J D 8 Posted August 1, 2023 Share Posted August 1, 2023 I had not thought of having a magnet in the bag, nice one Paul. Link to comment Share on other sites More sharing options...
Jon H Posted August 1, 2023 Author Share Posted August 1, 2023 Bit unusual for it to fail but as its impossible to know why i would just change it and move on. If you want to replace all of them you can, its no more work to do two springs vs one. But if you have to get into the 2nd head that might be more faff than its worth. Its up to you really. I would not recommend taking a spring from the 240v. While they are the same its not worth butchering one perfectly good engine to temporarily fix another. And for what? a week for the new springs to arrive? Its just not worth it. If it were something simple like an exhaust then ok, but none of the internal parts should be swapped around. You cant change the spring with the head on the engine. The head has to come off, rocker shaft screw out, rocker shaft out, rockers and spacers out, then you have access. Please remember to take the screw out. I have lost count of the number of times i have seen a rocker shaft beaten out of the head with its screw still in place. Link to comment Share on other sites More sharing options...
Jon H Posted August 1, 2023 Author Share Posted August 1, 2023 1 1 Link to comment Share on other sites More sharing options...
Ron Gray Posted August 1, 2023 Share Posted August 1, 2023 Like it! Link to comment Share on other sites More sharing options...
Artto Ilmanen Posted August 1, 2023 Share Posted August 1, 2023 Great video - thanks Jon! Link to comment Share on other sites More sharing options...
Engine Doctor Posted August 1, 2023 Share Posted August 1, 2023 16 hours ago, Artto Ilmanen said: Thanks Andy & Engine doctor good hint to use a plastic bag! Can you carry out the spring replacement without taking of the head? E fitted Not worth the hassle. Head comes off easily and you can rest the head on a piece of balsa cut to fit into the head to hold valves up in position while springs are fitted. I use a piece of brass tube cut away to hold down the spring retainer while fitting collets . Very simple to make. Jon probably has a mini spring compressor? Link to comment Share on other sites More sharing options...
Ron Gray Posted August 1, 2023 Share Posted August 1, 2023 Obviously you didn’t look at Jon’s vid ED! Link to comment Share on other sites More sharing options...
Engine Doctor Posted August 1, 2023 Share Posted August 1, 2023 (edited) 19 minutes ago, Ron Gray said: Obviously you didn’t look at Jon’s vid ED! Just did 🤗 and edited comment or thought I had, tablet is a pain sometimes. Surprised he doesnt have a small compressor though . Edited August 1, 2023 by Engine Doctor 1 Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted August 1, 2023 Share Posted August 1, 2023 17 hours ago, Artto Ilmanen said: Can you carry out the spring replacement without taking of the head? No you have to keep the valve closed while you are refitting the collets. On a 75 I changed a valve spring on I made up a wooden wedge which sat in the head and kept the valve shut while I held the head down. I used a small open ended spanner to compress the spring. Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted August 1, 2023 Share Posted August 1, 2023 3 minutes ago, Frank Skilbeck said: No you have to keep the valve closed while you are refitting the collets. On a 75 I changed a valve spring on I made up a wooden wedge which sat in the head and kept the valve shut while I held the head down. I used a small open ended spanner to compress the spring. "snap", I also did my .75 that way, a good old OS spanner,,, Link to comment Share on other sites More sharing options...
Artto Ilmanen Posted August 1, 2023 Share Posted August 1, 2023 It seems clear - and I will do the service on both heads. I just spoke to Jon and he thinks the age may have a contribution to the spring failure. Not any conclusive culprit, though. Anyways, as I need to demount the engine from the model to synchronize the carbs after remounting the head(s) I can do both heads for peace of mind as well. Jon will kindly submit me parts needed. Link to comment Share on other sites More sharing options...
Artto Ilmanen Posted August 1, 2023 Share Posted August 1, 2023 a question on tappet adjustment or setting the valve clearance: I have done this on combustion stroke when the pistonnis at TDC. I have ritated the engine until I see the intake valve opening, then I have kept rotating until the valve closes and the piston comes to TDC. I have then checked and if needed adjusted both valves to 0,05-0,1mm have I done the adjustment right? Link to comment Share on other sites More sharing options...
Chris Walby Posted August 1, 2023 Share Posted August 1, 2023 Assuming you are rotating the crankshaft in the right direction and you know where the piston is then yes. Link to comment Share on other sites More sharing options...
Artto Ilmanen Posted August 1, 2023 Share Posted August 1, 2023 1 minute ago, Chris Walby said: Assuming you are rotating the crankshaft in the right direction and you know where the piston is then yes. yes, counter clockwise and checking the piston height with a plastic tool Link to comment Share on other sites More sharing options...
Rocker Posted August 6, 2023 Share Posted August 6, 2023 Can anyone settle a little friendly argument Will a Laser 180 fly the Seagull Chipmunk.My mate said it will but I think the Laser 180 will be to big for the Seagull Chipmunk .Who is right ? Link to comment Share on other sites More sharing options...
Eric Robson Posted August 6, 2023 Share Posted August 6, 2023 59 minutes ago, Rocker said: Can anyone settle a little friendly argument Will a Laser 180 fly the Seagull Chipmunk.My mate said it will but I think the Laser 180 will be to big for the Seagull Chipmunk .Who is right ? Just been flying my Seagull 80" span Chipmunk today powered by a Laser 100, it will do a lot more than the full-size one ever could. So a 180 will make it ballistic. It flys scale like at about half throttle. Link to comment Share on other sites More sharing options...
Jon H Posted August 6, 2023 Author Share Posted August 6, 2023 Like Eric i recommend the 100. They fly like extra 300's on the 155 and a 180 is nuts. We have guys flying 1/4 scale (108 inch?) Chipmunks using the 180 and half power for takeoff. There is a video online somewhere showing one with a 155. I ended up having an argument with the bloke who posted it about the power. He said it would be 'boring' and the owner would want to sell it in a week if it was flown scale with the smaller engine. I suggested that maybe they simply bought the wrong model. I also have two club mates flying 80 inch Spitfires of probably 8lbs more AUW than the SG Chippy and the 180 pulls them along without issue. Chipmunks are essentially metal tiger moths with a wing missing. They arent powerful aircraft and as anyone who has flown in one (i have) will know you need to inform it in writing before you do anything aerobatic. You shouldnt be able to just stand it on its tail and the 100 will offer more than scale performance. 1 Link to comment Share on other sites More sharing options...
Artto Ilmanen Posted August 8, 2023 Share Posted August 8, 2023 Jon / gents, What is the recommended fuel tank for a Laser 150? Is a 12 fl oz (350ml) ok or should I get a bigger one? I hope to get about 8min flying time with some reserve, of course? thanks, Artto Link to comment Share on other sites More sharing options...
Jon H Posted August 8, 2023 Author Share Posted August 8, 2023 12 will be fine Link to comment Share on other sites More sharing options...
Chris Walby Posted August 8, 2023 Share Posted August 8, 2023 What prop nut does a inline 160 use? Cheers Link to comment Share on other sites More sharing options...
Artto Ilmanen Posted August 8, 2023 Share Posted August 8, 2023 5 minutes ago, Jon - Laser Engines said: 12 will be fine Thanks, Jon Link to comment Share on other sites More sharing options...
Jon H Posted August 8, 2023 Author Share Posted August 8, 2023 7 minutes ago, Chris Walby said: What prop nut does a inline 160 use? Cheers m8x1.25 so the same as the 100-155 1 Link to comment Share on other sites More sharing options...
Scott Edwards 2 Posted August 8, 2023 Share Posted August 8, 2023 "Chipmunks are essentially metal tiger moths with a wing missing." That's my quality laff of the day 🤣 Cheers 👍 Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 8, 2023 Share Posted August 8, 2023 And there was me thinking that a Chipmunk was a Mosquito made of metal with an engine missing! 2 Link to comment Share on other sites More sharing options...
Jon H Posted August 9, 2023 Author Share Posted August 9, 2023 DH did copy/paste quite a bit! In unrelated news, if anyone was ever interested to know how you make a PTFE piston pad here is a video showing the machine in action. VID-20230724-WA0002[1].mp4 3 Link to comment Share on other sites More sharing options...
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