Anyone consider mounting fan on their carbs?

[DimitriT]

The other day I was tuning the idle mixture and let the bike overheat in the garage. Very little airflow.

The bike stalled once it got too hot. No big surprise. That's what they do.

But it appears that the carbs also overheated and vapor locked. I wasn't able to start the bike again for several hours.

Although this probably won't happen to me on the road, I do run into situations where I am stuck in traffic and would hate to have this type of overheating happen on me.

I was thinking a small 12v switched fan to blow air over the carbs might be a good idea.

 

[JTGS850GL]

If you overheat an engine to the point of stalling it, then you probably have other issues now as well.

 

[tkent02]

T I do run into situations where I am stuck in traffic and would hate to have this type of overheating happen on me.

Wouldn't it make more sense to switch the engine off if you have to sit for a while?

 

[Gorminrider]

I was thinking a small 12v switched fan to blow air over the carbs might be a good idea.

My first thought was how hot is it where you live? southern states?
My second thought is "why not? Can't hurt!" one of those little fans out of an inverter/computer (little square brushless dc fans?) mounted over the carbs...
added- a good spot to help circulation behind engine

another thought is "oh, oh, you forgot that tip sometimes recalled on the forum-to put a fan in front of your bike when you are going to idle for a period of time carb-synching or whatever" as a precaution. (I'm not sure of this as soo effective equalizing engine temp where oil is not moving so quick at low rpm and a bike maybe kinda rich burning ? but it doesn't hurt.

But in traffic- tkent said. Shut the bike off. I do this with my car too

 

[DimitriT]

Wouldn't it make more sense to switch the engine off if you have to sit for a while?

Yea it would make sense. But once in a while you get one of those situations where you have to move two car lengths every 15 seconds. Like a toll booth.

 

[Gorminrider]

You've brought up a good point though. Timely with July/august coming.
I haven't been "stuck in traffic"on my bike in years, but I would normally start lane-splitting on a bike- not my fault the road is clogged with behemoths. If they were all on bikes, this wouldn't happen!

 

[DimitriT]

My first thought was how hot is it where you live? southern states?
My second thought is "why not? Can't hurt!" one of those little fans out of an inverter/computer (little square brushless dc fans?) mounted over the carbs...
added- a good spot to help circulation behind engine

another thought is "oh, oh, you forgot that tip sometimes recalled on the forum-to put a fan in front of your bike when you are going to idle for a period of time carb-synching or whatever" as a precaution. (I'm not sure of this as soo effective equalizing engine temp where oil is not moving so quick at low rpm and a bike maybe kinda rich burning ? but it doesn't hurt.

But in traffic- tkent said. Shut the bike off. I do this with my car too

Oh I use the big fan when I sync carbs. It's impossible to keep the bike running long enough in the garage unless it gets a little air flow.

I was just thinking that to avoid the problem where I'm limping along in traffic and the carbs get heat soaked, a small fan might get me through it.

 

[dorkburger]

Ive occasionally toyed with the idea of mounting a small fan to blow on my oil cooler while in traffic. So far its never made it past an idle thought....

 

[DimitriT]

If you overheat an engine to the point of stalling it, then you probably have other issues now as well.

It's not just stalling. The carbs get vapor locked and stop working for hours or until I drain them. Not something I want to happen on the side of the road.

I've never had it happen outside of the garage though so maybe a tiny amount of airflow is all you need.

 

[tkent02]

It's impossible to keep the bike running long enough in the garage unless it gets a little air flow.

Just curious how long it takes you?

 

[JTGS850GL]

It's not just stalling. The carbs get vapor locked and stop working for hours or until I drain them. Not something I want to happen on the side of the road.

I've never had it happen outside of the garage though so maybe a tiny amount of airflow is all you need.

Something else going on here as vapor locking the carbs is really hard to do on a properly vented gravity feed system. If you can't get it to fire up when put on prime then it's not vapor lock.

 

[Guest]

If you overheat an engine to the point of stalling it, then you probably have other issues now as well.

I think fuel boils at about 170 degrees F; that will stall an engine. What temperature an engine's internals would have to reach to damage internals at idle is a good one, but carb boiling is no indicator of that.

At idle the fuel in the bowls sits for a long time and gets hot. The oil is still circulating pretty quickly, by comparison. The fuel got hot because the heat left the engine. Convection and radiation is still cooling it when stationary, although the center cylinders don't see much of that.

 

[Gorminrider]

Ive occasionally toyed with the idea of mounting a small fan to blow on my oil cooler while in traffic. So far its never made it past an idle thought....

also an idle thought...Maybe BEHIND the oil cooler so it sucks air through it. ... and it occurs to me that the blades are going to spin with fan-motor off - a loosely spinning blade actually interferes with air flow. Like a dinner plate ...maybe another good reason to put it behind and not too close to cooler. Or another reason to procrastinate. (works for me! )

 

[DimitriT]

Just curious how long it takes you?

I haven't timed it but it will run for at least 15 minutes in a hot garage before it has trouble. If I roll it out to the driveway and there's a little breeze it can go all day.

 

[DimitriT]

Something else going on here as vapor locking the carbs is really hard to do on a properly vented gravity feed system. If you can't get it to fire up when put on prime then it's not vapor lock.

Hmm. Thing is the plugs look fine. Not wet or fouled. I can get it to keep running a bit if I hold the throttle open. So it's probably not the coils. What else could it be.

 

[JTGS850GL]

I think fuel boils at about 170 degrees F; that will stall an engine. What temperature an engine's internals would have to reach to damage internals at idle is a good one, but carb boiling is no indicator of that.

At idle the fuel in the bowls sits for a long time and gets hot. The oil is still circulating pretty quickly, by comparison. The fuel got hot because the heat left the engine. Convection and radiation is still cooling it when stationary, although the center cylinders don't see much of that.

Any fuel that's "boiled away" will vaporize and leave the float bowl via the vent lines. As the fuel level drops is will be replaced by fuel from the tank which will be MUCH cooler then the fuel in the bowls. Even if the fuel is completely boiled off in the carbs, it will still be fed by they tank if put in the "prime" position. I can't see any way that the engine would be stalled and not be able to be restarted for a long period of time unless something else (probably electrical) is inhibiting it.

 

[Gorminrider]

The fuel got hot because the heat left the engine.

Heat rises on a stationary bike so I'm still wondering about A) just how hot it was where you live, Dmitri and then , how best to remove the hot air given it's a real nuisance. Air rises so your fan should not blow down. It should "assist" present circulation. Do you smoke ? watching where the smoke goes would help set up the airflow.

 

[tkent02]

I haven't timed it but it will run for at least 15 minutes in a hot garage before it has trouble. If I roll it out to the driveway and there's a little breeze it can go all day.

I can't imagine taking 15 minutes to synchronize carburetors. Hell, five minutes is a stretch.

 

[DimitriT]

I can't imagine taking 15 minutes to synchronize carburetors. Hell, five minutes is a stretch.

I was adjusting the idle mixture.. but yea what can I say I'm slow.

 

[DimitriT]

Any fuel that's "boiled away" will vaporize and leave the float bowl via the vent lines. As the fuel level drops is will be replaced by fuel from the tank which will be MUCH cooler then the fuel in the bowls. Even if the fuel is completely boiled off in the carbs, it will still be fed by they tank if put in the "prime" position. I can't see any way that the engine would be stalled and not be able to be restarted for a long period of time unless something else (probably electrical) is inhibiting it.

I think what could happen is that fuel boils in carbs and we get a bubble somewhere in the network of tubes and pipes which keeps it from spitting fuel into the airflow. At least that's my 25 cent theory.