| Author | Message | ||
     Hildstrom |
I just finished adding and testing a rear fuel injector disconnect switch. It can be switched off and on while the bike is running. Idle coolant temperatures fell dramatically while running on one cylinder. I drove for a few miles on one cylinder up to about 40 mph and it seems like a dog compared to normal, but it still works. It seems to require more throttle and higher RPMs to make anything resembling smoother usable power, but it will work great in sweltering stop and go traffic here in San Antonio. This modification may even result in cooler oil and a cooler stator. This page has more discussion, some pics, and a video. http://hildstrom.com/projects/buellfi/index.html | ||
| Boogiman1981 |
hmmm. wonder what if any adverse effect that would have on the crank bearings due to the imbalanced load. also what about the rings sealing ability due to lack of combustion pressure and heat? | ||
| Jules |
Well, it's your bike and if that makes you happy then you go for it.. Personally, before doing something that extreme I'd buy a single cylinder thumper that was designed to run that way and leave the Buell at home. I can't belive that deliberately starving the rear cylinder of fuel and then loading the front to compensate is in any way good for the motor. Not to mention the fact that if I needed to get across a junction in a hurry I'd have to remember to flick a switch first... and I can pretty much guarantee that one day I'd forget the switch was in the "normal" position and end up flipping the bike as it was in "full power" mode. Definately not a mod that I'd consider, buy, hey - it's your dime  | ||
| Hildstrom |
The v-twin does not provide a balanced load to the crank bearings in the first place. The mass of the rotating assembly has not changed, just the number of power strokes per revolution. The rings on the rear cylinder will be kept lubricated and warm by the engine oil and the cylinder will still be kept warm by the coolant. Even if the rear rings are not operating at peak sealing ability, there is no combustion pressure to contend with in this state, just compression of air alone. Also, my motivation for this was to reduce heat in stop and go traffic, so torque and RPM will be kept low; I'm not racing with it in this configuration.  | ||
| Dannybuell |
Interesting. | ||
| Froggy |
Similar functionality already exists in the ECM programming to enable skip spark, I would rather use that than a manual switch. Easiest thing to do would be to change it to kick in at 200° instead of 230 or whatever it is stock. | ||
| Boogiman1981 |
good call Froggy. | ||
| Hootowl |
That's a good idea, but I'd also pair it with the condition that the engine must be below 1300 RPM, so it's only cutting fuel at idle, and when above 200 degrees. Granted, that's harder to do than a cutout switch. I don't think it'll hurt the motor. Auto manufacturers are doing this with their V8s to improve fuel economy on the highway, and if I recall correctly, the 1125 uses a single crankpin, so the pistons are darn near going up and down at the same time anyway. Not firing one would decrease the load on the bearings. Cool idea. (thank you, thank you very much) | ||
| Hildstrom |
Hmm, $30 for some wire, electrical tape, a switch, and some sort of small mounting plate... or... buy a new bike specifically for commuting in hot weather? I'm content trying to improve on the Buell for the ways I use it. Also, the ECU on many HD bikes does this automatically, but they call it "parade mode" or EITMS. It cuts fuel to the rear cylinder when temperature is high enough and speed is low enough. http://www.harley-davidson.com/en_US/media/downloa ds/safe_riding/extreme_conditions.pdf?locale=en_US &bmLocale=en_US http://www.hdtalking.com/engine_fuel_and_exhaust/2 8163-efi_heat_management.html I think totally automatic operation like HD's EITMS would be much more convenient and probably safer, but a manual switch is cheap, simple, and reliable. I did not feel like turning this into a microcontroller development effort. | ||
| Sprintst |
Harley uses this in their air cooled engines - called parade mode frankly, not something I'd want to try on my own. | ||
| Hybridmomentspass |
very cool idea you have. While I dont think itd be useful for me currently (do not have a lot of stop - and -go traffic to deal with), I think its good thinking on your part to 'fix' a problem youve come across. You've made a good point about V8s and their ability to shut off cylinders to save fuel with no harm to the motor. Please keep us updated how this works the longer you use this. Any idea what sort of MPG this creates? I figure you'd only be using half the gas, but as you said, youre going to have to give it more throttle to get going. But still, could be some awesome MPG out of the thing | ||
| Froggy |
Except that they have different lifters and special solenoids to control them, they aren't just shutting off an injector.
You will actually improve thermal efficiency by having one cylinder using say half power instead of two cylinders pumping out at 25%. Fuel economy will improve. I don't think its an issue on the 1125, but on a car having less cylinders running (also closed intake valves), the remaining cylinders have to fight less for air, reducing vacuum in the manifold. As result there is less of a pumping loss to get air into the cylinder. Again, probably non issue with canyon sized throttle body the 1125R has. I do wonder how it will affect the bikes with long term usage, as skip spark is mostly a last resort to prevent overheating, hence it only fires the rear cylinder once every other time. Now that I think about it, I'm not sure if skip spark cuts the fuel or not, it may just stop the ignition and allow the gas to cool the cylinder. | ||
| Hootowl |
"Except that they have different lifters and special solenoids to control them, they aren't just shutting off an injector. " That's to reduce pumping losses. I don't think it's a reliability issue. All the parts are still being cooled and lubricated. | ||
| Rogue_biker |
How about just getting a 250cc scooter for the city? The 1125 and bikes like it are really bad for city riding with lots of stop and go. That's like a caging a Lion instead of letting it roam the plains. Or a sportster 883 will work too. Those like to go slow with a lot of stopping (for bars and food). LOL! | ||
| Hybridmomentspass |
I think he addressed the 'buying another bike' part in an earlier post. | ||
| Xtreme6669 |
That's a great idea... I'm also in the boat where I don't do much slow or stopped riding so It's not for me, however I think it's an excellent idea and I'm surprised at all the flack you're getting! | ||
| Ratbuell |
froggy - parade mode cuts fuel. if it didn't, the cylinder would 'load up' and wash the rings (if it was in parade mode long enough). | ||
| Kenm123t |
Its similar to the lip home mode on the LT5 corvettes and later GM and Ford modular engines | ||
| Dhdjr |
Good post! Thanks for sharing your idea. | ||
| Tbowdre |
wow, pretty cool man. nice simple mod that seems to work, I love it | ||
| Kicka666 |
Sorry but I think its a bad idea, but its ideas like this that keep me in a job. What you are doing is going to eventually damage your engine, there your wheels so what ever floats your boat. | ||
| Ohsoslow |
kicka explain how this is going to hurt the engine. | ||
| Kicka666 |
Ask the engine designers @ BRP Rotax if this is good idea, I pointed out my opinion as a motorcycle tech, hey what would I know. | ||
| Hybridmomentspass |
Kicka - Yes, you pointed out your opinion, but gave zero reasons why/how it'd hurt the motor. Please tell us the reasons why you think this is bad for the motor. And telling us how youre a motorcycle tech does not automatically qualify you as an expert on the subject. Hell, HD techs are bashed a regular basis here for not knowing what they are doing on these bikes, or at all. | ||
| Mcrbuelligan |
if your worried about heat while your stuck in non moving traffic and I suggest 1 - learn / start to filter through traffic 2 - turn the engine off | ||
| Kicka666 |
Reason 1 of several: upper cylinder lubrication. I Never claimed to be an expert, just someone hoping that others dont try this & run the risk of engine troubles. I would like to see the result of long term use if the motor holds out, the end. | ||
| Hildstrom |
Mcrbuelligan, 1: dangerous, and I'm not more important than everyone else trying to get through stop lights during rush hour 2: wear and tear on the starter, relays, battery, lack of oil pressure during starting, convection cooling of the rear cylinder and subsequent convection heating of my crotch, etc Kicka666, A hot port-injection gasoline engine operating near stoichiometric ratio is going to receive practically nothing in the way of upper cylinder lubrication from the gasoline. The gasoline will be vaporized and mixed with the air; not coating the piston, valves, cylinder, or top ring as a liquid lubricant. Any upper cylinder lubricant properties of the fuel are much more important during cold starts before the oil is up to pressure and temperature. The rear cylinder will not experience any power strokes, so it will experience little if any wear. You said "Reason 1 of several", I'm curious about the others. | ||
| Hootowl |
Gasoline used to lubricate the valve seat, but that was when gas had lead in it. What does it lubricate now? Not the guide, not the seat. What then? | ||
| Poppinsexz |
Also I believe the newer fly by wire HDs when stopped if you roll the throttle forward it will cut out the rear cylinder. For use when stopped in traffic | ||
| Boogiman1981 |
gasoline is a solvent not a lubricant ask anyone that has ever put gas in a diesel and ran it... |
