aljken Posted December 28, 2016 Share Posted December 28, 2016 Well my exhaust muffler finally cracked. It's a vertical crack 7 to 10 cm long, not all of it going right through the steel muffler I don't think. I got it welded for £20 which has fixed most of it, except a few tiny spots where oil can be seen to have escaped after a flight (of 30 mins or more). The level of oil leak is now tiny (especially compared to the leak I used to get from where the muffler joins the motor (with springs holding it on, until that gunked up and stopped leaking). The welder's kindly offered to reweld it for me for free. This got me thinking: Is it a problem flying with a muffler with a tiny crack in it? Surely the power is just a tad lower in the engine, or does it have other effects? Does it lean it out? I realise it must be a weak spot while it's leaking a little - so probably worth fixing properly. What would others do? fix it via welding, buy a new one (new one is about £270)? I've heard of getting the muffler coated with ceramic, has anyone else heard about his or tried it? I'd appreciate your advice or opinions. Cheers, Alex Quote Link to comment Share on other sites More sharing options...
GR002 Posted December 28, 2016 Share Posted December 28, 2016 I would not fly with a cracked exhaust as crack will spread. A Piece could break off and damage your prop. I have welded mine in the past. Quote Link to comment Share on other sites More sharing options...
aljken Posted December 29, 2016 Author Share Posted December 29, 2016 Well I got it rewelded today. tested it out this afternoon and no little leaks after 1 hr of flying. I'd still be interested to hear of others experience and the coating of the exhaust with ceramic. Cheers, Alex Quote Link to comment Share on other sites More sharing options...
admin (Simon W) Posted December 30, 2016 Share Posted December 30, 2016 The ceramic coating is not a strength thing, it more a heat related tuning thing I found this nice simple explanation on www.cartuningtips.com Ceramic exhaust coatings are gaining popularity with performance car tuners. We will take a look at why so many people are getting ceramic coatings applied to their exhausts. In very general terms cooler air means greater potential engine power. We can assert this because it follows that the cooler the under bonnet temperature is the cooler the air intake charge will be. Cool air carries more oxygen so allows more fuel to burned. Even in cars where cold air is fed directly from the outside of the car into the intake you will still experience a minor power loss as heat is conducted through the intake system to the intake charge. It is also true that hot exhaust gases flow more quickly than cooler gases. Indeed a cooling of the exhaust can cause dramatic alterations to the flow characteristics of the engine. The aim then is to trap all this heat in the exhaust at least until the pipes clear the engine bay. This has the added benefit that the catalyst gets up to temperature more quickly and start working efficiently. Why choose ceramic then? Well ceramic is a very poor conductor of heat and is therefore a great insulator. It can be bonded to the exhaust permenantly, looks much better than a bare metal pipe and will help the exhaust to resist corrosion.-- Read more at: http://www.cartuningtips.com/112-ceramic-exhaust-coatings - (c) CarTuningTips SW 1 Quote Link to comment Share on other sites More sharing options...
Hann__ Posted December 30, 2016 Share Posted December 30, 2016 What motor is this on? Quote Link to comment Share on other sites More sharing options...
aljken Posted December 30, 2016 Author Share Posted December 30, 2016 This is for a Polin Thor 130. Thanks for the info about ceramic coating Simon. I doubt anyone actually knows if it will increase performance in a 2 stroke engine of not then? From what I understant then, ceramic coating a muffler would probably increase the heat of the exhaust gases. Who knows what this would cause? I think increasing the heat of a gas increases it's viscosity. Also increasing it might increase the pressure within the exhaust - who knows what effect this would have on the engines performance (and a crack in the exhaust). Maybe in the future this will become standard on paramotors?! Quote Link to comment Share on other sites More sharing options...
Vauxscott Posted January 3, 2017 Share Posted January 3, 2017 Another thing to consider with ceramic coating is if it cracks again it makes it very difficult to do a weld repair. You struggle to get the metal clean enough to weld properly. There isn't much benefit of coating a paramotor exhaust anyway other than the bling factor. The reason they crack is the horrible vibration they endure and they are made to be as light as possible using the thinnest material possible. It would be possible to make them from thicker material but the trend seems to be cut weight at any possibility. After years of racing motocross and suffering so many exhaust issues, they're treated as a consumable with a finite lifespan. I see no reason a paramotor should be different? Scott. 1 Quote Link to comment Share on other sites More sharing options...
aljken Posted January 5, 2017 Author Share Posted January 5, 2017 Yep I definitely think your last sentence sums the situation with paramotors up nicely! There's quite a bit of my motor which is not original now, but the good thing is that it's easy to replace and the motor works way better than when I bought it. Quote Link to comment Share on other sites More sharing options...
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