RobH wrote:
I've read plenty on this forum about the challenges with using the NSR150 pistons for a 300. Loads of development has been done at Tyga. I seem to remember it put a strain on the big end bearings. It would be worth looking at how machining affects the cases. I also remember Andy's comments that it didn't make a significant increase in power. Another thought, I wonder if the size of the cylinders would need a certain volume in the crank cases?
TYGA fixed the problems with the 300 kit some time go, but it took years of development by someone I consider to be quite possibly one of the most qualified NSR spanners outside of Japan. Indeed, his motors were actually protested by HRC a number of times in the Asia-Pacific championship!
It is true, that from what we've seen on the dyno, they don't make much more power than a 250, but do have heaps more bottom-end and mid-range. There is an increase in peak power, but it's more like 8-10%, not the 20% people seem to think will come from 20% increase in capacity. I would expect to see around 65rwhp from a "stock" 300 (maybe a little more with the VHM & Wiseco options included), but an extremely healthy increase in mid-range drive. 10% is nothing to be sniffed at though, of course.
I would expect something similar from the Malossi kit. What you have to bear in mind is you're making the motor way "over-square", and the further you go, the less efficient it will become.
We haven't experience any bottom-end failures specific to the 300. All the (early) failures were top-end, but as I say, that seems to be fixed, partly due to the loan of NSR500V parts we sent over to Matt back around 2015. While a big-bore isn't my cup of tea (I much prefer wringing the neck of an HRC-spec 250), I wouldn't detract anyone from going that route these days.
What you do get from the 300 kit is brand new OEM Honda barrels, which is something definitely worth consideration, but the "standard" 300 pistons are not OEM Honda ART pistons. Again personally, I'd take OEM Honda plating over ANY replated alternative. Similar, to a point, can be said about "new" Malossi barrels, but I wouldn't put them anywhere near the quality of OEM Honda. For example, we contacted Aprilia GP (the proper Aprilia!) about replating NSR500 barrels, and even they said nothing can come close to OEM Honda, and would rather dress a worn port/bore and reuse it than replate it, if we could get away with it! I don't expect Aprilia GP would go to Malossi to get barrels plated, if you see where I'm going...?!
I'd be lying if I said the Malossi 180 kit had never been considered before, but way back in the early days, when NSR's were only in black and white, genuine barrels were aplenty and relatively cheap, so I don't recall anyone going that route. In fact, when I first met Matt back around Y2K, I assumed the NSR300 leant against the back wall in TYGA's lockup at Bira circuit was fitted with Malossi barrels. It was only later that he explained it was NSR150SP barrels. I still feel a semblance of guilt getting him to fire it back up and develop it, as it cost him years of his life to get right, and I was very vocal about its shortcomings as I thought it went into "production" far too soon. I'm lucky... some may question "lucky" he still talks to me!
It will be interesting to see if you go the Malossi route. I think your first hurdle is going to be the pistons though. Pretty sure the NSR125 piston has a 16mm gudgeon pin....
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Andy.
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