No power ... in the rain

[Angel-be-Good]

Hey folks,

I have a fairly high-mile bike that's given me virtually zero issues for 55k+ miles. Today on my ride to work, however, it ran terrible.

I have a ~16-mile freeway ride to work. For the first ten miles today, it was totally fine. For the last six miles, it hardly made power, I could barely keep 60 mph. It often sputtered and pulsed, with power coming back intermittently.

It was raining. Not sure if connected, but it hasn't rained here in a while so this is the first time I've ridden in rain since last winter.

Any suggestions? I'm at the office now, will likely be riding the bike home -- or trying to.

[alex.s]

could be rain got in the tank... its heavier than water so it sinks down to the pickup and causes issues. if thats the case you can drain the tank and carbs and put in fresh gas. it might also be an electrical short that the rain is exacerbating.

[csmith12]

Check gas cap drain/overflow hole and hose for clogs.

[Angel-be-Good]

Originally Posted by alex.s

could be rain got in the tank...

How would that have happened?

Originally Posted by csmith12

Check gas cap drain/overflow hole and hose for clogs.

Sorry, where is the gas cap drain?

The problem seemed to get progressively worse once it started. Power dropped, then came back, then dropped. By the end of the commute, power was low consistently and only surged back in momentary spurts.

[csmith12]

I take a blowgun on the air hose and blow through them every now and then.

[subxero]

do you still have the stock airbox setup?

[Angel-be-Good]

Originally Posted by subxero

do you still have the stock airbox setup?

Yeah. The bike is largely unmodified -- just steel-braided brake lines and an aftermarket horn, both installed years ago.

[alex.s]

if it was raining enough it can get water in the gas tank vent and it seeps into the gas tank.

[Angel-be-Good]

So if water has gotten into the tank, (1) the issue will not resolve itself as the bike dries, but (2) filling the bike with gas may help? It's not empty, but I would normally fill it tomorrow -- so the mix of gas : water might become significantly affected if I fill it up. That sound accurate?

[subxero]

the water tends to collect in the carb float bowls. There is a drain at the bottom of each carb bowl. Simply attach a hose of the correct size and drain the bowl. Preferably into a clear container so you can see if there is any water. The water will lay on the bottom with the fuel in a second layer on top

[Angel-be-Good]

Originally Posted by subxero

the water tends to collect in the carb flow bowls. There is a drain at the bottom of each carb bowl. Simply attach a hose of the correct size and drain the bowl. Preferably into a clear container so you can see if there is any water. The water will lay on the bottom with the fuel in a second layer on top

Unfortunately I'm at my office with the bike now, not at home. Also, I've never worked with the carbs before but I'd be happy to try that out when I'm in my garage.

Thanks guys! I really appreciate the response. Any other suggestions?

[alex.s]

it's possible it will just solve itself.

[broilmebk]

Something like this had happened to me previously. It wasn't the first time riding in rain, but the next day it ran like crap. The problem didn't go away until I drained the bowls. It's quite simple to do, just make sure you have a long enough allen wrench for the left bowl.

[Angel-be-Good]

Alright, so I just went down to check on the bike and see how it's running. Without touching anything else, I started up the bike, put on the amount of choke I commonly use when started her, and let the bike idle. The problem was still there -- even on idle, I could hear the power coming in and out, the throttle response was ****, etc.

I stopped the engine, leaned the bike upright to check the oil level (it's fine). I opened the gas tank to check the vent and drain for anything obvious and didn't see any issues. The gas filler neck area is bone-dry, so I honestly don't think water got in, at least not through the filler cap. But maybe it dried between this morning and now (~5 hours).

However ...

I closed up the gas cap, deliberately tight as possible, and started the bike up again. It seemed to idle perfectly normal. I did a quick lap around the parking lot and it felt totally normal, but this is at 5mph so hard to conclude much.

Does it make sense that opening the gas cap and closing it back tight might have solved my issue? Or is it pure chance?

[broilmebk]

If the bike indeed runs perfectly fine now, it was vapor lock. The tank wasn't getting vented properly so it was starving the engine of fuel.

[Angel-be-Good]

Originally Posted by broilmebk

If the bike indeed runs perfectly fine now, it was vapor lock. The tank wasn't getting vented properly so it was starving the engine of fuel.

Hm, and what would be cause of not venting properly? One of the aforementioned clogs?

[Alex]

Yup, that could certainly explain it. The power loss you describe seems severe enough to me that it's either vapor lock completely strangling the motor, or something electrical that is keeping one cylinder from firing correctly at all. When the power is weak/surging, does the tone of the motor instantly change significantly, as if it were going from a twin to a single and back again?

EDIT: If it is a clogged vent line, opening and closing your tank cap didn't actually fix the problem. It fixed it temporarily, but in a little while the same clogged vent may cause the exact same symptoms. Popping the tank cap is a way to confirm that if it does immediately run right, it is a venting issue that needs to be dealt with.

[Angel-be-Good]

Originally Posted by Alex

If it is a clogged vent line, opening and closing your tank cap didn't actually fix the problem. It fixed it temporarily, but in a little while the same clogged vent may cause the exact same symptoms. Popping the tank cap is a way to confirm that if it does immediately run right, it is a venting issue that needs to be dealt with.

Awesome, thanks for the advice guys.

Now for diagnosing / fixing the venting issue, where should I start? I am a big dummy when it comes to anything outside of changing the oil and chain maintenance (and even then, I am apparently terrible at chain maintenance, despite my efforts).

[Angel-be-Good]

Not quite solved as I'd hoped.

Same day I posted this, I rode the bike home -- and it was perfectly, 100%, gloriously normal. Bike ran great.

But now it's not great again. I haven't really ridden it since that night ride home, but did a lap around the neighborhood the other night to see where it's at. Still gutless / down on power. Idles poorly.

I recorded a quick video of it idling. At this point, it was pretty warmed up and running without the choke.

Link to original page on YouTube.

https://www.youtube.com/watch?v=KnYcuCBm8Z0

[Motofool]

Originally Posted by Angel-be-Good

Not quite solved as I'd hoped.
.........

As above advised, drain the carbs and the tank with the petcock in prime:

http://faq.ninja250.org/wiki/Draining_the_carbs

http://faq.ninja250.org/wiki/How_do_...e_fuel_tank%3F

Collect the fluid in a glass container and you may clearly see how much water your fuel system has had since that day.

[broilmebk]

Yes, I would drain the fuel at this point. Also, when was the last time your valves were checked?

[Angel-be-Good]

I tried draining the carb bowls, got stopped early because I don't have an allen wrench long enough to reach the further screw, but did manage to produce some fluid from the nearer bowl. Poured it into a glass and it didn't separate into layers.

I had previously scheduled with a shop to replace my chain + sprockets, so I rode the bike in this weekend and asked them to investigate the poor running. They weren't able to reproduce it (and neither was I this weekend) so fingers crossed. Rode into work today without an issue.

Valves were serviced about 1,200 miles ago. The shop did note that the cam chain is noisy and recommends replacing it (the cam chain, or the cam chain tensioner? same thing? I am dumb) so that'll be happening soon.

[Hero Danny]

I'm guilty of not reading the whole thread

I would say that it's carbs, usually sputtering = carbs. (either that or vacuum leak) First thing you should do is drain out all the gas and replace it with new gas, then go ahead and run sea foam in it. Run the whole tank and fill again. If it's still doing it then you may need to clean your carbs.

[Angel-be-Good]

Another rainy commute today, same result. Poop.

[alex.s]

since you know the carbs aren't filled with water, it sounds like it's either an electrical issue or maybe your air filter is getting soaked in water? while it's happening, check out your air filter. theres a little thing on the side of the airbox to slide it out. is it full of water? maybe your snorkel isn't correctly positioned?

since you didn't complain about crazy tach or other electrical problems it sounds like its more likely to be an intake issue. or maybe your exhaust is filled with water? when you crank does it spit water out the back?

[Angel-be-Good]

I'll check the airbox tonight when I get home. No other issues happening at the same time (e.g. electrical issues). I have the stock exhaust installed, but will have to check if water is getting into it.

[jkv45]

One of my other cycles has a reputation for dropping (misfiring) the front cylinder (it's a V-Twin) in the rain when water gets into the plug-well. It's usually caused by a blocked drain, but the water diverts the spark from the plug into an easier ground, creating a misfire.

Not sure that's the case here, but if there was any amount of water on the plug-wires or in the plug-well it could be causing the problem.

[alex.s]

Originally Posted by jkv45

One of my other cycles has a reputation for dropping (misfiring) the front cylinder (it's a V-Twin) in the rain when water gets into the plug-well. It's usually caused by a blocked drain, but the water diverts the spark from the plug into an easier ground, creating a misfire.

Not sure that's the case here, but if there was any amount of water on the plug-wires or in the plug-well it could be causing the problem.

that happened on my fzr600 too. took awhile to figure out the drain was plugged with ****.

[jkv45]

Originally Posted by alex.s

that happened on my fzr600 too. took awhile to figure out the drain was plugged with ****.

Worth a look.

In a related note - We purchased a used car a few months ago for my son to take to college, and while giving it the once-over found that all 4 spark plug wells were completely filled with water.

Looks like they did an under-hood wash and the water got past the seal on the spark plug cap. It ran fine though.

[BrianATX]

I would like to echo what was said before in checking the spark plugs. I had a problem similar to this about a month ago in the rain. I found that there was a build up of debris on one spark plug. It was producing something very similar to what you are experiencing but mine was skipping a lot more. I replaced both spark plugs and cleaned my air box. Afterwards everything was back to normal.

While cleaning out my air box trying to figure out how it happened I found some debris somehow made it into the clean side of the air box. I used a vacuum to get it out. I just removed the clean air system using a block off plate this weekend. When I removed the air box Sunday it contained a few new pieces of debris in the air box but my spark plugs were still clean when I checked them. When I blew into the hose of the clean air system bits of debris came out the other end. My bike sat in the rain nearly all day Saturday here and the debris that was in the air box was wet when I removed it Sunday (I did not run it Saturday). I have no idea how that debris and water is getting into the clean side of the air box on my bike. However given my findings on Sunday I think that clean air system may be the culprit of the debris for me.

Sunday I removed the air box and clean air system completely and switched over to the K&N R-0990 pod with bigger jets. I hope this information helps in finding a resolution if your are experiencing something similar. Could be bikes just hate going to work? Good luck!

TL: DR Check your spark plugs

[CZroe]

Originally Posted by Angel-be-Good

Alright, so I just went down to check on the bike and see how it's running. Without touching anything else, I started up the bike, put on the amount of choke I commonly use when started her, and let the bike idle. The problem was still there -- even on idle, I could hear the power coming in and out, the throttle response was ****, etc.

I stopped the engine, leaned the bike upright to check the oil level (it's fine). I opened the gas tank to check the vent and drain for anything obvious and didn't see any issues. The gas filler neck area is bone-dry, so I honestly don't think water got in, at least not through the filler cap. But maybe it dried between this morning and now (~5 hours).

However ...

I closed up the gas cap, deliberately tight as possible, and started the bike up again. It seemed to idle perfectly normal. I did a quick lap around the parking lot and it felt totally normal, but this is at 5mph so hard to conclude much.

Does it make sense that opening the gas cap and closing it back tight might have solved my issue? Or is it pure chance?

That has solved my rain issues in the past, though it was pouring hard enough that I couldn't do it where my engine died (had to push it to a service station). It sputtered and ran poorly before it died and wouldn't start, but it's obviously a matter of degrees (not exactly a pun if you think about it ). If you encountered the rain after the engine was warm then the air in the tank contracts as the tank cools and forms a vacuum. As for the idle and on-going issues: I dunno.

[Angel-be-Good]

Problem solved in December, but I'll update here.

The spark plug comments were the right direction. Turned out the spark plug covers were cracked and one was letting water through. Both covers replaced and no more rain problems. Whew.

[Alex]

Thx for the update!