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Apr 07, 2018, 08:45 PM
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rocky7390's Avatar
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Help!

OS FT 160 Cylinder Jacket Screws


I have tried everything I can think of to remove the cylinder jacket allen head screws. I want to change bearings on a used engine I bought. Tried heating in oven. Heating with heat gun. Heating with torch. Soaking in penetrating oil. Since there is not a straight shot for the wrench I'm already approaching stripping the screw heads. I had one screw like this on the valve cover and was able to drive in a size 9 Torx bit. Did the trick but there is no room for that approach here. If you know this engine you know there is not a straight shot for the wrench which makes the grip less than perfect. A ball driver goes in but I'm afraid to put too much pressure. I even cut Allen wrenches to make the short end even shorter. They go in but start to cam out.
Any insights are appreciated.
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Apr 07, 2018, 09:09 PM
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rocky7390's Avatar
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Here is a picture of the problem
Apr 07, 2018, 11:29 PM
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I have done 3 sets of bearings on this type of engine . One because the owner wanted it done , a waste of time and money ! The second and third because of crashes , the third , a broken crankcase was the most complex as I had to tig and re machine . In neither , the bearings needed replacement but was prudent I suppose . I had trouble with a few of the socket headed bolts . Five I had to machine off the heads in the rocker covers and then loosen the studs with a small stud remover I made for the job , the cylinder/crankcase screws I lost one of , had to setup and machine off the head and remove the stud left . I have a small propane torch with a fine but hot flame that I heat the area around the thread , not the head and 99% of the time with a good quality metric key cut to a usable length , have got them out ok , but I stress , it must get HOT , not just warm or GEE THATS HOT , an oven and a heat gun just won't do it . I also think that OS at that time didn't seem , to me , to be using the usual quality of socket head screw as they normally used , but that's just my observation . My suggestion at this stage would be if the socket has started to round out , heat as I stated above and a good pair of small multi grip pliers . Failing this , machine off the heads and remove the studs as above . I wish you good luck with your project .
Apr 07, 2018, 11:38 PM
Registered User
I had a problem removing the valve cover screws on my OS Pegasus. The hexes just rounded out even after trying fresh Allen wrenches. I ended up drilling off the heads after which the shanks of the screws came out easily.
You may end up having to cut the heads off of those cylinder retaining screws as I can see that a drill won't fit into that space.
Apr 08, 2018, 12:07 AM
No more wasted spark 😉
ClubFlyer's Avatar
OS must have used red loctite on some of these engines. I bought my FT160 off Ebay, changed out the bearings, rods, and piston rings. Did not really have much of an issue dismantling the engine. On rare occasions when socket head screws are hard to remove, you can cut a slot across the socket head using a dremel tool, and then use a flat blade screw driver to get a better purchase on the socket head. Heating and then sudden cooling with liquid freeze will break the fiction lock.
Last edited by ClubFlyer; Apr 08, 2018 at 01:41 AM.
Apr 08, 2018, 02:41 AM
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Reginald's Avatar
I had the same problem on a 120 and did publish it here in another thread... I had to mill off the heads on all 8 bolts... but I do not believe that OS uses red loctite on any of their engines... in my case a previous owner did use the stuff and I am pretty sure your engine has the same history...
Apr 08, 2018, 07:28 AM
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Cougar429's Avatar
I just built one from two engines and the trick is to use a shortened stock allan wrench. The second engine had one in the box, but I had already made one by the time it arrived.

The key is to cut down the short length of a good quality wrench and do it slowly to avoid overheating and affecting the temper. Also, ensure the end is square. Don't have to remove much, just enough to allow the wrench to fit into the bolts.

This wrench will be required to adequately tighten the bolts upon reassembly, as well.

ps. Low quality wrenches will be soft to begin with so no amount of work will make that any better.
Apr 08, 2018, 09:45 AM
Let's Go Brandon
Gary Cee's Avatar
Seems the cylinder base and rocker cover screws are problem areas here more often than not.

The obvious need for a short sided hex key is the first step. It should be a good quality tool and unworn. I have used the 1/4 Apex type screwdriver bits that I shortened at both ends. You can then use a 1/4 open end wrench to turn the bit.

As Geoff Potter already said, the important element is indeed heat. The screws that OS used seemed a bit lame to me as well so I appreciate Geoff’s note in that regard too.

Just avoid wallowing out the hole !
Latest blog entry: Responsible fliers.
Apr 08, 2018, 11:52 AM
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rocky7390's Avatar
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Afraid I already "wallowed out" one or two of the holes to some extent. Not totally. I appreciate all the insight so far and will try to follow what you others have done. Any other suggestions are appreciated. I have tried to keep the heat to a minimum but as suggested it probably needs to be "hot". What type of torch are you using?
Apr 08, 2018, 12:10 PM
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I TOBOR's Avatar
Cut off Allen wrench and it needs to be exactly the correct size.
Apr 08, 2018, 12:22 PM
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Quote:
Originally Posted by I TOBOR
Cut off Allen wrench and it needs to be exactly the correct size.
And be sure you don't overheat the wrench while cutting it shorter. They can be cut with a fine pitch hacksaw blade.
Apr 08, 2018, 12:28 PM
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I TOBOR's Avatar
Jim, is this your 706? Thanks
Apr 08, 2018, 01:50 PM
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Quote:
Originally Posted by I TOBOR
Jim, is this your 706? Thanks
Actually it refers to an obscure telescope mounting that I purchased over 30 years ago. I'll let you look it up if you're curious.
Apr 08, 2018, 03:14 PM
Let's Go Brandon
Gary Cee's Avatar
In a similar situation with a 3 mm screw I drilled a sideways hole through the screws head , passed an Allen wrench through the holes and broke the screw loose T-bar style
LOTS of heat every time you try!

One of the last resorts is cutting the head off with a friction wheel in the Dremel.
Usually enough screw left to grip with vise grips.

Lots of heat
Latest blog entry: Responsible fliers.
Apr 08, 2018, 05:45 PM
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I TOBOR's Avatar
Quote:
Originally Posted by 706jim
Actually it refers to an obscure telescope mounting that I purchased over 30 years ago. I'll let you look it up if you're curious.
I see, pun intended, I thought maybe you were Canadian farmer.


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