paragliding training center
Most troubleshooting, assembly, & tips are the same as with the Top 80
Carburetor – The Thor 100 and 130 use the WG-8. The Thor 190 and 200 use the WB-37. The Thor 250
uses the Polini carburetor.
Compression, engine – 130-150 psi, depending on altitude. This is what you can expect for a new engine. Used will be less.
Cylinder Head Temperature Maximum 230°-250°C This may be increased to 265°C-280°C for brief periods. These values are from the Polini
User Manual which seem high. We use the TTO brand of gauges which register a lower average maximum running temperature than the
Polini values. Under full load, I have rarely seen the temperature exceed 180°C. In any case I would not run the engine above 200°C
using the TTO CHT.
Fuel filter Info – Use a 10 micron inline filter. We stock a commercial chainsaw filter. Contact us to order. Miniplane-USA also has them.
Fuel pump vacuum – 5" Hg (dry) 7" Hg (wet w/ fuel)
Fuel Info – Note: The Polini manual specifies that pilots use unleaded fuel. We contacted Polini and they specifically stated in writing (available
on request) that pilots may use AVGAS in any of their engines. AVGAS is greatly preferred over any gasoline containing ethanol.
Ignition, coil – The official Polini user manual states that the spark plug boot terminal to ground is 5K Ohms but a new Thor 130 measured 9K Ohms
which means that the secondary wire is a carbon-core ignition noise suppressing type i.e. some Thor models may have different values.
Ignition coil primary resistance (all models except the 190) – 1.6K Ohms (blue wire to engine ground)
Ignition coil secondary resistance – 9K Ohms ±10% (spark plug terminal to engine ground) Can be 5K Ohms on some models.
Ignition magneto coil resistance – 290 Ohms
Mounts, engine – 30mmL x 30mmW x 8mm (stud x socket) There are (4) mounts, total
Muffler spring removal – Use paraglider line to stretch the springs for replacement/removal. Do NOT use pliers to stretch the springs because
this will nick the tempered surface of the spring and weaken it. Here is a video on how to properly do it
Power output – Thor 100 20.5 @ 8,900 RPM
Thor 130 21.5 HP @ 8,800 RPM
Thor 190 27 HP @ 7,400 RPM
Thor 200 29 HP @ 7,400 RPM
Thor 250 36 HP @ 7,500 RPM (Dual Spark engine 36.5 HP)
Propeller shaft, seal – 26 x 36 x 7 mm (we stock these seals $8 free shipping, contact us to order)
Redrive oil – Here is a list of the correct oils that may be used in the Thor redrive.
Spark plug (other than the Thor 250) – NGK BR10EG, gap 0.9mm (0.035") This is a resistor type spark plug. Pilots may also use the B10EG/ES
or B9EG/ES. Use of a non-resistor plug will only increase the amount of noise created by the ignition that may be picked up by a two-way
radio. BE SURE TO PUT RED THREADLOCK ON THE PLUG TERMINAL OR IT WILL LOOSEN AND SELF DESTRUCT!
Spark plug (Thor 250) – see the Thor 250 page
Special tools for the Thor engines. These include the special pullers used to disassemble the engine.
Starter mounting screws – (3) 5mm x 80mm and (1) 5mm x 25mm. However, the bottom 80mm screw should be replaced with a 90mm screw
Threadlock – read this important page on threadlock and how to use it and when NOT to use it.
If you do not see the particular screw, bolt, or nut below, use the values in this table which are for Class 4.6 and 8.8 fasteners. The lower value is for 4.6 and the higher is for 8.8. The lower values should be used on aluminum fasteners and anything except hardened steel fasteners.
M4 1, 2.5 Nm
M5 2, 5 Nm
M6 3.5, 9 Nm
M7 6, 15 Nm
M8 8.5, 21 Nm
Carburetor screws 6mm – 8 Nm
Crankcase screws 6mm – 8 Nm
Crankshaft nut, clutch side – 60 Nm
Crankshaft nut, starter side – 40 Nm
Cylinder head nuts 7mm Thor 100,130 – 14 Nm
6mm Thor 200 – 12 Nm
8mm Thor 200 – 18 Nm
Engine to frame button head screws 8mm – 10 Nm – use Blue threadlock
Exhaust stud nuts 6mm – 10 Nm – use RED or Blue threadlock.
Magneto bolts – 9 Nm
Muffler button head screws 8mm – 10 Nm – use BLUE threadlock
Propeller central screw – 40 Nm – use BLUE threadlock
Reed valve screws 6mm – 8 Nm
Spark Plug – 21 Nm DO NOT USE THREADLOCK ON SPARKPLUGS!
Changing the redrive oil and the spark plug are the (2) most important maintenance items that must be done. Use a Sharpie to write reminders on the top of the redrive (or
other semi-flat area). Any other method will not be as effective. The markings are easily removed with brake cleaner or mineral spirits. This way, you won't forget! You have an
hour meter/tachometer installed right?
A. REDRIVE SERVICING It is very important to change the redrive oil on schedule because it gets quickly contaminated with clutch material. If your clutch oil appears really black when you change it, increase the change frequency. Note that the redrive will use oil because of slight leaks out of the relief valve.
B. Below are service items that are particular for the Polini. Pilots would do well to carefully study the servicing intervals for the Top 80 which I have developed to ensure long engine life for any 2 cycle aviation engine. The carburetor and fuel system are the most common items that must have regular service. Failure to regularly service the carburetor can result in permanent engine damage. It is advisable to measure the engine compression when it is new and use this value as a reference point.
C. The Polini Thor Flash starter has some major problems. See the Flash starter page for more information.
First 10 hours
Change redrive oil The exhaust assembly should be removed to get access to the drain plug. Use a cord to remove the exhaust springs.
Remove the two buttonhead screws that hold the exhaust assembly to the frame.
Starter – Either replace the Flash mechanism with the insert or secure the Flash spring to the pulley as soon as possible.
See the Flash page for more information. Newer Polini starters (2017) have the Flash spring secured.
Replace spark plug DO NOT FORGET TO USE RED THREADLOCK ON THE TOP TERMINAL! It WILL loosen, otherwise.
Change redrive oil (change every year, at a minimum). Note: The drain plug can only be removed if the muffler assembly is removed. Remove
the springs and the two button-head screws which attach the system to the engine. Tighten the oil fill plug on top of the redrive just snug.
If you over-tighten the plug, the gasket will be ruined and it will constantly leak oil. Be sure to use blue threadlock on the button-head screws
when re-installing them.
Replace muffler springs, as needed. They must be examined carefully for wear or damage.
Clean air filter (if you fly at the beach or a in a dusty environment, you may have to clean this filter more often)
Flash starter – it may fail by this time. See the Flash starter page.
Starter pulleys – these pulleys are poor quality and will self-destruct if not regularly lubricated with spray white lithium grease or light oil.
Check/Replace rubber mounts on engine and exhaust system, as needed. Cracks in the rubber mounts may be difficult to see!
100 hours – this is an extensive service interval which requires a lot of time to complete!
Replace air filter, as needed. If you do not replace one that is in good condition, clean it with soap and water.
Replace starter rope if there is any signs of wear.
Replace reed valve petals if they are leaking (a rare event).
Replace upper connecting rod bearing and circlips. If the wrist pin has any wear or marks/grooves, replace it.
Check piston rings for freedom of movement
Remove carbon and/or lead deposits from the top of piston and cylinder head. Use a scope to look into the cylinder via the exhaust port
to see what's going on. Use a razor blade and a Dremel wire brush. Failure to routinely remove deposits will increase compression and
combustion temperatures and will shorten engine life.
Clean out the decompression port with a #38 drill bit in the Thor 130, 190, and 200 models. Failure to clean this will result in greatly
increased effort needed to start the engine. If the Flash insert is used, most pilots will not be able to crank the engine over.
Replace piston and rings if compression is down by over 10% or engine power is significantly different than when the engine was new. If the
cylinder hone cross-hatch pattern is no longer present, the cylinder must be re-honed or replaced.
Replace all bearings and seals, if needed.
Replace crankshaft if play is excessive in the lower wrist/gudgeon pin bearing. Noisy engines probably need to be overhauled.