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</style></head><body id="compText">To all,<br><br>Just received these two messages from Troy Newman respecting Hatori o-ring he woud like me to post on the list. For some reason, he is not able to post.<br><br>Adrian<br><br><br><br>Message 1:-<br><pre class="WMmessagebody">the NMP replacement viton o-ring is sized to accept the NMP header NOT the <br>Hatori header. The Hatori is 15mm and the NMP is 5/8" the difference between <br>the or-rings is about 3.5-4 thousands on the ID. This will be enough to <br>cause it to leak. Hatori makes a Flourine o-ring that comes with the 821 <br>pipe. This o-ring is available via Central Hobbies as well as well. They <br>cost a few a couple extra $ because it is a Hatori part.<br><br>If you are using the Hatori header you need to replace the o-ring with the <br>Hatori original o-rings. And yes 50-75 flights is normal replacement time <br>frame. Better cooling of the engine will help this situation a ton. Lack of <br>good cooling will eat o-rings much much faster. The Hatori original <br>replacements are available from Central Hobbies as is the NMP adapter o-ring <br>for the NMP header..<br><br>Proper cooling on your engine and exhaust system will extend the life of the <br>o-ring, improper cooling and abuse will eat the o-ring in as little as 5-10 <br>flights.<br><br>The NMP o-ring replacement for the NMP header is a much more robust material <br>than the Hatori Original. The Viton material on the NMP will tend to last <br>quite a bit longer than the Hatori originals. I have models using both the <br>NMP header with the replacement o-ring to fit that header and the Hatori <br>header-and o-ring versions. I can get about 50% better life out of the NMP <br>header/NMP o-ring version. I think it has to do with the cooling properties <br>of the NMP header.<br><br>I have been running the replacement o-rings for several years.<br><br>With either setup, hatori header-hatori oring and hatori pipe or NMP header <br>and o-ring the better cooling you have the better the life you will get from <br>the o-ring.<br><br>The replacement of the o-ring is a quick and simple process.<br><br>This is the o-ring on the pipe header connection not the o-rings in the <br>engine. For those that are confused<br><br><br>Message 2:-<br><br>If you have your engine leaking it is because the engine has a leak, orings, <br>gaskets or the likes. On the DZ engine you can to some extent overcome this <br>issue by richening the pump a bit, however the leaks will always get worse <br>and worse. The black plastic check valve could be a source if you have <br>removed the little black clip that hold the fuel line to the intake tube. <br>The fuel line will pull on that check valve and cause it to wobble at its <br>base. Next thing is intake tube o-rings, valve cover gasket, and front <br>pushrod tube o-rings are next in line. A super rich pump setting can spit <br>from the carb intake " air valve" with excess oil that is in the bottom of <br>the engine. I have also seen loose head bolts cause this issue. If you have <br>an issue with the head bolts coming loose, replace the head gasket with a <br>new one and then tighten the head properly.<br><br>To solve the leaks replace the o-rings and or gaskets clean everything with <br>denatured alcohol and re-assemble with both parts clean and dry. In some <br>cases a small amount of alcohol will help lube the o-ring as it seats...but <br>do not install with any oil. Do not use rubbing alcohol for this as it <br>contains some water content. Denatured alky is the stuff to use. You can <br>make them absolutely dry as a bone doing this.<br><br>This issue can be masked if you have a leak in your header to pipe <br>connection as addressed ina previous email.<br><br>Troy Newman<br><br><br></pre><br><br><br></body>