I recently picked up a ns400r and the condition wasn’t good enough to restore back to showroom condition so I’m planning to upgrade the engine and suspension and use it as an occasional road bike. I was curious if anyone on here as any experience with racing or working on this engine and would be willing to pass along some tips? There isn’t a whole lot going on over at the ns400r forum in terms of sound information. From what I have seen on my engine, the stock port timing isn’t horrible however the port area and carb size both seem extremely small. Thanks, --Eric
Suspension wise you can upgrade it with cbr600 f1 wheels and forks. Engine ,most of the top end parts is NLA. Sent from my SM-G920T using Tapatalk
Thanks guys. I have done plenty of research already and Ian does look like the best resource for this bike. Just wasn't sure if I wanted to go the overbore path or not so I figured I see if anyone here had first hand experience tuning these engines.
Im working on a NSR250 and I am installing 2013+ CBR600RR forks... Still trying to find a reasonable rear wheel from a MC28 model or NC35 (RVF400)
That sounds like a cool project. I have a full MC16 also that I am working on upgrading with MC18 and MC21 components. Right now my plans are for MC21 wheels on both the 400 and 250 so I have eyes peeled for good deals on MC21 wheels.
hit me up if you see a MC28 rear wheel deal! It can be ugly as sin cosmetically as long as its straight. I will be stripping and re coating it.
Resist the urge to modify the motor more than pipes and good tuning. You want it to run smooth in the 3000 to 6000 range where it will be most often. They are capable of running very strong near stock. Change for bigger carbs and youll be pouring gas in like its a kids 85mx bike. Make it a runner and take it to big events like Barber Vintage, AMA nationals. Guys who been there done that will come over to gaze at the bike and tell you all about it. I have an RZ500 and RG400, hope to have money when I find an NS400.
Thanks for the feedback. As I mentioned previously I am not sold on going the big bore route, although it does provide better options for sourcing pistons. From what I have seen so far I think some good gains can be had with minor port changes and pipes. I do think I am going to go bigger on the carbs though, 26mm does not seem adequate even for the stock engine displacement and peak power RPM.
Check the transmission, they are prone to failure and no OEM parts exist. Nova Racing UK has very shiny billet gears which will destroy your credit card. Aftermarket pistons are avail and most space up the cylinders. https://photos.app.goo.gl/EYcyw6eMVD11WFKp2
