Breaking in a Thunder Pro 46

"procedure in the manual isn't very specific" ?

The Thunder Tiger advice for beginners has to be one of the best instruction sheets seen in the past 40+ years.

The first earlier productions units had a large A3 sheet folded to form 4 A4 pages whereas later units have a very finely produced booklet. First page of sheet has specific instruction sections on Mounting, Fuel, Props, "Special attention" Heat, cautions, and a very large section on page 2 relating to specific break in procedures. - in need email for a copy.

May I suggest you use fuel containing at least 5% castor and 15% synthetic oil, and 5% - 10% Nitro. 2% - 3% acetone is a bonus. NOTE: Thunder Tiger Engines are designed for the USA market - all fuel has minimum 5% Nitro most = 12.5% Nitro. To obtain full power and smooth running without Nitro, remove the shim from under the cylinder head.

Best pictures on why your engine is "tight" and conrod appears to click over when cold = ABC, ABN, Ringed & Lapped - differences ***

For general tuning / running in instructions refer to = Engines,Plugs,Tuning, Petrol, Turbines, Mufflers, Cleaning, Anodising etc at Thunder Tiger engines are arguably the best now available. Thanks in part to Mr. Mihara, who was the very respected chief designer at OS, but transferred to Thunder Tiger circa 1997. refer to - (in need copy & paste full URL in two parts)

An ABC/ABN engine like this one should be broken in only SLIGHTLY rich, not in a blubbering 4 cycle mode. Start the engine, and set the high speed needle to just into the 2-cycle mode, running smoothly. Run it on the ground at full throttle for about 3-4 minutes, back off to about half for a minute, then go back to full. Do this through about 4 8 oz. tanks, then finish the break-in in the air.

ABC/ABN engines also should have a castor/synthetic oil mix, such as Morgan's Omega.

Good luck with it. Dr.1 Driver "There's a Hun in the sun!"

You can read up via those links suggested by Alan T and follow through or read this practical guide. For run in I wouldn't bother removing that head shim even with zero nitro fuel.

1. Fit the engine with a low load prop. Fit the engine in the model

*without* the cowl if one is supplied (for superior airflow and assured cooling).

1. Fill the tank with fuel consisting of a *minimum* 20% oil. You can reduce to a lower % later if you wish - after running in.

For the fastest bed in of that tapered alloy composite piston and bi-metallic plated liner and to ensure good cooling through heat transference via oil, use a fuel with an oil content of not less than

20%, preferably 4% minimum of that oil volume consisting of a *degummed* *first grade* castor. Using an all castor fuel will give you a faster P&L mate. However if you want to use straight synthetic that's OK too. It'll just take longer.

If you're going to use a fuel containing nitro, until it's run in don't use more than 5%. Though you don't *need* it for run in and in terms of its power benefit its essentially wasted, the addition of nitro will make any engine easier on the needle to tune as well as assist in the stability of the low end idle. But it's of no use during run-in other than that and higher percentiles can hinder that process and present potential problems for anyone of an experience level who needs to ask how to run in a tapered composite P&L Schnuerled engine.

1. 'Kick her in the guts', *remove the ni-starter*, and tune the HS needle to an unmistakeably discernible 2 stroke on the clearly rich side of peak which the engine can sustain without struggling lean. Keep the idle trim a little on the high side for now.

1. Fly.

4a. Land and retune immediately if the engine gives any indication of being too lean. If it's much too lean, you won't have any option. :)

1. Fly again....and again! Retune the HS needle as necessary, leaning out as the engine wears in.

2. Within half a dozen tanks of fuel it should be sufficiently bed in that you can tune much closer to its power peak, allowing for reducing fuel draw with the vacating tank. You can consider it run in and ready for cowl fitment etc.

JL