Question for you guys who have put lots of miles on the NSR's.. How long do these engines typically last before needing new pistons? What about a bottom end rebuild?

..Just curious. My YZ engine specs every 30 HOURS. But that's a motocross race motor.. In an Aprilia RS frame..

..Anyway, just thought I'd ask and see how long these motors are holding up for.
I don't mind doing the rebuilding, but I don't know where I'd get a crankshaft..

10,000 miles should be achievable if you run fully synthetic oil. Cranks maybe longer.

What is the source for an MC18 crank?

Cheers

mk1 or mk2 . mr2 can use mc21 crank with a bit of machining or there is a bloke in australia that can rebuild all nsr cranks . mc18 no longer available new only mc21 cranks still acailable .
I would say nsr250 on the road there cranks get 30000 - 40000 kms give or take . But it all depends how they are looked after for the life of them .
As harryredchow said 10000 out of a topend . I would do rings at around every 5000km and see what the pistons are like and if they need replacing as it is fairly cheap to do.

Well I dunno.. What is my bike? 1989 MC18 in sig pic.. MK2 yeah? Don't know that much about 'em, that's why I'm here- to learn.

Cheers

When I pulled my good cylinder down to check the rings, I was surprised to see, after 8,000 km, that the rings were fine. Tyga gapped them to their specs, 0.35 - 0.40 mm. I checked the gap and it was 0.38, so I imagine that if it wasn't for the seized front cylinder, I could have gone another eight! I'd recommend at least checking the rings and piston clearances at 12,000. All depends on how you ride and what oil you use. As for me, I ride road, and use TTS-Power.

yeah your mk2 r5k mc18 the mc21 cranks can be machined a few millimetres to fit they are the same bearings . Or you can buy the bearing from mixalisen a forum member here .

Thanks for the info!

Although after searching for some time, I can't seem to locate a source for the MC21 cranks either. Do you know of a supplier?

Cheers

Check out Tyga performance ! Great products

Top of this page... rotating banner... RedLine Powersports. They're a Supporting Vendor, and in the USA.

Before you get (possibly) stung for import duty and shipping, try local! Don't forget to mention you're an NSR-WORLD Titanium Member, as that gets you discount on some parts.
_________________
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.

Check us out on Facebook! Please "like" our page!

Hey thanks alot Andy- Just spoke with them, said they would try to locate one and let me know in a couple days.
Figure I may as well stock up just incase I need to do the rebuild in the future.

Cheers
Aydin

just remember if you go the mc21 crank it will have to have the webs machined to fit your motor or get mc21 cases