little dave Posted March 14, 2009 Share Posted March 14, 2009 i live in the desert, it regualry gets over 100 deg farenheit. I ride a 74 dt175. what happens if i overheat? how will i know if it does? what will happen if i do? does it cause permanent damage? also, i was thinking of using manifold tape on the exhaust from the engine to the expansion chamber. good idea or bad? i was going to do this to help keep my right leg a bit cooler. not concerned about hp gain, although it would be nice. Link to comment Share on other sites More sharing options...
Rapco Posted March 14, 2009 Share Posted March 14, 2009 i live in the desert, it regualry gets over 100 deg farenheit. I ride a 74 dt175. what happens if i overheat? how will i know if it does? what will happen if i do? does it cause permanent damage? also, i was thinking of using manifold tape on the exhaust from the engine to the expansion chamber. good idea or bad? i was going to do this to help keep my right leg a bit cooler. not concerned about hp gain, although it would be nice. man if you're bike overheat it will just die. The piston will seize, thats the worse case. I can also do little seizure, but no t get completely welded to the cylinder. If you're piston seize, you will know because the rear wheel will look and you will be sent flying over. But i dont know how you can know if it's overheating before it destroy it-self. Just dont stay full throttle in first gear for an hour, that all i can say. i know that four-stroke that over-heat do backfire. If you're does backfire, stop it immediately. There might be something to do with the spark plug, like move to a colder type. you might foul many more of them but you would have less chance of blowing a hole the piston. But again i'm not sure. Rapco Link to comment Share on other sites More sharing options...
Nor Cal Ed Posted March 14, 2009 Share Posted March 14, 2009 i live in the desert, it regualry gets over 100 deg farenheit. I ride a 74 dt175. what happens if i overheat? how will i know if it does? what will happen if i do? does it cause permanent damage? also, i was thinking of using manifold tape on the exhaust from the engine to the expansion chamber. good idea or bad? i was going to do this to help keep my right leg a bit cooler. not concerned about hp gain, although it would be nice. Hey little dave, found this post in the bar and it said it was moved and now im here in the workshop so i have not read any posts pertaining to your question but here is my opinion. Air cooled two strokes rely on getting the heat they generate away from itself via the cooling fins. I have ridden alot in the Glamis sand dunes on a YZ 465 years ago during the summer months and when its hot outside and you are running it hard, and in the sand dunes with a 14 cup paddle tire you have to stay on the pipe even down hill, you start to hear and feel it bog. What is happening is the piston is expanding from heat so is the cylinder and they are starting to seize. Time to stop and let it cool down. good practice to let it cool down before you get to that point but if you dont know where that point pay attention to your bike and if you start to feel power loss at all pull over and shade up for awhile and enjoy the sights. Real critical to two strokes is their pre mix or oil injection oil. Use a good quality oil this will help protect the top and bottom end from heat. Yamaha has good stuff, back in the day we liked Bel-ray blue. But good oil wont fix stupid. I seized a 125 one time and got lucky. I took the head off and gently used a raw hide mallet to knock the piston loose, after it was stone cold of course, squirted a little injector oil on the top of the piston and exercised the piston up and down a bit feeling for any galling (roughness) making sure the cylinder didnt move up or down, put the head back on and fired it back up. Got lucky. As far as your heat tape is concerned the exhaust wrap is designed for four stroke engines. The idea is that the heat in the exhaust coupled with a tuned headder, four or? equal length tubes coming together in a collector, on a natually aspirated engine, carburated, is supposed to help with the scavenging affect created by individual pulses from each cylinder which cause this syphinning action through the cylinder while the exhaust and intake valve are both open on the intake stroke pulling the inert gases, already burnt, form the cylinder and pulling a full charge of fuel/air into the cylinder before the exhaust valve closes. A two stroke exhaust creates a prescribed amount back pressure which regulates the fuel/air mixture in the cylinder since the two stroke does not have valves. They used to call them expansion chambers. The exhaust would go from the headder pipe to the expansion chamber and create pull affect to a constriction sort of creating a pumping action pulling new charges into the cylinder/bottom end but keeping the charge put by the constriction. adding heat tape would not be recommended. A heat shield would be more appropriate. You want to get heat away from the engine and exhaust not contain it. Besides air circulating around a heat shield will remove heat faster than insulating it with the tape. Remember I said this is my opinion and I will stand corrected by anyone with a better understanding than I have. I am not above learning and welcome any corrective criticisms. Hope this helps a little Little Dave. Also I responded to your offer for help. I would like the phone number to the cycle salvage place you mentioned. And if anyone can help me out my first post to this club is in the Bar titled," yank needs help from across the pond" from Nor Cal Ed Ed Link to comment Share on other sites More sharing options...
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