that is designed for chainsaws not lawnmowers and that says "suitable for 2% or 50:1 mix" on the label

(3) Remove the aircleaner (it'll need a good clean before it goes back on), open the choke and tip half a teaspoon of gas down the carb.  Close the choke, turn it on and pull a few times.  It should splutter, start, run briefly and then stall.  Try it a couple times.  If that doesn't work, probably tinkering with the carb won't fix it

If that does work, then . . .

(4)  Carb settings:  There will be two screws probably side-by-side on one side of the carb.  High speed mixture and low speed mixture.  Also somewhere there'll be an idle speed device - probably as a throttle stop?  With a bit of luck on the plastic housing there will be two screwdriver holes marked maybe "H" and "L" (high and low) or similar?  It'll be obvious that you need a small flat-bladed screwdriver

Blow the whole area clean with compressed air and screw both screws in gently until they stop.  Then screw them out again one and a quarter turns (probably one and an eighth is gonna be closer to ideal but one and a quarter will get you started)

At those settings the saw should start and run and rev (but probably not rev very cleanly) and it might idle of the throttle stop is OK

If that stuff works OK you should google "chainsaw carb tuning" or similar to get it just right

The aircleaner needs to be spot on clean and in good shape too

Good luck

It may be that 20-odd BHP won't run a 40" chipper?

I seem to remember maybe a 60kW motor on the timber chipper at the last mill I worked at?  Been a while, and I could easily be wrong?

Might be worth doing some homework first?

Cheers

That would have been a Brilliant Conversion!
Shame your brother didn't appreciate it.  Must have taken some doing to get that configuration Motor  in there!

I had a google and of course there are some vids.  They fit in the hole really well!  And it's an older Toyota (read bullet-proof if you maintain it) with good low-RPM torque.  What a good conversion!

Beats hell out of the just-waiting-to-explode Ford V6.  Only good thing about that was the acceleration from the combination of the low final drive ratio and the 90-odd HP

Beautiful-looking genset.  All you need to do now is get rid of that truck and buy a Toyota and you'll be set 

Hi there

Please see PDF attached which is a summary of some work by one of the "Masters" on here a while back

Briefly:  Valve clearances are about (a) operating clearance and (b) valve open-and-closing timing

(b) being the thing that matters as long as there's working clearance

So see PDF?  Try using the valve clearance adjustment to open the intake and close the exhaust at the degrees of rotation (timing) as per the PDF and never mind the actual clearance . . .

Others may wish to chime in?