Help - ST90 timing advance plate removal

Discussion in 'CT90, CT110, ST70, ST90 Discussion' started by Thumper1500, Feb 11, 2018.

  1. Thumper1500

    Thumper1500 New Member

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    Hi all,

    I'm new to this, but working on a '73 ST90 K0 project. It's generally going well, but I ran into an issue. Per the Clymer's manual, you simply remove the points plate, remove the center bolt and the timing advance plate is supposed to come right off. However, it won't budge and I don't want to screw anything up. I've been applying WD-40 for two days now and have tried gently prying upward via various means while tapping the center shaft lightly with a hammer, but it won't budge. Any help you can provide would be much appreciated! Attached is a pic I took before removing the center bolt.

    ST90 timing advance plate.jpg
     
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  3. b52bombardier1

    b52bombardier1 Well-Known Member

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    That 10 mm bolt should easily come off with a counterclockwise turn. Is the engine spinning as you turn that bolt CCW? If yes, you may need to put a socket on the flywheel to keep the engine from rotating. No prying required here and that bolt does not need to go back on with the same level of torque you are now experiencing. Bring a friend over to help or sew another pair of arms onto yourself at the waist because this quickly becomes unwieldy. There could also be some rust on those 10 mm bolt threads and a little propane torch heat might break that bond.

    After removing the advancer assembly and BEFORE taking the major pieces of the advancer apart for cleaning and lubrication - USE A SHARPIE MARKER to note how those pieces came apart and go back together. You have a 50-50 shot at guessing wrong here at re-assembly and if you are like me, you will say a lot of horribly bad words and drink too much beer when you figure out why your engine only sputters. This is because your spark will occur 180 degrees out of phase for engine timing even though there is only one way that advancer assembly goes back onto the end of the camshaft.

    Trust me here . . . . that hump cam shaft lobe will be in the wrong place if you re-assemble the advancer wrong.

    Rick
     
  4. b52bombardier1

    b52bombardier1 Well-Known Member

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    Ah . . . I get it now. You already have the bolt out. I'm a pictures guy, I guess. I'm thinking heat from a small torch will still be the answer here. My prediction is the seal behind the advancer has leaked oil and it has cooked to the point that you can't remove it. That and a little rust and it can be stuck pretty good.

    It will come off and I have an extra advancer if you need it. Just don't lose your springs . . . they are 30 bucks a set from Yamiya in Japan plus shipping - last time I checked. Same springs as on an early to mid 70's Honda 750.

    Rick
     
  5. Thumper1500

    Thumper1500 New Member

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    Thanks for both pieces of advice Rick! I hadn't thought of using heat, but that's a good idea - I'm going to keep WD-40 on it to hopefully disolve the gunk/oil/whatever, and then I'll try the heat too. There's just no good way to pry on it. I took the bolts out of that cover behind the advancer and am applying gentle pressure upward on it, but have to be careful not to mar the gasket surface and I can only get about 1/4" anyway. I'll let you know if that works out in a few days.
     
  6. Thumper1500

    Thumper1500 New Member

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    Well, I tried heat, carefully, but no go. After a week of WD40, I started using penetrating oil. After another week of letting it soak, I tried carefully prying up with the base cover whilst tapping on the center sleeve with a hammer to see if I could loosen it. Nothing. Then I soaked it for two days using kerosene and tried again. No go. I finally decided the only possibility would be to find a small, two-arm puller I could get under the edges of the advancer plate where the perimeter dips inward on each side. I couldn't find what I was looking for, so finally decided to try a valve spring compressor sort of like the one below - I just removed the E-clip and all that center piece. It took a small amount of grinding to get the ends narrow enough to squeeze in, but it worked and it's finally free! There was either baked oil or corrosion in there that was holding it on.

    spin_prod_214458601?hei=832&wid=832&op_sharpen=1.jpg
     
  7. b52bombardier1

    b52bombardier1 Well-Known Member

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    Excellent work!! And I'm fascinated by the tool pictured above. Looks like something out of the tool drawer for a dinosaur dentist.

    Rick
     
  8. katiedog

    katiedog New Member

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    Hello,

    I am having the same exact problem with my 79 and just received the puller that you showed above. I am by no means a seasoned mechanic and relying on the expertise of those in these forums. How exactly did you use this puller to get the assembly off? Does it need to be modified? Do you have any photo's? Any suggestions to get this off the camshaft would be greatly appreciated. Beyond frustrated with this as every video I have seen show it sliding right off??

    Scott
     

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