General Category => Engine & Transmission => Topic started by: Mike Sal on April 03, 2012, 04:20:04 AM
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I ordered a new one from Wayne, but it looks awful. It looks like a jitterbug sander was used on part of it. The only reason I ordered a new one was that mine was dull looking & I didn't know how well it would clean up. What's up with the finish Wayne put on it? It will take a lot of sanding & finish work to make it look ok. I'd be better off with my old one.
Mike Sal
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I got one from Wayne last year and it was a smooth mill finish on it. Call him and see what's up.
Rick
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I've got one ordered and on the way probley come to me latter this week.nothing to compare it to my original is MIA. Let you know how it looks.
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I had thought about just making one from some stainless steel (I have whitney hole punches and some stock laying around), but I wanted to have the "stock" appearance.
Mike Sal
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A bit swirly but just happy to have it , ill polish on it some see what happens
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I thought I would post a pic here of the back side of the compression plate I've never seen one before until today and its been a bit of a mystery to me as to what it was, so if any other guys out there have ever wondered mystery solved.
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That is not a factory compression plate. Wayne does not have any used ones so he started making aluminum ones. I don't think you need the cover plate with those, as I assume in is solid. The factory plates are stamped steel, and are dished,that is why they use a cover.
Rick
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I've wondered if it would be of any benefit to put a filler in the "hole" between the compression plate and the cover. I would think that any "rattle" in the engine would be amplified by the "drum" created by that space. Any thoughts?
Mike Sal
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My '48 just has a flat disc. What is the point of the inserted section?
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The portion of the compression plate that "goes inside" the crankcase is to take up space to even out the volume above & below the piston. I wonder how differently your bike would run with one vs not having one. I seem to recall someone saying that the motor would be harder to start.
Mike Sal
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I was told they wouldn't run at all. Mike could you post a pic of an original with both pieces
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When I got my bike it had two of just the covers and no insert piece. I thought that to be a bit redundant so only used one of the flat discs. Truth is they do run without the insert piece. I have been doing it for years. Things is it makes perfectly good since that it would take up volume thus being able to charge the cylinder better. Mine has always started well.
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Those plates or there so when the piston travels up it will create enough vacuum in the block to draw air/fuel mixture in. If you take it out and just have a flat plate there you would cut the vacuum down by over 50% or more. The smaller the space the quicker vacuum starts as the piston travels up so more air/fuel mixture is drawn in.
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I'm really surprised to hear that an engine would even run without a compression plate. Your motor must have outstanding vacuum. Tom, have you done this on any other simplex motors, or just this one? Wayne at one time had a high compression cover, but I don't know if it really helped or not.
Rick
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Here's what the stock compression plate looks like.
Mike Sal
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Runs well now. Can't wait to see how it runs with one! Being that I restored the running clearance of the rotary valve via all of the machine work must be the trick.
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I have a 52, and mine does not have the inner piece, just the cover, now i am wondering if it is going to run correctly after i get the crank back in it?
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Before Tom said his ran without one, I would have bet money on NO. Now, I guess it can!
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I would think it would have to run better with the plate. I wonder how much the gas mixture has to be adjusted from with and without the plate in place?
Mike Sal
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My servi-cycle went under the knife today. I am making the crankcase insert. I have taken all the dimensions I need but the ones pictured look alot deeper than mine will be. It will be inserted 7/8". Does this sound about right. I just wonder if earlier blocks were shallower and didn't require one so intensively. Maybe when I get to Portland I will ask Wayne. None the less it can't hurt and one is in the works!
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I noticed that the picture of the compression plate Mike Sal posted has 12 bolt holes where as mine has 8 bolt holes.
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The depth of my plate is 1.062 inches. I never noticed that the older crankcases were 8 holers. I wonder if they added the extra bolts when they made the bigger crankcase to accommodate the bigger crank?
Mike Sal
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Crankcase stuffers were not uncommon on early 2 stroke engines. Many racers increased the volume of the stuffer to get better fuel-air intake. Wayne promoted his stuffers as greatly improving starting due to the incresed volume.
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Crankcase stuffers were not uncommon on early 2 stroke engines. Many racers increased the volume of the stuffer to get better fuel-air intake. Wayne promoted his stuffers as greatly improving starting due to the incresed volume.
I spoke with Bob Kerr, and he does not think this does anything at all. The compression takes place above the piston, and the amount of air drawn in is determined by piston travel.
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I would think that by reducing the volume of the crank case, it would servce to make sure more oil had the chance to "fall out" of the air and onto the crank bearing & cylinder surfaces where it's needed and not on surfaces (addtional crankcase wall surface area) where it's not needed.
Mike Sal
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in waynes defence, they dont come polished. i have 10 that i had waterjet made. you have to polish them yourselves. the cost would be alot more if they came polished. ???
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I know mine starts way better with it. Went with out it for years AND there is a difference. Being of the third port design is is necessary to have base Pressure to charge the cylinder and it would stand to reason that if the case volume was larger than the cylinder volume it may caause is issues. recalling the 2-strokes I have worked on seems like there was just enough room for the crank to spin. Waynes experience told him that a model M wouldn't "hardly run at all" without one and the early blocks will but run better with it.