Would you experts have a look at this crankshaft please

We were at replacing a cylinder on a 426 and noticed some signs of heating on both crankshaft bearings. One seams worse than the other but both are affected at only one place, and traces of heating are aligned.

Would you consider this a major problem?

Here are the pics

IMG_1260.jpg

IMG_1259.jpg

The crankshaft rotates effortlessly, no weird sounds at all...

Second question: the piston rod is a little loose laterally. We can move it a little from side to side (by maybe 1 or 2 mm) is this normal?

Thanks for your help!

Bump! :applause:

i would just replace the rod setup and run with it. i had the same thing on my 400.

I believe the rod is supposed to have some play in it from side to side. Just not up and down. As far as the discoloration on the bearings, obviously something isn't quite right. But the big question to spend a fortune trying to figure it out or just run it until it breaks. Since changing those bearings is such a pain in the ass, my lazy self would just run it until it starting acting up. Then I would replace the whole crank. Unless of course, you have money to burn or access to smart people with the good tools. Probably not a lot of help, but that is my opinion. Who knows you may go a few years without a problem.

My 426 looks the same way...I mthink it's from where they heat the crnk halves to open up the holes when they press the rod in. I ordered a new crank from the TT store yesterday (the primary drive nut backed off and dorked up the splines on the drive side), so when it gets hgere I'll post my observation of what a new, never been used part looks like (I expect it will be the same).

As far as "lateral" movement, if it's only side to side, that's ok. You don't want the wrist pin lands on the piston to pinch the connecting rod. Any radial (up and down or fore and aft) slop is not good.

If you are talking about sideways play at the big end, there should be some. The allowable limit is in the book. Same comment for radial slop tho. If there is any, get the crank rebuilt.

I suspect its normal. Here is the deal. There is heating, either from the hardend crank or the fact it was heated to push in the crank pin. I doybtr tghis showed up when it was running, or something would of already let loose. Side play is a MUST, up and down should be almost none. I suspect there is zilch wrong with your rig.

I've got the top end of my fiancee's 250F apart right now for some freshening up, and the crank looks the same way. It was the same on my 426 when I reringed it too. Totally normal, as long as the rod is tight and does not have any up and down slop in it.

Normal, put it back together and ride it.

We were at replacing a cylinder on a 426 and noticed some signs of heating on both crankshaft bearings. One seams worse than the other but both are affected at only one place, and traces of heating are aligned.

Would you consider this a major problem?

Here are the pics

IMG_1260.jpg

IMG_1259.jpg

The crankshaft rotates effortlessly, no weird sounds at all...

Second question: the piston rod is a little loose laterally. We can move it a little from side to side (by maybe 1 or 2 mm) is this normal?

Thanks for your help!

the manual says: free play of top of the rod up to 2 mm (side to side).

Thanks for all the comments and info guys! :bonk:

We're talking about my cousin's bike.

From what you say, everything is normal then.

It occured that the rings were done, the worse beeing the rippled oil ring followed by the middle ring. The top one was out of specs as well but it was the less dammaged.

We could still see the traces of honing in the sleeve. Plus, we put the new rings in the sleeve and they were right in the specs which tend to demonstrate that the sleeve was not dammaged at all. No major scratches on the piston or the sleeve either. Ring slots are tight

We put the sleeve back on.

Concerning the head, before disassembly, intake valves were .102/.102/.127

Exhaust valves were .203/.203

We'll probably put the head back on as is, check the valves back after cam install, kick and run.

My cousin bought that bike used in 2004 (it's a 2002) and ran it end of 2004 and 2005. Looks like he did not get screwed... the bike looks solid form the inside. :applause:

Math

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now