16 replies to this topic

[Pooky]

Just been having a closer look at my crank+conrods (deciding whether to take them out) when i noticed a few things!

<-click to enlarge


Red arrows - Definately looks like its been ground down here and another place, was this done in the factory or could i have a balanced crank?

Blue arrows - Numbers scored into the big ends. Again was this factory or could someone have inspected these in the past?

Green arrow - bit of green paint on here and on other parts of the crank. What's that about?!

Any idea?

[The Matt]

Have you had the bearing caps off the big ends to see if it's had a regrind? It could have been ground and balanced at some point??

The heavy grinding on the edge facing us in that photo, near the green paint, is where they are ground down to clear the distributor shaft aint it??

by the way good on ya for gettin stuck in with it!

Oh, and the numbers on the big end caps will be where someone has taken it apart at some point, not a factory ID.

[Pooky]

I've not taken anything off as yet and i might not if you lot reckon some one has in the past...

[The Matt]

It's prolly worth popping a big end cap off and having a look at the condition of the crank whilst you're in there. As long as you've got a torque wrench to tighten it back up correctly??

[Sprocket]

One grinding point is for clearance of the dizzy drive the other grinding point is where it has been balanced and most likely factory. If the caps are numbered 123 then it has been stripped before and not factory. The green paint is a bearing journal size indication and is factory.

Seing as it has been stripped before, you will have to measure the bearing journals to see if its been re sized. Another good indication would be to look at the numbers on the back of the bearing shells and reference them up.

[Pooky]

I've coloured in one number on the back of one bearing shell on the left (is that it?)

cheers guys!

[Sprocket]

Where???


You mean the 12G number. Thats not the bearing but the bearing cap, you need to remove the bolts, remove the cap, then remove the bearing from the cap. The number is on the steel back of the bearing.

[Pooky]

got one bearing out has
[Æ] [D] BY
[G] S653SA
STD
B

written on it. Mean anything to anyone?

[The Matt]

yup, the STD either means it's got a naughty infection, or the bearings are standard size, indicating that the crank has not been reground or had oversize bearings fitted.

Are there any scores on the inside of the bearing or crank journal? Got any piccies Pooky?

[Pooky]

What you reckon? I have no idea but i reckon the journal's ok but the bearings will definately want replacing

[The Matt]

well, I reckon the shells are a definite. It's hard to tell from the piccies on my carppy laptop screen, but the crank journals don't look massively scored. What do they feel like if you run your finger nail over them? Any little ridges?

To be honest though. I always think it's best to get a regrind if in any doubt. It's better to do it now than do it in 3000 miles time.

[Pooky]

The big end journal is probably the smoothest thing i have ever felt in my life lol, and the Main journal has only the very slightest grooves.

[The Matt]

.............probably the smoothest thing i have ever felt in my life.................

Again, it's kinda hard to tell over the net, but if you reckon it's smooth then it may be OK. Do both shells say STD on the back? Maybe the big ends have been ground -0.010" and the mains are at standard if the big ends are smoothies?

[Pooky]

Nah both say STD

[The Matt]

well, for a regrind and new shells and thrust wahers, you'll prolly be lookin at £100-130 depending on where you go and who you know!

IMHO I would go for a regrind anyway as there is some scoring (even though it may be only little). It's down to how much confidence you have in the crank if you don't get a regrind really.


That probably aint helped you decide at all! sorry