Cold Weather Running Question (and history) | GTAMotorcycle.com

Cold Weather Running Question (and history)

WestBrantKid

WestBrantKid

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I have an 01 Katana, and an 03 Katana.
Overall, the 03 is in better condition, and was my original bike. The 01 was bought complete, but as a donor.
I don't know if it was the exhaust or some other mechanicals, but I liked the sound of the 01 better, so last summer I switched to riding the 01. I winter proofed it with heated grips, Bark Busters, winter tires, etc., and road it through the winter. I think I only missed one full week the whole winter. It ran great. It started right up every time, and took only minutes to warm up on the coldest days, and didn't bog or hesitate at all.
My 03 on the other hand has always ran just as good when warm, but in the cooler spring and fall weather it can take a few tries to get started, and after 5 minutes of idling, will hesitate and bog pretty bad for the first couple Kms, then it'll run good. I doubt I would get it started in the winter months.
After a winter of riding the 01, I stripped the fairing to give it a good cleaning and found more corrosion and rust than I had expected. This brought me to the decision to use one bike in the winter, the other in the summer.
I rebuilt the carbs on my 03, and couldn't get the float position right after 3 attempts, so I cheated and took the carbs of my 01. This is what I've been running all summer. Now that the weather is cooling that 03 is starting to act up when it's cold. I would have thought the carbs would have solved that issue, but I'm clearly wrong.
My whole point to the post is, what is likely the cause of the cold weather hesitation, if not the carbs?
 
Are they theoretically the same bike (i don't know katana history)? Which size engine? Same oil in both bikes? A vacuum leak could affect cold running more than hot (less vacuum signal, less gas being drawn in with more air). How is choke operated? Does choke fully deploy on the 03?
 
Most engines will run better in the cold providing they are at proper operating temp. Things I'd check:

1) Oil. Once you get below 10C, 5W-30 or 0-W30 gives your motorcycle better protection and performance than 10W-40 or 20W-50.
2) Cooling. Your cooling system needs to maintain operating temp. A thermostat stuck open in the summer may not be noticeable, but in cooler temps the bike will not come up to operating temp.
3) We're gonna have some summer in the next few days. Try a ride when it's 22c, see if that's noticeably different than the cold day hesitation. If it's still there on a warm day, it't probably a tuning or mechanical issue -- not so much the cold.
 
Mad Mike said:
Most engines will run better in the cold providing they are at proper operating temp. Things I'd check:

1) Oil. Once you get below 10C, 5W-30 or 0-W30 gives your motorcycle better protection and performance than 10W-40 or 20W-50.
2) Cooling. Your cooling system needs to maintain operating temp. A thermostat stuck open in the summer may not be noticeable, but in cooler temps the bike will not come up to operating temp.
3) We're gonna have some summer in the next few days. Try a ride when it's 22c, see if that's noticeably different than the cold day hesitation. If it's still there on a warm day, it't probably a tuning or mechanical issue -- not so much the cold.
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This should be an air/oil bike. Don't think there is a thermostat. I wouldn't be running 0W oil in a 20 year old air cooled bike. That's asking for problems imo.
 
GreyGhost said:
Are they theoretically the same bike (i don't know katana history)? Which size engine? Same oil in both bikes? A vacuum leak could affect cold running more than hot (less vacuum signal, less gas being drawn in with more air). How is choke operated? Does choke fully deploy on the 03?
Click to expand...
They are identical bikes (other than rim dimensions, as I discovered). 750cc air cooled carbureted (obviously). The choke is manual thumb lever. I turn it on the start and gradually turn it off within the first minute of running.
Same fuel, oil, and filters. Both up to date on regular service and maintenance.
Something I forgot to mention, which is probably important, I hear gravel (clicking? ticking?) in my engine on take-off. I suspected my drive train, but it's new, well maintained and not too loose or too tight. My research has led me to believe this is a loose timing chain, so I hope to rebuild this engine over the winter if I can hide a few dollars from Trudeau to cover the cost.
 
Mad Mike said:
Most engines will run better in the cold providing they are at proper operating temp. Things I'd check:

1) Oil. Once you get below 10C, 5W-30 or 0-W30 gives your motorcycle better protection and performance than 10W-40 or 20W-50.
Click to expand...
I read about the oil thickness recently, but I can't remember if I factored that in when I changed the oil on the 01 for last winter. I'll look into that. Thanks.
Being air cooled, I don't have to worry about the thermostat, but I do have an oil cooler. I should clean that off, although that wouldn't be a cause for this issue. Thanks again for bringing that to mind.
 
WestBrantKid said:
They are identical bikes (other than rim dimensions, as I discovered). 750cc air cooled carbureted (obviously). The choke is manual thumb lever. I turn it on the start and gradually turn it off within the first minute of running.
Same fuel, oil, and filters. Both up to date on regular service and maintenance.
Something I forgot to mention, which is probably important, I hear gravel (clicking? ticking?) in my engine on take-off. I suspected my drive train, but it's new, well maintained and not too loose or too tight. My research has led me to believe this is a loose timing chain, so I hope to rebuild this engine over the winter if I can hide a few dollars from Trudeau to cover the cost.
Click to expand...
Why turn the choke off so early if it's still running like crap? Valve timing/clearance differences can obviously affect how an engine runs.
 
WestBrantKid said:
I read about the oil thickness recently, but I can't remember if I factored that in when I changed the oil on the 01 for last winter. I'll look into that. Thanks.
Being air cooled, I don't have to worry about the thermostat, but I do have an oil cooler. I should clean that off, although that wouldn't be a cause for this issue. Thanks again for bringing that to mind.
Click to expand...
For the winter, you may want to block off the oil cooler. It can probably dump enough heat even with much lower airflow than summer conditions.
 
GreyGhost said:
For the winter, you may want to block off the oil cooler. It can probably dump enough heat even with much lower airflow than summer conditions.
Click to expand...
I'll look into that and see if/how it can be done. I assume theres a motor to circulate the oil, but it could be the same system that gets the oil to the moving parts for lubrication. That would make sense for keeping the engine warm and effecient.
 
WestBrantKid said:
My whole point to the post is, what is likely the cause of the cold weather hesitation, if not the carbs?
Click to expand...
We don't know... we're here, and you and the bike are on the other side of an internet connection, and contrary to popular opinion, you can't tune a bike over the internet. It could be any one, or three, of a million different problems.
That being said: Ambiant air temps have a HUGE affect on jetting. More the pilot circuit than the main, but a rule of thumb is to go up one jet size on the main(2.5) for every drop of 10 degrees F. The pilot USUALLY just needs adjustment.
Motors DO NOT run better when it's cold. Motors run better, with respect to jetting, when they're jetted correctly for the environment they are operating in. If your motor runs better when it's cold, it means you are over jetted for when it's not cold. "CORRECT" jetting is RIGHT NOW, it can change in a minute. At the drag track we would re jet the car at least 3 times a day, usually 4 times. (... and I am over simplifying about temps, we ran a weather station and I am more interested in the dew point... but that's for another day....)
All things being equal; a motor will POTENTIALLY make more horse power in a colder environment, but I don't think that's what we're supposed to be talking about.
Blocking off the oil cooler will only heat up the head, and only by a couple of degrees, 10-15 degrees F. With the bike at operating temp, put your hand on the oil cooler, if it's warm, you're good. GS motors don't have a problem making heat in the head... their problem is they make too much heat in the head... hence the oil cooler connected to the head.
DO NOT put 0-30 or 5-30 oil in it. There is nothing to be gained, and a LOT to lose. Those new oils are for cars with real tight main bearings (which your bike doesn't have) and will PROMOTE bearing wear. The only time 0-30 oil is at 0 viscosity is when it's sitting in the oil pan, with the motor not running. As soon as you start the motor and the 0 viscosity oil gets jammed through the oil pump, with the friction of getting jammed through the oil pump gears, it heats up and is at 30 viscosity.
The ONLY time you want to change the viscosity from the recommended oil is when the starter strains to turn over the motor (and if it's THAT cold, you don't want to ride).
Does the bike have FRESH gas? Gas contains an emulsifier that makes it turn to mist easier. "Winter gas" has more. Your carb doesn't "vaporize" fuel as well in the cold, the mist of fuel condenses on any surface more readily in the cold... that's why we choke it. You still get big blobs of gas, but with the choke on, you get more blobs.
 
bitzz said:
Does the bike have FRESH gas? Gas contains an emulsifier that makes it turn to mist easier. "Winter gas" has more. Your carb doesn't "vaporize" fuel as well in the cold, the mist of fuel condenses on any surface more readily in the cold... that's why we choke it. You still get big blobs of gas, but with the choke on, you get more blobs.
Click to expand...
It has fresh gas, but I'm not sure the pumps here have switched to winter gas yet? That could make a difference.
I've had this 03 since 2008, and it's been an issue for at least the last ten years. Runs great in the heat, and acts up when it cools in the fall. I assumed it was just how it is, but then I got the 01, and it ran great throughout the winter with no issues. I only noticed the gas milage dropped some, but that's it.
I assumed that when I took the carbs from the 01 and put them on the 03, it would solve that issue, but now that the weather is cooling the bike is acting up, as explained, unlike the 01. I was just looking for other things to look into.
The winter gas could be it since last fall was pretty warm, and it's possible that the winter gas came to the pumps before the temperatures were cool enough to cause the bike to act up. It's something I can test.
 
Obvious first step is to check that things are within specifications - valve clearances being the first prime suspect, condition of spark plugs the second, float levels and idle-mixture-screw adjustments the next, and make sure the carburetors don't have any clogged jets, particularly the slow / pilot jets. Also make sure it hasn't got vacuum leaks (if you spray WD40 at the rubber boots between carbs and engine and "something changes" then you've got a leak). If it has a vacuum-operated fuel petcock valve, make sure that isn't leaking. ASSuming all that is OK ...

The symptoms that you describe are those of lean carburetion off the bottom. Bear in mind that the carburetion on your bike was probably set up based on non-ethanol fuel, and that is no longer available. 10% ethanol acts like 3% leaner jetting, and if it was on the bleeding edge but barely OK before, it may be just short of the bleeding edge now. This could be why you have a bike that used to run OK but now doesn't.

"things that are wrong" that can cause this: Vacuum leak, clogged slow jets, clogged idle mixture adjustment screw and passages, float level set too low.
"things that the manufacturer set up for emissions" that can cause this: Idle mixture adjustments set too lean, slow jet too lean, needle position on the vacuum slide set too far down (lean).

I gather that your situation involves hard cold starting and then it starts and runs OK after it's warmed up, and that points to idle mixture adjustment and slow jets. If it runs OK during warm-up with the choke on a little smidge, and pulls away from a stop decently when it's like this, that would point to the needle being in the ballpark. If it refuses to accept throttle with the choke on just enough to keep it idling, the needle is probably too lean.

So, the first step after ruling out "things that are wrong", is to establish what the idle mixture screws are supposed to be set to, and find out where they are set to now. If wrong, make them correct. If correct, turn them out half a turn further, and see if that makes a difference.

Fuel for idle flows through the pilot jets, and the idle mixture screws make less and less of a difference as you turn them out (and less and less difference as you open the throttle), so if this did not solve the problem, the next step is to find out what pilot jets are in there, first verify that they are not clogged and are the size as per original specifications, and then obtain some that are one size bigger. (Winners Circle in Toronto should be able to get them)
 
You mention corrosion being a concern. In the UK riders use ACF-50 ANTI-CORROSION spray and swear by its effectiveness.


fortnine.ca

ACF-50 Anti-Corrosion Lubricant Formula

ACF-50, Anti-Corrosion Formula, is a state of the art, anti-corrosion lubricant compound, specifically designed for the Aerospace Industry. It is an ultra Thin Fluid Compound (TFFC) that actively treats metal using advanced polar bonding technology. ACF-5
fortnine.ca fortnine.ca
 
ReSTored said:
You mention corrosion being a concern. In the UK riders use ACF-50 ANTI-CORROSION spray and swear by its effectiveness.


fortnine.ca

ACF-50 Anti-Corrosion Lubricant Formula

ACF-50, Anti-Corrosion Formula, is a state of the art, anti-corrosion lubricant compound, specifically designed for the Aerospace Industry. It is an ultra Thin Fluid Compound (TFFC) that actively treats metal using advanced polar bonding technology. ACF-5
fortnine.ca fortnine.ca
Click to expand...
I'll look into this. Thanks.
What I did though, in the spring after I discovered it, was clean it good then coated all the problem areas and bolt/screw heads with belt dressing. Belt dressing works great for battery posts to prevent corrosion. I was given this tip by an old-timer "Battery Doctor" 30 years ago, and I've been using it since.
 
Brian P said:
Obvious first step is to check that things are within specifications - valve clearances being the first prime suspect, condition of spark plugs the second, float levels and idle-mixture-screw adjustments the next, and make sure the carburetors don't have any clogged jets, particularly the slow / pilot jets. Also make sure it hasn't got vacuum leaks (if you spray WD40 at the rubber boots between carbs and engine and "something changes" then you've got a leak). If it has a vacuum-operated fuel petcock valve, make sure that isn't leaking. ASSuming all that is OK ...

The symptoms that you describe are those of lean carburetion off the bottom. Bear in mind that the carburetion on your bike was probably set up based on non-ethanol fuel, and that is no longer available. 10% ethanol acts like 3% leaner jetting, and if it was on the bleeding edge but barely OK before, it may be just short of the bleeding edge now. This could be why you have a bike that used to run OK but now doesn't.

"things that are wrong" that can cause this: Vacuum leak, clogged slow jets, clogged idle mixture adjustment screw and passages, float level set too low.
"things that the manufacturer set up for emissions" that can cause this: Idle mixture adjustments set too lean, slow jet too lean, needle position on the vacuum slide set too far down (lean).

I gather that your situation involves hard cold starting and then it starts and runs OK after it's warmed up, and that points to idle mixture adjustment and slow jets. If it runs OK during warm-up with the choke on a little smidge, and pulls away from a stop decently when it's like this, that would point to the needle being in the ballpark. If it refuses to accept throttle with the choke on just enough to keep it idling, the needle is probably too lean.

So, the first step after ruling out "things that are wrong", is to establish what the idle mixture screws are supposed to be set to, and find out where they are set to now. If wrong, make them correct. If correct, turn them out half a turn further, and see if that makes a difference.

Fuel for idle flows through the pilot jets, and the idle mixture screws make less and less of a difference as you turn them out (and less and less difference as you open the throttle), so if this did not solve the problem, the next step is to find out what pilot jets are in there, first verify that they are not clogged and are the size as per original specifications, and then obtain some that are one size bigger. (Winners Circle in Toronto should be able to get them)
Click to expand...
But he swapped the 01 carb onto the 03 and the 01 was running fine during the winter.
 
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