Can anyone tell me how to determine whether or not the crank is within specifications?

A friend of mine mentioned they used to measure the tolerance with the crank still in the engine casing. Can you do this with the NSR crank or does it need to be in V-Blocks?

Also I noticed one of the bearings (closest to the flywheel side) has the retaining pin broken off. The other two bearings are fine. Will the bearing spinning around in the crankcase be a problem?

Thanks

rip

ALL the crank specs are in the Tech pages, where you obviously didnt look yesterday when talking about the puller. I think you are a prime candidate for subscribing to the new Members section (http://members.nsr-world.com) when it opens , as there is going to be a full English Workshop Manual on there which will be near idiot proof!

Yes the main bearing will need to be replaced as like you said its possible for it to spin. This will then damage the crankcase its self. Well worth changing while you have its stripped down.
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If I have to take the carbs off once more...

A set of OEM Koyo main bearings is available from Dietmar Schulz, currently the ONLY reliable supplier of OEM bearings we know of, for a very respectable price.

Find a link at the very top of the Classifieds page.
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Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

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When was the last time you read an instruction book. No one ever reads an instruction book

Besides if we were all experts at doing this type of stuff, we wouldn't have forums would we?

So, that leads me to two dumb questions for all us non-experts:

1. Do we need v-blocks to measure the tolerance or can it be done in the crankcase?

2. What is the relevance of the 63mm, 33mm and 7mm measurements in the crank specs?

Thanks

rip - "the town-idiot"

Rip ready, I know you said that a bit tongue in cheek, but Andy has spent months of his life discovering, writing up and hosting the info in those pages, so people could look it up without asking the same questions over and over. Please do him the courtesy of reading them, then asking questions eh? There's a good chap.
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I thought the honda cranks had locating pins in them to stop them rotating?.
Its so long ago that i took the crank out that i have forgotten must remember to get a new one and put it back again.
How true are the cranks as shipped?.

Don't get me wrong. I appreciate all the hard work Andy has done and the answers from everyone on the forum. Actually, I didn't even know about the Technical Pages until I ran across them by accident. As Murphy's Law would have it, I found it right after I posted the message.

So maybe I'm a little more clueless than most but I can't seem to find the answer to the two questions above. Is that information provided somewhere?

If you want to find how true the crank is then you will need a set of centers and a good dial guage. and measure off not only the webs but also the bearing surfaces.

If your after just measuring the con rod end float then all you need is feeler guages.
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If I have to take the carbs off once more...

Measureing the crank is quite simple if you follow the guide lines in the service manual. It pretty much tells you where to sit it on blocks, where to measure, and the 'out of true' tolerence.

If it's out of spec it's not a complete disaster as the webs can be teased back into position with a precision tool. I use a carefully calibrated bloody great big copper hammer.

What I do is measure the crank as is, then give it a gentle whack and see how far it moves. If it goes right past where I wanted it and a good way beyond then I'll be prepared to bin the crank as it generally means that the crank has lost it's mojo and it'll move again first time it's back in the mota.

If it's a good 'un then I'll pop it back in the blocks and measure seven points and note down the runout. This helps me determine the shape of the crank compared to it's 'true' centre line. I'll then bash it about until it's as true as I can get it.

Honda give you a huge tolerence as you can see on the Techy bit. And if your cranks actually on the limit you can quite easily see it wobble around on the blocks.

The cranks are not that bad out of the box, and 99 times out of 100 are within spec, but they can be trued a lot closer. A well trued crank will give more power, smoother acceleration and a higher rev ceiling 'cos it's not losing all it's energy jumping around.

Difficult to say how long it takes to do as every crank's different. In the best case it could be half an hour, but I've spent well over that in the quest for the best.