'88 CBR 250R M19 50+mpg

[theycallmeebryan]

Originally Posted by marcexec

Regarding my attempt to fill her only every 1 1/2 days - that failed, sort of.

I was trying to reach the station directly at the motorway but I had to switch to reserve after 210km on the tank. I filled her with 10.35l, that's all I can get int her. The tank is supposed to hold 13 Litres + 2 Litre Reservoir.

Even worse, since coming near the "end" of the tank, probably some old gunk got loose and now she's running rough at certain rpms...

Summary:

Never change a running system!

I would drain the float bowls on your carbs, you probably have a bit of water/gunk in there.

[marcexec]

I have still not gotten around to drain/clean the carbs, will probably do that tomorrow, if the weather permits.

Thanks for all the good advice, since the (supposed) gunk/water went by the fuel filter I probably should check for a new one.

The funny thing is, @ 8krpm she is running smotth as silk, can barely be heard.
So it's probably the idle jet(s).

I have just added the last 2 fuelings, due to filling her really high the other day I got a "virtual" 54mpg, but it was noticably less for sure.

[beatr911]

Are you still commuting at 120kph or have you been able to slow down a bit? Also if you can find some opportunities for clutch in coasting down hills or well before braking and stopping the engine at traffic signals you should see an additional decrease in fuel use. Keep it up, you'll get there.

[marcexec]

I was able to slow down a bit. I am going 100-110 most of the time on the motorway (preferably hiding behind a van or fast truck).
After entering the M50 (Dublin City ring) I have to sit up and filter through anyway, the cages are bunching up all the time...

Since last weekend, when I exchanged the fuel filter, there is more power available above ~10krpm, so I suppose there was a bottleneck...
Additionally, yesterday evening I did not just lubricate the chain, but cleaned it beforehand as well. It might be a placebo, but I think she is smoother now and might need a little less throttle - we'll see.

AFAICS I could improve mileage a good part if I could improve drag, because I can see how it goes down if there are strong headwinds on the way back (mostly west wind in Ireland ) and strong tailwinds in the mornings, nice as they are, do not make up for it.

I am consindering to get some polycarbonate (e.g. lexan) to play around with.

I fear I will not have much time to do that in the near future, the reason is my wife's Mini

And then there's also my own car and that broken RS125...

We always have out hands full with those projects, haven't we?

[marcexec]

just entered my fueling from yesterday:
statistically 54.8 mpg
If need be I could always add a little more fuel, I just fill her to the edge of the pipe that goes into the tank if that makes any sense.

More important is my overall: 49.7 and still rising!
I have been following your advice and managed to start my commute a few minutes earlier.

I have made a very important modification to my bike:

I added a clock! (cheap watch for 5,-€, with hands that glow in the dark)

Helps a lot!