With my midlife crisis in overdrive, I’ve bought a race prepped 1989 NSR250.
(Like most people of my vintage, all my first {dirt} bikes were 2 stroke. That carried over to RD350LC, RZ350, and a fragil RGV250)

Problem.
I’ve tidied the bike up, put a new battery in etc.
The bike starts easy, sounds good, rides up and down the street ok, and when warmed up really seems to go well when “on the pipe”, then after a few 1st/2nd gear runs, it dies.
If I had to guess, I’d say it sounds like its out of fuel. After a little while I can repeat the process.

The new plugs look nice - not wet after the dying episode. BR9ECM - $25 each!
No issue with fuel flow from the tank. (Blocked breather etc)
The RC valves seem to operate normally. (Tried the test with the TPS disconnected)
The fuel was a bit old. 25:1 that I had lying around for my VMX bike. (It was 50/50 “98/100LL)

I’ve drained all the fuel, and will try again with fresh fuel today.
I’m planning to run PULP 98 at 32:1 with Motul 800 - any issues? (I don’t want to start an “oil thread” but am happy to take advice)

Basically: it runs strong for 2 or 3 1/4 mile passes, then dies when doing the 5th U turn, almost but not quite like a kill switch issue. More like fuel.

Thanks for any suggestions. I will report back.


Last edited by skypig on Sun Dec 10, 2017 12:43 pm; edited 1 time in total