normal engine operating temperature

[brucealmighty]

Today, it was around 20 degrees. Whenever I start the bike, but more so in the cold, I choke it all the way, hit the starter, and it immediately fires, for a few seconds, then quits. I figure that must be because of a certain amount of residual fuel mixture from the last run. But once that's gone, then I have to crank it for a long time to get it to fire again. Today, I had just removed the float charger, and it's a brand new battery, so I know I had all the juice I could possibly have to begin with. But, I had to crank if so long that it almost ran the battery all the way down anyway. Is there any way to avoid this scenario? Here's an idea! If cold air is more dense, therefore increasing the amount of O2, then it is making the mixture more lean, as I assume the amount of fuel is not changing. What about taking a hair dryer and blowing hot air at the carbs while cranking it, thereby making the intake air less dense, decreasing O2 content and making the initial mixture richer?

[trbig]

If you have decent compression, good spark, and the motor is cranking at a decent pace and it's still hard to start, I would look at the carb enrichener circuit just about every time.

Just wondering what everyone's thoughts were on hitting the intake with a shot of ether at this point. I've heard don't use it, use it sparingly, and don't worry about it. What's the general concensus?


Tod

[Crazcnuk]

Ether is one of those things that you just tell everyone not to use as it can cause serious damage.

It's use, on gas engines, requires a fairly good understanding of what it does, how it does it and what can happen if you use it wrong.

I've used it with gas and diesel engines, and have also used propane in the same way.

It's like asking if you should use a match to check for gas leaks.

[brucealmighty]

Originally posted by trbig
If you have decent compression, good spark, and the motor is cranking at a decent pace and it's still hard to start, I would look at the carb enrichener circuit just about every time.

Just wondering what everyone's thoughts were on hitting the intake with a shot of ether at this point. I've heard don't use it, use it sparingly, and don't worry about it. What's the general concensus?


Tod

Is there just one carb enrichener circuit, or is there one in each of the four carbs?

By "ether", do you mean the starting fluid that comes in aerosol spray cans?

[trbig]

The enrichener circuit actually has a jet on the edge of the BOWL of the carbs... and yes there's one on each carb.




Where the black arrow is pointing is where the jet is. When you spray carb cleaner down into this jet, if it's clear, you will be promptly sprayed in the eye with cleaner from this hole with a white arrow for a reward! Just take turns spraying into each hole with that plastic tube they give you with the can of cleaner. A good squirt into the hole with the white arrow should shoot really well and hit the ceiling if it's clear (Or wherever it happens to be pointed!)

It wouldn't hurt to clean the other jets while you're in there...


Tod

[brucealmighty]

Originally posted by trbig
The enrichener circuit actually has a jet on the edge of the BOWL of the carbs... and yes there's one on each carb.




Where the black arrow is pointing is where the jet is. When you spray carb cleaner down into this jet, if it's clear, you will be promptly sprayed in the eye with cleaner from this hole with a white arrow for a reward! Just take turns spraying into each hole with that plastic tube they give you with the can of cleaner. A good squirt into the hole with the white arrow should shoot really well and hit the ceiling if it's clear (Or wherever it happens to be pointed!)

It wouldn't hurt to clean the other jets while you're in there...


Tod

Thanks for the pic and the info. Inevitably, at some point in course of my owning this XJ1100, I'm sure I'll be tearing down the carbs and rebuilding them, so I'll be sure to pay close attention to that area. In the meantime, I'm wondering if anyone has any thoughts on my idea of blowing a hair dryer on the carbs before trying to start the bike. Hmmm... pretty cold out there right now. Think I'll go try that. Updates to follow.

[brucealmighty]

IT WORKS! I got my wife's hair dryer and aimed it at the air intake while cranking it over and it fired up almost immediately, and kept running. Before, I would have had to crank it almost to the point of draining the battery.
Theory: Cold air is more dense. Drawing cold air in while trying to start the engine causes the mixture to be lean. more dense air = more O2. Carbs are not jetted to run at that mixture, hence, difficult starting. Run warm air into carbs while starting. Warm air = less O2, mixture is richer, bike starts easier.
Try it, it works!

[Crazcnuk]

The hard starting when cold is because the engine has a hard time atomizing the fuel at first. The fuel mostly trys to condense on the cold manifolds and intake runners.

That is why there are chokes, or enrichener curcuits to make the starting charge rich enough to start.

Once the intake manifolds and cylinder head(s) get up to temperature, the mixture becomes too rich and you have to turn the choke off.

[wingnut]

Frosted Plugs

On aircraft aircooled engines after primeing and starting if you let it die, don't keep it running with the primer or accel pump, you can frost over the plugs in the cold. If they frost over they can be a real bit of a ch to get started. When I lived in Michigan my 69 Mustang did not have a choke, big 4 barrel, and it would do that on very cold mornings. Only way to get it started after frosting it over would be the hair dryer on the plugs trick. As the XS uses an enrichment system vs a choke I would think this could happen but we never get that cold here so I can't test the theory

[brucealmighty]

Re: Frosted Plugs

Originally posted by wingnut
On aircraft aircooled engines after primeing and starting if you let it die, don't keep it running with the primer or accel pump, you can frost over the plugs in the cold. If they frost over they can be a real bit of a ch to get started. When I lived in Michigan my 69 Mustang did not have a choke, big 4 barrel, and it would do that on very cold mornings. Only way to get it started after frosting it over would be the hair dryer on the plugs trick. As the XS uses an enrichment system vs a choke I would think this could happen but we never get that cold here so I can't test the theory

Then you're saying that the XS's don't have chokes? My XJ1100 does have a choke, so does that mean it doesn't have enrichment circuits?

[XMRGWX]

Hey Bruce
If you have a stock carburetor set on your xs then you have an enrichment circuit. A choke will richen the fuel mixture by restricting air flow into the carburetor, usually with a baffle plate. An enrichment circuit will richen by adding more fuel to the airflow. The confusion lies in the fact the word "choke" is often used to describe both systems.

[snowdog51]

cold

in most groups i'm the crazy one nice to be in this group where i'm just one of many. iride in the twentes if it's not all snowy.

as ever bill

ps i show this forum to my wife she sez
great a ton of you crazies.