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  1. #1

    Join Date
    Jul 2002
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    geraldton, AUSTRALIA
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    97

    Saito FA 80 valve clearance??

    I have a Saito FA 80 thats about 8 years old. It hadn't been used for about 2 years untill about 3 weeks ago. It's now making a horrible harmonic type grinding noise, and will not produce full power. I shut it down straight away. I think the bearings seriously need replacing. I don't have a local hobby shop that can do this for me, so I thought I could have a go myself. I have never done this to a four stroke before. Can anyone give me a link to the procedure, or at least the valve clearances.

    Thanks heaps
    Greg

  2. #2
    Moderator w8ye's Avatar
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    Dec 2001
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    Shelby, OH
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    37,112

    Saito FA 80 valve clearance??

    CHANGING BEARINGS
    OS 46FX
    The bearings are the last thing to come out of the crankcase when you are taking a motor completely apart.

    First you must get the connecting rod off the crankpin. To do this you must raise the sleeve out of the crankcase. To do this, you must heat the motor up in the oven with it on a low setting. (Some where between 200-300 F.) (Make certain that you mark the orientation of the sleeve relative to the crankcase before removing.) Then you push the sleeve up with a dowel from inside the crankcase. (While the motor is still hot) When you get the sleeve up, (and the engine cools) make sure you mark the back side of the connecting rod then you can take the connecting rod off the crankpin and push it up out of the way and remove it.

    Now it is best to put the crankcase back in the oven to warm it up again. While still hot, press the crankshaft to the rear and out of the crankcase. It should come out rather easy. But it’s best that you don't hammer it at all. You are trying to force the crankshaft through the front bearing and the prop drive washer. The rear bearing should most likely stay on the crankshaft. I use a drill press to do this.

    Then when the crankshaft and rear bearing are hot, I generally get the rear bearing off the crankshaft by prying in behind it with a small screwdriver and then a larger one.

    To get the front bearing out of the crankcase, you have to have the crankcase hot and push the bearing from the rear. It should almost fall out the front.

    Look at your new bearings, generally, you remove both seals from the rear bearing and leave the front seal on the front bearing, but do whatever you want to.

    To put it back together, heat up just the rear bearing and put the crankshaft in the freezer. Now put the hot rear bearing on the cold crankshaft and press it into place. Let it cool.

    Heat up the crankcase and put The crankshaft and rear bearing in the freezer. Now put the cold crankshaft into the hot crankcase. if it didn't go all the way in, you might could pull it on through with a nut and washer(s) on the nose of the crankshaft.

    Place the front bearing in position on the front of the crankshaft. Try to draw it into position with the washer and nut method. At some point, you can use a wrench socket as a spacer to push the front bearing home. (Do not hammer it).

    Place the drive washer in position and when you install the prop, it will be locked into position.
    Now you can assemble the rest of the engine by re-inserting the piston/rod onto the crankpin making certain that you get the rod oriented correctly. Now you can insert the sleeve making sure you have your mark aligned with the crankcase.
    Re-install the remaining covers, carburetor, etc.
    Attended the CutFinger Institute of DirtNap University for years but never did graduate....
    Recipient, Mangledhand award August 2008
    Club Saito Member #7
    Original AMA #31261

  3. #3
    Moderator w8ye's Avatar
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    Dec 2001
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    Saito FA 80 valve clearance??

    ADJUSTING VALVES
    From a thread on rcuniverse
    The original writer is unknown
    It is the best explanation I’ve seen

    Adjusting the Saito, Magnum, OS, ASP, or Y-S valves can be accomplished by anyone with the right directions. The valve clearance is the same for all of them. Here is the method I have been using with Saito and the other 4 stroke engines.

    Go to the auto parts store and get a blade type feeler gauge with .001, .002, .003 and .004 (one through 4 thousandth's INCH) blades. .002 is the minimum valve clearance and .004 is the maximum recommended by the manufacturers. I like to set to the minimum clearance so that the valve is open the maximum amount of time per cycle (more gas in, more exhaust out!).

    The engine must be absolutely cold (not run that day - room temperature is fine).

    Remove the valve cover(s). You may have to tap it (them) with the handle of a screwdriver to loosen them - pull it (them) off carefully, the gaskets (if present) can tear.

    Bring the piston to the top dead center (TDC) of the compression stroke. It’s very easy to feel. If you are not sure, rotate the prop counter-clockwise until you feel compression, then remove the glow plug and look to see when the piston is at the top of the stroke. If you can't see, insert a straw or small plastic tube (only) vertically into the glow plug hole and slowly rotate the prop counter-clockwise until you feel the piston is at the top of its stroke.

    Hold the prop at the exact position of TDC. It helps if you have 4 hands to do this job, but can be done with only 2. You should now be able to wiggle both rocker arms up and down a bit, as they should have some play.

    Do one rocker arm at a time. Complete one, then do the other.

    Using the tools, unscrew (counter-clockwise) the nut on top of the rocker arm about 1/2 turn. Leave the wrench on the nut.

    Insert your Allen wrench or screwdriver in the top of the adjustment screw on top of the rocker arm - this is the shaft, which the nut is tightened onto. If you have an older engine, it will have a small straight screwdriver slot instead of an Allen wrench fitting. It helps if the wrenches are just about even with each other when loosened so you can hold them with one hand.

    Open your feeler gauge and spread out blades .001, .002 and .003. Make sure no other blades are sticking to them! Fold all the others back into the handle.

    Looking directly at the junction between the rocker shaft and valve stem, try to insert the .002 blade between the rocker arm and the valve stem shaft. I use the side of the blade, but some folks prefer the end of the blade. If you cannot slide it in, turn the Allen wrench or screwdriver counterclockwise a 1/4 turn, and press down on the push rod end of the shaft (the one with the nut on it) with just light finger pressure until you can slide the blade into the gap. Don't open the gap too much, or the push rod can slide out of the socket on the bottom of the rocker arm. If that happens, just re-center it and continue.

    Hold the nut in place with the wrench, and turn the Allen wrench or screwdriver slowly (small amounts!) clockwise while sliding the .002 blade back and forth between the rocker arm and valve stem. When you have a very slight drag (Very Slight!) on the .002 blade, hold the Allen wrench or screwdriver in that exact position and tighten the nut down. Doesn't take a lot of pressure. Use a fingertip only at the end of the wrench to tighten the nut snugly. Remove the Allen wrench or screwdriver and nut the drive wrench. Check again with the .002 blade for a very slight drag.

    Now, rotate the crankshaft two complete turns so that you are exactly at top dead center on the compression stroke again. Recheck your gap. The .001 should slide easily in and out without any pressure. The .003 should not fit, but may if you press hard, because it will cause the valve stem to open the valve slightly. The .002 should fit exactly with a very slight drag. If not correct, and repeat the procedure. A little practice here and you will have it down! Don't use much pressure fitting the blades, they are thin enough to slice your fingers!

    Do the other rocker arm.

    While the covers are off, use a small screwdriver to check that the shafts on which the rocker arms rock are tight - again, not much pressure here.

    Oil the assembly before putting the covers back on.

    Turn the engine upside down and put a drop of oil on:
    the contact point between each rocker arm/valve stem,
    the contact point between each rocker arm/push rod,

    Tilt the engine sideways - put a drop of oil on each valve stem shaft through the spring - don't touch the spring, just let it drip through so the valve stem seal on the head will be lubed during the next step.

    Turn the engine upright: Put a drop of oil on each side of the rocker arm where it rides on the rocker shaft. Finally, put 4-5 drops down each push rod tube. Put the covers back on. You're done. Do about once a year or 10 hours flying time on the engine.

    Do the lubing before starting the engine anytime it has not been run for more than a month. Squirt several drops into the crankcase drain nipple and move the engine around to get the oil into the bearing at the same time. I use a 50/50 mix of Marvel Mystery oil and automatic transmission fluid for my lube oil.

    I hope this has not been too basic - absolutely no insult is intended, just trying to help.
    Attended the CutFinger Institute of DirtNap University for years but never did graduate....
    Recipient, Mangledhand award August 2008
    Club Saito Member #7
    Original AMA #31261

  4. #4
    Moderator w8ye's Avatar
    Join Date
    Dec 2001
    Location
    Shelby, OH
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    37,112

    Saito FA 80 valve clearance??

    Four Stroke Timing
    The proper way to set the timing in all O.S. single-cylinder four-stroke engines As well as the Magnum/ASP types with the front camshaft is:

    1) Rotate engine so that the piston is at Top Dead Center.

    2) Locate the timing mark on the side of the cam gear.

    3) Insert the cam gear so that the timing mark is in a direct line with the center of the cam followers and the centerline of the pushrods. It is NOT at a 90 degree angle to the crankshaft. The angle will be slightly back.

    4) Replace the cam cover and you're ready to go!
    Attended the CutFinger Institute of DirtNap University for years but never did graduate....
    Recipient, Mangledhand award August 2008
    Club Saito Member #7
    Original AMA #31261


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