facthunter Posted Friday at 08:14 AM Share Posted Friday at 08:14 AM It's there and it's a good idea and you can see the corresponding support cast into the piece it bolts to. It may be a link Cantilever small dia shafts are a bad idea unless they act as a QUILL and deliberate break point for an overload situation. Gear mesh must be maintained to a close tolerance on load or the gear strength is compromised rapidly and teeth fail. They will also run noisily when on load.. Nev Link to comment Share on other sites More sharing options...
facthunter Posted Friday at 08:23 AM Share Posted Friday at 08:23 AM Starter motors cop a lot. #Engines can kick back against them and reengaging when still turning subjects them to shock loads. They all have time limits or they overheat. Ball bearings have various failure modes. Most starters use Plain sintered self oiling bearings one at each end of the motor shaft. Circlip grooves make stress points. Nev 1 Link to comment Share on other sites More sharing options...
BrendAn Posted Friday at 09:05 AM Share Posted Friday at 09:05 AM 49 minutes ago, facthunter said: It's there and it's a good idea and you can see the corresponding support cast into the piece it bolts to. It may be a link Cantilever small dia shafts are a bad idea unless they act as a QUILL and deliberate break point for an overload situation. Gear mesh must be maintained to a close tolerance on load or the gear strength is compromised rapidly and teeth fail. They will also run noisily when on load.. Nev i think you are talking about the mounting bolts. if you look at the service bulletin danny posted there are 2 long bolts , no pin. 1 Link to comment Share on other sites More sharing options...
Red Posted Friday at 11:35 AM Share Posted Friday at 11:35 AM 2 hours ago, BrendAn said: i think you are talking about the mounting bolts. if you look at the service bulletin danny posted there are 2 long bolts , no pin. Exactly, but I've had enough of Facthunter and the mysterious pin that only he can see, Its like asking a Trump supporter to accept he didnt win the last US Election.🙄 1 Link to comment Share on other sites More sharing options...
Red Posted Friday at 02:02 PM Share Posted Friday at 02:02 PM For info, here is an exploded layout of a typical Denso motorcycle starter of the type Rotax seem to be using. 1 Link to comment Share on other sites More sharing options...
facthunter Posted Friday at 10:58 PM Share Posted Friday at 10:58 PM Resorting to "personal" insults is poor form. You couldn't design a starter cheaper than that. Nev Link to comment Share on other sites More sharing options...
Red Posted Saturday at 07:22 AM Share Posted Saturday at 07:22 AM (edited) 8 hours ago, facthunter said: Resorting to "personal" insults is poor form. You couldn't design a starter cheaper than that. Nev Indeed It's a wonder really that the design has proved so reliable in the millions of motorcycles its been fitted to in the last few decades They really should have given you a call before releasing it to the world, you could have told them to fit a pin in the end Edited Saturday at 07:23 AM by Red 1 Link to comment Share on other sites More sharing options...
BrendAn Posted Saturday at 07:26 AM Share Posted Saturday at 07:26 AM 2 minutes ago, Red said: Indeed It's a wonder really that the design has proved so reliable in the millions of motorcycles its been fitted to in the last few decades They really should have given you a call before releasing it to the world, you could have told them to fit a pin in the end the reliability of thousands of 9 series rotax is well proven. they have the runs on the board. 1 Link to comment Share on other sites More sharing options...
facthunter Posted Saturday at 07:47 AM Share Posted Saturday at 07:47 AM Sarcasm isn't becoming. There are much better starters in some motorcycles than that example.. . Have your feeding frenzy if it makes you feel better.. A gear that size has little margin for change of relationship with the one it's meshing with before it weakened. Saying "IT WORKS" doesn't address the situation. Aeroplanes deserve the BEST design. reasonably achievable. Nothing Rotax is cheap in price. I'd expect better.. Nev 1 Link to comment Share on other sites More sharing options...
danny_galaga Posted Sunday at 11:57 PM Author Share Posted Sunday at 11:57 PM On 11/10/2024 at 6:03 PM, onetrack said: I can't, despite going through the whole thread and all the links carefully. I've never seen a starter shaft with a pin in the end - a circlip groove and circlip, yes - but never a pin. However, I'm always open to being proved wrong, and just as you think you've seen it all, some engineer decides it has to be done differently. I'm quite confused now too. Are we still talking about the 912 starter? That just has a splined armature shaft. If we are talking about the sprag clutch inside the engine, I have no idea.. maybe there's a pin in that somewhere 🤔 1 Link to comment Share on other sites More sharing options...
facthunter Posted Monday at 12:14 AM Share Posted Monday at 12:14 AM The pin is the logical way to overcome the deficiencies of a cantilevered gear. which is NOT a good design feature. In the image I refer to it also showed the lug and machined hole the pin went into to locate it in the part it mounted to. Whether you have found this Image or not doesn't alter the fundamental argument of what a good design is.. The proper MESH of gears must be maintained under load or they are noisy and weaker.. Nev 1 Link to comment Share on other sites More sharing options...
fallowdeer Posted Monday at 12:45 AM Share Posted Monday at 12:45 AM By crikey reading this thread just makes me so grateful that every one of the thousands of times I’ve hit the starter on a 912 over the last fifteen years or so it’s actually worked……. 2 Link to comment Share on other sites More sharing options...
facthunter Posted Monday at 12:56 AM Share Posted Monday at 12:56 AM Just keep on doing what you're happy with. Are you getting value for money? No don't even worry about that. It's got Rotax on the packet.. I've never advocated modifying because it makes you a test pilot.. One of the reasons Rotax's do OK is because people don't often fiddle with them. Nothing's PERFECT. Believe me. I'd fly a plane with a 3 cyl ANZANI in it but I'd pick the aerodrome. I operate out of. Nev 1 Link to comment Share on other sites More sharing options...
BrendAn Posted Monday at 12:59 AM Share Posted Monday at 12:59 AM 44 minutes ago, facthunter said: The pin is the logical way to overcome the deficiencies of a cantilevered gear. which is NOT a good design feature. In the image I refer to it also showed the lug and machined hole the pin went into to locate it in the part it mounted to. Whether you have found this Image or not doesn't alter the fundamental argument of what a good design is.. The proper MESH of gears must be maintained under load or they are noisy and weaker.. Nev No it didn't. What U think is a pin is actually a mounting bolt. Look at the service bulletin . 1 Link to comment Share on other sites More sharing options...
BrendAn Posted Monday at 01:02 AM Share Posted Monday at 01:02 AM 14 minutes ago, fallowdeer said: By crikey reading this thread just makes me so grateful that every one of the thousands of times I’ve hit the starter on a 912 over the last fifteen years or so it’s actually worked……. According to someone here that's impossible because Rotax are so poorly designed and he knows better than they do. Even though they are the most popular LSA and gyro engine on the market . 1 Link to comment Share on other sites More sharing options...
facthunter Posted Monday at 01:04 AM Share Posted Monday at 01:04 AM Your OPINION Brendan. I'm NOT referring to a Rotax service bulletin.. 1 Link to comment Share on other sites More sharing options...
facthunter Posted Monday at 01:11 AM Share Posted Monday at 01:11 AM That's a stupid assertion to make and just convenient to your argument incorrect and insulting. ALL mechanical designs can be improved Rotax don't make their starter motors.. We seem to be unable to really discuss these things so let it pass shall we.? . Nev 1 Link to comment Share on other sites More sharing options...
BrendAn Posted Monday at 01:16 AM Share Posted Monday at 01:16 AM 1 minute ago, facthunter said: That's a stupid assertion to make and just convenient to your argument incorrect and insulting. ALL mechanical designs can be improved Rotax don't make their starter motors.. We seem to be unable to really discuss these things so let it pass shall we.? . Nev there is no pin that you keep referring to. you need to scroll down a bit more and look at the other diagram you must admit nev, you make a lot of comments about rotax yet they are good engines. according to you they should be unreliable but they are not. 1 Link to comment Share on other sites More sharing options...
facthunter Posted Monday at 01:44 AM Share Posted Monday at 01:44 AM Plenty of engines ALL? have weaknesses in them. There's lots of restrictions on operating a Rotax. They are also EXPENSIVE for parts. . I used to be Mates with Bert Flood. He told me a little more than you know. . . I've done plenty of hours behind 912's Just a few posts back I said Rotax's DO OK Because..... You read into things what suit the point you wish to assert. and act as if the Rotax is "JUST Perfect" and beyond any criticism... Nev 1 1 Link to comment Share on other sites More sharing options...
danny_galaga Posted Monday at 02:33 AM Author Share Posted Monday at 02:33 AM Fact Hunter, there's a lot to scroll through, can you describe in simple terms what this pin is doing, and what it goes in to? When I had my 912 starter out, I noticed nothing remarkable about it except that is a Denso motorcycle starter motor. I don't specifically remember a pin somewhere, but I wasn't looking for one either. 1 Link to comment Share on other sites More sharing options...
BrendAn Posted Monday at 02:54 AM Share Posted Monday at 02:54 AM the only thing i can see is the mounting bolt which does look like a pin in this pic. 1 1 Link to comment Share on other sites More sharing options...
danny_galaga Posted Monday at 06:02 AM Author Share Posted Monday at 06:02 AM 3 hours ago, BrendAn said: the only thing i can see is the mounting bolt which does look like a pin in this pic. Oh yes, that's an unfortunate perspective 😄. I can definitely confirm that's just the through bolt and nothing to do with the armature shaft. 2 Link to comment Share on other sites More sharing options...
Red Posted Monday at 06:42 AM Share Posted Monday at 06:42 AM (edited) I explained this to facthunter some time ago Danny but he won't listen Whatever I'll report back on the starter I've ordered when I get to trial fit it and try get the thread back on track.😁 Edited Monday at 06:43 AM by Red 2 1 Link to comment Share on other sites More sharing options...
facthunter Posted Monday at 06:45 AM Share Posted Monday at 06:45 AM Its NOT on the standard Rotax starter and I have never said it was . . Thanks Danny and I've also mentioned the part it mated to . I'm sorry for any confusion caused and sick of the response. . I found a couple of similar starters in my den one being brand new. They have precision ball races in both ends of the armature probably Japanese made unit. The drive gear is much the same and the larger gear it meshes with is shouldered to make the teeth stronger. It probably has to be forged. . All I'd do with the Rotax unit is remove it and check it periodically as it has bushes to support the shaft and check the commutator and brushes at the same time.. Wear in the bushes changes the gear mesh and may also allow the armature to "Pole". Nev 1 Link to comment Share on other sites More sharing options...
BrendAn Posted Monday at 06:59 AM Share Posted Monday at 06:59 AM 8 minutes ago, facthunter said: Its NOT on the standard Rotax starter and I have never said it was . . Thanks Danny and I've also mentioned the part it mated to . I'm sorry for any confusion caused and sick of the response. . I found a couple of similar starters in my den one being brand new. They have precision ball races in both ends of the armature probably Japanese made unit. The drive gear is much the same and the larger gear it meshes with is shouldered to make the teeth stronger. It probably has to be forged. . All I'd do with the Rotax unit is remove it and check it periodically as it has bushes to support the shaft and check the commutator and brushes at the same time.. Wear in the bushes changes the gear mesh and may also allow the armature to "Pole". Nev 🙄 Link to comment Share on other sites More sharing options...
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