Low & Slow's Ninja 250 project

[PaulB2]

About a chain oiler, take a look at the loobman too. Lots of folks like them, simple and cheap. As to non-oring chains, I started riding when that was the only kind there was. They didn't fall apart in the rain, don't worry. The trick is to keep oil on them. The Brit bikes I used to ride put enough on them to keep the back end of the bike a bit oily, heh. Non-oring chain would be about the first mod I would try.

[sendler]

Congratulations Vic on getting your photos posted on CraigVetter.com.
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22011 Vetter Streamliner-Chap 56
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It is very cool that you are a part of something which will one day be such an important part of everyday life.

[low&slow]

Thanks Sendler, Craig is one of my heroes so I feel very honored that he thinks enough of my efforts to recognize them on his website. It just motivates me to push harder to develop a successful Vetter Challenge machine and to hopefully help others join our revolution.
You are also correct about the 15/33 gearing causing my Ninja to turn about 5900 RPMs at 70 mph. I had been a little frustrated riding it in very windy conditions that would force it out of top gear in order to maintain my cruising speed. Yesterday was much calmer and I found that the bike was able to cruise in top gear most of the time. This week its supposed to rain a lot so it should be the perfect opportunity to clean and adjust the carbs. Things are progressing well for my project and I'm in good shape for the May Carmel Vetter Challenge.

[sendler]

Originally Posted by low&slow

I had been a little frustrated riding it in very windy conditions that would force it out of top gear in order to maintain my cruising speed.

Using your other gears shouldn't mean a reduction in fuel economy. You don't have to be a slave to 6th gear just because it is the biggest. Your gearing is now more than two gears longer than a stock Ninja! Stock gearing puts 6th gear 70 mph at 8610 rpm. Your new gearing puts 70 mph at 7660. In 4th! It might be fun to connect an old school vacuum gauge and stick it to the dash so you can see when you are lugging the engine. Peak efficiency for accelerating should be about 2 inches of vacuum in whatever gears run the rpm in the range either side of the first torque peak of 7000 for your current speed. This is a little more than too powerful on this bike so you will be back out of acceleration quickly and into a light cruise which will favor the lowest rpm that is not lugging under the given load. You could play with the gauge at different rpms, 4000, 5000, 6000, to see where you reach a point where dialing in more throttle doesn't seem to produce any further results. You might see a sudden curve in the vacuum where it starts out linear with increasing throttle and then starts to dive down showing that there is nothing else good to gain in that gear by twisting further. Which might be barely off idle at 4000. Just thinking out loud again.

[renault_megane_dci]

Actually, with their CDI and no proviso for a proper advance curve, most bikes are not tuned for rpm under 4K in the ignition departement so everything under 4K is not as efficient as it could (as it would have been in a car)

When I use my bike again (soon I hope), I'll do a tank always over 4K just to see if there is some to be gained

[alvaro84]

Originally Posted by renault_megane_dci

Actually, with their CDI and no proviso for a proper advance curve, most bikes are not tuned for rpm under 4K in the ignition departement so everything under 4K is not as efficient as it could (as it would have been in a car)

When I use my bike again (soon I hope), I'll do a tank always over 4K just to see if there is some to be gained

I thought about it pretty much, but never could actually try it.

Just for the record, "over 4k" would mean always being in the upper half of the rpm range with Teresa, as the limiter is at 7k or 7.5k (I don't really know what it depends on, speed, gear, mood, weather, constellations, perhaps...?), therefore I'm rarely over 4k. OTOH, under ~2.5k doesn't work either because of the definite complaints on her side (strange noises like pinging). So I use a pretty narrow range, which also makes engine braking kind of useless (except for some declines), so when I learned about coasting I embraced the idea wholeheartedly

[low&slow]

Latest update: I decided to clean my carbs. They actually didn't look too bad inside. I got it all back together and rode around some today and refueled.... 92.1 mpg
It appears the improved tail and taller gearing are doing their job. I need to adjust the carbs some more as it has some flat spots as I accelerate. Once I'm above 6K rpms it runs very well.

[beatr911]

Vic, did you verify the height of the fuel level in the carbs? Use some clear vinyl tubing on the bowl drain, curve it up in a U shape next to the carb, put the petcock on prime, open the bowl drain screw. Make sure this is correct before shimming the needle.

[low&slow]

Hi Garth, I checked the float levels and adjusted them 1 mm lower than the recommended 17 mm. I found that the major problem was that I mistakenly installed the needle spring clips on top of the springs rather than on the bottom. It runs much better now with a flat spot between 4K to 5k rpms that is most noticeable in the higher gears. We'll see how it goes.

[renault_megane_dci]

Originally Posted by alvaro84

I thought about it pretty much, but never could actually try it.

Just for the record, "over 4k" would mean always being in the upper half of the rpm range with Teresa, as the limiter is at 7k or 7.5k (I don't really know what it depends on, speed, gear, mood, weather, constellations, perhaps...?), therefore I'm rarely over 4k. OTOH, under ~2.5k doesn't work either because of the definite complaints on her side (strange noises like pinging). So I use a pretty narrow range, which also makes engine braking kind of useless (except for some declines), so when I learned about coasting I embraced the idea wholeheartedly

Teresa being a big single cylinder engine makes it a little special regarding rpm potential and in the bike world (I use to own a big single : Suzuki Freewind 650 cm3 personal best a 4 liters to the 100 kms with a +1 font sprocket and a worn chain)

Anyway, best efficiency is at peak torque, I bet peak torque is around 4,5 to 5K and that the engine runs around this rpm at 70 mph in standart trim.

Personnaly, I wouldn't want to lug a big single at to slow a rpm cause it spells failure in my book.