Serious issues

[mack]

So I had my cases stripped down and was trying to install new bearings. I plasti gauged browns, blacks and blues and the guage readings never changed. 0.051 consistently. So I changed my procedure and did it all again after turning the crank 90 degree's. No change. Now I'm learning, so I figure I'm doing something wrong. Re read all the manuals and followed to a T, still no change. Now after a couple beers and a staring contest with the cases, I decided to check the mating surfaces. I had hand polished everything so there is nothing preventing the mating but when I place a trouble light inside the transmission cavity (no crank shaft installed) and look through the seam at the front, I can see light between the rear seam. I installed bolts 18 & 19 and torgued to spec but still have light. Took the lower crank shells out and reinstalled and torqued to spec, still have light , but only between #2 & 3 journals. It would seem that my cases have warped a bit, after being trough a couple years of being apart and going through a fire. The fire wasn't hot enough to blister paint but who the f...k knowns. I'm not sure what to do. I can't just put in blues and hope for the best. Has anyone ever had any luck with having the upper and lower case machined, and not had any issues with tolerences afterward.
I'm considering removing bolts 10, 9 ,8 , 7 and taking them to a guy who has a large oven and bringing it up to 400 degrees and see if that doesn't straighten the cup out.
Any thoughts.

[trbig]

As flexible as aluminum is, I can't see those big bolts around the crank not sucking it together, if you are absolutely certain that nothing else could be hanging it up. For a proper torque, you are supposed to lube the heads of the bolts to slide against the washers. (Or against the case with bolts # 1 and 2)

Not sure I'm understanding exactly what you're talking about in reference to a "Rear seam", but you also have to remember there will be a slight bit of room taken up due to whatever case gasket material you use.

[mack]

articulation

I probably wasn't clear in my description. I didn't put in all the forward edge bolts because the procedure doesn't call for it, so I'm able to look through a slight crack in the front seam. When I do, I can see light between the stanceions holding bolts 3,4,5,6, basically the towers that hold the bolts. I know there is no rear seam in the upper case beteen the outer limits of the oil pan itself, so light should be expected in the middle but I can't figure out why they aren't seating enough to cause a change in the plasti guage readings. I'm going to take the crank in monday and have the run checked as I don't own a dial guage but I'm sure the error is in the case halves. I could be wrong, I'm a virgin at this so whats under the covers is to some extent "a wonderous mystery"

[vedgar]

Yamaha manual.

Mack ,
I suppose you are using mm as your .051 spec. If so that is still way out of spec no matter what bearing cap you use. Manual calls for installing the crank and torqueing all bolts 1-10 to spec. From your description, you have not done that ? The case is aluminum and should pull together. The outside case bolts 11-15 and 18 -24 will do the rest that. Set the beer down and start over without the beer ! Ha Ha
Vance

[vedgar]

Bearing cup is what I meant to type

As in bearing shell.

[mack]

yes

It is mm. 0.051 is the best i could get with brown,black or blue. Thats what makes me believe the mating surfaces are the problem. 1 thru 10 installed and torqed to209 inch pounds. 18 &19 added for good measure and torqued to 109 in/lb. Still the guage reads 0.051. It isn't supposed to be this difficult.

[vedgar]

Bolts bottoming ?

Make sure nothing is in the holes and the bolts are not bottoming. Hmmm.
I will stay with you until we fix this one.
Vance
I used to build v12 engines for Jaguars and they are not as complex as this.

[mack]

I've had the cases

apart and together so often in the last few days that now I just pick up a torque wrench and the bolts jump in the holes on their own. The only thing I haven't done is install the crank end seals during the process, but I can't see that, that would make any difference.

[TomB]

Has anyone ever had any luck with having the upper and lower case machined, and not had any issues with tolerences afterward.
Any thoughts.

Forget machining the mating faces, game over if you do that.

The cases should pull up with ALL bolts fitted IF there is nothing else hanging up. I rebuild 600bhp dragbike race engines that have crank cases (GSX1100) really out of shape, if they pull up yours will easily.

The other one to look for is do you have a matching set of cases, they should be stamped on both halves with a code, somewhere like the back of the gearbox. A local mate kept rebuilding his motor and couldn't figure out why his gearbox was stiff as hell, I spotted he was using two different halves.

[mack]

Codes

I'll check today before the football starts. I don't think the motor has been apart before. It only has 16,299 km on it (10K miles.) A girl owned it first and she only put 2.5 k on it in five years. She sold it to the guy I got it from and he didn't even know that there was a kick start lever under the tool kit. He had a set of vice grips on the stub and was using that to try to turn over the motor.
I'm going to go over it again today with a large flat edge and take the crank in to a guy with a dial guage and check the run out. With such low milage it should be good but maybe neither PO's ever changed the oil. I have have a feeling that it was red lined quite a bit. But that is conjecture at this point. I have an 1179 kit ready to go in if I can get the new bearing tolerances to spec. So no matter how hard it was ridden, it will be practically new when I'm done.

[Schming]

JAT... You could check irregularity in the surface by using a glass table or mirror, maybe even hold the mating surface under the glass to see better.

GL

[trbig]

I can't seem to find a parts list on those bearings where it shows the actual thickness of each bearing, but it was determined that it didn't really matter which one you used. I'm wondering, if the difference is just a few ten thousandths, then it's not going to change the reading you're getting from different colors when only reading to the thousandth?

If the run-out on your crank was bad, your plastigauge numbers would change when you rotated the crank 90 degrees.

Oh.. and these motors laugh at red-lines. Make sure all your valve springs are intact (I've broke a couple) and don't let that bother you. If the oil was really bad and they never changed it, the old crank and cam bearings would have deep gouges in them from debris.

[mack]

Well here goes

I checked and the upper and lower case have the same number 1A56 stamped into them at the rear of the tranny housing. I put a machinists flat edge on the mating surfaces laterally and longitudinaly and the surfaces look good. However when I installed the shells and ran a straight edge across the tops of the shells this is what I found on all them.

You can clearly see that the shells stick up above the mating surface on both halfs. I chercked the originals the same way and they were good. The original had numbers stamped into them of D7L on both the brown and blacks, while the new kit has D9A for brown and D9D for black with the blues being D4C. I have no idea what to do here. It's probable the shells aren't fitting properly not allowing the crank to settle down into the cradle making the readings high.
Any thoughts?

[mack]

Big

My SF certainly had no problem with red lining and I'll admit that a few times I buried the needle by mistake. It gets real busy real fast when your racing out of the hole. But, my oil was always pretty fresh and my cam chain was always adjusted before I raced anyone.
I'm not putting the original head back in this one, I have a couple spare 2h7's here that don't need all the work of rust removal that the rest of this motor did so I'm putting the original aside for now and will get to it in the future when I'm not under the gun. Same goes for the carbs. They may be goners, pretty rough shape but I'll have a go at them and see how the turn out next winter.

[TomB]

What are the shells like in the upper half of the cases, the same?? or are they under the mating face level?