Low & Slow's Ninja 250 project

[redyaris]

[QUOTE=low&slow;291833]

Originally Posted by beatr911

The taller gearing has magnified poor part throttle response; I need to clean, check and adjust my carbs to hopefully correct this.

I too have had part throatle problems with the GS500 in sixth gear. What I suspect is, that when the GS500 engine is at 3500rpm or lower in sixth gear,
the carb. may be running on the off idle cucuit, because the throatle is almost closed. This cucuit is for first gear starting and is not all that good for sixth gear...
You may be having the same problem. What I have desided to do is optimise the final drive to keep the GS500 above 3500rpm, in 6th gear, at highway speed of 65 - 70mph, until I can come up with a better solution. I am day dreaming about a single carb setup with my own intake manifold.

[blownb310]

[QUOTE=redyaris;291991]

Originally Posted by low&slow

I am day dreaming about a single carb setup with my own intake manifold.

Yes, this is the answer. As we all know, multiple carbs are tuned for power not economy. By going to a single throttle valve, you can run at a larger throttle opening and lower the amount of "negative work" the engine has to do as well.

Mike

[MPG_Plus]

To jkv357, the rear camera I used is a "Rear View Safety" Model # RVS-770617N from ebay for $55 (currently $69). There is a good write up on Amazon. It is a great little camera. My only minor beef is at higher RPM I see a little speckle in the display and if I installed it again I would add shielding to the video line that inevitably is in the vicinity of the spark plug wires. I say that because it is more than the 12 Volt power which I heavily filtered to no avail. The speckle I mentioned is really splitting hairs and I recommend this camera, but it could be even better with a little shielding, I am just too lazy to redo the installation. The display fits nicely above the spedometer and I used plastic weld to the windshield. Also another mod I left off is the Axio tail bag that has a hard case and improves the aerodynamics.

[MPG_Plus]

low&slow , you mentioned "Pulse and hold" earlier , is that the same or similar to P&G (glide)? Also for DWL do you use a vacuum gauge ? I don't get the fine points of DWL , it seems the optimum would be to glide up a hill until you just coasted just past the top assuming no traffic or to the point where you just stay in top gear with traffic.

[sendler]

Might as well go with the new Ecotrons fuel injection if you are going to change the carbs.

[low&slow]

MPG+, Welcome to our forum and kudos to you for your efforts.

When I refer to " Pulse and Hold " I'm trying to describe accelerating to a target speed and then maintaining that speed with as small a throttle opening as possible. "Pulse & Glide" would describe accelerating to a target speed and then coasting in neutral or with the clutch in with throttle closed and the engine either idling ( ICE-On) or shut off ( EOC ). The coasting would be maintained until the speed had dropped to the bottom selected , then to be accelerated back to the target speed , repeating this cycle for optimum fuel consumption. Driving with Load refers to maintaining the throttle position on the flats and going uphill rather than accelerating to maintain the cruising speed. I hope that clarifies my the actions I'm describing. Others, please feel free to correct this statement or expand on it if I have misspoken.

For the uphill scenatrio you describe I would maintain my throttle position and bleed off speed as I climbed to the top , even if I had had to downshift , with just enough speed to be safe for the traffic conditions and then let the potential energy of going downhill accelerate me back to either my target speed or let me take advantage of an extended opportunity to coast in neutral. I hope this helps.
best wishes, L&S

[alvaro84]

Originally Posted by low&slow

For the uphill scenario you describe I would maintain my throttle position and bleed off speed as I climbed to the top , even if I had had to downshift , with just enough speed to be safe for the traffic conditions and then let the potential energy of going downhill accelerate me back to either my target speed or let me take advantage of an extended opportunity to coast in neutral. I hope this helps.
best wishes, L&S

On the hills I usually hold a speed that the actual gear can handle (so I don't downshift), pulse at the top and coast downhill. Most hills around here can't compensate for the aero drag at the speeds I prefer outside town (70-80km/h where the speed limit is 90 and the traffic sparse), so coasting there is more than safe. If the decline is long enough I even stop the engine, on a bike you won't lose steering not the brakes, so it's still pretty safe (just keep an eye on your mirrors!).

There are a few places where I DWL uphills, though. The best example in our vicinity is road 81 which is a busy road so I often stick to the speed limit (90km/h), except the place where there's a 60km/h speed limit around the crest of a hill. There I DWL down from 90 to 65-70 (which is the bottom of 5th on Teresa), and I may even downshift and go down to 60 (yes, I speed when I dont ).

Now if you use a Canon APS-C camera you're an expert at multiplying/dividing by 1.6, you know the mph values on sight If not, I'm sorry, this post would be a mess if I used 2 measurement systems in parallel

And the places where I'm in trouble: open roads with steep downhill stages, especially those of varying steepness. Engine brake is mostly too strong to hold a steady speed down, but if I coast, I accelerate to a speed too high for the bends. I'm in a pinch then: I either FAS and wear the friction brakes, or use the engine brake and go to coast time to time, while using gas to idle and brake - I can't fint the optimal way.

On using gas to engine brake: I have a technique to force Teresa into DFCO (just use the kill switch to stop fuel injection when the tranny is engaged and switch it on again in the same moment you grip the clutch to go coast - should work on any EFI bike, I suppose) but it's complicated and feels a bit like abusing her - after an extended period of forced DFCO she likes to stall when I coast. It seems the firmware can't handle my methods

[sendler]

Originally Posted by alvaro84

If the decline is long enough I even stop the engine, on a bike you won't lose steering not the brakes, so it's still pretty safe (just keep an eye on your mirrors!).

Just keep in mind that most motorcycles use engine oil pump pressure to lube the transmission bearings so it is theoretically possible to lock up a bearing while engine off coasting. I know one guy locked his Ninja transmission by hitting the kill switch so they could talk, and coasting down during a dyno run. EOC is probably just as well left to competition only.

[alvaro84]

Hm, I've heard this somewhere before. It could even be you, because it was about a Ninja. I've had no problem for the last ~60000km in which I utilized engine off coasting, though.

[sendler]

The BMW trans may be splash lube like a car. You can ask your repair tech. I am going to switch to Motul 300v brand 5W30 oil which is a group 5 double ester synthetic oil which is supposed to be good at magnetically sticking to the metal to maintain a film. It is also very thin at cold temps for the best fuel economy.