coolhand Posted May 1, 2017 Share Posted May 1, 2017 Hi, did anyone by any chance have to replace their Magneto (Thor 200 evo)? After the last flight this weekend a burning smell became apparent. The cool itself does not smell weird. When I turn the propeller the smell becomes stronger as the fan drives air past the engine. Besides this the engine did not start as easy as normally (Sparks plug alsof black and wet). Now looking for any info on replacing the Magneto + wiring. Does the engine have to be remover from the frame or can IT be accessed via the harnessside? Quote Link to comment Share on other sites More sharing options...
GR002 Posted May 1, 2017 Share Posted May 1, 2017 When working on this side of any engine I find its worth removing engine completely as this does not take long. Then you get a clear work area on the engine Quote Link to comment Share on other sites More sharing options...
coolhand Posted May 2, 2017 Author Share Posted May 2, 2017 Removed the motor from the frame this afternoon (20 min. job ) After measuring resistance of the blue/black/white wires coming from the coil I measure the following: Between: 1 and 2 ==> 1,2 ohm 1 and 3 ==> 1,2 ohm 4 and 3 ==> Infinite (or something like 45 ohm when turning the flywheel) 4 and 2 ==> infinite (or something like 45 ohm when turning the flywheel) In my opinion the measurements between 1 and 2 and 4 and 2 should both be somewhere in the same region (as should the measurement between 1 and 3 and 4 and 3 be)..... Am I correct in my thinking or is it correct that these values are not be the same?? The wireloom between the cutout (stop) switch and the black wire coming from the coil (4) measures approx. 1 ohm, so this part is definitely correct. Quote Link to comment Share on other sites More sharing options...
noddyc Posted May 2, 2017 Share Posted May 2, 2017 Hi Looking at your magneto drawing and resistance you got this is what I know, I use to rewind these long ago . .. Between 1 and 2 this is your power coil wired with a 0.8mm wire. The resistance you got sound right. Between 2 and 4 it's is your magneto/cdi coil , wired with 0.12 to 0.28mm wire (around 2000 turns) The resistance can be from 30 to 120 ohm(or higher) Point 2 would be commen on both coils with a cable going to your coil/cdi. The best way would be to have a look at the stator coils and see if there is any burned coils. Testing with a meter generally will only give you an idea that you have a broken wire ,even if the coils are burned and shorted between turns the meter will not tell you. We normaly would strip them and yust wound them. Did you check if your charge regulator is working , that could burn your power coil out , and would course your cdi coil to give your coil wrong information/ power as that also calculate your timing. I have not been able to find the factory values Hope this help. Casey Quote Link to comment Share on other sites More sharing options...
morgy Posted May 3, 2017 Share Posted May 3, 2017 I have seen a few people having to change stator and fly wheel on the thor's, All the parts are in stock with us.. www.sussexparamotors.co.uk Quote Link to comment Share on other sites More sharing options...
GR002 Posted May 3, 2017 Share Posted May 3, 2017 Whats the reason that flywheel and stators need replacing? We have a Thor 100 and I had to set the plug gap from 0.9 down to 0.6 mm to run and now there is no spark. I have tried a new spark plug so I think its either coil or stator Quote Link to comment Share on other sites More sharing options...
noddyc Posted May 3, 2017 Share Posted May 3, 2017 We had its problem when people started using 4 wheel motorbikes for crop spraying. These were air cooled engines, they were driving slow with not enough cooling , they were running so hot that the insulation on the coil wiring fail. The magnets on the flywheels never failed as far as I know. It could be a combination of vibration and hot temperatures causing the coils to fail. Quote Link to comment Share on other sites More sharing options...
coolhand Posted May 4, 2017 Author Share Posted May 4, 2017 Thnx for all the great comments sofar. Last night compared the values I got with an almost brand new Thor 200 and I got matching results, so I guess the aircraft side of the wiring is ok. The regulator itself is toast, on a side note: do not mount your regulator on the cage frame right below the reserve (I have a reserve behind my head). For now the regulator only became very hot, when the flight would have lasted longer it could very well have erupted in flames (which is not particularly nice, behind your head below your reserve....). I attached a document stating the factory values of the magneto and coil. Punt Factory Actual New Thor Coil A -> B 3,5 - 7 KΩ 8,8 KΩ 9,5 KΩ Magneto C -> D 0,3 - 1 Ω 1 Ω 1 Ω D -> E 200 - 500 Ω 282 Ω 250 Ω Just to make sure I will be replacing the sparkplug, hopefully tonight I will manage to get some spare time to mount the motor back to the frame and do some testruns. After talking it through with some local friends I think the max. power output of the accessory side of the magneto was too much ( max. 50 W) for the fitted regulator (max 6W) combined with the strobes which draw 4 W, causing the regulator to overheat and eventually drawing too much power from the magneto which resulted in substantial power loss due bad ignition (I flew at full throttle barely maintaining altitude), hence the wet and black sparkplug. polini-coils-resistance.pdf Quote Link to comment Share on other sites More sharing options...
noddyc Posted May 4, 2017 Share Posted May 4, 2017 That is good news to pin down what caused the problem ,then the fix is easy. I Don' t even have a regulator fitted on my thor200 ( electric start), I could not remember where all the wires go , yust left it off. I would suggest to start it and run it (test it without a regulator ) If you still have problems or smoke from it then you could have burned /shorted turns on your power coils caused by the regulator shorting them out. Casey Quote Link to comment Share on other sites More sharing options...
coolhand Posted May 5, 2017 Author Share Posted May 5, 2017 Hi Casey, Did you connect the starter directly to the battery (of course with a switch in between) so your battery is not being charged during the flight? Tried finishing up on the installation of the motor, however not yet finished. Will continue this afternoon and hopefully the testrun this evening will show no abnormalities anymore Quote Link to comment Share on other sites More sharing options...
noddyc Posted May 5, 2017 Share Posted May 5, 2017 Hi Yes , I connect directly and are using lipo's and running my temp sensors direct from the battery as well. The ' power ' wires from the magneto is taped up I charge them of the mains (on my jpx I get around 50 starts before charging) Quote Link to comment Share on other sites More sharing options...
coolhand Posted May 6, 2017 Author Share Posted May 6, 2017 Hi Casey, That sounds great! Can you maybe share the specs of the lipo('s) you use and maybe a picture, quite interested. I fired my unit back up yesterday and she started with one pull (just replaced the sparkplug) and ran fine at Idle. Today I will do some high power runs to see if the transit from idle to takeoff power and back is as it should be. I just adjusted the Idle rpm from barely 1400 to 1700(ish). Quote Link to comment Share on other sites More sharing options...
noddyc Posted May 6, 2017 Share Posted May 6, 2017 Hi I bought a genuine bosch 18v 4ah drill battery and took it apart (they have a 6Ah battery now).I trust these batteries as I have never heard of one catching fire. For my thor200 I plan to do the same, but yust cut them down to 12v . They use 18560 cells in parallel . l flattened them out ,soldered heavy cables onto it , added balance charging cables as well as plugs to make install and removal easy. The whole setup got put inside heat shrink for a solid unit . I kept the charge indicator witch is very useful and use an I-max charger. They fit inside my zenith chassis plate and are tied down with cable ties. I will post some photos when I am home again. Quote Link to comment Share on other sites More sharing options...
AndyB Posted May 7, 2017 Share Posted May 7, 2017 16 hours ago, noddyc said: Hi I bought a genuine bosch 18v 4ah drill battery and took it apart (they have a 6Ah battery now).I trust these batteries as I have never heard of one catching fire. For my thor200 I plan to do the same, but yust cut them down to 12v . They use 18560 cells in parallel . l flattened them out ,soldered heavy cables onto it , added balance charging cables as well as plugs to make install and removal easy. The whole setup got put inside heat shrink for a solid unit . I kept the charge indicator witch is very useful and use an I-max charger. They fit inside my zenith chassis plate and are tied down with cable ties. I will post some photos when I am home again. Just a warning.........I have used LiPos for 20 years. The saying always goes "never heard of one catching fire"....until one does. I nearly burnt a house down! Quote Link to comment Share on other sites More sharing options...
AndyB Posted May 7, 2017 Share Posted May 7, 2017 ps. best price LiPos usualy found here.... https://hobbyking.com/en_us/batteries/lipoly-all-brands.html Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.