Fuel Injection in the Rain

During a season of major drought, I will always welcome some rain. But yesterday, it came unannounced, and it came hard! My commute home starts in downtown San Antonio, travels due west (usually on a major highway) for about twenty-five miles to my neighborhood. Leaving the parking lot, I made a quick decision based on the almost blackened skies, that I was going to avoid the highway. It hasn't rained in quite some time, so when it does, it is slick as snot. Also, cagers seem to drive erratic when it gets wet. I decided to take the neighborhood roads that I seldom drive on, much less ride on. So, the lil thumper came up to some railroad tracks with a nice double sagging whoop section ... more throttle, got some air. The dips, small pot holes and grooved pavedment did not unsettle the handling at all, I was surprised at this. For such a light bike, it has the grace of a much larger machine. A few miles later, the sprinkles come and I start pre-determining turns, braking points and what not. But, I really could not detect any sliding. Another mile, the sprinkles brought along some gusty winds, blowing leaves and dirt along with stinging little rain drops. By now, I am getting nervous, since not only am I dealing with the weather, but there are some cars going too slow, and others speeding up, due to the weather. I was caught somewhere in the middle. After a few blocks of squeezing yet harder on the brakes and accelerating to higher revs before shifting, I realized, this bike is stuck to the pavement in a way I have never experienced before in wet weather. I eventually did get some skidding, but everything was so predictable that it was just fun, nothing scary. Just as I am coming to grips with my surroundings, another level of rain kicked in and now its full on pouring rain! Big drops! In minutes every car around me was hydroplaning at 45mph, kicking up water to my shoulders. The r2 never wiggled. By this time, I am getting annoyed by the constant spashing, so after gaining some confidence with the grip level, I snapped the throttle open and got a head of the cars. They were slowing down, I was speeding up. After another few miles, I decided to go ahead and get back on the highway now that I felt good about how the bike handles in the rain. It was about this point, I started feeling as if the motor was ready to stall out. Twisting the throttle did not have the same snappy response, and I wondered if perhaps Fuel Injected single cylinder motorcycles and water are a bad match. There was no where to stop, so I just grabbed some more throttle and keep going. On the access road leading up to the highway (and its a couple miles long) I realized that first off, I was fighting a 20-25 mph headwind, and secondly, there was a lot of standing water on the road surface. The motor kept running just fine and I just concluded that it felt sluggish due to the first two factors. Once on the highway, I kept up 70mph while passing most cars who seemed to barely be able to maintiain 50mph without sliding back and forth on the road. I just wanted to stay clear of anything bigger than me. I made it home dodging lightning bolts, darting through 4-way stops where the signal lights were out due to power outage, and trying to pull a wheelie in the wet. I had no rain suit (I own one, but it wasn't supposed to rain), so my dress slacks and shirt were completely drenched, with fish falling out of my boots. Bottom line is that little blue machine just surprised the heck out of me at how composed it was ... just giving me reassurance while braking, turning, or just going, that it was not going to freak out and do something erratic.

So, the big question ... was it the bike, or the tires?

I did 2 years in Houston and a sportbike was my sole transport, I know exactly what you mean about the slick roads when it rained.

Sounds like you were experiencing an adrenaline rush of sorts.
I've been in similar situations before. :)

texascycle wrote:

So, the big question ... was it the bike, or the tires?

i'm guessing you are still using the stock tires.....the stock tires are fantastic street and rain tires but will get you hurt offroad.
the bike's geometry helps too,for as long as i can remember yamaha has leaned towards stability over quick turning.

I doubt it was the FI system, since I've seen R2s going through creek crossings and not miss a beat. It was most likely the tires, there's a lot of torque at that rear wheel, and knobbies, even the infamous Trailwings, don't have that much in the way of traction. Hell my old KZ440 would start loosing "power" in the rain, had nothing to do with the engine. The rear tire was skipping every couple of times the power was cranked on... what little power that heap had anyways.

Well, the throttle response felt weird as soon as it was raining heavy ... not the traction. I was thinking more along the lines of how much adjustment the FI system does when the air density changes rapidly, or there is suddenly a lot of moisture in the air ... not so much water messing up the electronics.

I wouldn't be surprised if he was on to something. I've had some experiences with elevation changes and heat at the same time. Bike just didn't seem to have the power it should. I always just contributed it to the wind though.

I've felt what you are talking about two different times. Both were interstate then highway rides on my way home from work in strong down pours.

Both times, when I got on the interstate, the bike was already warmed up and I was running an indicated 85+ mph for the first few miles, which is wide open when my dirtbags are full and sticking out into the strong headwind I was fighting. Then the rain hit. After one or two miles in the rain, I started loosing rpm and ended up down around an indicated 74mph when wide open. The wind hadn't picked up. There was probably a little more rolling resistance from the water on the road surface (it was pretty minor). Only other thing I could think of was the dry air had changed to a super wet air and the bike was liking it.

No idea why it behaves that way, but it is repeatable, so I just expect it now. The bike still ran good, just wouldn't pull the usual rpm with a given load, so down on power for whatever reason. I'll just blame the saturated air until some other theory catches my fancy.

You may just be expecting too much out of this little engine system. It doesn't have all the sensors that your car or truck has. It is a very basic EFI system. Bare bones to fit on a small bike and work under most conditions. The systems on this bike doesn't have the ability to figure MAF or MAP readings and we in the US don't even have the O2 sensor, so you kinda have to take the performance with a grain of salt. It runs well, but not perfect in all weather conditions. It's a trade off for being a small bike as oppossed to having a full blown EFI system on say, a Cadillac or Lincoln, with all the bells and whistles feeding the ECU to optimize things better than our little 250.

Chadx wrote:

I've felt what you are talking about two different times. Both were interstate then highway rides on my way home from work in strong down pours.

Both times, when I got on the interstate, the bike was already warmed up and I was running an indicated 85+ mph for the first few miles, which is wide open when my dirtbags are full and sticking out into the strong headwind I was fighting. Then the rain hit. After one or two miles in the rain, I started loosing rpm and ended up down around an indicated 74mph when wide open. The wind hadn't picked up. There was probably a little more rolling resistance from the water on the road surface (it was pretty minor). Only other thing I could think of was the dry air had changed to a super wet air and the bike was liking it.

No idea why it behaves that way, but it is repeatable, so I just expect it now. The bike still ran good, just wouldn't pull the usual rpm with a given load, so down on power for whatever reason. I'll just blame the saturated air until some other theory catches my fancy.

I rode home about 35 miles in the rain today.. FI & bike in general worked fine. But i did notice a little more 'sluggishness' when accelerating in 6th. With the rain, i was tucked down, & the wind was all over the place, but i wonder if the wet pavement or added rain resistance caused it.

Mind you, this is not scientific... just anecdotal. But it seemed less powerful in 6th.

scotty