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-   -   Crank spins a little less freely after torquing primary gear (https://www.horizonsunlimited.com/hubb/yamaha-tech/crank-spins-little-less-freely-98559)

Jens Eskildsen 13 May 2019 09:43

I did excatly the same thing on my wr450f. I took a piece of pipe and fitted it over the crank end, together with a large washer, and then used the crank nut to put tension on it.
This acted as a "puller" similar to what you did.


It was very satisfying to see the crank move, after a lof of frustration. :D

Doubleyoupee 13 May 2019 11:46

Quote:

Originally Posted by Jens Eskildsen (Post 600234)
I did excatly the same thing on my wr450f. I took a piece of pipe and fitted it over the crank end, together with a large washer, and then used the crank nut to put tension on it.
This acted as a "puller" similar to what you did.


It was very satisfying to see the crank move, after a lof of frustration. :D

Yeah, that *tick* was quite satisfying. Took very little pressure too. However I guess it offered just a little bit more resistance than bending the C3 bearing.
In my case it was the bearing on the timing gear side.
On this engine, I don't think it's even possible for the primary-gear side bearing to become bent when torquing the nut:

https://i.imgur.com/kMclkE2.png

Spacer #16 actually lies against the inner race of the bearing. So when you're torquing the nut, you're actually pressing against the inner race and pulling the crank axle through it.

Anyway, this just shows that you can do everything from the book, and still mess up a rebuild if you don't think or use common sense.

I know of a story of someone who completely rebuilt a Honda FMX 650, only to have the bearings ruined within 1000KM.
I can now see how this would happen.

Anyway I'm not celebrating yet. I still have to get the piston in and hope everything lines up - I'm not using OEM bearings and the crank has been pressed.... who knows what i'll find in the next days.
First... the clutch! :)

dzl 13 May 2019 15:33

As you showed, if in doubt check it out, as you did in this case. would have been easy to continue on with the build if you hadnt noted the slight resistance.

Ive generally only bought factory crank bearings as had trouble finding the the correct C4 clearance type. The rest Ive just sourced from bearing supplier and no issues.

One anomaly I had on my last 3TB rebuild was the transmission output shaft has a slight horizontal movement of slightly more than 1mm. I checked my other engines I have about the place and they dont have any notable movement. I know it is all assembled correctly so assume is some wear somewhere but cant really understand where. The front sprockets used on this engine have always tended to wear a shiny section on one side where the chain tended to rub due to slight misalignment. I never thought much of it but noticed the play when installing the sprocket after last rebuild.

Not going to do anything about it as no real issue but something to watch for in future when putting engine together. Out of interest, does your engine have any play in this area Doubleyoupee or anyone else reading this?

Doubleyoupee 13 May 2019 17:41

Quote:

Originally Posted by dzl (Post 600250)
As you showed, if in doubt check it out, as you did in this case. would have been easy to continue on with the build if you hadnt noted the slight resistance.

Ive generally only bought factory crank bearings as had trouble finding the the correct C4 clearance type. The rest Ive just sourced from bearing supplier and no issues.

One anomaly I had on my last 3TB rebuild was the transmission output shaft has a slight horizontal movement of slightly more than 1mm. I checked my other engines I have about the place and they dont have any notable movement. I know it is all assembled correctly so assume is some wear somewhere but cant really understand where. The front sprockets used on this engine have always tended to wear a shiny section on one side where the chain tended to rub due to slight misalignment. I never thought much of it but noticed the play when installing the sprocket after last rebuild.

Not going to do anything about it as no real issue but something to watch for in future when putting engine together. Out of interest, does your engine have any play in this area Doubleyoupee or anyone else reading this?

Yeah, I wanted to get OEM crank bearings at first too, but they are €72/piece. Even at €50/piece I find it way too much.
The C3 bearings I ordered were only €9/piece.
I talked to XT guru David Lambeth (he prepares/rebuilds long-distance XTs for money) and he said he's using C3 and never had any crank bearing fail.
That's good enough for me :).

Regarding the play in the output shaft - I have none on my engine. Not even 0.1mm.
All my other bearings are non-C3, that's what David said as well, if I remember correctly.

dzl 14 May 2019 09:37

Yeah I know C3's have been used no problem by many others but it helps me sleep better at night having factory spec ones's in there !! Get them straight from japan for $30 oz dollars or 18 euro each so not too bad. Sounds like your yammy dealers there really take you guys for a ride of their own with their pricing?

Hopefully wont be pulling that engine apart of mine with output play for few years now so will only have to guess why it has movement in the meantime.


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