Apologies if this has been covered before, but I don't remember that it has and I couldn't find an answer when I did a search. I'm wondering if anyone knows what Honda estimates the service life of the crank on an MC21 to be for a street bike. I know the actual mileage will depend on how the bike is used etc., but I'd like to get some idea if I am riding on borrowed time or what. I have 20,000 kilometers on a used engine I bought from Tyga several years ago (crank mileage at the time of purchase unknown unfortunately, though the crank seals were new). The motor has had a pretty easy life during its time with me because I am old and, well, slow. So does anyone know what Honda says? Or alternatively, what is the highest number of miles people have had on a crank before blowing or replacing it? Thanks for any info.
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-Jim
'93 MC21

I'd say that Andy's got the record, so not doubt he'll spout up at some point.

If there's no crank bearing noise, or conrod wear/wobble, and it pressure tests ok then you could be ok.

A good test is to grab the flywheel and try to wiggle it about. If you can feel any movement at all then you'll need to be thinking about shelling out some cash.

Thanks for that, Matt. So has anyone had more than 20,000 kilometers on an NSR crank and lived to tell about it? If so, it would be great to hear how many miles you got. Thanks.
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-Jim
'93 MC21

I reckon mine had done at least 30,000km, maybe 40,000km (the speedo cable snapped at about 8000km, some 10 years ago!!) before the crank was finally pronounced DOA.

It was always fed fully synthetic 2T, any always hit 12,000rpm in every gear on every journey at some point, so it had a pretty hard life!

It was bolloxed when it was removed though!!

I'd expect to be looking closely at any crank with 25,000km on it, especially if you don't know it's history. I had my MC21 from 3000km, and even in that short a time I'm not convinced it was that well cared for!
_________________
Andy.
NSR-WORLD.COM

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Oh, and er...

We can rebuild cranks now!

Sorry for the blatant plug, but hey... it is my site!!

I'm working on a new "Performance Services" section of the Site at the moment, where we will be offering, amongst other things:

Crank rebuilding

Crankcase modification

Crankcase/barrel matching

Lightened components (flywheels, clutch baskets, sprocket carriers etc.)

All coming soon, so e-mail me with any questions. (Please DON'T PM me, as my inbox is always full of crap questions that can either be answered by reading the Main Site, or are already in the Forum archives!! )

Cheers,
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Andy.
NSR-WORLD.COM

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excellent information and timely news about the potential for rebuilding, Andy! Hoping to squeeze a bit more out of the crank, but who knows how that will go?! (it occurs to me the same could be said about the wife.... but I digress.)
Thanks!
_________________
-Jim
'93 MC21

Great news! Does anybody want to buy a crank that needs to be rebuilt?
_________________
james
Its not how fast you go...Its how you go fast.
MC21 Rothmans
RS250
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748R
Porsche (many)
http://members.rennlist.com/j911brick/rennlist3_002.htm

pah , i got 76 000ks outa my mc16 before i got any crank trouble

whoa, now THAT is impressive! I think we have our winner...but I'm not sure if it counts.... isn't most of the riding in NZ downhill? Seriously, it is great to know such mileage is possible. Go Honda! Thanks.

p.s. Paul, while I am no doubt old enough to be your Pah, I've never been to NZ and will require DNA evidence before admitting anything of the kind.
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-Jim
'93 MC21

paul wrote:pah , i got 76 000ks outa my mc16 before i got any crank trouble

Ah what he didnt say was that he was on the 7th engine LOL

original motor, it died from what i think was a blown head gasket, siezed at speed and when i pulled it down the top cl was full of water and all rusty, it was a couple of months till i got round to stripping it
was a real mess to

LOL, Just messing, Thats really good, Shows that if you look after them theyll keep on going and going!!!

another local got 56 000 odd ks out of his mc16 before he sold it, only problem he had was cracking of the exhast port
my mc21 got a new crank at 21 000 ks though, but i think it had been sitting in a warehouse in japan for some time

What you need to appreciate though is that there aren't many MC16's making much over 45~50hp, and the cranks (although not the same) are very similar to later items that are regularly seeing 30% more power.

35~40,000kms + 30%... 50,000kms - 30%... anyone good at arithmetic?

Pretty much same same!!
_________________
Andy.
NSR-WORLD.COM

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ah ha tricky
40 000ks + 30% is 52000ks
but the old 16 had 76000 on it and did i mention that it had been raced, although only 5 or 6 meets and had pipes and mc21 barrels on it for over half those ks, it was an awsome bike, just kept on taking a thrashing, and thrash it i did(i owned it in my teens)