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| Engines Discuss engines |
Topic Review (Newest First)
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| 09-14-2016 04:09 PM | |
| hitechflyer |
Re: OS Surpass 70 Problem All my four strokes were mounted inverted, made for better exhaust exit. You can get a wrench inside the cowl with out making a big hole to reach. |
| 09-14-2016 03:59 PM | |
| williame3590 |
Re: OS Surpass 70 Problem That's where the high heat silicone comes in Rob. Your situation is not at all uncommon. Just make sure the silicone is fully cured prior to starting the engine. Bill |
| 09-14-2016 03:53 PM | |
| bbbair |
Re: OS Surpass 70 Problem All VERY good points guys. BUT! The problem was caused by the use of a Cowl.  The Cowl would not fit on over the muffler pipe, so off came the pipe! On went the Cowl and then I had to wiggle the pipe and muffler into position and tighten as best I could through the cowl.  Needless to say I did not do a perfect job every time that I mounted the Muffler. This would be an 'OOPS' and a good lesson for all,  So.... Save an engine... NEVER USE A COWL! 
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| 09-14-2016 08:30 AM | |
| hitechflyer |
Re: OS Surpass 70 Problem I always retighten after a good warm up. Never had a problem. |
| 09-14-2016 05:10 AM | |
| floyd |
Re: OS Surpass 70 Problem I don't back off the header to line it up. I use aluminum washers from a coke can to line up my header. Or the aluminum spacers that come with the Saito straight pipes. I also use plumbers tape to tighten it up and keep it tight. Cheers Floyd |
| 09-13-2016 02:36 PM | |
| RAMJET |
Re: OS Surpass 70 Problem This engine was never intended to use thread locker nor is it necessary to use it if you tighten it correctly is what I was saying ,but they need to be pretty damn tight or they will come loose, it's not like there is a rash of os mufflers falling off LOL so most guys figure it out without busting the port. I can see using loctite if you have buggered the threads from not tightening it correctly in the first place . Obviously tightening something so much you are breaking parts would be no better then leaving it too loose .I guess the best Idea would be to get help from someone having success not guys breaking there ports off LOL.. |
| 09-13-2016 09:05 AM | |
| kip51035 |
Re: OS Surpass 70 Problem The threads in this engine are a fine thread in a cast aluminum head making it very easy to strip the thread. The casting at that point is quite thin and over tightening actually broke a piece out of the casting on my engine. Your favourite high temp thread locker, epoxy aluminum, metal set or one of those is a better choice. Over tightening can cause permeant damage. Try cutting a 1/16" off the end of the pipe so the threads can catch what is left and use something to glue it in place. |
| 09-10-2016 07:35 PM | |
| RAMJET |
Re: OS Surpass 70 Problem This was likely caused by the muffler not being tight enough at some point. you really need to crank those pipes tight on a 4 cycle ,but once the threads are damaged the only real fix is a new head and pipe. if the thread is the same on both ends of the header pipe you may try to put the muffler end of the threaded pipe into the head (some versions had a one piece pipe and muffler so this would not work) the other option would be to cut the pipe and put a metal flex pipe between the header pipe and muffler and strap the muffler to the plane (the weakened threads may be able to support just a header pipe without the weight of the muffler attached ) also check to make sure the prop is well balanced to prevent excessive vibrations. actually this is not a common problem at all unless you don't tighten the lock nut correctly or like mentioned above don't get the header threaded in all the way. you could actually try red or green loctite but it would likely release at the running temps of the 4 cycle engine anyway . loctite is easily released with a bit of heat if service was needed (propane torch works well for this ) even permanent loctite will release no problem with a bit of heat and that is why this is not the best solution for this problem but it can't hurt to try . anyway good luck cheers Roger |
| 09-10-2016 05:45 PM | |
| Cougar429 |
Re: OS Surpass 70 Problem I have at least a dozen 4-strokes in service and many more run on the stand before storage. NONE have ever come loose. The best way to ensure they remain tight is to clean any residue oil from both tube and head, thread the nut all the way down to the other end, bottom the tube completely, then back it out ONLY as much as needed to aim where you want. If you bottom the tube you can add quite a bit of grunt to the lock nut safely. If not full engagement that amount can tear the threads out of the head. Only problem is if vibration has worn the threads to the point you cannot tighten the lock nut very snug without risk of further damage. If that's the case the teflon tape may help. You still have to lock that nut solid or it will work loose again. DO NOT use any Loctite products. Most of the low strength will soften with heat and the ones that don't are permanent, meaning you will likely tear the threads out of the head upon removal. |
| 09-10-2016 05:23 PM | |
| williame3590 |
Re: OS Surpass 70 Problem Teflon tape works or a little high heat silicone on the threads. Bill |
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