New Engine too Tight ?

[Scooterbrain]

Yes of course I have Torque wrenches.
They do not measure ring gap however which is what I said that I forgot to do. I was hoping to avert tearing this thing back down to check a ring gap that may be ok but certainly its easier to do that now than after the engine is back in the bike and exibiting an issue.

 

[Scooterbrain]

That being said...I actually only own a ft lb wrench and really do not trust it as it is cheap. Good point on that

 

[Scooterbrain]

Yes I agree. I do need to know exactly what I have going on there so I will take it back down and verify the ring gap. Thanks for the opinions. Thank all...

 

[retiredgentleman]

That being said...I actually only own a ft lb wrench and really do not trust it as it is cheap. Good point on that

Even though you don't trust the cheap torque wrench, it would still be interesting to us all, what reading it shows, as compared to my engine.

 

[Paul Sutton]

I have a cheap torque wrench, but I first calibrated it by putting it in a vice and hanging a range of heavy training weights on it. It was within 2ftlb at 20 and within 1ftlb at 7. About a +10% error. Must check it at 30 to 80 sometime.

Method: Place plastic drain pipe on wrench to extend the distance. Select a torque setting then move the weight to the point where the wrench clicks. Measure the length in inches and divide by 12 to get Feet. Multiply Feet x Weight (Pounds) to get ftlb value and then compare with setting.



Actual Example:

Setting = 45ftlb. Weight = 22lb. Length = 23.75 inches or 1.98 Feet.
Wrench clicked at 22lb x 1.98 Feet = 43.5 ftlb.

 

[lakeview]

Please report to us your findings, your post #1 reminded me of how tight it was to turn over my fresh bore and rering when I completed it. Ring gaps had been verified by the machinist. That engine has not been started yet for other reasons.

 

[xjwmx]

The guy in this video gives nice clear instructions and uses a special grinder to adjust the gap, but it would be nice to know how other people are doing this.

I only had to do it one time, a long time ago, on a car engine. I used a regular flat file with strokes going from the outside toward the inside. I only had to take off a very few thousandths. I was thinking at the time of only what the feeler gauge would pass and don't remember thinking about the part that might be wider due to not holding the file straight Which could affect compression a little I guess. I did try to keep the file parallel to the end though. I think the normal thing is or was the file; never heard of the little machine until recently.

 

[5twins]

I started out years ago filing rings by hand but it really was a pain in the ass, and eventually I even ended up breaking one. But mine usually require more than a few swipes with the file. I'm usually fitting 1st oversize rings into a standard bore. I bought the ring grinder and I'm glad I did. It makes the job so much easier. I have the one that guy in the video doesn't like but it's always worked fine for me. I've probably done 30 to 40 rings with it already over the years.

 

[Scooterbrain]

I have not torn it back down yet but I got a New cheap 3/8 drive torque wrench and tested in increments up and down and in both directions. I found that the exact point at which it begins to move is 12.5 ft lb. The wrench range is 5-80 ft lb and claims to be accurate +_ 4%

 

[5twins]

The thin oil rails or rings can sometimes pop out of the grooves and get jammed between the piston and bore when fitting things together. I think you did your assembly the hard way, with the pistons already mounted on the rods and the cylinder block then fitted down onto them. Like I said, that's the hard way, hard to get the rings into the bores (working 2 pistons at once) and hard to see what you're doing. The easy way is to fit the loose pistons into the bore first then lower the pistons/block assembly down onto the rods and stick the pins through.

 

[Scooterbrain]

Also just for comparison my re-ringed 71 Bonneville takes a value Less than 5 lb which is as low as the wench go. The Yamaha seems a bit looser after 20 turns and some lube but I have not committed either way yet.

 

[Scooterbrain]

Thanks for the reply 5twins. you are correct I did it the harder way . I was really hoping to redo this without popping the cam chain again but Likely not. This is a 70 model and their is a web cast between the cylinders that will prevent dropping the chain down and just sliding the barrels off. Of well, looks like Back to the web for another master-link and might as well do the base and head gasket as well. It is like someone said earlier, It does not feel right so it does not matter how many opinions I get its still on me and there is absolutely no reason to be in a hurry. Not like its my ride to work or anything.
Thanks again all.

 

[Scooterbrain]

Well I have narrowed this down now. Looks like I installed the cam chain Dampener upsidedown. when I unloas the chain there is minimal resistance on rotation. Makes sense. aathat made a pinch spot between the pivot point of the tensioner arm and the topo tall upside down Dampener . I will pull the head now and lift the barrels enough to correct that.

 

[xjwmx]

Thanks for the reply 5twins. you are correct I did it the harder way . I was really hoping to redo this without popping the cam chain again but Likely not.

You can leave the cam chain intact if you didn't realize it. Remove the tensioner and then slide the bearings off the end of the camshaft. The camshaft will just lift out. At that point you should be able to let the chain drop into the cylinder and you should be able to lift the cylinder up enough to get the chain guide out. You might have to get it out of the top of the cylinder. My memory is slightly vague on this already but I think that will work. You can lay the engine on its side so you don't have to prop the cylinder up. Take your time and make sure the guide is straight.

 

[Scooterbrain]

Thanks again for the response . I have discovered an issue that will de-rail me for a bit and I will stop short of calling myself an idiot even though I should.
When I released all tension from the chain as I said, I found that there was no longer any resistance on the rings " at all " and in a partially disassembled state I "thought " I saw an improperly installed Dampener but I was wrong. All of the tensioners's are correct so I am unsure of where the problem was !! The issue was definetly drag on the chain causing the resistance but I have not determined the source yet.
However "this is embarrassing and deservedly so" I discovered in the process that I had mis-calculated the clearance between the piston and the bore " way too much " so I have to back up a bit and go ahead and have the machine shop calculate that bore and recommend the appropriate re-sized pistons. I will take them the New pistons and Rings and let them determine the correct fit for all and then pay close attention at re-assembly time.

 

[Scooterbrain]

Good Advice 650 Skull. And you were right.
I need to get out of a hurry and remember that this is a hobby and I have all the time in the world to get it right. It didn't feel right and it was not. tks for the kick.

 

[Scooterbrain]

Yep XJWMX I figured that one out when I forgot to install the dampener in the first place. Thank you though..Man I shouldn't have admitted that. Yeah I should..... We all screw up now and again. I am glad that there is a forum to help sort this stuff out and I will at some point try to contribute from my experience.

 

[xjwmx]

Yep XJWMX I figured that one out when I forgot to install the dampener in the first place.

The reason I would never forget to install the dampener is because while it was coming in I was constantly worrying about its quality, and figuring out a way to insure it was centered The resistance you say you're feeling...you have the transmission in neutral don't you?

 

[Scooterbrain]

Oh yes. Clutch is not even built. Just the baskets. The whole crank, rod and ringed piston assembly now turns very nicely without the can chain installed and the Cam and bearings are free as a bird.

 

[xjwmx]

I had to ask. You understand.