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Torque plates??

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Torque plates are plates bolted to the top and bottom of the cylinder to simulate the cylinder in the motor. The torque plates in this case are toqued to 27 ft lbs, same as if they motor was assembled.

Are they required?

My motor has 1 3/8 aluminum plates , one top , one bottom with threw bolts torqued to this 27 FT lbs.

The block was bored out, the sleeve pressed in and then the sleeve was bored to the required diameter, It was honed for .0025 to .003 cleanance. The recommended it .0035 but I don't beat on my bike so a little tighter.

The torque plates remaind on for all this but tonight after carefully rechecking the bore they were removed and once agian the bore gage was used to check the roundness.

My once .003 round hole in places went to .006 in one dimension and .001 in the other?? It was like that all over except the part that hands below the cylinder, the part in the crankcase, it remain relatively round.

The torque plates are a necessity. Without them you have a round cylinder until the motor is assembled and then you perfectly round cylinder becomes an oval, like mine.

I am hoping once the motor is assembled the bolts torque my cylinder once again returns to being round.

Torque plates are required for any boring so don't let a machine shop do the job without them if you are building a 780 or even the 725.

My torque plates also make it easy to hold the cylinder on the lathe for boring

jq49xd.jpg

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My once .003 round hole in places went to .006 in one dimension and .001 in the other??

Wow! That is some major deflecting.... really makes me think about the next deflecting force involved... heat. A good question is how much tweaking is going on when everything is up to operating temp? There certainly has to be some. I wonder if preheating the cylinder and torque plates to something around operating temp would be of any value? Hopefully your decision to tighten up the clearance doesn't cause you issues down the road. :) Very interesting info. Thanks for sharing. :lol:

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Wow! That is some major deflecting.... really makes me think about the next deflecting force involved... heat. A good question is how much tweaking is going on when everything is up to operating temp? There certainly has to be some. I wonder if preheating the cylinder and torque plates to something around operating temp would be of any value? Hopefully your decision to tighten up the clearance doesn't cause you issues down the road. :banghead: Very interesting info. Thanks for sharing. :lol:

Yes it is scary. I ended up going closer to .003 clearance then the original .0025 I thought. I chickened out. the specs call for .0035.

I have know about torque plates 40 years ago and have used them on every engine since then.

Used them on the harley last year.

Yes my .003 went to .006 in one direction and shrank down to .001 in the other.

I am tempted to use my old gaskets, top and bottom and reassemble the torque plates, torque to bolts to 27 foot pounds and once agian check the bore for roundness. I am just afraid of what I will find.

heating the cylinder would be another good test but I don't know if I want to really know.. I do know that some engine shops talked about running hot water through the block while machining? to simulate the hot engine.

I tend to be annal about most things but sometimes you don't want to learn the truth.:):smirk:

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This is been the subject of a lot of debate on the Buell forums, where HD specs any bore measurement be done with a torque plate.

The discussions range from alum to steel bore plates, to heat distortion, to whether plate to cyl contact should have a gasket, etc etc.

Personally I'm from the school of doing the best you can with the eqpt you have and trust your instinct, If that .001 clearance doesn't seem right to your it's probably not.

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The cylinder was round with the torque plates. Approximatley .003 no matter where you checked it so yes I was happy with the clearnace.

After removing the torque plate and rechecking for round it was .006 by .001.

When assempling the motor and I am hoping the cylinder goes back to round but for a simple check I could assemble the motor with torque plates and old gaskets and once again satisfy myself that I have a round bore.

I am annal. I check and double check everything.

I put $20,000 in a car motor and leave nothing to chance.

Putting $2500 in a DR and it will get the same attention as the car motor.

It will be right , or as right as I can get it or I will not build it.

This is why I do all my own work.

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yes torque plates should used on any build. also make sure deck is square.before bolting on plates. years ago we used to heat up before machine work but really no advantage. engine runs at different temps anyway depending on load[ day temps,type of riding etc.]

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is this for a big bore sleeve, what di it measure before you dropped the sleeve in

This is the sleeve installed and bored to specs and honed. I am ready to check the ring gap. I did check the part of the sleeve that hangs OUT of the block, the part that goes into the crank case and it remained round so I will use that area to check the ring gap.

If the gap is ok or once corrected the block could be put on.

I am going through the head.

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