---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Tue 01/31/17: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:32 AM - Hard starting.. help required from round engine pros (JL2A) 2. 05:06 AM - Re: Hard starting.. help required from round engine pros (A. Dennis Savarese) 3. 07:20 AM - Re: Hard starting.. help required from round engine pros (George S. Coy) ________________________________ Message 1 _____________________________________ Time: 02:32:13 AM PST US Subject: Yak-List: Hard starting.. help required from round engine pros From: "JL2A" Gentlemen, We have a Jacobs R755 powered Agcat used for commercial Joy Flights. We also have two CJ6s, and realise this is a eastern bloc forum but hopefully there's a few of you here that have experience with other types of round engines (paging George Coy??!) The aircraft has not done multiple flights in a day for many years, however we are working the aircraft quite a bit lately (which is great!) and it is proving to be a real sob to start, at seemingly random times. Once running, the thing is great and purrs smoothly and runs well, however the starting sequence has many quirks, the most frustrating of which is the Im not going to start at all We have tried everything! - prime like crazy while cranking. nothing - flooded start, idle cut-off, throttle open, crank. nothing - every possible variation of prime, from nothing to too much with all combinations And when I say nothing, I mean nothing! Not a chug, cough, smoke, nothing. It is like there is actually no spark at all. Unlit fuel vapour can be seen coming from the exhaust whilst cranking. The only thing that does seem to work is walking away, coming back 30 minutes later and then shell start second blade! Unfortunately by then the customers have been refunded and have left. We have had the magnetos overhauled, shower of sparks inspected and all found serviceable. We had some drag car racers as customers the other day and their comment was 'it's like there's no spark'. Which is what it 'feels' like to us too. Too rich/lean starting mixtures engines behave differently, with some cylinders firing or not etc. This one is either perfect all 7 cylinders start, or absolutely nothing. Obviously there is a spark, otherwise nothing would happen - but I'm thinking maybe it is such a weak spark from the shower of sparks that the mixture has to be juuuust right in order for it to go. Would the starter be taking so much voltage that the SoS is not getting it's required amount? Any ideas are welcome! Thanks in advance! Anatole Mills PS Sometimes while starting one jug will fire way early and drives the engine backwards against the starter which makes us wince. Fear for the life of the starter. This may be an independent problem. The R755 is timed to 31BTDC (running, static) PPS After operating the R985 and R755 the HS6A looks more and more like an engineering masterpiece! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=465595#465595 ________________________________ Message 2 _____________________________________ Time: 05:06:39 AM PST US From: "A. Dennis Savarese" Subject: Re: Yak-List: Hard starting.. help required from round engine pros You mentioned a shower of sparks as a possible culprit.=C2- We have seen the same thing with the Huosai and M14 (not with M9-35's which are timed AF TER TDC and in theory do not require a shower of sparks) engines as well an d yes, a weak shower of sparks will cause the engine not to start. What I typically do on the M14 and Huosai engines is test the shower of spa rks by removing the shower of sparks lead from the magneto cap and placing the tip of the wire about 3/8" to 1/2" inch from a metal surface.=C2- The next step applies to an air start engine.=C2- We'll discuss your Jake sh ortly.=C2- We make sure the air system forward of the main air valve is b led off completely.=C2- This eliminates any residual air in the air lines from rotating the engine when the start button is pressed.=C2- Next we t urn on the battery and the ignition switches and press the start button.=C2 - With the shower of sparks held (by a second person) or held in place cl ose to a metal surface in the engine compartment, the shower of sparks lead should jump a spark from the tip of the wire to the metal surface.=C2- I f the spark does not jump about 3/8" and we have to move the wire tip close r to the metal to see the spark jump, we must conclude the shower of sparks is weak and not generating enough energy to fire the spark plugs.=C2- Lu ckily on the Huosai and M14 engines with their shower of sparks (ie: starti ng coil which is identical on both engines) we can clean and adjust the poi nts inside the unit and improve the spark. Remember, whatever you see at the tip of the shower of sparks lead has to t ravel down the spark plug wire to the spark plug.=C2- If the spark is wea k at the tip of the wire, you can be assured it does not have enough energy after traveling down the plug wire to the spark plug. As for the Jake, don't assume because you recently had the shower of sparks checked that it is outputting adequate spark.=C2- I would (if possible) remove the magneto caps from the magnetos and then remove the shower of spa rks lead from whichever magneto it is affixed to.=C2- Next do the same th ing as described above: place the shower of sparks wire close to a metal su rface.=C2- Then turn on the battery and ignition switches and press or en gage the start switch.=C2- Yes the engine will rotate, but it can not sta rt with the mag caps removed.=C2- But the shower of sparks wire should ju mp a spark to the metal surface it is close to.=C2- Again, if the spark i s weak, then the shower of sparks/starting coil is also weak.=C2- The wea k spark will not fire the spark plugs. Hope this helps.Dennis From: JL2A To: yak-list@matronics.com Sent: Tuesday, January 31, 2017 5:31 AM Subject: Yak-List: Hard starting.. help required from round engine pros Gentlemen, We have a Jacobs R755 powered Agcat used for commercial Joy Flights. We also have two CJ6s, and realise this is a eastern bloc forum but hopeful ly there's a few of you here that have experience with other types of round engines (paging George Coy??!) The aircraft has not done multiple flights in a day for many years, however we are working the aircraft quite a bit lately (which is great!) and it is proving to be a real sob to start, at seemingly random times. Once running, the thing is great and purrs smoothly and runs well, however the starting sequence has many quirks, the most frustrating of which is the =C3=A2=82=AC=CB=9CIm not going to start at all=C3=A2=82=AC=84=A2 We have tried everything! - prime like crazy while cranking. nothing - flooded start, idle cut-off, throttle open, crank. nothing - every possible variation of prime, from nothing to too much with all comb inations And when I say nothing, I mean nothing! Not a chug, cough, smoke, nothing. It is like there is actually no spark at all. Unlit fuel vapour can be seen coming from the exhaust whilst cranking. The only thing that does seem to work is walking away, coming back 30 minut es later and then she=C3=A2=82=AC=84=A2ll start second blade! Unfortu nately by then the customers have been refunded and have left. We have had the magnetos overhauled, shower of sparks inspected and all fou nd serviceable. We had some drag car racers as customers the other day and their comment wa s 'it's like there's no spark'. Which is what it 'feels' like to us too. To o rich/lean starting mixtures engines behave differently, with some cylinde rs firing or not etc. This one is either perfect all 7 cylinders start, or absolutely nothing. Obviously there is a spark, otherwise nothing would happen - but I'm thinki ng maybe it is such a weak spark from the shower of sparks that the mixture has to be juuuust right in order for it to go. Would the starter be taking so much voltage that the SoS is not getting it' s required amount? Any ideas are welcome! Thanks in advance! Anatole Mills PS=C2- Sometimes while starting one jug will fire way early and drives th e engine backwards against the starter which makes us wince. Fear for the l ife of the starter. This may be an independent problem. The R755 is timed t o 31=C3=82=C2=B0BTDC (running, static) PPS After operating the R985 and R755 the HS6A looks more and more like an engineering masterpiece! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=465595#465595 S - WIKI - - =C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin. ________________________________ Message 3 _____________________________________ Time: 07:20:42 AM PST US From: "George S. Coy" Subject: RE: Yak-List: Hard starting.. help required from round engine pros It is most probably ignition problems. Either timing or weak spark at starting. The Jacobs that I had was on a Cessna 195 had one magneto and one distributor (like on a car). The distributor had an mechanical advance built into the rotor, used a coil, points and capacitor. I recall the Jacobs on the Bamboo Bombers ( Cessna Bobcat) also had the same ignition system. I also found out when the engine was warm or hot it was often hard to start with the starter, but would easily start by hand propping. I suspected the voltage to the coil was low during start and made a weak spark. I replaced the coil, the capacitor, the lead from the coil to the distributor on mine to help starting. I also installed fine wire plugs to help starting. I had a friend with a 195 who had a reluctor wheel made to replace the cam, replaced the points with a pick up from a Toyota and installed a capacitive discharge system (the FAA did not know any better). It fired up every time. The Franklin B9F engine on the SeaBee had a similar system and we always replaced the coils and =with modern coils. George ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message yak-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Yak-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/yak-list Browse Digests http://www.matronics.com/digest/yak-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.