Piston Stop Tool

[Mark44]

I had to put down the iPhone and get out the laptop to update this one...

Piston stop tools are used for finding EXACT top dead center. NOT FOR HOLDING THE ENGINE WHILE YOU TORQUE ON/OFF A FLYWHEEL OR COUPLER. TBM is straight up retarded for recommending this.

The correct use of a piston stop tool goes like this:

1. remove flywheel cover

2. make a pointer. I use a paper clip and a short 10mm bolt (actually a 6mm x1.0 bolt, but it used a 10mm socket) that I screw into the top hole.

3. install piston stop in #1 spark plug hole and set it so the piston stops just before TDC. (turn the engine over by hand) Make this point on your flywheel at the pointer.

4. turn the engine over the opposite direction until the piston gently hits the stop again. Make another mark.

5. measure between the two marks and mark the MIDDLE. This is your EXACT TDC.

For some dumbass reason I used a piston stop while installing my new Cold Fusion couplers. I knew better but I was being lazy. The piston stop damaged the top of my front piston.

Aaron

I have had to stand on a breaker bar and use heat on a couple couplers so yes I would not use the stop tool if the torque was that great. Never had an over torqued fly wheel so the stop tool would work ok. I think it is more of a common sence type tool.

Mark44

 

[WAB]

The bad thing about the rope in cyl method is that all the force is right on your dome in the head which can crack.
I use a chain wrench (vice grips) around the flywheel.

I don't see how you can get the flywheel off w/o pulling the gastank. flywheel pullers taht I have seen will not fit in there w/o pulling the tank....

 

[Waternut]

The bad thing about the rope in cyl method is that all the force is right on your dome in the head which can crack.

How is that any different from normal combustion?

 

[Motorheads5]

I actually bought two of them thinking that i would spread the stress out on two pistons at once but one seems to be more than adequate.
IN2-H20


?? UMM not sure what you are thinking here.

 

[parrdaddy]

I had to put down the iPhone and get out the laptop to update this one...

Piston stop tools are used for finding EXACT top dead center. NOT FOR HOLDING THE ENGINE WHILE YOU TORQUE ON/OFF A FLYWHEEL OR COUPLER. TBM is straight up retarded for recommending this.

Aaron

Interesting, as Yamaha Motor Corporation also reccomends a piston stop for removing items on the crankshaft.

For the record, I have used one several times with no problems yet. If you go back and look at a piston, it is solid from the dome to the pin.....and pretty thick at that. If you punch through all that material with a piston stop, I would find it hard to believe that you would have gotten off the stuck part any other way either. And from a column buckling standpoint, I can't see how a rod would bend before the piston stop since it should be a fair bit larger on a section view.....but that all depends on the tool and rod. On a yamaha motor, the rod would pretty much have to be previously damaged for a piston stop to bend it more. Of course this is all my meaningless opinion based on the yamaha 701 platform, but each case is different.

 

[OCD Solutions]

I actually bought two of them thinking that i would spread the stress out on two pistons at once but one seems to be more than adequate.
IN2-H20


?? UMM not sure what you are thinking here.

Install one in each piston and spread out the force. The force is the same but instead of all of it focusing on a single point on one piston, it's spread out over twice the area, pretty simple physics, I hope you were hung up on my wording and not the concept. :dunno:

 

[parrdaddy]

Install one in each piston and spread out the force. The force is the same but instead of all of it focusing on a single point on one piston, it's spread out over twice the area, pretty simple physics, I hope you were hung up on my wording and not the concept. :dunno:

I think he was hung up on how you would get both pistons at BDC at the same time :Banane37:

 

[OCD Solutions]

If one is at BDC then the other is TDC, the idea is to have everything in alignment isn't it and not at any angles?

 

[Algonquin]

If one is at BDC then the other is TDC, the idea is to have everything in alignment isn't it and not at any angles?

But still one is moving up while the other is moving down. Plus due to the angles the pistons virtually do not move during the 10 or so degrees of crank throw when the pistons are at tdc and bdc.

Plus to minimize the force on the piston and rods you want it in the middle of its stroke. This makes the lever arm the largest.

I don't like using these tools or rope. I always use impacts for removal and for proper torquing made a tool that can be bolted to the three bolt holes in the flywheel. Its more for piece of mind

 

[Motorheads5]

Install one in each piston and spread out the force. The force is the same but instead of all of it focusing on a single point on one piston, it's spread out over twice the area, pretty simple physics, I hope you were hung up on my wording and not the concept. :dunno:

Never are both piston's going up or down together at the same time. there is only ever a need for one tool. That is what I was getting at.

 

[OCD Solutions]

Gottcha now, my bad. Thanks for straightening me out guys.

 

[parrdaddy]

Plus to minimize the force on the piston and rods you want it in the middle of its stroke. This makes the lever arm the largest.

I agree, and that is the length I used when I made my stop tool.

 

[crammit442]

Interesting, as Yamaha Motor Corporation also reccomends a piston stop for removing items on the crankshaft.

For the record, I have used one several times with no problems yet. If you go back and look at a piston, it is solid from the dome to the pin.....and pretty thick at that. If you punch through all that material with a piston stop, I would find it hard to believe that you would have gotten off the stuck part any other way either. And from a column buckling standpoint, I can't see how a rod would bend before the piston stop since it should be a fair bit larger on a section view.....but that all depends on the tool and rod. On a yamaha motor, the rod would pretty much have to be previously damaged for a piston stop to bend it more. Of course this is all my meaningless opinion based on the yamaha 701 platform, but each case is different.

You got me wondering last night so I went and looked at my OE manual. It actually says use a spanner tool for holding the flywheel. I couldn't find anything specifically on coupler removal. FWIW.:scratchchin:

 

[Motorheads5]

Gottcha now, my bad. Thanks for straightening me out guys.

It's all Good

 

[GIL]

You got me wondering last night so I went and looked at my OE manual. It actually says use a spanner tool for holding the flywheel. I couldn't find anything specifically on coupler removal. FWIW.:scratchchin:

Are you talking about part# YB-06139/90890-06522 ??? This is the flywheel holder tool that my oem manual shows. My manual says to use this to remove coupler from crank and hold flywheel to remove/torque flywheel bolt. :scratchchin: FWIW

The World Famous

 

[parrdaddy]

You got me wondering last night so I went and looked at my OE manual. It actually says use a spanner tool for holding the flywheel. I couldn't find anything specifically on coupler removal. FWIW.:scratchchin:

I'm not sure about the manuals, I was told this by a friend that went to Silver and Gold training at YMMC. He said they used them there during class.......so I would assume they don't disagree with use of this type of tool.

 

[Matt_E]

You were told by a friend that went to.....that told him......

I'd go by manual. :clown:
I have yet to talk to a builder that uses a piston stop tool for this. FWIW.

 

[parrdaddy]

You were told by a friend that went to.....that told him......

No, I was told by a friend that sat through the classes and did the lab work, at Yamaha, with a piston stop tool, supplied by Yamaha. Is that better?

Of course, I'm sure most manufacturers keep tools around that they don't intend to use, he probably dipped into the wrong toolbox :shhh:

 

[Idok]

any chance you have pix of the yamaha tool???

 

[parrdaddy]

any chance you have pix of the yamaha tool???

Not me. I made my own but I'm not sure how similar it is.